Other reactions

A few other special procedures are quoted elsewhere in this book Methods for preparing ozonides (pp. 406—409) and for formation of mercury(II)-acetate adducts of unsaturated lipids (p. 402) procedures for esterifying fatty acids with diazomethane (p. 175) and for acetylation of alcohols with acetic anhydride (p. 175). The procedures described for preparing trifluoroacetates or trimethylsilyl ethers can be applied to aliphatic alcohols. 

Detailed procedures can also be found in a recently published book [225]. 

Other Reactions.—A review on the preparative methods of acetal formation contains steroidal examples.62 Periodic acid was reported to be useful for regeneration of ketones from thioacetals.63 The reaction of lithium acetylide with the 14p-hydroxy-17-ketone (47) gave stereospecifically the 17 (3-hydroxy-compound (48) whereas the 

The full accounts71 of hydrocyanation of 3-oxo-Ax-steroids and analogues were reported,72 73 and a full account was available for the acid- and base-catalysed additions of thiols to 3-oxo-A1- and related steroids,74 75 and thiourea was observed to react with androst-l-en-3-ones to give the adduct (58). Reaction of 2-bromo-A1- 

Other Reactions.—Hofmann degradation of 5a-cholestan-4)8-yltrimethylammon-ium salts gives the Saytzeff (A ) product the large 4 -10)5-interaction gives the elimination El character, as found previously in the 6)S-derivative. The 4a-yl-trimethylammonium salt, like some other equatorial derivatives, suffers N-demethylation, with some elimination to give the ( Hofmann ) product.  

Aziridino-steroids (e.g. 486) are available by reduction of suitable iodo-azides with lithium aluminium hydride, but fewer side-reactions occur if the iodo-azide (484) is first treated with triphenylphosphine, or with a phosphite ester. Loss of nitrogen leads to the iV-phosphonium aziridine derivative (485), which is smoothly reduced by lithium aluminium hydride to give the aziridine. The exact mechanism of nitrogen loss in the first step is uncertain. 

Aziridino-substituents (487) have been obtained by cyclising 2 -hydroxy-ethylamino-steroids (488) with thionyl chloride, followed by alkali, or in a single step by reducing chloroacetamido-steroids (489) with aluminium hydride. 

Secondary nitro-steroids are smoothly reduced by chromium(ii) chloride, giving oximes by isomerisation of intermediate nitroso-derivatives.  

The configurations, conformations, chiroptic properties, and pyrolytic elimination reactions of steroidal sulphoxides and sulphinates, at C-3, C-6, and C-7, have been studied in detail. In general, though not without exception, the direction of elimination is controlled by the configuration at the sulphur atom, whenever two possibilities exist for the essential syn mechanism. The favoured 

Other Reactions.—Becker et have shown that prolonged u.v. irradiation of hydrogen sulphide or methanethiol mixed with methane, ethane, water, and ammonia produces ethanol, organic acids, amines, and amino-acids. The quantum 

Some information on the effect of translational energy on the reactions of photochemically generated atoms other than hydrogen has appeared. The cross-section of reaction (87) decreases with increasing energy, so that chlorine atoms of initial energy 58 kJ mol produced by photolysis of CU at 337 nm react with HI faster after thermalization.  

Other Reactions. A synthesis of 3-deoxy-A-homovitamin D3 has been reported which involved treatment of 5a-cholest-6-en-3-one with diazomethane to give a mixture of the A-homoketones. In contrast to the behaviour of diazomethane, diazocyclopropane reacts with A -3-oxosteroids to give ring-expanded products in the absence of Lewis acid catalysts.  

A useful ring-expansion reaction involves addition of dichlorocarbene to cyclic enol ethers and treatment of the resulting alkoxydichlorocyclopropanes with methyl-lithium and tetramethylethylene diamine followed by an acidic work-up thus 1-ethoxy-cyclododecene gave a mixture of E- and Z-isomers of 3-methylcyclotridec-2-en-l-one. The suggested mechanism involves elimination of hydrogen chloride from 

Hiyama T. Mishima, K. Kitatani, and H. Nozaki, Tetrahedron Letters, 1974, 3297. 

5- dihydroanisole or its 3-methyl derivative, was boiled with pyridine, the pyridinium salt (78 R = H or Me) was formed, possibly ria cycloheptadiene (79 R = HorMe).  

Silver nitrate-catalysed rearrangements in methanol of dibromocyclopropyl propellanes have been examined. For example, (80 R = Br) gave a mixture of the corresponding methyl ketal (80 R = OMe) and bicyclo[5,4,0]undec-l(7)-en-2-one, together with minor products. One step in a reported synthesis of 1,7-methano-[12]annulene involved addition of dibromocarbene to tricyclo[4,4,l,0 ]undeca-3,8-diene (81) followed by silver acetate-catalysed ring-opening of the resultant bis-dibromocarbene adduct to give a mixture of isomeric acetates.  

Other reactions include acylation [169-171], amination and imination [172-176], halogenation [177-179], silylation [180,181], and carbonylation [182], as shown in Eqs. (7.85)-(7.89), respectively. 

Omae I (1986) Oiganometallic intramolecular-coordination compounds, J Organomet Chem Library 18. Elsevier, Amsterdam 

Omae I (1998) Applications of organometaUic compounds. WUey, NewYork 

Padilla R, Salazar V, Paneque M, Alvarado-Rodrtguez JG, Tamariz J, Pacheco-Cuvas H, Vattier F (2010) Organometeillics 29 2835 

Other Reactions. The conversion of 4-aminoisothiazoles into 4-acyl-l,2,3-thiadiazoles is described in the chapter dealing with the former ring system (see p. 569). 

The oxidation of 2-hydrazono-iVAriV 7V -tetramethylthio-oxamide (12) by various reagents does not yield the expected 4,5-bis(dimethylamino)- 

Properties.—The mass spectra of a number of mono- and di-substituted 

3- thiadiazoles have been discussed in detail. The elimination of a molecule of nitrogen from the molecular ion usually precedes any fragmentation involving substituents. The behaviour of 1,2,3-thiadiazoles under 

In a preliminary report, the photolysis of 1,2,3-thiadiazoles (16) has been outlined. It proceeds with quantitative elimination of nitrogen and dimerization, with loss or uptake of sulphur, to yield main products such as (18 CIS and trans), (19), and (20), as well as others formed in smaller yields. The observations are accountable in terms of the initial formation of the reactive 1,3-diradical (17).  

Other Reactions, The allyl Grignard reagent (601) cyclizes on heating by a Cope-like transition state. The product after hydrolysis is predominantly the c/j-cyclopentyl-olefin (602), and a m-cyclopentane (603) is also obtained in the ene rearrangement of the corresponding diene. A non-cyclic mechanism is known to operate in intermolecular addition where intramolecular electrophilic assistance is available in the olefin, e.g, (604).  

A search for an ionic Cope rearrangement has included (608). A concerted mechanism can only interchange (608) and (609), whereas (610) may intrude if ions (radicals) are involved. In fact, (610) is the product, and the absence of chemically induced dynamic nuclear polarization (CIDNP) effects together with trapping of the intermediate carbonium ion with borohydride as anethole support an ionic mechanism.  

Fclkin, J. D. Umpleby, E. Hagaman, and E. Wenkert, Tetrahedron Letters, 1972, 

The kinetics of the Cope rearrangement have been measured using 1,1-dideuteriohexa-1,5-diene and the possibility of a boat transition state in the Cope rearrangement of hexa-1,5-diene has bwn examined. Trifluoromethanesulphonates (triflates) have been used to study the stereochemistry of solvolytic displacement at unsaturated (vinyl sp ) carbon. Solvolysis of the (Z)- and ( -triflates (611) and (612) in trifluorethanol gives rise to dissimilar ratios of products (613) and (614) a greater proportion of (613) is formed from (611) than from (612). The resultsarebestaccommodated 

Two of the important mechanisms of nucleophilic vinylic substitution of a leaving group X by a nucleophile Nu are the nucleophilic addition-elimination route and the S nI route. Other routes such as the elimination- 

Other Reactions. A report describing the reduction of a variety of functionalized aldehydes to the corresponding alcohols by 5-siamyl-9-borabiorclo[3,3,l]nonane 

Oxidation of trialkylboranes with MoOgjHMPA followed by hydrolysis has been reported to give alcohols in 73—78 % yields, while oxidation of organo-boranes derived from cyclic alkenes with an excess of pyridinium chlorochromate provided ketones in yields of 81—92%,  

The reagent 5-bromo-9-borabicyclo[3,3,l]nonane has been used to cleave a variety of ethers of representative structural types.  

The electrochemical reaction of organoboranes in the presence of propenoic acid esters has been reported to be a convenient synthesis of carboxylic esters while with acetone, trialkylboranes react electrochemically to yield dioxaboro-lanes (6) and dioxaborinanes (7) [reaction (3)]. The first direct synthesis of carboxylic acids from organoboranes has been published and involved the reaction of trialkylboranes and the dianion of phenoxyacetic acid in THF [reaction (4)].  

Takahashi, K. Yuasa, M. Tokuda, M. Itoh, and A. Suzuki, Bull. Chem. Soc. Japan, 1978,51, 339. 

Other Reactions.—An Indian group have investigated three means of effecting hydroxylation of unsaturated acids sulphation and hydrolysis, autoxidation and reduction, and allylic bromination (A-bromosuccinimide) and hydrolysis. French chemists have prepared and examined some mono-and di-oxo-enoic acids. They find that unsaturated 1,4-dioxo-acids rearrange spontaneously to 1,2-dioxo-isomers  

12-Oxostearic acid has been converted to 12-aminostearic acid by reductive amination.  

The possibility that fatty acids should react preferentially at the co-position when the acid molecules are suitably oriented in a packed layer has been examined with chlorine atoms and with ethyl radicals, with partial success. For example, chlorination of octanoic acid usually gives all possible mono-chloro-octanoic acids but in the presence of alumina, on which the fatty acid is adsorbed and aligned, the content of the 2- to 5-chloro-octanoic acids 

separation of cis- and /m/w-epoxy-esters forms the basis of a new procedure for determining the proportion of cis- and tra/w-isomers in a mixture. The report that w-chloroperbenzoic acid can be used at 90 without decomposition in the presence of suitable radical inhibitors may be of value when epoxidizing alkenes of reduced reactivity. Several fluorostearic acids have been prepared by interaction of mesyloxy-acids with tetrabutyl-ammonium fluoride in acetonitrile. A procedure for methylation (by diazomethane in the presence of boron trifluoride) and demethylation (by reaction with sodium borohydride and iodine, followed by methanol), with retention of optical activity, could prove useful in the synthesis of compounds of known configuration.  

Isopropenyl esters, conveniently prepared from carboxylic acids and propyne in the presence of the zinc salt, readily effect the acylation of ise-thionic acid and of A-methyltaurine.  

Other Reactions.— The compounds [PtX(CNMe)(PR3)2]+X can be demethylated by refluxing in benzene suspension this is the reverse of the standard alkylation of metal cyanides. The mechanism suggested, on somewhat meagre evidence, is halide attack at the platinum to give a five-co-ordinate intermediate which can eliminate methyl halide. Reaction of /ranj-[Pt(mesityl)(SnCls)(PEta)2] with nucleophiles, in 1,2-dichloroethane solution, proceeds by attack of the nucleophile at the tin rather than at the platinum.  

The autoxidation of CoCl2(PEt3)a to CoCla(P OEt s)a, which occurs in several solvents, is initially first-order in complex and first-order in molecular oxygen. Failure to detect any compounds 0=PR (0R)3 amongst the product contra-indicates a dissociative mechanism a cobalt-molecular oxygen complex is the suggested intermediate.  

Oxygen exchange with mixed chromium(m)-oxalate complexes [Cr(ox)(LL)2]+ has been described.  

The remarkable capacity of ionophores of low molecular weight, such as valinomycin, to render biological and artificial membranes selectively 

Mildvan and M. Cohn in Advances in Enzymology , Wiley-Interscience, New York, 1970, vol. 33, p. 1. 

Other Reactions.—As in the case of quaternary ion PTC, several different types of reaction are catalysed by complexing agents such as crown ethers, in both the liquid-liquid and solid-liquid mode of operation. Among these are metal boro-hydride reductions of ketones, permanganate oxidation of alkenes in non-polar solvents (hence purple benzene ) and cyanide-mediated benzoin condensations (Equation 13).  

Wittig reactions (Equation 3) in non-polar media can be initiated by solid-liquid phase transfer of potassium carbonate or t-butoxide with 18-crown-6. Typical salt-free product distributions (Z-disubstituted alkene predominant) are observed with non-stabilized ylidcs in THF, but they are surprisingly reversed in dichloro-methane solution. -Alkenes usually predominate in both solvents when stabilized ylides are involved. Two-phase Wittig-Horner syntheses of ajS-unsaturated sulphides etc. (Equation 5) are also crown-catalysed, as is the Darzens-type process (Equation 14).  

Several reports of the use of crown-solubilized superoxide anion radical (see earlier) as an oxidizing agent have appeared. 

Rosenthal and A. Frimer, Tetrahedron Letters, 1976, 2805 Y. Moro-Oka, P. J. Chung, 

Other Reactions. l,2-Dibromo-3,3,6,6-tetramethylcyclohexene reacts with sodium in ether to give (51a) as a major product, possibly via (51b). There may be some analogy with an uncharacterized dimer previously reported for 3,3,7,7-tetramethylcycloheptyne.  

The preparation of l,6-dimethylcyclohepta-l,3,5-triene by bromination-dehydrobromination of l,6-dimethylbicyclo[4,l,0]hept-3-ene is described.  

Formolysis of cis-bicyclo[4,l,0]hept-3-yl tosylate followed by reduction gives cyclohept-3-enol as the major (63 %) product. The preparation of 4-chlorocycloheptene from cis-bicyclo[4,l,0]heptan-2-ol is also discussed.  

The acid-catalysed ring expansion of cis-thujopsene to (52) and the rearrangement to (53) are discussed. Hydrochlorination of thujopsene gives (54).  

Formolysis of (55) gives 2-hydroxycycloheptanone. Silver-ion-promoted ring expansion of 7,7-dibromobicyclo [4,1,0] heptane gives largely the expected 

Other Reactions.—A method which has been particularly stressed by Russian workers, e.g. Flerov et al., and which bears a superficial resemblance to the above, is what might be called the prompt fission reaction. Here two heavy nuclei are caused to fuse, giving transiently a very large mass which undergoes prompt fission to give a wide spectrum of products, including, it is hoped, some superheavy nuclei. 

The reasoning is based on an extrapolation from results on heavy-ion fission yields by Karamyan et who find that on increasing the mass of the 

Other Reactions.—Further examples of condensation of a 5-methylene group in thiazolidines with aldehydes have been reported. 3-Aryl-2-arylimino- 

Methyl 3-methyl-2-methylenethiazoIidine-a-dithiocarboxylate (106) reacts with dimethyl acetylenedicarboxylate to give the spiro(thiazolidine cyclopentadiene) (107), whilst o-aminobenzenethiol reacts with 3-substituted 5-methoxycarbonyl-methylene-2-oxo-(or thioxo-)thiazolidin-4-ones to give compounds (108 X = O 

Some minor reactions of quinoxaline A -oxides are illustrated in the following classified examples. 

The A-oxide tautomer, l-hydroxy-5,6,7,8-tetrahydro-2(l//)-quinoxalinone (284) gave l-benzyloxy-5,6,7,8-tetrahydro-2(l//)-quinoxalinone (285) (PhCH2Cl, 

2-Methylquinoxalme 4-oxide (287) gave an isolable amount of either 2-hydroxy-2-methyl-2,3-dihydro-3-indolecarbaldehyde (286) hv, H2O %) or 2-methyl-3,l,5-benzoxadiazepine (288) hv, CeHi2 %), in each case accompanied by other products related substrates behaved somewhat similarly.  

2-(A( -p-Bromobenzylidene-A-meihylhydrazino)-6-chloroquinoxaline 4-oxide (289) gave dimethyl 4-(A( -p-bromobenzylidene-A(-methylhydrazino)-8-chloro-3a//-isoxazolo[2,3-fl]quinoxaline-2,3-dicarboxylate (290) [Me02CC = CC02Me (1 mol), dioxane, reflux, 2 h 95%].  

Likewise, 6-chloro-2-piperidinoquinoxaline 4-oxide (291) gave dimethyl 8-chloro-4-piperidino-3 a//-isoxazolo [2,3 -a] quinoxaline-2,3 -dicarboxylate (292) 

For reaction other than first order, the reaction probability depends on the time that a molecule has been in the reactor and on the concentration of other molecules encountered during that time. The residence time distribution does not allow a unique estimate of the extent of reaction, but some limits can be found. 

The molecules in the system are carried along by the balls and will also have an exponential distribution of residence time, but they are far from perfectly mixed. Molecules that entered together stay together, and the only time they mix with other molecules is at the reactor outlet. The composition within each ball evolves with time spent in the system as though the ball was a small batch reactor. The exit concentration within a ball is the same as that in a batch reactor after reaction time tf,. 

We have just described a completely segregated stirred tank reactor. It is one of the ideal flow reactors discussed in Section 1.4. It has an exponential distribution of residence times but a reaction environment that is very different from that within a perfectly mixed stirred tank. 

FIGURE 15.12 An arbitrary residence time distribution modeled as PFRs in parallel. 

Example 15.12 Find the outlet concentration from a completely segregated stirred tank for a first-order reaction. Repeat for a second-order reaction with = —kcp-. 

For a second-order reaction, abatch(0 = a J( + ajit), and Equation 15.47 gives 

The condensation reactions between alcohol and carboxylic acid over acidic catalysts are thermodynamically reversible with water formed as by-product  

In MRs, liquid reactants are fed to one side of the membrane while vacuum is applied to the other side (pervaporation operation). Water permeates preferentially through the membrane and evaporates at the vacuum side, driving the esterification reaction toward the product side with the result of enhanced product yields. Beneficial aspects of pervaporation also include low energy consumption and the possibility of selecting the reaction temperature. 

Some typical dehydration reactions performed in porous MRs with improved product yield are summarized in Table 2.11. 

The decomposition of VOCs in contaminated air stream or flue gas by catalytic or photocatalytic oxidation represents a typical application of 

Examples of these reactions are listed in Table 12 and are discussed below. 

Li (dt) Li, Li (dHe ) He These reactions have been observed [32] the ground state groups are wide and both Li and He break up in the second stage of the reaction. 

The excitation function for the production of tritium by the reaction JA [dt) was followed by Macklin and Banta from 0.4 to 4.0 MeV. The tritium was recovered and estimated by counting beta disintegrations in a proportional counter. 

Be (dt) Be (dHe ) Li The [dt) reaction to the ground state of Be has long been known the absolute cross section was measured for a range of 

Burcham Nuclear Reactions, Levels, and Spectra of Light Nuclei. Sect. 53- 

In this section, original reactions catalyzed by rhodium or ruthenium nanoparticles in various media are reported. Traditionally, these reactions were carried out in homogeneous or heterogeneous approaches. 

Among other characteristic reactions of nitrocellulose worthy of notice is the transesterification of cellulose nitrate performed by means of acetic anhydride. In this way cellulose mononitro-diacetate was obtained (Berl and Smith [58]). 

Clement and Riviere [59] also reported that cellulose acetate or a mixed ester — a nitrate-acetate — can be obtained by reacting cellulose nitrate with acetic anhydride, acetic acid, and sulphuric acid. According to more recent contributions, e.g. Wolfrom, Bower and Maker [60], the reaction should be performed as follows Cellulose nitrate is dissolved in the cold in a little sulphuric add and acetic anhydride, the surplus of acetic anhydride is then hydrolysed also in the cold, and cellulose acetate is extracted with a suitable solvent, such as chloroform. Other methods of acetylating nitrocellulose consist in reduction, for instance with zinc and hydrogen chloride, which entails denitration of the ester, followed by acetylation with acetic anhydride. All these reactions are carried out in the same vessel. Further, it is possible to synthesize mixed esters, cellulose nitrate-acetates, by subjecting cellulose to the action of a mixture that includes nitric acid, acetic add and acetic anhydride in the presence of sulphuric acid (Kruger [61]). The use of a large amount of nitric acid favours the formation of nitrocellulose only. Mixed esters are formed 

Animation of cellulose is a relatively new reaction (Scherer and Feildt [63]). It occurs if nitrocellulose in liquid ammonia is exposed to the action of sodium or potassium amide, according to the equation  

Only half the nitrate groups present in cellulose dinitrate is substituted by amine groups, the other half undergoing hydrolysis. 

Aminocellulose is a reddish-yellow hygroscopic powder that dissolves readily in water. It can be diazotized and coupled with phenols to yield reddish dyes. 

Various other radiation-induced reactions have been studied for potential use in the industry on a pilot-plant scale. Among these may be mentioned hydrocarbon cracking (i.e., production of lower-molecular-weight hydrocarbons from higher-molecular-weight material), isomerization of organic molecules, and synthesis of labeled compounds with radioactive nuclei. When organic compounds are irradiated in the pure state or in aqueous solution, dimeric 

Furthermore, a vast number of organometallic catalyzed reactions can be performed in a biphasic manner thus proving that also uncommon reactions may be worth to be investigated in liquid/liquid systems. For instance, Braddock describes the atom economic nitration of aromatics in a two-phase process [192], Nitration of aromatics leads usually to excessive acid waste streams and the classical Lewis acid catalysts such as boron trifluoride are destroyed in the aqueous quench after the reaction thus making any recycle impossible. In the method of Braddock the ytterbium triflate catalyst is solved in the aqueous phase and can be recycled by a simple evaporative process. Monflier and Mortreux [193] investigated the nickel catalyzed isomerization of olefins, for instance allylbenzene, in a two phase system yielding good yields of cis- and trans-methylstyrene. 

Hydrodehalogenation of aliphatic or benzylic halides were catalyzed by water soluble ruthenium phosphine complexes in the presence of sodium formate as hydrogen donor [194], Hydroxycarbonylations could also be performed with high palladium catalyst activities in biphasic systems [195-197]. 

The concept of biphasic catalysis requires that the catalyst and product phases separate rapidly to achieve a practical approach to the recovery and recycling of the catalyst. It is obvious that simple aqueous/hydrocarbon systems form two phases under nearly all operating conditions and thus provide rapid product-catalyst separation. Ultimately, however, the application of water-soluble catalysts is limited to low-molecular-mass substrates which have appreciable water-solubility. The problem is illustrated by the data in Table 1, which gives the solubility of some simple alkenes in water at room temperature [1], Although hydrocarbon (alkene)-solubility in water increases at higher temperature, most alkenes do not have sufficient solubility to give practical reaction rates in catalytic applications. The addition of salts further decreases the solubility of hydrocarbons in water. Substrate solubility in water is a significant issue and it is no accident that so-far the practiced and proposed commercial applications of water-soluble catalysts for hydroformylation are limited to propene and butene. 

The addition of co-solvents to the aqueous phase has been investigated extensively as a means of improving the solubility of higher olefin substrates in the cat- 

Aqueous-Phase Organometallic Catalysis, Second Edition 

Mukaiyama aldol reaction using chiral Sn(II) Lewis acids and other utilities have been previously reviewed in some articles [69]. 

The stoichiometric transfer of allenylidene ligands from one metal fragment to another metal center has been scarcely documented, the only examples known involving the allenylidene transfer from chromium compounds [Cr(=C=C= CR R )(C0)5] (R R = aryl, amino or alkoxy groups) to [W(C0)5(THF)] [9d]. DFT calculations indicate that the reaction proceeds by an associative pathway, the initial reaction step involving the coordination of W(CO)5 to the Cc(=Cp bond of the allenylidene ligand in the chromium precursor. 

Cationic allenylidene complexes containing a hydrogen atom in the 6 position, that is, [M] =C=C=C(R )CHR R, are known to undergo deprotonation processes upon treatment with bases affording neutral 0-enynyl derivatives [M]-C=CC(R )= CR R. Representative examples include deprotonation of [Ru(t] -C9H7)(=C= 

In addition to the reactions discussed above, there are still other alkyne reactions carried out in aqueous media. Examples include the Pseudomonas cepacia lipase-catalyzed hydrolysis of propargyMc acetate in an acetone-water solvent system, the mthenium-catalyzed cycloisomerization-oxidation of propargyl alcohols in DMF-water, an intramolecular allylindination of terminal alkyne in THF-water, and alkyne polymerization catalyzed by late-transition metals. 

Brandsma, L., in Preparative Acetylenic Chemistry, Heus-Kloos, Y. A., Van Der Heiden, R., Verkrnijsse, H. D., eds., 2nd ed. Elsevier, New York, 1988 Brandsma, L., Vasilevsky, S. F., Verkruijsse, H. D., Application of Transition Metal Catalysts in Organic Synthesis. Springer-Verlag New York, 1999. 

Sonogashira, K., in Handbook of Organopalladium Chemistry for Organic Synthesis, Negishi, E., ed. Wiley, Hoboken, 2002, p. 493. 

Vlassa, M., Ciocan-Tarta, L, Margineanu, F., Oprean, I., Tetrahedron 

Chodkiewicz, W., Ann. Chim. (Paris) 1957, 2, 819 Chodkiewicz, W., Cadiot, P., Corpt. Rend. Hebd. Seances Acad. Sci. 1955, 241, 1055. 

In addition to the methods previously described in this chapter, there are numerous other ways to make aldehydes and ketones, depending on the stcirting materials. These include using alkynes, doing a Friedel-Crtifts acylation of an acid chloride and an aromatic compound, using organic nitriles, and the use of carboxylic acid. We examine each of these in the following sections. 

Creating ketones Mo Wags With organic nitriles 

The preparation of acetophenone from benzene and acetyl chloride. 

Using a Grignard reagent to convert a nitrile to a ketone. 

A partial mechanism forthe conversion of an alkyl halide to a nitrile, which reacts to form a ketone with a Grignard reagent. 

While the hydrolysis of N205 is believed to represent its major loss process, there are other possibilities that have potentially interesting implications under certain conditions. For example, N2Os reacts with the components of sea salt particles such as NaCl, NaBr, and Nal to form nitryl chloride, nitryl bromide, and nitryl iodide, respectively (e.g., Finlayson-Pitts et al., 1989a, 1989b Behnke and Zetzsch, 1990 Zetzsch and Behnke, 1992 Junkermann and Ibusuki, 1992 George et al., 1994 Behnke et al., 1994, 1997 Leu et al., 1995 Fenter et al., 1996 Barnes et al., 1991 Schweitzer et al., 1998)  

Besides the reactions already discussed, the application of water can be found in a number of other reactions, which can only be briefly mentioned because of the limited format of this review. 

Reduction under WGSR conditions can be accompanied by cyclizations, as in the following example of the formation of indoles and quinolines from readily available o-nitrochalcones [177]  

Water is so extensively used in catalytic oxidation reactions that usually this fact is regarded as a natural feature and remains unnoticed. Wacker oxidation of olefins by palladium complexes involves water as a nucleophilic reagent, and thus the whole Wacker-type chemistry, which has developed into a powerful and versatile method of organic synthesis, is derived from aqueous catalysis [178]. The role of the nature of the co-oxidant and the mechanism of deactivation of the palladium catalyst due to aggregation and growth of inactive metal particles were recently investigated, and such study may have relevance for other processes catalyzed by phosphine-less palladium catalysts [179]. 

Catalytic epoxidation of olefins in systems containing metal catalyst and stoichiometric oxidant is often carried out in the presence of water. Water is often present in such systems just because some of the most popular stoichio- 

Other types of oxidative processes include the activation of saturated CH bonds. Such processes are especially interesting, from the practical point of view of processing the hydrocarbons from oil refining, and because such processes can occur in living organisms, and thus are definitely catalyzed by transition-metal complexes in aqueous environments. Among recent work on the development of model systems for such a purpose is the following. Water-soluble Ru(lll)-EDTA complexes are usable for activation of C(sp H bonds, e.g. in the oxidation of adamantane to a mixture of 1- and 2-adaman-tanols and adamantanone [184]. 

Numerous intercalation reactions are known in which one reactant enters the lattice of the other. Such behaviour is conveniently illustrated by reference to two recent studies. Lithium undergoes a low temperature (298 K) topochemical reversible reaction with transition metal compounds (e.g. TiS2, NbSe3) [1211] in which the host lattice structure may be partially retained (e.g. in Li TiS2, LijNbSe3). The reaction [1212] 

Electrophilic radicals, such as halogen atoms, hydroxy, alkoxy, and amino radicals, do not seem to have great value in reactions with heterocyclic compounds. 

Heteroaromatics very reactive toward electrophilic species, such as furan and pyrrole, are not suitable for homolytic aminations owing to their low stability under the reaction conditions. Thiophene, however, can be aminated, leading to 2-dialkylamino derivatives.  

Minisci, R. Galli, and M. Cecere, Oazz. Chim. Ital. 94, 67 (1964). 

In the presence of azide ions the alkoxyazido derivative was obtained [Eq. (55)]. 

The reaction of furan with benzoyl peroxide gave in good yield the cis- and rans-2,5-dibenzoyloxy-2,5-dihydrofuran. ° Analogously, the electrolysis of sodium acetate in the presence of furan gave 2,5-diacetoxy- 

Chain polymerisation necessarily involves the three steps of initiation, propagation, and termination, but the reactivity of the free radicals is such that other processes can also occur during polymerisation. The major one is known as chain transfer and occurs when the reactivity of the free radical is transferred to another species which in principle is capable of continuing the chain reaction. This chain transfer reaction thus stops the polymer molecule from growing further without at the same time quenching the radical centre. 

Typical chain transfer reactions involve the abstraction of an atom from a neutral saturated molecule, which may be solvent or a chain transfer agent added to the polymerisation mixture specifically to control the final size and distribution of molar masses in the polymer product. The chain transfer reaction may be represented as in Reaction 2.7. 

The newly generated free radical is then free to react with a molecule of monomer and thus lead to the establishment of a new polymer molecule. 

Other chain transfer processes may occur. For example, the radical may abstract an atom from along the backbone of a previously formed polymer molecule, and thus initiate the growth of a branch to the main chain. There can also be chain transfer to monomer, which in the nature of the polymerisation process must be a relatively rare phenomenon. However, it can occur infrequently and give rise to a restriction in the size of the polymer molecules without ceasing the overall radical chain reaction. 

The reactions mentioned so far all take place with the generation of a free radical of high reactivity which is capable of sustaining the chain reaction. 

This finding was followed by a comprehensive preparative, structural characterisation and kinetics study of the conversions typified by the reaction above.268 These reactions were accorded the term metal exchange reactions. The heterobimetallic complexes with a, n bridging thiophene or selenophene ligands (ij 1 ij5-XCRCHCHCMn(CO)5)Cr(CO)3 (X = S, R = H (1) R = Me (2) X = Se, R = H 

It was also noted that of the metal exchange reactions investigated the thermodynamically favoured product was always less polar than the starting material. 

Reactions of this type are postulated as equilibria in synthetically important insertion reactions of alkenes, alkynes and other unsaturated molecules into the Pd-C bonds of dimeric palladacycles.271,272 Further, this reaction can form the basis for 

Besides the H-I-H2 reaction, the F-I-H2 reaction is the most investigated system [74, 170]. For other reactions like Ne-I-Hj or N+H2, detailed investigations have been performed most recently. Results of different hyperspherical applications are presented by Nakamura in [69], and the influence of spin-orbit effects in reactions has been studied in the work of Schatz et al. [171]. 

It should be clear from the preceding sections that there are now a variety of exact ways to solve the Schrodinger equation for three dimensional atom-diatom reactions. 

At present the two leading approaches to quantum reactive scattering are hyperspherical coordinate methods, and variational methods based on the 

Several other important problems also await detailed theoretical formulations and efficient three dimensional numerical implementations. These in- 

We have mostly talked about triatomic reactions. For further information on four-atomic and polyatomic systems the reader is referred to the work presented in [69, 79, 172, 173] and the special issues in Physical Chemistry Chemical Physics (1999), Faraday Discussion 110 (1998) and Faraday Transactions Vol. 93 (1997). 

The successful demonstration of the fluorous biphasic concept for performing organometallic catalysis sparked extensive interest in the methodology and it has subsequently been applied to a wide variety of catalytic reactions, including hydrogenation [59], Heck and Suzuki couplings [60, 61] and polymerizations [62]. The publication of a special Symposium in print devoted to the subject [63] attests to the broad interest in this area. 

Fluorous solvents would seem to be particularly suitable for performing aerobic oxidations, based on the high solubility of oxygen in fluorocarbons, a prop- 

Catalytic oxidations with hydrogen peroxide have also been performed in fluorous media (Fig. 7.19) [67]. 

Oxidative addition of methyl iodide to [Ir(cod)(phen)] proceeds by two competing routes, both involving five-coordinate intermediates. The preferred pathway is coordination of 1 to form [IrI(cod)(phen)], hence the reaction is catalyzed by free I. The other route is electrophilic attack of CH3. The comparison with oxygen oxidation, which also preferentially proceeds through this five-coordinate iodide adduct, is interesting. 

The reactions of equation (35) were examined by O nmr spectroscopy and T-jump methods to explore the relationship between square-planar. 

Substitution Reactions of Inert Metal Complexes— Coordination Numbers 6 and Above Chromium 

This review covers the period between the end of the previous report and literature available up to July 1982. Two reviews have appeared, one dealing with chromium coordination chemistry, and a second concerning attempts to distinguish between D and Id mechanisms.  

4-Dihydroisoquinolines, e.g. (484), are basic and form quaternary salts, e.g. (521). With alkali these salts form carbinolamine pseudo-bases, e.g. cotamine (522 Y = OH), which can be oxidized to lactams or which disproportionate on standing. The quaternary ions can also react with other nucleophilic reagents, e.g. (521) + RMgBr — (522 Y = R) (521) + MeCOMe — (522 Y = CH2COMe) (521) + CN — (522 Y = CN) (521) + RNH2 —+ (522 Y = NHR). The pseudo-bases are in equilibrium with open-chain compounds since aldehyde derivatives can be prepared. 

Reduction of dihydro compounds to the tetra- or hexa-hydro derivatives is usually possible. For example, dihydroisoquinolines of type (484) form the corresponding tetrahydroisoquinolines with H2/Pd or with Na/Hg-EtOH. 

C-Styrylpyridines undergo photocyclization to give azaphenanthrenes, and Y-styrylpyridinium cation forms an azoniaophenanthrene (523 — 524). 

The only species present in an aqueous solution of D-fructose absorbing and undergoing photolysis at 254. nm is the open-chain form. Its primary fragmentation involves carbon-carbon bond cleavage to the carbonyl group. Products are formed from the subsequent disproportionation and combination reactions or from 

Addition of furfural inhibits the reaction of aldoses with ampicillin due to the formation of a Schiffs base which cannot attack the -lactam carbonyl group. 

The degradation of o -D-glucose at 419K initiated by irradiation at doses of 2-10 Mrad proceeds by a chain mechanism to yield carbonyl compounds. A study of the effect of nitrates, phosphites, chlorides, and sulphates of polyvalent cations on the rate of degradation of D-glucose by sulphur dioxide solution (simulating the pulping process of wood) has shown that they all 

Schaum, and G.Simon, Z. Naturforsch., Anorg. Chem., 

Ishizaki, H.Kato, and M.Goto, Nippon Kagaku Kaishi. 1982, 

The presence of two types of catalytic centers (e.g., oxidative and reductive) in the same material can give rise to the possibility of multi-step photocatalysis in a one-pot procedure. C-C coupling, for example, is a field of great interest and a recent very good review was published [221]. C-N coupling reactions are also of interest. 

The thermolysis of sucrose in DMSO has been shown to yield a fructofuranosyl carbonium ion and a-D- lucose, which subsequently anomerizes. If the latter is generated in the presence of benzyl alcohol, benzyl o - and 3-fructofuranosides result. The carbonium ion was thought to be the precursor for the formation of 2,6-anhydrofructofuranose in thermolysis reactions of sucrose. 

An examination of the role of anthraquinone in alkaline wood-pulping processes has been carried out using cellobiose, glucose, and glycoaldehyde as model substrates. Each gave a wide range of acid products. 

The terpene menthol is widely used in organic synthesis, and serves as a chiral auxiliary for several asymmetric reactions [39]. (-)-Menthol 53 could be produced in one step from isopulegol 55 by hydrogenation of the carbon-carbon double bond, and the latter compound could be prepared by a Lewis acid-induced carbonyl-ene reaction [40] of f-(y )-citronellal 54. Nakatani and Kawashima examined that the ene cyclization of citronellal to isopulegol with several Lewis acids in benzene (Sch. 22) [41]. The zinc reagents were far superior to other Lewis acids for obtaining 

Yamamoto et al. [42] reported a highly enantioselective ene cyclization with a chiral zinc reagent as Lewis acid catalyst. Cyclization of 3-methylcitronellal 57 by at least 3 equiv. catalyst prepared in-situ from (i )-l,T-bi-2-naphthol (BINOL) 58 and Mc2Zn afforded the frans-cyclohexanol 59 in 86 % yield with 88 % ee as the sole product (Sch. 23). Reducing the amounts of the chiral zinc catalyst reduced both the chemical yield and the enantioselectivity. 

The system was also applicable to the cyclization of citronellal 54. Treatment of (f )- and (5)-citronellal with the chiral zinc reagent derived from (/ )- and (5)-BINOL 58 afforded the exclusive formation of /- and d-isopulegol 55, respectively. The asymmetric induction is totally controlled by the C-3 chiral center on the substrates and is independent of the chirality of the BINOL. 

The Simmons-Smith reaction is an efficient and powerful method for synthesizing cyclopropanes from alkenes [43]. Allylic alcohols are reactive and widely used as substrates, whereas a,j8-unsaturated carbonyl compounds are unreactive. In 1988, Ambler and Davies [44] reported the electrophilic addition of methylene to a,/3-unsaturated acyl ligands attached to the chiral-at-metal iron complex. The reaction of the racemic iron complex 60 with diethylzinc and diiodomethane in the presence of ZnCl2 afforded the c/s-cyclopropane derivatives 61a and 61b in 93 % yield in 24 1 ratio (Sch. 24). 

ZnCIa (4 equiv) EtaZn (1.5 equiv) CH2I2 (4 equiv) toluene 20 °C (93%) 

Kharasch et al. proposed the mechanism shown in Eqs. (39) to (42) to account for the formation of 4-(a-benzoxybenzyl) pyridine 

The decomposition of di- e -butyl peroxide in the presence of diethyl phosphite and an aromatic substrate leads to free-radical phosphination, Eqs. (43) and (44). 

Dibenzofuran and carbazole gave yields of 69 and 80%, respectively, of the phosphinated derivative, but the position of substitution was not determined.  

The reaction of 2,6-di-tert-butylpyridine with SO3 at elevated temperatures gives (43) in addition to the 3-sulfonic acid.  

The intramolecular attack on the alkyl side chain is suggestive of a free-radical process. 

The following unusual cyclization took place by the reaction of p-benzoquinone coordinated by palladium with two moles of butadiene at 60°C to give the tricyclic compound, 128 (117). 

A comparison of the kinetics of alkaline hydrolysis of methyl, isopropyl and butyl acetates in propan-2-ol-water and t-butanol-water has revealed that the observed effects correlate with solvent structure.  

Tetracyanoethylene (TCNE) has been shown to be a mild catalyst, which possessed some stereoselectivity, for the hydrolysis of the esters of steroidal alcohols. For example, 3/3, b/S-diacetoxy-Sa-hydroxyandrostan-n-one (12a), when treated with TCNE in toluene-methanol (1 1) at 50 °C for 8h, yielded the 3/3-hydroxy compound (12b), the 6/3-acetoxy group having survived unscathed.  

Kinetic studies of the alkaline hydrolyses (pH 11-14) of a series of pentachlorophenyl esters of -(/7-hydroxyphenyl)alkanoic acids (19 m = 1-4) have been reported. The reasonably high nucleofugality of the pentachlorophenoxide (pK  

Reactions of a wide range of substituted phenyl acetates with six a-effect nucleophiles have revealed little or no difference, compared with phenolate nucleophiles, in the values of the Leffler parameters. As a result, the case for a special electronic explanation of the a-effect is considered unproven. Studies of the kinetics and mechanism of the aminolysis and alkaline hydrolysis of a series of 4-substituted (21) and 6-substituted naphthyl acetates (22) have revealed that, for electron-withdrawing substituents, aminolysis for both series proceeds through an unassisted nucleophilic substitution pathway. 

The kinetics of the alkaline hydrolysis of 2-methylpentyl salicylate (24) have been studied in various aqueous propanol and r-butanol mixtures and in mixtures of water and ethane-l,2-diol. ° Further smdies of the aminolysis of ionized phenyl salicylate (25) have been reported, in which it was observed that, in mixed acetonitrile-water solvents, glycine, 1,2-diaminoethane and 3-aminopropanol all reacted as did simple amines, via an intramolecular general-base-catalysed process.  

The rates of acid-catalysed methoxy exchange between methanol and the three diastereomers of 2-methoxy-4,6-dimethyl-l,3-dioxalane (37a-c) were measured in benzene and methanol-chloroform. Rate constants were evaluated in a novel way using 1D-EXSY NMR pulse sequence and a weighted least-squares analysis. The critical intermediate is (38) and rates of methanol attack on it in benzene show a 24-fold axial selectivity whereas in methanol-chloroform the selectivity difference is ninefold.34 

Potential energy profiles have been determined for two series of reactions  

Energies of all stationary points were evaluated at the Hartree-Fock and the second-order Moller-Plesset (MP2) correlation levels with 6-3111++ G for (i) and 6-31+G for (ii). Acyl transfers can proceed through single-, double-, or triple-well energy profiles in the gas phase depending on X, the nucleofuge Y, and the R group.35 Comparative molecular field analysis (CoMFA) has been used in an unusual 

A Bac2 mechanism is proposed for the saponification of ethyl benzoate in ethanol-water.37 The reactions of aryl benzoates in absolute ethanol with ethoxide, aryloxides and acetophenone oximates occur via a stepwise mechanism in which the formation of the tetrahedral intermediate is rate determining.38 A stepwise mechanism is also supported for the reactions of /Miitrophcnyl-substitutcd benzoates with hydroxide and p-chlorophenoxidc. The evidence comes from breaks in Hammett plots as the acyl 

The reaction of 2,4-dinitrophenyl benzoate with secondary cyclic amines in DMSO-water shows a break in a Bronstcd plot near pA a 9.1 and the microconstants for the various stages in the reaction have been obtained and these gave good straight line Bronsted plots.46 The a-effect was observed as a positive deviation in the linear log k vs pKa plot for the reaction of /Miitrophcnyl X-substituted benzoates (43) with primary 

Compounds containing two carbonyl groupings in the ara-position of the type X, where Ri = R2 = H (Xa) Ri = R2 = CH3 (Xb) R = R2 = C6H5 (Xc), show unusual polarographic behaviour. With two carbonyl 

When reactions (40b) and (40d) proceed slowly, the product of reaction (40 a) is not further reduced. This species is further reduced only when it is transformed by the acid- (40 b) or base- (40 d) catalysed reactions to an acetophenone derivative. The range of pH in which the 

Treatment of diphenylketene (407) with a catalytic amount of Co2(CO)8 produces tetraphenylethylene (410,) involving a carbene complex as an intermediate. In this reaction carbene complex 408 is formed from 407 and Co2(CO)8, the cobaltacyclo-butanone 409 is generated by cycloaddition of 407 and 408, and cleaved to give 410 [130], 

It is known that vinylidene complexes 412 are formed by isomerization of the terminal alkynyl complexes 411 [131] their reactions are treated in Section 3.5.2.2. 

Complexes of Pd, Pt and Ru catalyse enyne metathesis, giving similar products to those obtained by the Ru-carbene complex 22 as described in this chapter. These enyne metatheses are discussed in Section 7.2.6. Other mechanisms, without involving carbene complexes as intermediates, have been proposed. 

Grubbs, Comprehensive Organometallic Chemistry, Vol 8, 499, Pergamon Press 1982 R. H. Grubbs and S. H. Pine, Comprehensive Organic Synthesis, Vol. 5, Chapter 9, Pergamon Press, (1991) K. J. Ivin, Olefin Metathesis, Academic Press, 1983. 

Synthetic reactions via transition metal carbene complexes 

Unfortunately, intuitive predictions of reactivity on the basis of stereoelectronic effects are not always possible, because these effects are subtle and can easily be overridden by steric, inductive, or field effects, or by conformational changes during the reaction [58]. It must also be kept in mind that hyperconjugation in the transition state, and not in the ground state, will be have the largest effect on the reaction rate. 

As discussed above, 2-halotetrahydropyrans tend to adopt a conformation in which the halogen is located axially, and which is stabilized by negative hyperconjugation of the type nQ — cr C-Hai- X-ray structural analyses have shown that in these 

Numerous other examples have, moreover, been reported in which bonds with antiperiplanar lone electron pairs react more slowly than, or at rates similar to, comparable bonds without antiperiplanar lone pairs [52, 63-67]. 

Stereoelectronic effects can have a profound effect on the ground-state structure of molecules, and can often help to explain counter-intuitive conformational preferences or spectroscopic features. Their effect on the energy of transition states is, however, less straightforward to predict. As stated by the Curtin-Hammett principle [75] (Section 1.4), reactions will proceed via energetically unfavorable conformers if these are more reactive (as is often the case) than better stabilized conformers. In such instances ground-state stabilization of certain conformers or the weakening of bonds by hyperconjugation will not necessarily be predictive for the outcome of a reaction. 

The examples discussed above illustrate that reactivity and stereoselectivity are subject to numerous, often subtle, influences. Continuous improvements in molecular modeling have enabled clarification of many, previously unexplained observations in the future even solvent effects might, perhaps, be taken into account. Predictive models based on such calculations should, however, always be substantiated by experimental data. 

Interestingly, compact flow reactors have been applied to prepare hundred of grams of bicyclic azepines using this photochemical strategy [78]. 

Fluorination of aromatics with fluorine usually occurs explosively fast. However, pyrimidin-2(l//)-ones have been successively fluorinated by fluorine in acetic or hydrofluoric acids (77CCC2694), and 5-substituted barbiturates by perchloryl fluoride (79JOU357). 

Rates of cleavage by iodide of B(OH)2 from thiophene have been determined (65AJC1527) there are no other reports of this reaction for heteroaromatics. 

Reactions Involving Formation of Carbocations at Side Chain a-Positions 

The reactivity of an aromatic ring toward an electrophilic reagent is usually measured by the ease with which it stabilizes the transition state arising from electrophilic attack [e.g., Eq. (5.1)]. An alternative quantita- 

The method can clearly measure not only the effect of a substituent upon the reactivity of benzene as outlined above, but also the reactivity of a different aromatic system, by placing it instead of the substituted benzene in, for example, Eq. (5.2). This method was introduced by Taylor (62JCS4881), who used, however, a different reaction, the pyrolysis of 1-arylethyl acetates (described below) This was the first application to the determination of heterocyclic reactivities. 

Nakane, M. Endo, H. Yamashita, Y. Oyamada and S. Motoki, Chem. Lett. 135, (1986) 

Capuano,B.Dahm,V. Port, R.Schnur and V. Schramm, CT7m.Be/ 121,271 (1988) ILL. Capuano, V. Hammerer and V. Huch, Lieb. Ann. Chem. 23 (1994) 

Noguchi, K. Onimura, Y. Isomura and S. Kajigaeshi, J. Hetrocycl. Chem. 28, 885 

Molina, A. Arques, A. Alias, M.C. Foces-Foces and A. Luis, J. Chem. Soc., Chem. Commun. 424 (1992) 

Ohkubo, H. Kuboki, M. Maeda, K. Tsuda, T. Karakasa and S. Satsum-abayashi, J. Chem. Soc., Perkin 1 3065 (1998) 

Raper and DeMore photolyzed solutions of O2 in CO at 77 °K with 2537 A radiation and found evidence for a reaction between electronically excited O2 and CO. They postulated the following mechanism 

They concluded that [O2] and 35 [CO] are both S0.1 under their experimental conditions. 

Verdurmen and Bank ° reported the exchange of O atoms between O2 and CO in a quartz vessel at temperatures above 450 °C to occur in a process parallel with CO2 production. They concluded that the atom exchange occurred by a gas-phase reaction, and the rate varied as [CO]° [02]° at 500 °C. They argued that either formation of O atoms at the walls which then form an excited intermediate, CO2, or the direct reaction ( — 33) could explain their results. The CO2 production occurred on the surface. 

The shock-tube oxidation of CO has been studied by Myers et with Ar-diluted mixtures of CO and O2 containing less than 1 p.p.m. of hydrogenous impurities. The reaction was studied at 1500-3000 °K. Above 2400 °K, they believed that the contamination of hydrogeneous material was negligible and they proposed the mechanism  

Their results indicated that /C38 = (3.5 1.6) x 10 exp [( —51,000 7000)/l r] and 7 24 = (1.4+1.1)x 10 exp [(—39,000 7000)/i r]l.mole sec for temperatures between 2400 and 3000 °K. In their study of the radiation during the oxidation they concluded that electronically excited CO2 could transfer energy to O2 with an activation energy of 31 kcal/mole. 

2-Chloropyrazine 1-oxide with phenylmagnesium bromide in tetrahydrofuran at reflux gave 2-chloro-6-phenylpyrazine 1-oxide (733b). 

Certain a-chloromethylpyrazine A -oxides have been deoxygenated with phosphorus trichloride. Treatment of 2-amino-5-chloromethyl-3-cyanopyrazine 1-oxide (and 2-amino-3-cyano-5-methoxymethylpyrazine 1-oxide) with phosphorus trichloride at room temperature in tetrahydrofuran resulted in smooth deoxygenation to 2-amino-5-chloromethyl-3-cyanopyrazine (and 2-amino-3-cyano-5-methoxy-methylpyrazine) (529), whereas 2-amino-6-chloromethyl-3-cyanopyrazine 1-oxide was best deoxygenated to 3-amino-5-chloromethyl-2-cyanopyrazine by phosphorus trichloride in refluxing tetrahydrofuran (534). The more vigorous conditions necessary for the last reaction may be a reflection of increased steric hindrance at the fV-oxide grouping (529). Use of solvents like chloroform or dioxane led to slow reactions which were accompanied by the formation of numerous unidentified by-products (534). 

2-Amino-5-chloromethyl-3-cyanopyrazine 1-oxide was also deoxygenated by sodium hydrosulfite (dithionite) in boiling water to give a poor yield of 2-amino-5-chloromethyl-3-cyanopyrazine, but 2-amino-6-chloromethyl-3-cyanopyrazine 1-oxide under the same conditions underwent both deoxygenation and reductive dehalogenation to 2-amino-3-cyano-6-methylpyrazine (529,534). 

All except methanoic acid are not oxidised, except by burning to carbon dioxide and water. 

They are not easily reduced, except by a very strong reducing agent, e.g. lithium tetrahydroaluminate(TII), (LiAlH4), more commonly known as lithium alvuninium hydride. The product is the corresponding primary alcohol. 

This is not yet a route to oligomerisation in the conventional polymer chemistry sense, but gold particles should be considered as centres for gathering pol3Tnerisable molecules together. This proves once again that gold nanoparticles are indeed very reactive species. 

The water-splitting reaction (dissociation of water to produce hydrogen and oxygen) is an alternative for the production of hydrogen, which is a clean 

It has been reported that cross-metathesis reactions can be performed on olefins using nanoparticulate gold catalysts [579]. The introduction of various organic functional groups onto organic thin films is a first step in their application in sensors, catalysis and nanotechnology in general. 

Choi and co-workers [579] studied the reactivity of vinyl-terminated self-assembled monolayers (SAMs) of undec-lO-ene-1-thiol on gold (see Fig. 6.32) toward olefin cross-metathesis (CM). Vinyl groups on SAMs were successfully converted into a, P-unsaturated carbonyl groups by CM with acrylic acid, methyl acrylate, and acrylamide. Result shows that various useful functional groups can be introduced to SAMs on gold (and other solid surfaces) by olefin CM and suggests an alternative to the S3mthesis of desired molecules in solution [579]. 

The hydrosilylation of C-C multiple bonds provides a very convenient route to the preparation of organo-silicon compounds, which have found industrial application as photo resistors, semiconductors, adhesives, binders 

Various aldehydes and ketones were treated with MesSiCN to furnish the corresponding cyanohydrin trimethylsilyl ethers (Table 3.8). 

The reusability of the catalyst was checked and a consistent activity was observed after several cycles in the model reaction between p-chlorobenzal-dehyde and McaSiCN. 

As physical destruction of the polymer matrix by stirring might deactivate the catalyst, an automatic shaker instead of a magnetic stirrer was utilized, allowing preservation of the catalyst activity, even after multiple use, to afford the homoallylic alcohol in high yields (1st cycle 90% yield, 2nd cycle 86% yield, 3rd cycle 86% yield). 

The reaction could be extended to different aldehydes to afford the corresponding products in good yields (66-95%), although 300 mol.% of catalyst 103 and long reaction times were required to complete the reactions in some cases. 

Supported Organic Bases A Green Tool for Carbon-Carbon Bond Formation OH 

An unusual rearrangement converts 3-benzoyl-A -pyrazolines into phenylpyridazinones 83H(20)2385 . The azido/tetrazok tautomerism of 3-azido-A -pyrazohnes has been studied by H and C NMR 84CS195 . Maas 92CB1227 has described the so-called homopyrazoles (2,3-diazabicyclo[3.1.0]hex-3-enes) (170a) which exist in equilibrium with 1,4-dihydropyrazines (170b). 

Hurst 93AHC(58)215 has summarized the results of nitration of 1-phenyl-A -pyrazolines for instance, l,5-diphenyl-3-aryl-2-pyrazolines are nitrated by potassium nitrate in sulfuric acid to afford the 1-p-nitrophenyl derivative in quantitative yield. Thermal ring opening of A -pyrazolin-3-carboxylic acids has been used as a method of preparation of )8-aminonitriles 94T7543 , while base-promoted ring opening of 1,1 -disubstituted-3-amino-A -pyrazolinium salts affords either N,N-disubstituted hydrazines or a,)S-unsaturated amidrazones 86SC585 . 

Direct replacement of hydrogen by an amino group can be effected only in a few special cases but then has considerable preparative interest. Animating agents requiring consideration are alkali amides, hydroxylamine, and A-halo amines. 

In early work, Sachs383 found that certain naphthalene derivatives, such as naphthylamines and naphthols, are aminated in the aromatic ring, preferentially at the 5-position, when melted with sodamide. This reaction, however, has greater importance for the preparation of amino derivatives of certain N-heterocycles.384 385 

Kovadc in G. A. Olah s Friedel-Crafts and Related Reactions, Interscience Publishers, New York-London-Sydney, 1964, Vol. 3, Part 2, p. 1493. 

The sodio derivatives of hydrazine or 1,2-dimethylhydrazine can be used in the same way as sodamide thus Kauffmann and Schoeneck394 obtained 2-pyridylhydrazine by heating pyridine in anhydrous hydrazine for 8 hours, the yield being about 40%. In the absence of free hydrazine hydrazo compounds are formed.395 

Aromatic nitro compounds are comparable with pyridine derivatives in reactivity and can sometimes be aminated directly. l-(4 -Nitro-l -naphthyl)-piperidine was obtained from 1-nitronaphthalene and sodium piperidide (sodamide and piperidine).396 Nitrobenzene and the alkali derivative of carbazole397 or diphenylamine398 gave the corresponding /7-amino derivative, 9-(/7-nitrophenyl)carbazole (70%) and 4-nitrotriphenylamine (45%). Huisgen and Rist399 record the reaction of nitrobenzene with lithium piperidide. 

Catalytic Oxidation of Fe(II) in Aqueous Media A detailed study of this reaction was carried out recently, where the influence of the AC surface chemistry was assessed [211]. Two situations were considered  

Fe + oxidation without O2. In this case the proposed mechanism was 

Hydrodehalogenation Incineration is one of the techniques available for the disposal of halogenated wastes, but incomplete combustion of halogen-containing aromatics can lead to the formation of harmful products such as dioxins. An alternative approach that is receiving increasing attention is hydrodehalogenation  

The use of carbon as a catalyst was reviewed. It was shown that interesting activity correlations could be obtained by studying the catalytic performance of a series of carbon materials prepared from the same precursor with similar tex-mral properties and different amounts of surface functional groups. The redox couple quinone-hydroquinone was found to be involved in the oxidative dehydrogenation of hydrocarbons, while carboxylic acid groups are the active sites for the dehydration of alcohols. In both cases, thermal treatments at different temperatures were used to identify the nature of the active sites, aud correlations 

The deposition of metals has been observed in a number of catalytic processes in ionic liquids and this will be discussed in Section 6.3. This has encouraged the exploration of the possibility of the chemical deposition of metals from solutions in ionic liquids. For instance, lr(0) nanoparticles 2.3 0.4 run in diameter have been prepared by the reduction of [Ir(cod)Q]2 in [BMIMjfPFs] with H2 [24]. In a particularly elegant experiment, palladium nanoparticles were first formed by the thermal decomposition of paUadium(ii) acetate in the presence of triphenylphosphine (to give a regular particle size of 1 run) in [BMIM][Tf2N]. A silica aerogel support was then formed around the nanoparticles by adding (EtO)4Si and formic acid to the mixture [25], 

The decomposition of D-glucose in the presence of CrCla, AIQ3, or TiCla has been shown to proceed by a first-order reaction to give MeC0CH2CH2G02H (10%), HCO2H (3%), CO2 (3%), OHCCO2H (6%), and HO2CCH2CH2CO2H 

study of the initial stages of heat-induced decomposition of dextrose in neutral solution has shown that two intermediates with identical u.v. spectra consistent with 3-deoxyhexosone structure are formed. After about 20 min, 5-hydroxymethylfurfural appeared. 5-Hydroxymethylfurfural has also 

Sandtnerova, T. Sticzay, V. Kovicik, M. Kulhanek, and M. Tadra, Carbo-hydr. Res., 1979, 76, 290. 

Reference to the synthesis of l-deoxy-D-n/tro-heptulose, which is accumulated by transketolase mutants of Bacillus pumilus, is made in Chapter 11. 

Lopez Aparicio, M. Gomez Guillen, and I. Izquierdo Cubero, Anales Quim., 1977, 73, 1168 (Chem. Abs., 1979, 90, 23 427j). 

The carbon skeletal rearrangements of aldoses induced by molybdate have been reviewed. 

The effect of calcium ions on the rearrangement of aldos-2-uloses 

Thirteen compounds have been identified In the reaction of D-glucose and L-lysine in slightly acidic aqueous solution the reaction is of importance in nutritional loss during cooking,particularly In relation to the essential aminoacids such as lysine. 

Mukaiyama, Noauckl Kenkyusho Jlho. 1983, 7 (Chem. Abatr.. 1984, 

Mukaiyama and S.Shoda, Yuki Gosei Kagaku Kvokaishl. 1984, 474 

In a similar way, a-selenylation is also possible. Use of selenium may benefit from several advantages a) relative stability of allq lselenenyl aldehydes, b) commercial availability of iV-(phenylseleno)phthalimide, c) no additional step to cleave the N-Se bond, as this weak bond is broken under 

The first use of the catalyst Cla in an aldehyde oxygenation with molecular oxygen was published by the Cordova group.Singlet oxygen was generated from molecular oxygen by catalytic amount of tetraphenylporhyrin (TPP) in 

Electrophilic a-amination reactions were also included in organocascade sequences. Jorgensen developed a formation of hydro) - and amino-esters in combination by aminocatalysis using diaiylprolinol silyl ether and a redox reaction followed by acyl transfer to the corresponding esters using NHC catalysis. This useful method did not require an inert atmosphere or anhydrous conditions to form the corresponding products in excellent enantioselectivities and high yield. 

In a similar way, aziridination is also possible. The first synthesis of aziridines from aliphatic a,p-unsaturated aldehydes and acylated hydrojgr-carbamates was developed by Cordova in 2007. The products of this reaction were obtained in moderate yields and diastereoselectivities, but with 

Another example of combination secondary- and primary-amine catalyst is described by Moreau, Greek and coworkers in Michael/a-amination sequence for construction of quaternary stereocentres. °  

The alkaline degradation products were of minor importance at temper-o 

Osinovskii and B.V.Erofeev, Dokl. Akad. Nauk BSSR, 1984, M, 1006 (Chem. Abstr.. 1985, 102, 95 926). 

Misawa, and H.Meguro, Agric. Biol. Chem.. 1985, 239. 

Paulsen, M.Schuller, M.A.Washed, A.Heitmann, and H.Redlich, Tetrahedron Lett.. 1985, 26, 3689. 

Chlorosulfonic acid is a strong oxidizing agent, thus alkanes are readily oxidized by sulfur trioxide, oleum and chlorosulfonic acid, so attempted sulfonation of an n-alkane generally yields a complex mixture of oxidation and sulfonation products (see Chapter 5, p 146). 

Anthracite is oxidized to mellitic acid by heating at 130 °C with a mixture of chlorosulfonic and nitric acid in a stream of air. Charcoal, on warming with chlorosulfonic acid, is converted into a mixture of sulfur dioxide, carbon dioxide and hydrogen chloride (see Chapter 7, p 226). 

Organophosphorus compounds 33 are oxidized, on treatment with chlorosulfonic acid in a homogeneous liquid phase, to give the corresponding phosphoryl analogues 34 (Equation 12).  

As a specific example, methylphosphonous dichloride reacted with an equimolar quantity of chlorosulfonic acid at 25-30 °C to give methylphosphonic 

Watanabe, and M. Sato, Tetrahedron Lett., 1980, 21, 2869. Reaction of RMgX and HCO2H. 

Hayashi, M. Konishi, K. I. Yokota, and M. Kumada, Chem. Lett., 1980, 767. Cl[l,r-(Ph2P)2ferrocene]Ni as catalyst for cross couplings. 

This chapter provides a snapshot of recent impressive advances in non-proline amino acid catalysis. A good range of enantioselective processes were reaUzed by 

L gratefully acknowledges the generous financial support provided by the National University of Singapore, the Ministry of Education (MOE) of Singapore, GSK-EDB, and the Singapore-Peking-Oxford Research Enterprise. 

17 (a) Mahrwald, R. (ed.) (2004) Modern Aldol Reactions, vols 1 2, Wiley-VCH Verlag GmbH, Weinheim (b) Xu, LW., Li, L, and Cai, Y.F. (2011) Aldol reaction-homogeneous, in Encyclopedia of Catalysis, 2nd edn (ed. I. Horvath), John Wiley Sons, Inc., Hoboken, p. eoc219. 

How would you accomplish each of the following transformations Some may require more than one step  

Predict the outcome of each of the following reaction sequences  

NaHDMS is sodium M(trimethylsilyl)amide, NaN(SiMe3)2, a strong, nonnucleophilic base. PROBLEM 20.3 

The benzoin condensation is catalyzed by thiamine in the presence of base. Propose a mechanism for the following reaction  

1(b) tra s-Geometry suggests an epoxide intermediate. So use MCPBA to prepare the epoxide, then open with MeNHj. The regiochemistry of the epoxide opening might be considered problematic, but the allyl position is the more easily substituted. 

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Hammen equation A correlation between the structure and reactivity in the side chain derivatives of aromatic compounds. Its derivation follows from many comparisons between rate constants for various reactions and the equilibrium constants for other reactions, or other functions of molecules which can be measured (e g. the i.r. carbonyl group stretching frequency). For example the dissociation constants of a series of para substituted (O2N —, MeO —, Cl —, etc.) benzoic acids correlate with the rate constant k for the alkaline hydrolysis of para substituted benzyl chlorides. If log Kq is plotted against log k, the data fall on a straight line. Similar results are obtained for meta substituted derivatives but not for orthosubstituted derivatives. 

Similar calculations enable the equilibrium constants for other reactions to be calculated. 

One of the reactions is projected in that part of the Kohonen network where mostly reactions leading to the preferred regioisomer pyrazole were projected. The other reaction was projected in neuron (7,7), which lies in a region where reactions with low yield are projected. 

The algebraic form of the expression (9.24) for the enhancement factor is specific to the particular reaction rate expression we have considered, and corresponding results can easily be obtained for other reactions in binary mixtures, for example the irreversible cracking A—2B. ... 

Hydroxamic acid formation resembles amide formation (pp. 117-119) and therefore certain other classes of substances will respond to the test, e.g., acid chlorides and acid anhydrides, but these substances are readily distinguished by other reactions. 

The following account refers primarily to commercial apparatus suitable for conducting hydrogenations under pressime the apparatus can, of coimse, be employed for other reactions under high pressures, but slight modifications of experimental procedime wiU probably be necessary. 

We conclude that the beneficial effects of water are not necessarily limited to reactions that are characterised by a negative volume of activation. We infer that, apart from the retro Diels-Alder reaction also other reactions, in which no significant reduction or perhaps even an increase of solvent accessible surface area takes place, can be accelerated by water. A reduction of the nonpolar nature during the activation process is a prerequisite in these cases. 

The technique most often used (i.e., for an atom transfer) is to hrst plot the energy curve due to stretching a bond that is to be broken (without the new bond present) and then plot the energy curve due to stretching a bond that is to be formed (without the old bond present). The transition structure is next dehned as the point at which these two curves cross. Since most molecular mechanics methods were not designed to describe bond breaking and other reaction mechanisms, these methods are most reliable when a class of reactions has been tested against experimental data to determine its applicability and perhaps a suitable correction factor. 

These systems nitrate aromatie eompounds by a proeess of electro-philie substitution, the eharacter of whieh is now understood in some detail ( 6.1). It should be noted, however, that some of them ean eause nitration and various other reactions by less well understood processes. Among sueh nitrations that of nitration via nitrosation is especially important when the aromatic substrate is a reactive one ( 4.3). In reaetion with lithium nitrate in aeetie anhydride, or with fuming nitrie aeid, quinoline gives a small yield of 3-nitroquinoline this untypieal orientation (ef. 10.4.2 ) may be a eonsequenee of nitration following nucleophilic addition. ... 

The phenomenon was established firmly by determining the rates of reaction in 68-3 % sulphuric acid and 61-05 % perchloric acid of a series of compounds which, from their behaviour in other reactions, and from predictions made using the additivity principle ( 9.2), might be expected to be very reactive in nitration. The second-order rate coefficients for nitration of these compounds, their rates relative to that of benzene and, where possible, an estimate of their expected relative rates are listed in table 2.6. 

Dramatic rate accelerations of [4 + 2]cycloadditions were observed in an inert, extremely polar solvent, namely in5 M solutions oflithium perchlorate in diethyl ether(s 532 g LiC104 per litre ). Diels-Alder additions requiring several days, 10—20 kbar of pressure, and/ or elevated temperatures in apolar solvents are achieved in high yields in some hours at ambient pressure and temperature in this solvent (P.A. Grieco, 1990). Also several other reactions, e.g, allylic rearrangements and Michael additions, can be drastically accelerated by this magic solvent. The diastereoselectivities of the reactions in apolar solvents and in LiClO EtjO are often different or even complementary and become thus steerable. 

Three oxidative reactions of benzene with Pd(OAc)2 via reactive rr-aryl-Pd complexes are known. The insertion of alkenes and elimination afford arylalk-enes. The oxidative functionalization of alkenes with aromatics is treated in Section 2.8. Two other reactions, oxidative homocoupling[324,325] and the acetoxylation[326], are treated in this section. The palladation of aromatic compounds is possible only with Pd(OAc)2. No reaction takes place with PdCl2. 

The reaction of hydrosilanes with butadiene is different from other reactions. Different products are obtained depending on the structurelof the hydrosilanes and the reaction conditions. Trimethylsiiane and other trialkylsilanes react to give the I 2 adduct, namely the l-trialkylsilyl-2,6-octadiene 74, in high yields[67-69]. Unlike other telomers which have the 2,7-octadienyl chain, the 2,6-octadienyl chain is formed by hydrosilylation. On the other hand, the 1 I adduct 75 (l-trichlorosilyl-2-butene)is formed selectively with trichlorosilane, which is more reactive than trialkylsilanes[69]. The Reaction gives the Z form stereoselectively[70]. A mixture of the I 1 and I 2 adducts (83.5 and 5.2%) is... 

Reactions with Carbon and Oxygen Nucleophiles, and Other Reactions... 

Aikynes undergo a variety of reactions using either Pd(H) or Pd(0), and they are treated separately oxidative reactions of alkynes with Pd(Il) are treated in Chapter 3, Section 8. Pd(0)-catalyzed reactions of alkynes with halides in Section 1.1.2 in this chapter, and other reactions in this section. 

In addition to the more traditional reaction media discussed in Section 7.1.1, there arc a number of other reaction system.s which have been investigated. Some of their specific characteristics are outlined in the succeeding paragraphs. 

In this section you have seen how heats of com bustion can be used to determine relative stabilities of isomeric alkanes In later sections we shall expand our scope to include the experimentally determined heats of certain other reactions such as bond dissociation energies (Section 4 16) and heats of hydrogenation (Section 6 2) to see how AH° values from various sources can aid our understanding of structure and reactivity... 

In this as m other reactions m which achiral reactants yield chiral products the product IS formed as a racemic mixture and is optically inactive Remember for a substance to be optically active not only must it be chiral but one enantiomer must be present m excess of the other... 

We have seen this situation before m the reaction of alcohols with hydrogen halides (8ection 4 11) m the acid catalyzed dehydration of alcohols (8ection 5 12) and m the conversion of alkyl halides to alkenes by the El mechanism (8ection 5 17) As m these other reactions an electronic effect specifically the stabilization of the carbocation intermediate by alkyl substituents is the decisive factor The more stable the carbo cation the faster it is formed... 

We have already discussed one important chemical property of alkynes the acidity of acetylene and terminal alkynes In the remaining sections of this chapter several other reactions of alkynes will be explored Most of them will be similar to reactions of alkenes Like alkenes alkynes undergo addition reactions We 11 begin with a reaction familiar to us from our study of alkenes namely catalytic hydrogenation... 

You will recognize the side chain oxidation of p xylene to terephthahc acid as a reaction type discussed previously (Section 11 13) Examples of other reactions encoun tered earlier that can be applied to the synthesis of carboxylic acids are collected m Table 19 4... 

Other reactions are controlled kinetically, and the most stable product is not the major one observed. In these cases, you must look at the reactant side of the reaction coordinate to discover factors determining the outcome. Klopman and Salem developed an analysis of reactivity in terms of two factors an electrostatic interaction approximated by atomic charges and a Frontier orbital interaction. Fleming s book provides an excellent introduction to these ideas. 

Other reactions between reagent gas ions and molecules (M) can occur. As examples, ions [M + X] can be formed, where X is Na, NO, or NH4. 

Elsewhere in this chapter we shall see that other reactions-notably, chain transfer and chain inhibition-also need to be considered to give a more fully developed picture of chain-growth polymerization, but we shall omit these for the time being. Much of the argumentation of this chapter is based on the kinetics of these three mechanistic steps. We shall describe the rates of the three general kinds of reactions by the notation Rj, Rp, and R for initiation, propagation, and termination, respectively. 

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