C-a-Vinylation

Schildknecht, C. A., Vinyl and Related Polymers, pp. 323, New York, John Wiley and Sons, 1952. 

Allylamines are not easily cleaved with Pd catalysts, but the carbonylation of the allylic amine 395 proceeds at 110 C to give the /3,7-unsaturated amide 396 by using dppp as a ligand[252], Dccarboxylation-carbonylation of allyl diethyl-carbamate under severe conditions (100 C, 80 atm) affords /3,7-unsaturated amides[2531. The 3-vinylaziridine 397 is converted into the a-vinyl-J-lactam 398 under mild conditions[254]. 

Note that this inquiry into copolymer propagation rates also increases our understanding of the differences in free-radical homopolymerization rates. It will be recalled that in Sec. 6.1 a discussion of this aspect of homopolymerization was deferred until copolymerization was introduced. The trends under consideration enable us to make some sense out of the rate constants for propagation in free-radical homopolymerization as well. For example, in Table 6.4 we see that kp values at 60°C for vinyl acetate and styrene are 2300 and 165 liter mol sec respectively. The relative magnitude of these constants can be understod in terms of the sequence above. 

A Vinyl-2-pyrrolidinone. l-Ethenyl-2-pyrrohdinone [88-12-0] C H NO, A/-vinylpyrrohdinone, was developed by Reppe s laboratory in Germany at the beginning of World War II and patented in 1940 (215). 

Although most aromatic modified C-5 resins are typically higher softening point resins, certain appHcations, such as adhesives, require lower softening points. Copolymerization of a C-8—C-10 vinyl aromatic fraction with piperylenes in the presence of a C-4—C-8 mono-olefin chain-transfer stream yields resins with softening points ranging from 0—40°C (44). A particular advantage of these Hquid resins is the fact that they eliminate the need for plasticizers or oils in some pressure sensitive adhesive appHcations. 

Vinyl ethers are prepared in a solution process at 150—200°C with alkaH metal hydroxide catalysts (32—34), although a vapor-phase process has been reported (35). A wide variety of vinyl ethers are produced commercially. Vinyl acetate has been manufactured from acetic acid and acetylene in a vapor-phase process using zinc acetate catalyst (36,37), but ethylene is the currently preferred raw material. Vinyl derivatives of amines, amides, and mercaptans can be made similarly. A/-Vinyl-2-pyrroHdinone is a commercially important monomer prepared by vinylation of 2-pyrroHdinone using a base catalyst. 

Vinyllithium [917-57-7] can be formed direcdy from vinyl chloride by means of a lithium [7439-93-2] dispersion containing 2 wt % sodium [7440-23-5] at 0—10°C. This compound is a reactive intermediate for the formation of vinyl alcohols from aldehydes, vinyl ketones from organic acids, vinyl sulfides from disulfides, and monosubstituted alkenes from organic halides. It can also be converted to vinylcopper [37616-22-1] or divinylcopper lithium [22903-99-7], which can then be used to introduce a vinyl group stereoselectively into a variety of a, P-unsaturated systems (26), or simply add a vinyl group to other a, P-unsaturated compounds to give y, 5-unsaturated compounds. Vinyllithium reagents can also be converted to secondary alcohols with trialkylb o r ane s. 

Ma.nufa.cture. The principal manufacturers of A/-vinyl-2-pyrrohdinone are ISP and BASF. Both consume most of their production captively as a monomer for the manufacture of PVP and copolymers. The vinylation of 2-pyrrohdinone is carried out under alkaline catalysis analogous to the vinylation of alcohols. 2-Pyrrohdinone is treated with ca 5% potassium hydroxide, then water and some pyrroHdinone are distilled at reduced pressure. A ca 1 1 mixture (by vol) of acetylene and nitrogen is heated at 150—160°C and ca 2 MPa (22 atm). Fresh 2-pyrrohdinone and catalyst are added continuously while product is withdrawn. Conversion is limited to ca 60% to avoid excessive formation of by-products. The A/-vinyl-2-pyrrohdinone is distilled at 70-85°C at 670 Pa (5 mm Hg) and the yield is 70-80% (8). 

Pyrolysis. Pyrolysis of 1,2-dichloroethane in the temperature range of 340—515°C gives vinyl chloride, hydrogen chloride, and traces of acetylene (1,18) and 2-chlorobutadiene. Reaction rate is accelerated by chlorine (19), bromine, bromotrichloromethane, carbon tetrachloride (20), and other free-radical generators. Catalytic dehydrochlorination of 1,2-dichloroethane on activated alumina (3), metal carbonate, and sulfate salts (5) has been reported, and lasers have been used to initiate the cracking reaction, although not at a low enough temperature to show economic benefits. 

At least two catalytic processes have been used to purify halogenated streams. Both utilize fluidized beds of probably noimoble metal catalyst particles. One has been estimated to oxidize >9000 t/yr of chlorinated wastes from a vinyl chloride monomer plant (45). Several companies have commercialized catalysts which are reported to resist deactivation from a wider range of halogens. These newer catalysts may allow the required operating temperatures to be reduced, and stiU convert over 95% of the halocarbon, such as trichlorethylene, from an exhaust stream. Conversions of C-1 chlorocarbons utilizing an Englehardt HDC catalyst are shown in Figure 8. For this system, as the number of chlorine atoms increases, the temperatures required for destmction decreases. 

The additional coupling (9.8 Hz) of the cyclopropane proton A at <5// = 1.60 is the result of a vicinal H atom in the side-chain. This contains a methyl group B, a vinyl group C and an additional substituted ethenyl group D, as may be seen from the one dimensional H and C NMR spectra and from the CH COSY diagram. 

Figure 13.1. (a) Polychlorotrifluoroethylene (PCTFE). (b) Polytetrafluoreoethylene (PTFE). (c) Poly(vinyl fluoride), (d) Poly(vinylidene fluoride)... 

FINCH, c.A. (Ed.), Polyvinyl alcohol Properties and Applications, Wiley New York (1973) PRITCHARD, J.G., Poly(Vinyl alcohol) Basic Properties and Uses, Macdonald, London (1970) Properties and Applications of Polyvinyl Alcohol (SCI Monograph No. 30), Society of the Chemical Industry, London (1968)... 

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