Patent GB-646960-A (GB)
Title: Improvements in production of derivatives of gamma-bromo-alkanoic acids
Filed: 1948-01-30
Abstract: Styrene, ethyl acrylate and allyl chloride yield polymers when heated with alpha-bromoesters in the presence of a polymerization catalyst which generates free radicles under the conditions of the reaction, e.g. diacetyl and dibenzoyl peroxide.  For list of typical alpha-bromoesters (see Group IV (b)).ALSO:Alkyl esters of gamma bromo-alkanoic acids are obtained by heating a compound of general formula R-CH=CH-R1, wherein R is a substituted or unsubstituted aliphatic hydrocarbon radical which contains no double-bonds conjugated with respect to the olefinic double bond and R1 is hydrogen or methyl, with an alkyl ester of an alpha bromo-alkanoic acid in the presence of a catalytic quantity of a polymerization catalyst which generates free radicals under the conditions of the reaction.  When the p  above gamma esters are ethyl esters on heating they eliminate ethyl bromide to form the corresponding gamma lactone which may also be obtained generally from any of the described gamma esters on acidifying the solution obtained by hydrolyzing the said ester with aqueous fixed alkali.  Preferred alphabromo-esters are the alkyl esters of alphabromo-normal-alkanoic acids which may be mono- or di-basic and conform to the general formula <FORM:0646960/IV (b)/1> where R is alkyl, R1 is methyl, hydrogen or carbalkoxy and R11 is hydrogen, or an alkyl group and amongst numerous esters specified the following may be mentioned: methyl-bromo-acetate, ethyl-alpha-bromo-propionate, propyl-alpha-bromo-n-valerate, methyl-alpha-bromo-stearate, alkyl esters of mono-bromo-malonic acid and dimethyl-alpha-, alpha1-dibromo-adipate.  Propene, butene-1 and -2, hexene-1, octene-1, dodecane-1, diallyl and other olefinic hydrocarbons are mentioned together with esters of vinyl acetic and undecylenic acids and allyl acetate and chloride as compounds conforming to the formula R-CH=CH-R1.  Catalysts specified are to be found in U.S. Patent 2,402,137 and of these diacyl peroxides such as diacetyl and dibenzoyl peroxides are preferred.  Temperatures used should be sufficient to decompose the peroxide, the range 20-150 DEG C. being preferred.  With these temperatures, times of heating may range from 1 to 50 hours.  Preferably an excess of ester, e.g. from one to twenty mols., over olefinic compound is employed.  In examples: (1) to (7) the reactants are kept at 90 DEG  C. and diacetyl peroxide added in the bromo-ester during 3-10 hours under a nitrogen atmosphere, heating being maintained for 1-2 hours after the addition of the peroxide and thus octene-1 is reacted with (1) ethyl-bromo-acetate; (2) ethyl alpha-bromo-propionate; and (3) ethyl alpha-bromo-n butyrate to produce ethyl 3-bromo-decanoate, ethyl 3-bromo-1-methyl-decanoate and ethyl 3-bromo-1-ethyl decanoate, respectively; propylene is reacted with (4) ethyl bromo-acetate and (6) ethyl alpha-bromopropionate to produce ethyl gamma-bromo-n-valerate and ethyl gamma-bromo-alpha-methyl-valerate respectively; in (5) allyl chloride reacts with ethyl alpha-bromo-propionate to produce ethyl 4-bromo-5-chloro-2-methyl-n-valerate; and in (7) butene-2 with ethyl bromo-acetate produces ethyl gamma-bromo-betamethyl valerate; in (10)-(12) dibenzoyl peroxide is used as catalyst, conditions otherwise being similar, and in (10) octene-1 is reacted with diethyl alpha-bromo-malonate to produce ethyl alpha - carbethoxy - gamma - bromo - decanoate; in (11) allyl acetate and diethyl alpha-bromo-malonate produce ethyl alpha-carbethoxy - gamma - bromo - delta - acetoxy valerate; and in (12) diallyl and ethyl alpha-bromo-butyrate produce ethyl 2-ethyl-4-bromo-octene-7-oate or with an excess of the butyrate the diethyl ester of 4,7-dibromo-2,9-diethyldecanedioic acid is obtained; in (8), (9) and (12) gamma lactones are obtained from the products of (4), (1) and (12) respectively, by (8) and (12) refluxing with aqueous potassium hydroxide followed by acidification with hydrochloric acid, and (9) and (12) heating under reduced pressure to remove ethyl bromide and by the latter method ethyl gamma - bromo - alpha - methyl valerate and ethyl gamma-bromo-alpha,alpha-di-methyl caprate may also be lactonized.