Preparation and properties

Triorganotin hydroxides and oxides are usually prepared by the hydrolysis of the corresponding chlorides under alkaline conditions. A recent patent reports the formation of trialkyl-, dialkyl-, and monoalkyl-tin oxides by passing an alcohol in the gas phase over tin powder in the presence of a Lewis acid at 200-400 °C,9 for example  

The simple trialkyltin hydroxides can be obtained as soft, low-melting, waxy solids, when the oxides are stirred with water at 0-5 °C, but on warming they usually readily lose water to give the corresponding oxides.10 The hydroxides and oxides differ little in their elemental analyses and, in solution, they may exist in equilibrium, and sometimes the two families of compounds have been confused for example, trineophyltin oxide is readily hydrolysed to the hydroxide under humid conditions, but the compound that is always isolated from solutions is the oxide, and the compound which was initially identified as (PhMe2CCH2)3SnOH, is in fact [(PhMc2CCn2)3Sn 20.11 12 The hydroxides 

Organotin Chemistry, Second Edition. Alwyn G. Davies Copyright 2004 Wiley-VCH Verlag GmbH Co. KGaA. ISBN 3-527-31023-1 

The principal exception to this pattern of behaviour is trimethyltin hydroxide [v(OH) 3620, 8(OH) 920 cm-1] which sublimes unchanged above 80 °C it can be dehydrated with sodium in benzene13 or with calcium hydride14 to give the oxide [vas(SnOSn) 740 cm4], but this fumes in air as it is hydrolysed back to the hydroxide. 

Thermogravimetric analysis shows that triphenyltin hydroxide loses water at 80-100 °C to give the oxide,18 but tri-o-tolyl- and tri-o-anisyl-tin hydroxides can be characterised only in solution, and revert to the oxides when they are isolated.20 

The compounds of lithium and magnesium are the most important of the group lA and IIA organometallics from a synthetic perspective. The metals in these two groups are the most electropositive of the elements. The polarity of the metal-carbon bond is such as to place high electron density on carbon. This electronic distribution is responsible for the strong nucleophilicity and basicity of these compoimds. 

The reaction of magnesium metal with an alkyl or aryl halide in diethyl ether is the classical method for synthesis of Grignard reagents. 

One test for the involvement of radical intermediates is to determine if cyclization occurs in the 6-hexenyl system, in which radical cyclization is rapid (see Section 12.2.2 in Part A). Small amounts of cyclized products are formed upon preparation of the Grignard reagent from 5-hexenyl bromide. This indicates that cyclization of the intermediate radical competes to a small extent with combination of the radical with the metal. A point of considerable discussion is whether the radicals generated are free or associated with the metal surface.  

If such bridged intermediates are involved, the larger steric bulk of secondary systems would retard the reaction. Steric restrictions may be further enhanced by the fact that organomagnesium reagents are often present as clusters (see below). 

The usual designation of Grignard reagents as RMgX is a useful but incomplete representation of the composition of the compounds in ether solution. An equilbiium exists with magnesium bromide and the dialkylmagnesium. 

The discovery by Grignard that organic halides react with metallic magnesium to give nucleophilic organomagnesium compounds was a landmark in organic synthesis. The reaction of a halide with metallic magnesium in diethyl ether remains the principal method of synthesis. The order of reactivity is RI RBr RCl. 

The mechanism of the Grignard reaction has not been specified precisely. The reaction takes place at the metal surface. One likely mechanism commences with a one-electron transfer, followed by rapid recombination of the organic group with a magnesium ion. The carbon-bromine bond must break prior to or during the reaction with magnesium. 

Solutions of organomagnesium compounds in diethyl ether contain aggregated species. Dimers predominate in ether solutions of alkylmagnesium chlorides. The 

Most simple organolithium reagents can also be prepared by reaction of the appropriate halide with lithium metal. The simple alkyllithium reagents exist mainly as hexamers in hydrocarbon solvents. In ethers the evidence indicates that tetramers are dominant. The tetramers, in turn, are solvated with ether molecules. Certain highly hindered alkyllithiums have been observed to be more reactive than simpler alkyl systems. This has been attributed to steric hindrance, which prevents the formation of the tetramer. Higher reactivity is generally associated with the less-aggregated species.  

They also abstract protons rapidly from all OH and NH groups to generate the hydrocarbon. From the point of view of wide synthetic utility, the most useful of the 

General Reference G. E. Coates and K. Wade, Organometallic Compounds, Vol. I, Methuen and Co., London, 1967, pp. 1-176. 

A special technique that has been used to prepare Grignard reagents from unreactive halides is known as entrainment. The halide of interest, along with a more reactive halide, is added to the magnesium and solvent. Ethylene dibromide is useful as the reactive halide, since it decomposes to ethylene rather than giving a second organomagnesium reagent, which would compete in subsequent reactions  

Acetylenes are sufficiently acidic to act as proton donors toward alkyl Grignard 

Chloroprene, (2-chloro-1,3-butadiene), was first discovered as late as 1930 by Carothers and Collins (US Patent 1 950431) following work 

In the older acetylene route, acetylene is first dimerized to monovinyl acetylene in a concentrated aqueous solution of a complex salt of cuprous chloride. 

The purified monovinyl acetylene is then hydrochlorinated in a concentrated solution of hydrochloric acid and cuprous chloride. The reaction first involves 1,4- addition of hydrochloric acid to give a chlorallene which promptly rearranges to give the desired monomer together with a by-product, l,3-dichloro-2-butene, (Carothers et al., 1932 1933). The dried polychloroprene is then separated from this and other by-products by vacuum distillation in the presence of inhibitors  

The alternative route from butadiene involves, in sequence, chlorination, isomerization and dehydrochlorination  

The monomer is a colourless, highly reactive liquid boiling at 59-4T. It is toxic, flammable and forms explosive mixtures with air in the 4-20 vol% concentration range. The free radical activity of the monomer is enhanced by the electron-rich chlorine atom which stabilizes the product of free radical attack in an active mode thus permitting sequential reaction. 

Cyclic acetals of ketoses are prepared most commonly from acetone or benzaldehyde formaldehyde, acetaldehyde, butanone, and cyclohexanone have been used occasionally. These carbonyl reagents are frequently used directly, although such derivatives as 2,2-di-methoxy- or 2,2-diethoxy -propane (acetone dialkyl acetals), or l,l-dimethoxyethane (acetaldehyde diethyl acetal), are often employed in experiments in which intermediate acetals are of interest,or in which the presence of water in the reaction mixture adversely affects the yield of products. A polymeric form of an aldehyde is the reagent to be preferred whenever the monomer is volatile for example, acetaldehyde is often used in the form of a trimer, paraldehyde, and formaldehyde is employed as formalin solution, as paraformaldehyde, or as polyoxymethylene. An excess of the carbonyl reagent is generally used as the solvent, and the condensation is usually effected at room temperature. 

The factor most influential in determining the outcome of a condensation reaction is the catalyst. The catalysts most commonly employed are mineral acids, although copper(lI) sulfate, phosphorus pentaoxide, ethyl metaphosphate, cation-exchange resins in the acid form, and zinc chloride (alone - or in combination 

The concentrations of mineral acids generally used are 0.2-1.5% of hydrogen chloride or 0.25-5.0% of concentrated sulfuric acid, although the use of sulfuric acid at concentrations ranging up to 50% has been reported. The use of 75% of phosphoric acid as catalyst in the formation of methylene acetals has also been described.  

The concentration of catalyst and the time for reaction is especially important when isomeric products can be expected. For example, several workers - - have shown that the proportions of l,2 4,5-di-0-isopropylidene-)8-D-fructopyranose (1) and 2,3 4,5-di-0-isopropyli-dene-)8-D-fructopyranose (2), in the product of the reaction of D- 

Condensations may be conducted under very mild conditions by using anhydrous copper(II) sulfate alone,or combined with a low concentration (0.1%) of sulfuric acid. At room temperature, in the absence of acid, the reaction is allowed to proceed for periods of from 2 days up to 7 days.  

Metal Cyanides, Carbides, Carbonyls, and Alkyls Metal carbonyls Preparation and properties 

The compounds of CO with the alkali metals and the alkaline-earths are quite different in structure from those of the transition metals. The compound K2(CO)2 formed by the action of CO on the metal dissolved in liquid NH3 is a salt containing the linear acetylenediolate ion (OC CO) in which the bond lengths are C—C, 1-21 A, and C—O, 1-28 This salt is also formed from CO and the molten metal at low temperatures at higher temperatures (above I80°C) the productis predominantly Cj(OK)j. The so-called carbonyls of the alkaline-earths made from the metals and CO in liquid NH3 are mixtures of the metal acetylenediolates and methoxides with ammonium carbonate. 

Certain of the salts of the I B subgroup metals combine with CO forming, for example, CuQ(CO). 2 H2O, Ag2S04. CO, and AuCl(CO), of which the last is a comparatively stable volatile compound. The structures of these compounds are not known, and we shall confine our attention here to the carbonyls and related compounds of transition metals. 

The carbonyls are in general volatile compounds with an extensive chemistry which presents many problems as regards valence and stereochemistry. Some are reactive and form a variety of derivatives, as shown in Chart 22.1 for the iron compounds, while others are relatively inert, as for example, Cr(CO)6 etc. and Re2(CO)iQ. This rhenium compound, although converted to the carbonyl halides by gaseous halogens, is stable to alkalis and to concentrated mineral acids. A few carbonyls may be prepared by the direct action of CO on the metal, either at atmospheric pressure (Ni(C0)4) or under pressure at elevated temperatures (Fe(CO)s, Co4(CO)i2)- Others are prepared from halides or, in the case of Os and Re, from the highest oxide. The polynuclear carbonyls are prepared photo-synthetically, by heating the simple carbonyls, or by other indirect methods. 

The carbonyl hydrides are prepared either from the carbonyls, as shown in the chart for Fe(CO)4H2, by reduction with Na in liquid NH3, for Ni2(CO)6H2, or directly from the metal by the action of a mixture of CO and H2. Cobalt in this way gives Co(CO)4H. 

More than a century ago, Weyl [71] discovered that alkali metals dissolved in liquid ammonia to give a stable, blue solution. It was not until 1908, however, that Kraus [72], as a result of electrolytic and conducti-metric studies, suggested that the blue colour was due to the solvated electron. Subsequent experiments confirmed this [73]. 

One of the interesting properties of the solution of sodium metal in liquid ammonia is its high equivalent conductivity. It is tempting to suggest, as did early postulates, that this conductivity is due to the equilibrium 

This is an oversimplification since later work showed that, at high concentrations of alkali metal, the equivalent conductivity increases with metal concentration [74], Results are shown in Fig. 5. At high concen- 

The complexity of metal—liquid ammonia solutions indicates that care must be taken in interpreting reactions in this system. Thus it is important to be able to distinguish between reactions of the single reducing species and those of aggregates. 

Several models have been proposed for the structure of the ammoniated electron. One which has shown qualitative agreement with experimental 

The primary crystalline polymer based on CHDM is the terephthalate, poly(l,4-cyclohexylenedimethylene terephthalate) (PCT). This polyester was originally developed for fiber applications but has since found wider utility as a reinforced polymer for injection molding and (when copolymerized with a small amount of isophthalic acid) as a material for crystallized food packaging trays. The key property of PCT which sets it apart from other thermoplastic polyesters in tliese latter applications is its melting point. 

When made with the normal 70/30 trans/cis CHDM isomer ratio, the melting point of PCT is about 290 °C. The melting point varies substantially with isomer 

The strong sub-Tg relaxation in PCT also contributes to increased toughness of this polymer in the amorphous state. When measured on amorphous specimens, the notched Izod impact strength of PCT is greater than 1000 J/m, while that of PET is less than 100 J/m [22]. 

If PCT is modihed with relatively high levels of comonomer, substantially amorphous materials result (see die following sections on PETG, PCTG and PCTA). However, it is possible to maintain ciystallinity at lower levels of modification. For example, replacing up to about 10 mol% of die terephdialate units widi isophdialate results in a polymer widi reasonable crystallization rates and ultimate degrees of ciystallinity. 

Ciystalline polyesters from CHDM and aliphatic diacids are possible, but generally of little interest because of low melting points and low glass transition temperatures. Cyclic aliphatic diacids offer some potentially attractive possibilities. For example, tire polyester of CHDM with a high-frans isomer 1,4-cyclohexanedicarboxylate has a melhng point ( 225 °C) similar to drat of PBT [53]. 

Soderquist JA (1995) In Paquette LA (ed) Encyclopedia of reagents for organic synthesis, vol. 1. Wiley, New York, p 622 

Koster [1] was the first to report the preparation, isolation, and characterization of 9-borabicyclo[3.3.1]nonane as a dimer (9-BBN)2 has been obtained from the thermal disproportionation of tetra-n-propyldiborane and B-n-propyl-9-BBN (Eq. 3.1). B-alkyl-9-BBN preparation is itself a two-step process, thus restricting the utility of the 9-BBN for synthetic purposes. 

However, the direct and convenient synthesis of (9-BBN)2 has been reported by Knights and Brown [2], and this development opened the door for its application in hydroboration [2-5]. The synthesis involves the cyclic hydroboration of 1,5-cyclooctadiene with a borane-tetrahydrofuran (THF) complex [2, 3] in a 1 1 ratio, followed by refluxing the mixture at 65 °C, thus producing a solution containing (9-BBN)2 in ca. 90% yield. 

In fact, the borane adds to 1,5-cyclooctadiene to afford 1,4- and 1,5-isomers in a 30 70 mixture. With simple thermodynamic considerations, it is apparent that the 1,4-isomer, which has a seven-membered ring fused to a five-membered ring, is less stable. Consequently, the 1,4-addition product is easily isomerized to the 1,5-isomer at 65 C (Eq. 3.2). This process affords a microcrystalline product with a melting point (m.p.) of 142 C. This material is further purified by vacuum sublimation, with an increase in m.p. to 152-155 °C [5]. 

9-BBN exists as the dimer [A] both in the vapor state and in a crystalline solid state. The chair-chair conformation of the dimer and the B-H bridge has been confirmed by spectral studies [5] and crystal structure determination [6]. 

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Ebbesen T W 1997 Carbon Nanotubes—Preparation and Properties (Boca Raton, FL Chemical Rubber Company)... 

Nuzzo R G, Fusco F A and Aiiara D L 1987 Spontaneousiy organized moiecuiar assembiies. 3. Preparation and properties of soiution adsorbed monoiayers of organic disuiphides on goid surfaces J. Am. Chem. Soc. 109 2358-68... 

Pathmamanoharan C and Philipse A P 1998 Preparation and properties of monodisperse magnetic cobalt colloids grafted with polyisobutene J. Colloid Interface Sol. 205 304-53... 

If an unknown compound gives a positive test with the 2 4-dinitrophenylhydrazine reagent, it then becomes necessary to decide whether it is an aldehyde or a ketone. Although the dimedone reagent (Section 111,70,2) reacts only with aldehydes, it is hardly satisfactory for routine use in class reactions. It is much simpler to make use of three other reagents given below, the preparation and properties of which have already been described (Section 111,70). 

Preparation and properties of nitronium salts The first preparation of a nitronium salt by Hantzsch, who isolated the perchlorate mixed with hydroxonium perchlorate, and some of the subsequent history of these salts has already been recounted ( 2.3.1). 

Unlike most ethers epoxides (compounds m which the C—O—C unit forms a three membered ring) are very reactive substances The principles of nucleophilic sub stitution are important m understanding the preparation and properties of epoxides... 

We 11 begin by describing the preparation and properties of p keto esters proceed to a discussion of their synthetic applications continue to an examination of related species and conclude by exploring some recent developments m the active field of synthetic car banion chemistry... 

In this article the preparation and properties of typical high performance fibers are discussed, then their appHcations are classified and detailed. 

The preparation and properties of these tertiary aminimides, as weU as suggested uses as adhesives (qv), antistatic agents (qv), photographic products, surface coatings, and pharmaceuticals, have been reviewed (76). Thermolysis of aminimides causes N—N bond mpture foUowed by a Curtius rearrangement of the transient nitrene (17) intermediate to the corresponding isocyanate ... 

A review covers the preparation and properties of both MABS and MBS polymers (75). Literature is available on the grafting of methacrylates onto a wide variety of other substrates (76,77). Typical examples include the grafting of methyl methacrylate onto mbbers by a variety of methods chemical (78,79), photochemical (80), radiation (80,81), and mastication (82). Methyl methacrylate has been grafted onto such substrates as cellulose (83), poly(vinyl alcohol) (84), polyester fibers (85), polyethylene (86), poly(styrene) (87), poly(vinyl chloride) (88), and other alkyl methacrylates (89). 

D. Rubiu, Polj(1 -Putene) Its Preparation and Properties, Gordon Breach, New York, 1968. 

Preparation and Properties of Organophosphines. AUphatic phosphines can be gases, volatile Hquids, or oils. Aromatic phosphines frequentiy are crystalline, although many are oils. Some physical properties are Hsted in Table 14. The most characteristic chemical properties of phosphines include their susceptabiUty to oxidation and their nucleophilicity. The most common derivatives of the phosphines include halophosphines, phosphine oxides, metal complexes of phosphines, and phosphonium salts. Phosphines are also raw materials in the preparation of derivatives, ie, derivatives of the isomers phosphinic acid, HP(OH)2, and phosphonous acid, H2P(=0)0H. 

Light-focusing plastic rods and other optical devices with graduated refractive indexes may use DADC and other monomers (29). Preparation and properties of plastic lenses from CR-39 are reviewed in reference 30. 

R. K. Obedander ia B. E. Leach, A., Aluminas for Catalysis Their Preparation and Properties, Vol. 3, Applied Industrial Catalysis, Academic Press, New York, 1984, pp. 98-102. 

H. Alter and J. J. Duim, Jr., Solid Waste Conversion to Energy Current European and U.S. Practices, Marcel Dekker, Inc., New York, 1980, Chapt. 5 H. Alter andj. A. CampbeU, in J. L. Jones and S. B. Radding, eds.. The Preparation and Properties ofDensified Refuse-Derived Fuel, Thermal Conversion of Solid Wastes andBiomass, American Chemical Society, Washington, D.C., 1980, pp. 127—142. 

J. F. Smith and co-workers. Thorium Preparation and Properties, Iowa State University Press, Ames, Iowa, 1975. 

R. Benesch and R. E. Benesch, iu E. Antonini, L. R. Rossi-Bemardi, and E. Chiancone, eds.. Methods in En mology Hemoglobins, Academic Press, New York, 1981, pp. 147—158. Preparation and properties of hemoglobin modified with dedvatives of Pyridoxal. 

Chlorosulfuric acid preparation and properties were described in 1854 (1), but the stmcture was debated for many years until it was shown in 1941 by magnetic susceptibiUty measurements that the chlorine was bonded direcdy to the sulfur atom (2). The chlorosulfuric acid stmcture (Cl—SO2—OH) is analogous to the stmcture of sulfuric acid, the chlorine replacing one of the hydroxyl groups (see SuLFURic ACID AND Sulfurtrioxide). This stmcture has been substantiated using Raman spectra (3,4). 

Sodium ionophore V (ETH 4120) [4-octadecanoyloxymethyl-A, A, A, A -tetracyclohexyl-1,2-phenylenedioxydiacetamide] [129880-73-5] M 849.3. Purified by recrystn from EtOAc. [Preparation and properties Anal Chim Acta 233 295 1990],... 

RAFF, R. A. V. and DOAK, K. w. (Eds.), Crystalline Olefin Polymers, Interscience, New York (1964) RUBIN, I. D., Poly-1-butene its Preparation and Properties, Macdonald, London (1969)... 

The foregoing facts of relevance to the preparation and properties of silicone polymers may be summarised as follows... 

Carbon Nanotubes Preparation and Properties, ed. T.W. Ebbesen, 1997, CRC Press, Boca Raton. 

Lin, R. Y. and Economy, J., Preparation and properties of activated carbon fibers derived from phenolic resin precursor, Appl. Polym. Symp., 1973, 21, 143 152. 

Oya, A., Yoshida, S., Aleaniz-Monge, J. and Linares-Solano, A., Preparation and properties of an antibaeterial aetivated earbon fiber eontaining mesopores. Carbon, 1996, 34(1), 53 57. 

See, e.g., Endo, M., Saito, R., Dresselhaus, M. S. and Dresselhaus, G., From carbon fibers to nanotubcs. In Carbon Nanotubes Preparation and Properties, ed. T. W. Ebbesen, CRC Press, Boca Raton, FL, 1997,... 

Ohki, Y., New Tc-electron materials preparation and properties. In Supercarbon, Synthesis, Properties and Applications, ed. S. Yoshimura and R. P. H. Chang. Springer-Verlag, Heidelberg, 1998, pp. 149 166. 

Preparation and Properties of Chiral Ruoroorgamc Compounds Bravo, P, Resnati G Tetrahedron Asvmmetry / 661-692 300 ... 

Several studies have investigated the preparation and properties of trifluo-romethyl and pentafluorophenyl cadmates [132, 733]... 

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