Similar Reactions

Figure C2.17.8. Powder x-ray diffraction (PXRD) from amoriDhous and nanocry stalline Ti02 nanocrystals. Powder x-ray diffraction is an important test for nanocrystal quality. In the top panel, nanoparticles of titania provide no crystalline reflections. These samples, while showing some evidence of crystallinity in TEM, have a major amoriDhous component. A similar reaction, perfonned with a crystallizing agent at high temperature, provides well defined reflections which allow the anatase phase to be clearly identified.

The strongly electronegative (p. 49) chlorine atom becomes a chloride ion, the proton accepting the electron pair donated by the nitrogen atom. A similar reaction occurs when ammonia is passed into water, but to a much lesser extent as oxygen in water is a poorer donor of the electron pair ... 

The aluminium ion, charge -I- 3. ionic radius 0.045 nm, found in aluminium trifluoride, undergoes a similar reaction when a soluble aluminium salt is placed in water at room temperature. Initially the aluminium ion is surrounded by six water molecules and the complex ion has the predicted octahedral symmetry (see Table 2.5 ) ... 

A similar reaction occurs with chlorine, to give nitrosyl chloride... 

Similar reactions occur with organic compounds which contain hydroxyl groups, thus... 

A somewhat similar reaction is the power of sulphur oxide dichloride to remove water of crystallisation from hydrated chlorides, the hydroxyl groups of the water molecule reacting as do those in the acid molecules in the above reaction. 

Clearly, the nex.t step will be to investigate the physicochemical effects, such as charge distribution and inductive and resonance effects, at the reaction center to obtain a deeper insight into the mechanisms of these biochemical reactions and the finer details of similar reactions. Here, it should be emphasized that biochemical reactions arc ruled and driven basically by the same effects as organic reactions. Figure 10.3-22 compares the Claisen condensation of acetic esters to acctoacctic esters with the analogous biochemical reaction in the human body. 

A similar reaction occurs only very rarely with aliphatic hydrocarbons. 

A similar reaction occurs when an aqueous solution of a diazonium compound is made strongly alkaline and then warmed with an alkaline solution of stannous chloride. This reaction, however, involves the intermediate formation of the... 

By a similar reaction ethanol gives acetaldehyde (tests, p. 341) and isopropanol gives acetone (tests, p. 345). -Butanol gives butyr dehyde (pleasant characteristic odour and precipitate with 2,4-dinitrophenyl-hydrazine, m.p. 122 ). 

By the action of concentrate aqueous ammonia solution upon esters. This process is spoken of as ammonolysls of the ester, by analogy with hydrolysis applied to a similar reaction with water. If the amide is soluble in water, e.g., acetamide, it may be isolated by distillation, for example ... 

The usual directive influences are not operative in this and similar reactions for ortho - para substitution occurs (this may be modified by steric hindrance) irrespective of the nature of R in the aromatic liquid CsHjR, e.g. phenyldlazo hydroxide and nitrobenzene yield 4-nitrodiphenyl this supports the assumption that neutral free radicals are formed. 

If the structure of the intermediate for a very similar reaction is available, use that structure with a quasi-Newton optimization. 

In a similar reaction the bis-tosylate shown below was to be converted into a bis-malonate derivative. In this cyclic derivative both groups are hold closely together and intramolecular reactions proved to be so much faster than intermolecular substitution under all ex-... 

Cis-olefins or cis./rjns-dienes can be obtained from alkynes in similar reaction sequences. The alkyne is first hydroborated and then treated with alkaline iodine. If the other substituents on boron are alkyl groups, a cis-olefin is formed (G. Zweifel, 1967). If they are cir-alkenyls, a cis, trans-diene results. The reactions are thought to be iodine-assisted migrations of the cis-alkenyl group followed by (rans-deiodoboronation (G. Zweifel, 1968). Trans, trans-dienes are made from haloalkynes and alkynes. These compounds are added one after the other to thexylborane. The alkenyl(l-haloalkenyl)thexylboranes are converted with sodium methoxide into trans, trans-dienes (E. Negishi, 1973). The thexyl group does not migrate. 

The elimination of 3-hydrogen of Pd alkoxide (17) to afford a carbonyl compound is a similar reaction. 

Disilanes add to conjugated dienes by splitting their Si—Si bond. 1.1.2.2-Tetramethyl-1.2-disilacyclopentane (82) reacts with butadiene at 100 C to give l,l,5,5-tetramethyl-l,5-disilacyclotrideca-7,l 1-diene (83) in 8330 yield[77]. The six-membered carbodisilanes undergo a similar reaction to give 14-membered compounds. 

The cyclohexadiene derivative 130 was obtained by the co-cyclization of DMAD with strained alkenes such as norbornene catalyzed by 75[63], However, the linear 2 1 adduct 131 of an alkene and DMAD was obtained selectively using bis(maleic anhydride)(norbornene)palladium (124)[64] as a cat-alyst[65], A similar reaction of allyl alcohol with DMAD is catalyzed by the catalyst 123 to give the linear adducts 132 and 133[66], Reaction of a vinyl ether with DMAD gives the cyclopentene derivatives 134 and 135 as 2 I adducts, and a cyclooctadiene derivative, although the selectivity is not high[67]. 

As the polarity of the medium is increased 3-alkylrhodanine (161) is obtained (389, 393). 2-Thiophosphonyl derivatives have been obtained by a similar reaction (394). 

A similar reaction of benzyl radicals is observed in the thermolysis at 200 C and in the presence of powdered copper of N-benzylthiazolium... 

In a similar reaction, bromosuccinic acid and thiobenzamide in ethyl-acetate yielded an acyclic intermediate (229), Ri = Ph, R2 = CH2C02H, which by heating in water cyclizes to the thiazole (230), Rj = Ph and R2 = CH2C02H. (260). 

A similar reaction from disulfide (261) and a-chloroalkanoic acids is reported by DahJbom (Scheme 134) (392). 

A similar reaction in which ammonia and carbon dioxide are heated under pres sure IS the basis of the industrial synthesis of urea Here the reactants first combine yielding a salt called ammonium carbamate... 

Formation of aryl Grignard reagents (Section 14 4) Aryl halides react with magnesium to form the corresponding arylmagnesium halide Aryl iodides are the most reac tive aryl fluorides the least A similar reaction occurs with lithium to give aryllithium reagents (Section 14 3)... 

Unsaturated aldehydes undergo a similar reaction in the presence of strongly acid ion-exchange resins to produce alkenyUdene diacetates. Thus acrolein [107-02-8] or methacrolein [78-85-3] react with equimolar amounts of anhydride at —10°C to give high yields of the -diacetates from acetic anhydride, useful for soap fragrances. 

A similar reaction occurs when polyacrylamide is mixed with glyoxilic acid [298-12-4], C2H2O2, at pH about 8. This reaction produces a polymer with the CONHCH(OH)COOH fiinctionahty, which has found appHcation in phosphate ore processing (53). 

In acetic acid solvent, ethylene gives 1,3-propanediol acetates (46) and propylene gives 1,3-butanediol acetates (47). A similar reaction readily occurs with olefinic alcohols and ethers, diolefins, and mercaptans (48). 

Ai,A/-bis(hydroxymethyl) formamide [6921-98-8] (21), which in solution is in equiUbrium with the monomethylol derivative [13052-19-2] and formaldehyde. With ben2aldehyde in the presence of pyridine, formamide condenses to yield ben2yhdene bisformamide [14328-12-2]. Similar reactions occur with ketones, which, however, requite more drastic reaction conditions. Formamide is a valuable reagent in the synthesis of heterocycHc compounds. Synthetic routes to various types of compounds like imida2oles, oxa2oles, pyrimidines, tria2ines, xanthines, and even complex purine alkaloids, eg, theophylline [58-55-9] theobromine [83-67-0], and caffeine [58-08-2], have been devised (22). 

A variety of a-amino acid derivatives, including the acids themselves, haUdes, esters, and amides can be transformed iato hydantoias by coadeasatioa with urea (67). a-Hydroxy acids and thek nitriles give a similar reaction (68) ... 

Reaction with Meta/ Oxides. The reaction of hydrogen chloride with the transition-metal oxides at elevated temperatures has been studied extensively. Fe202 reacts readily at temperatures as low as 300°C to produce FeCl and water. The heavier transition-metal oxides require a higher reaction temperature, and the primary reaction product is usually the corresponding oxychlorides. Similar reactions are reported for many other metal oxides, such as Sb202, BeO, AI2O2, andTi02, which lead to the formation of relatively volatile chlorides or oxychlorides. 

The radicals are then involved in oxidations such as formation of ketones (qv) from alcohols. Similar reactions are finding value in treatment of waste streams to reduce total oxidizable carbon and thus its chemical oxygen demand. These reactions normally are conducted in aqueous acid medium at pH 1—4 to minimize the catalytic decomposition of the hydrogen peroxide. More information on metal and metal oxide-catalyzed oxidation reactions (Milas oxidations) is available (4-7) (see also Photochemical technology, photocatalysis). 

Make acid yields coumaUc acid when treated with fuming sulfuric acid (19). Similar treatment of malic acid in the presence of phenol and substituted phenols is a facile method of synthesi2ing coumarins that are substituted in the aromatic nucleus (20,21) (see Coumarin). Similar reactions take place with thiophenol and substituted thiophenols, yielding, among other compounds, a red dye (22) (see Dyes and dye intermediates). Oxidation of an aqueous solution of malic acid with hydrogen peroxide (qv) cataly2ed by ferrous ions yields oxalacetic acid (23). If this oxidation is performed in the presence of chromium, ferric, or titanium ions, or mixtures of these, the product is tartaric acid (24). Chlorals react with malic acid in the presence of sulfuric acid or other acidic catalysts to produce 4-ketodioxolones (25,26). 

This reaction is one example of several possible radical transition-metal ion interactions. The significance of this and similar reactions is that radicals are destroyed and are no longer available for initiation of useful radical reactions. Consequentiy, the optimum use levels of transition metals are very low. Although the hydroperoxide decomposes quickly when excess transition metal is employed, the efficiency of radical generation is poor. 

A similar reaction leads to the precipitation of gold or silver from cyanide solution using zinc powder. 

In a reversal of the reaction with SiCl, aluminum can be introduced into the framework by reaction of the hydrogen or ammonium form with gaseous AlCl (36). Similarly, reaction with aqueous ammonium fluoroaluminates replaces framework-Si with Al (37). When alumina-bound high siUca 2eohtes are hydrothermaHy treated, aluminum migrates into framework positions and generates catalyticaHy active acid sites (38). The reaction can be accelerated by raising the pH of the aqueous phase. 

In the reduction of nitro compounds to amines, several of the iatermediate species are stable and under the right conditions, it is possible to stop the reduction at these iatermediate stages and isolate the products (see Figure 1, where R = CgH ). Nitrosoben2ene [586-96-9] C H NO, can be obtained by electrochemical reduction of nitrobenzene [98-95-3]. Phenylhydroxylamine, C H NHOH, is obtained when nitrobenzene reacts with ziac dust and calcium chloride ia an alcohoHc solution. When a similar reaction is carried out with iron or ziac ia an acidic solution, aniline is the reduction product. Hydrazobenzene [122-66-7] formed when nitrobenzene reacts with ziac dust ia an alkaline solution. Azoxybenzene [495-48-7], C22H2QN2O, is... 

Ammonia forms a great variety of addition or coordination compounds (qv), also called ammoniates, ia analogy with hydrates. Thus CaCl2 bNH and CuSO TNH are comparable to CaCl2 6H20 and CuSO 4H20, respectively, and, when regarded as coordination compounds, are called ammines and written as complexes, eg, [Cu(NH2)4]S04. The solubiHty ia water of such compounds is often quite different from the solubiHty of the parent salts. For example, silver chloride, AgQ., is almost iasoluble ia water, whereas [Ag(NH2)2]Cl is readily soluble. Thus silver chloride dissolves ia aqueous ammonia. Similar reactions take place with other water iasoluble silver and copper salts. Many ammines can be obtained ia a crystalline form, particularly those of cobalt, chromium, and platinum. 

The N-oxides of isoquinolines have proved to be excellent intermediates for the preparation of many compounds. Trialkylboranes give 1-alkyl derivatives (147). With cyanogen bromide in ethanol, ethyl N-(l- and 4-isoquinolyl)carbamates are formed (148). A compHcated but potentially important reaction is the formation of 1-acetonyLisoquinoline and 1-cyanoisoquinoline [1198-30-7] when isoquinoline N-oxide reacts with metbacrylonitrile in the presence of hydroquinone (149). Isoquinoline N-oxide undergoes direct acylamination with /V-benzoylanilinoisoquinoline salts to form 1-/V-benzoylanilinoisoquinoline [53112-20-4] in 55% yield (150). A similar reaction of AJ-sulfinyl- -toluenesulfonamide leads to l-(tos5larriino)isoquinoline [25770-51-8] which is readily hydrolyzed to 1-aminoisoquinoline (151). 

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