Process for preparation of 1,4-haloallylic esters from dienes
AssigneeSCM Corporation
InventorCarlos G. Cardenas
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Abstract
A process for the synthesis of 1,4-haloallylic esters from conjugated dienes which comprises preparing a reaction mixture of the conjugated diene, a halogenating agent, and a carboxylic acid and then adding to said reaction mixture a catalytic amount of a strong acid having a high dissociation constant. The invention is particularly described with reference to the synthesis of isoprene-1,4-chloroacetate(1-chloro-4-acetoxy-2-methyl-2-butene) from isoprene wherein a reaction mixture is prepared of isoprene with t-butyl hypochlorite in excess glacial acetic acid, to which is added H.sub.2 SO.sub.4 followed by stirring at 50.degree. C.
Claims9
In a process for the synthesis of 1,4-haloallylic esters from C.sub.4 -C.sub.8 conjugated alkadienes which comprises reacting the conjugated alkadiene, a halogenating agent and a carboxylic acid, said carboxylic acid being a compound selected from the group consisting of alkanoic acids having one to eight carbon atoms, and benzoic acid to form a reaction product mixture containing 1,4-and 1,2-halocarboxylates and 1,4-haloethers, the improvement comprising;
- a. adding to said reaction product mixture a catalytic amount of strong acid having a dissociation constant above about 1 .times. 10.sup.-3 ;
- and
- b. stirring the mixture at room temperature to 100.degree. C. for a sufficient period of time to convert a substantial portion of the 1,2-halocarboxylate product and haloethers in the reaction mixture to the 1,4-halocarboxylate product.
In a process for the synthesis of 1-chloro-4-acetoxy-2-methyl-2-butene which comprises reacting isoprene with t-butyl hypochlorite in excess glacial acetic acid to form a reaction product mixture containing 1,4-and 1,2-chlorocarboxylates and 1,4-chloroethers;
- the improvement comprising
- a. adding a catalytic amount of product H.sub.2 SO.sub.4 to said reaction mixture;
- and
- b. stirring the same at room temperature to 100.degree. C for a reaction period sufficient to convert a substantial portion of 1,2-isoprene chloroacetate and chloroethers to 1-chloro-4-acetoxy-2-methyl-2-butene.
In the preparation of haloesters from C.sub.4 -C.sub.8 conjugated alkadienes wherein said alkadienes are reacted with a chlorinating agent and a carboxylic acid selected from the group consisting of alkanoic acids having one to eight carbon atoms, and benzoic acid to form a reaction product mixture containing 1,4- and 1,2-chlorocarboxylates and 1,4-chloroethers, the improvement comprising the steps of adding to said reaction product mixture a catalytic amount of a strong acid having a high dissociation constant above about 1 .times. 10.sup.-3, and stirring the mixture at room temperature to 100.degree. C. for a sufficient period of time to convert a substantial proportion of the 1,2-chlorocarboxylate and 1,4-chloroethers to the 1,4-chlorocarboxylate.
Dependencies are inferred from the claim text.