Vinylic compounds

Vinyl compounds. Vinyl chloride (prepared from acetylene and hydrogen chloride) 3 ields polyvinyl chloride (P.V.C.), which is employed as a rubber substitute and for other purposes. Vinyl acetate (from... 

Pd(II) compounds coordinate to alkenes to form rr-complexes. Roughly, a decrease in the electron density of alkenes by coordination to electrophilic Pd(II) permits attack by various nucleophiles on the coordinated alkenes. In contrast, electrophilic attack is commonly observed with uncomplexed alkenes. The attack of nucleophiles with concomitant formation of a carbon-palladium r-bond 1 is called the palladation of alkenes. This reaction is similar to the mercuration reaction. However, unlike the mercuration products, which are stable and isolable, the product 1 of the palladation is usually unstable and undergoes rapid decomposition. The palladation reaction is followed by two reactions. The elimination of H—Pd—Cl from 1 to form vinyl compounds 2 is one reaction path, resulting in nucleophilic substitution of the olefinic proton. When the displacement of the Pd in 1 with another nucleophile takes place, the nucleophilic addition of alkenes occurs to give 3. Depending on the reactants and conditions, either nucleophilic substitution of alkenes or nucleophilic addition to alkenes takes place. 

Copolymerization can be carried out with styrene, acetonitrile, vinyl chloride, methyl acrylate, vinylpyridines, 2-vinylfurans, and so forth. The addition of 2-substituted thiazoles to different dienes or mixtures of dienes with other vinyl compounds often increases the rate of polymeriza tion and improves the tensile strength and the rate of cure of the final polymers. This allows vulcanization at lower temperature, or with reduced amounts of accelerators and vulcanizing agents. 

Uses. The a2obisnitriles have been used for bulk, solution, emulsion, and suspension polymeri2ation of all of the common vinyl monomers, including ethylene, styrene vinyl chloride, vinyl acetate, acrylonitrile, and methyl methacrylate. The polymeri2ations of unsaturated polyesters and copolymeri2ations of vinyl compounds also have been initiated by these compounds. 

The elastomer process is very similar to the Dennis process. It involves a number of steps in which a gas, formerly carbon dioxide and now fluorocarbon, is mixed with a plastisol under pressure. When released to atmospheric pressure, the gas expands the vinyl compounds into a low density, open-ceUed foam which is then fused with heat. 

Organosodium compounds are prepared from sodium and other organometaUic compounds or active methylene compounds by reaction with organic haUdes, cleavage of ethers, or addition to unsaturated compounds. Some aromatic vinyl compounds and aHyUc compounds also give sodium derivatives. 

Polymerization. Carbon monoxide forms copolymers with ethylene and suitable vinyl compounds. No large-scale uses for the copolymers or their further reaction products such as polyalcohols and polyamines have been found (75). 

H. J. Caesar and P. J. Davis "Flame Retardant Vinyl Compounds," 33rdA.nnua/ Technical Conference Atianta, Ga., May 6, 1975. 

Pure polymeric acrylonitrile is not an interesting fiber and it is virtually undyeable. In order to make fibers of commercial iaterest acrylonitrile is copolymerized with other monomers such as methacrylic acid, methyl methacrylate, vinyl compounds, etc, to improve mechanical, stmctural, and dyeing properties. Eibers based on at least 85% of acrylonitrile monomer are termed acryHc fibers those containing between 35—85% acrylonitrile monomer, modacryhc fibers. The two types are in general dyed the same, although the type and number of dye sites generated by the fiber manufacturing process have an influence (see Eibers, acrylic). 

Maleimides have three principal reaction pathways. These are radical addition to vinyl compounds the Michael addition with compounds having active hydrogens and the Diels-Alder reaction with dienes (Fig. 3). Any of the three can be tools for forming thermosetting adhesives. 

There has been only one major use for ozone today in the field of chemical synthesis the ozonation of oleic acid to produce azelaic acid. Oleic acid is obtained from either tallow, a by-product of meat-packing plants, or from tall oil, a byproduct of making paper from wood. Oleic acid is dissolved in about half its weight of pelargonic acid and is ozonized continuously in a reactor with approximately 2 percent ozone in oxygen it is oxidized for several hours. The pelargonic and azelaic acids are recovered by vacuum distillation. The acids are then esterified to yield a plasticizer for vinyl compounds or for the production of lubricants. Azelaic acid is also a starting material in the production of a nylon type of polymer. 

A special case of C-20 oxygen removal is the treatment of the 17,20-aceto-nide of a 21-brorao-17a,20(o or )-dihydroxy steroid with sodium in aqueous dioxane to produce a 17a-hydroxy-17jS-vinyl compound in 60% yield... 

Chloromethylbenzo-l,2,4-thiadiazine 1,1-dioxide forms quaternary salts, e.g. 8 (n = 1), with pyridine, 2- and 3-picolines, and iso-quinoljne, but the 3-(2 -chloroethyl) compound gives a lower yield of the salt, e.g. 8 (% = 2), because some of the halogen derivative is converted into the 3-vinyl compound. ... 

Following the data in publications (54TZV803 72ZOB802 74KGS310), which indicate that the vinyl compounds are phosphorylated more readily in benzene than in POCI3, the reaction was carried out in this last solvent. Accordingly, only chlorides 13a, 14a were formed from 4-acetyl-l,3-dimethylpyrazole (12a) in... 

In general, hydrogenolysis of vinylic compounds is favored by platinum and hydrogenation by ruthenium and rhodium 31,55,59,72,106). In the reduction of 4-methyl-1-cyclohexenyl ether, the order of decreasing hydrogenolysis to give methylcyclohexane was established as Pt Ir > Rh > Os Ru = Pd (52). 

As with vinyl compounds, the outcome of an allylic hydrogenation is the resultant of two competing reactions. 

Kamachi, M. Influence of Solvent on Free Radical Polymerization of Vinyl Compounds. Vol. 38, pp. 55-87. 

Formation of a vinyl-substituted pyrrolizidine derivative is also observed in case of an allylstan-nane cyclization94. Since the allylstannane moiety is acid sensitive, the iV-acyliminium ion is generated by exposure of the hydroxylactam to methanesulfonyl chloride and triethylamine in dichloromethane. The very rapid cyclization produces the endo-vinyl compound with very high stereoselectivity. 

Lithiochloromethyl phenyl sulfoxide 99 was found to react with aryl or alkyl halides in the presence of one equivalent of hexamethylphosphoramide to afford alkylated products 100 in high yields135. Thermal decomposition of these products in the presence of a catalytic amount of hydroquinone in xylene gave the corresponding vinyl compounds 101. 

Grubbs et al. reported that the ruthenium-catalyzed RCM of a conjugated diene proceeds in such a way that the less hindered olefin moieties participate in the reaction. Consequently, RCM of 115 gives exo-methylene compound 116, and not exo-vinyl compound 117 (Scheme 24) [105]. This regioselectivity is complementary to that observed for enyne metathesis of 118, which gives exclusively 117 (Scheme 24) [106a]. 

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