Patent GB-654243-A (GB)
Title: Improvements in or relating to esters of beta-chloro and beta-bromo carboxylic acidsand methods of preparing same
IPC: C07C69/63
Filed: 1946-09-03
Abstract: Chloroisopropenyl acrylate produced by reacting 1,3-dichloroisopropanol with hydrogen chloride and distilling the product under reduced pressure (see Group IV (b)), polymerizes in the presence of peroxide catalysts to form a hard polymer.ALSO:An ester of a beta-chloro or beta-bromo carboxylic acid or an ester of an alpha-beta unsaturated carboxylic acid derived by dehydrohalogenation thereof is obtained by reacting a beta-lactone of the general formula <FORM:0654243/IV (b)/1> wherein each one of the groups R1, R2, R3, R4 is a hydrogen atom or an alkyl group, an alcohol and hydrogen chloride or hydrogen bromide.  When the ester formed contains a plurality of halogen atoms, as when a polyhydric alcohol or a halogenated alcohol is used, it is generally unstable and loses one or more molecules of hydrogen halide when heated to form the unsaturated ester.  When beta-propiolactone and an alkyl alcohol are employed the products are beta-halo propionic acids and these esters may be converted to alkyl acrylates by treatment with alkali metal hydroxides or strong acids.  Such treatment may be applied directly to the reaction mixture which is then distilled to yield the alkyl acrylate.  Other beta-lactones specified are those listed in the parent Specification.  The reaction may be effected in the presence of a metal halide catalyst, e.g. zinc chloride, aluminium chloride, ferric chloride and aluminium bromide.  Solvents for the reactants may be present especially when the alcohol is a solid.  When ethylene glycol, beta-propiolactone and hydrogen chloride are used the product first formed is ethylene glycol di-beta-chloropropionate which is unstable and may be dehydrochlorinated, e.g. by distillation, to produce ethylene glycol diacrylate.  In examples: (1) ethyl beta-chloropropionate is obtained by saturating absolute ethanol with anhydrous hydrogen chloride, refluxing the solution and slowly adding a solution of beta-propiolactone in ethanol while hydrogen chloride is continuously introduced; (2) hydrogen chloride is introduced into a solution of beta-propiolactone and ferric chloride in ethanol, the solution being maintained at 0 DEG  to 10 DEG  C.  The mixture is allowed to warm to room temperature and after saturating with hydrogen chloride is allowed to stand overnight, poured into ice-water and the oil extracted with ether, yielding the ester obtained in (1); (3) beta-propiolactone is added to a solution of hydrogen chloride in ethanol at 2-10 DEG  C., hydrogen chloride being also passed in during the addition to keep the solution saturated. Distillation yields the same ester product as in (1); (4) and (5) the procedure of (3) is repeated using n-butanol instead of ethanol, the solution temperature in the second case being 25 DEG  to 30 DEG  C. n-Butyl beta-chloropropionate is obtained; (6) to (8) methanol, n-propanol and 2-ethyl hexanol are used, the corresponding beta-chloropropionic ester being obtained employing the procedure of (3); (9) beta-propiolactone is dissolved in ethanol and hydrogen bromide added at 2-5 DEG  C. Distillation yields ethyl beta-bromopropionate; (10) hydrogen chloride is bubbled into a solution of beta-propiolactone in ethylene chlorhydrin at 0 DEG  to 10 DEG  C., yielding beta-chloroethyl-beta-chloropropionate; (11) beta-propiolactone dissolved in ethylene chlorhydrin is added to ethylene chlorhydrin heated to reflux temperature and then hydrogen chloride bubbled in.  On distilling, hydrogen chloride is liberated, yielding 2-chloroethyl acrylate.  By distilling at higher pressure further dehydrochlorination may be effected and vinyl acrylate obtained; (12) hydrogen chloride is passed into a solution of 1,3-dichloro-isopropanol at 10-15 DEG  C.  Distillation of the product under reduced pressure yields chloroisopropenyl acrylate. Other alcohols specified are isopropyl alcohol, tert.-butyl alcohol, amyl, hexyl, heptyl, octyl, decyl, and dodecyl alcohols, unsaturated aliphatic monohydric alcohols, e.g. allyl alcohol; cyclohexanol, benzyl alcohol, furfuryl and tetrahydrofurfuryl alcohols, diethylene glycol, glycerol, diethylene glycol monoethyl ether, beta-ethoxy ethanol, trimethylene chlorohydrin (or bromohydrin), glycerol alpha-chlorohydrin, alpha-beta glycerol dichlorohydrin, nitro-substituted alcohols, e.g. 2-nitro ethanol; lactic acid, methylol urea and beta-mercapto ethanol.  Specification 654,251 is referred to.  The Specification as open to inspection under Sect. 91 also includes the additional beta-lactones listed in the parent Specification, as open to inspection, and mentions hydrogen iodide as hydrogen halide.  U.S.A. Specification 1,864,884 also is referred to. This subject-matter does not appear in the Specification as accepted.