Patent GB-654242-A (GB)
Title: Improvements in or relating to beta-chloro and beta-bromo carboxylic acids and method of preparing the same
IPC: C07C51/363
Filed: 1946-08-30
Abstract: Beta-chloro and beta-bromo carboxylic acids are obtained by reacting in solution in a polar solvent, other than an alcohol, for the reactants, a beta-lactone of the general formula <FORM:0654242/IV (b)/1> wherein each one of the groups R1, R2, R3, R4 is a hydrogen atom or an alkyl group, with hydrogen chloride or hydrogen bromide. Water is the preferred polar solvent but acetic acid and other liquid organic acids and nitro-paraffins may also be used.  An excess of the hydrogen halide is preferably used and temperatures of -25 DEG  to 25 DEG  C. are preferred although temperatures as low as -30 DEG  C. or as high as 100 DEG  C. may be used.  The hydrogen halide either in the gaseous form or dissolved in a polar solvent may be added to a solution in a polar solvent of the beta-lactone or the beta-lactone may be added to a solution of the hydrogen halide in the polar solvent. In examples: (1) gaseous hydrogen chloride is bubbled into a solution of beta-propiolactone in water at 0 DEG  to 5 DEG  C., yielding beta-chloro propionic acid; (2) beta-propiolactone is added to aqueous hydrochloric acid yielding the same product as in (1); (3) and (4) hydrogen bromide is bubbled into a solution of beta-propiolactone in water and in glacial acetic acid, respectively, at 0 DEG  to 5 DEG  C., yielding beta-bromo-propionic acid. Other beta-lactones specified are beta-butyrolactone, beta-isobutyrolactone, beta-valerolactone, beta - isovalerolactone, beta - n - caprolactone, alpha-ethyl-beta-propiolactone, alpha - methyl (or ethyl) - beta - butyrolactone alpha-isopropyl (or butyl)-beta-propislactone, and beta - methyl - beta - valerolactone. Specification 649,028, as open to inspection under Sect. 91, is referred to.  The Specification as open to inspection under Sect. 91 states that beta-lactones containing cycloalkyl, aryl and aralkyl substituents, e.g. beta - cyclohexyl - beta - propiolactone, betaphenyl - beta - propiolactone, alpha - phenyl - beta-propiolactone, beta-benzyl-beta-propiolactone or any beta-lactone in which the groups R1, R2, R3, R4 are hydrocarbon groups free from aliphatic unsaturation, may be used.  Other beta-lactones specified are those of unsaturated beta-hydroxy carboxylic acids, mono-beta-lactones of dicarboxylic acids and dilactones of dicarboxylic acids such as alpha, alphadimethyl - beta - propiolactone - beta - carboxylic acid, trimethyl-beta-propiolactone-alpha (or beta)-carboxylic acid, beta, beta-dimethyl-beta-propiolactone-alpha-carboxylic acid, and citrylidene malonic acid beta-delta-dilactone. Beta-lactones in which the alpha and beta carbon atoms are attached to groups containing elements such as oxygen, nitrogen, sulphur and halogen, e.g. those containing amino, nitro and hydroxy groups or ether linkages, may also be used.  Examples of these compounds are alpha- or beta-nitrophenyl-beta-propiolactone, beta - (o - nitro - m - chlorophenyl) - beta - propiolactone; beta-(o-nitro-m-methoxyphenyl)-beta - propiolactone, alpha - hydroxy - beta - phenyl - beta - propiolactone and alpha - bromobeta, beta - dimethyl - beta - propiolactone - alpha-carboxylic acid.  This subject-matter does not appear in the Specification as accepted.