IL41781A - Alpha,alpha'-dichloro and dibromo alkanoic acid anhydrides and a process for their preparation - Google Patents

Description

d broiao alkanoic acid anhydrides and a process for their preparation Plantex The present invention relates to new or dibr aliphatic acid anhydrides of general formula I X t X in which R stands for an alkyl radical having carbon atoms and X stands for either chlorine or The ne anhydrides are intermediates in a process for the preparation of or acids having at least 13 carbon they are themselves valuable chemical compounds and may be for as There is known a process for the preparation of up to aliphatic acids having 12 carbon which consists in the bromination of the corresponding acid anhydrides with bromine in a stoichometric proportion at a temperature of about temperatures are indicated herein in degrees to yield a mixture of the corresponding and the corresponding this when applied to having more than 12 carbon atoms does not yield the above mixture but yields the corresponding aliphatic acid anhydride in substantially theoretically There has been developed a which is the subject matter of Application 41782 for the preparation of aliphatic acids which have up to 12 carbon atoms in which the corresponding acid anhydride is first with a small amount of preferably about to of the anhydride and then chlorinated with the appropriate amount of chlorine to yield a mixture of the corresponding in this process when an acyl anhydride having more than 12 carbon atoms is utilised there was no mixture of the acyl chloride and of the but the acid was The present invention thus consists in a process for the preparation of the dibromp aliphatic acid anhydride of general formula I and the corresponding acids in which either the corresponding acyl anhydride having atoms is with bromine in a substantially stoichometric amount or said acyl anhydride is first initiated with a small amount of bromine and then chlorinated with the appropriate amount of chlorine and the anhydride obtained if subjected to hydrolysis in order to yield the corresponding In the procedure chlorination the preferred amount of bromine utilised is about of the anhydride advantageously about Said acids are also valuable plasticisers and intermediates for the preparation of other chemical The and chlorination reaction should be performed at about The hydrobromic or hydrochloric acid ed is absorbed by methods known per The hydrolysis is preferably performed with sodium The acids are then precipitated by the addition of hydrochloric The invention will now be illustrated with reference to the following examples without being limited by Example 1 In a three neck flask provided with condenser and dropping 44 gr of myristic acid anhydride were heated to 32 g of were then added in the additional hour at 110 The reaction product was washed with water at room temperature and recrystallized from petroleum yield 49 g of acid The acid anhydride was suspended in water and a aqueous solution containing g of was The free acid was precipitated by the addition of a aqueous solution of The acid was filtered washed with water and Yield Example 2 In a three neck flask provided with condenser and dropping funnel 49 gr of palmitic acid anhydride were heated to 32 g of bromine were added in the course of two The reaction mixture was heated for one additional hour at The reaction product was washed with water at room temperature and recrystallized from petroleum yield 55 g of palmitic acid The acid anhydride was suspended in water and g of as a aqueous solution was added to the The sodium salt palmitic acid was obtained and a aqueous solution of HC1 was added to precipitate The acid was filtered washed with water and yield Example 3 In a three neck flask provided with condenser and dropping funnel gr of stearic acid anhydride were heated to 32 gr of were The reaction mixture was heated for one hour at after the had been added in the course of three The reaction product was washed with water and recrystallized from petroleum ether to yield 60 g of acid The acid anhydride in water suspension was treated with g of aqueous solution to get the sodium salt of the In order to obtain the free acid a aqueous solution of HC1 was added until the precipitation The bromostearic acid was filtered washed with water and insufficientOCRQuality

Claims (1)

1. \ Claims , α-Dichloro- or dibromo aliphatic acid anhydride of general formula I X » X in which R stands for an alkyl radical having u-t—iea¾-fc 12 -20 carbon atoms and X stands for either chlorine or bromine. a.a'-Dibromomyristic acid anhydride; α,α'-Dibromopalmitic acid anhydride* α,α'-Dibromostearic acid anhydride. A process for the preparation of the α,α'-dichloro-or dibromo aliphatic acid anhydride of general formula I as defined in Claim 1 and the corresponding a-chloro or bromo-aliphatic acids in which either the corresponding acyl anhydride having ΛΛΤ -21 least 13 carbon atoms is brominated with bromine in a substantia ially stoichometric amount or said acyl anhydride/firstbrominated with a small amount of bromine and then chlorinated with the appropriate amount of chlorine and the a.a'-dichloro- or di- bromo-acyl anhydride obtained is, if desired, subjected to hydrolysis in order to yield the corresponding a-chloro- or bromo-aliphatic acid* A process according to Claim 5, wherein the amount of bromine utilised is about 0.5 - 3$ of the anhydride utilised.; A process according to Claim 6, wherein said amoun is about 2#.. 41781/2 8· A process according to any of Claims 5 to 7» wherein the reaction is performed at 80-100°. 9. A process according to any of Claims 5 to 8, wherein the hydrolysis is performed with sodium carbonate. 10. A process for the preparation of α,a '-dichloro- or dibromo aliphatic acid anhydrides of general formula I as defined in Claim 1, substantially as hereinbefore described with reference to the Examples. 11. ά,α' -dichloro- or dibromo aliphatic acid anhydrides oi> general formula I as defined in Claim 1 whenever obtained by the process according to any of Claims 5 to 10. 12. A process for the preparation of o-chloro- or bromp- aliphatic acids having 13 to 21 carbon atoms, substantially as hereinbefore described with reference to the Examples. 13. . a-chloro-or bromo-aliphatic acids of general formula I as defined in Claim 1 having 13 to 21 carbon atoms, whenever obtained by the process according to any of Claims 5 to 9 or 12. For the Applicants Dr. Yitzhak Hess