5- -2,2-dimethyl Isobutyryl chloride

The preparation of ketenes has been discussed by Hanford and Sauer in Organic Reactions Dimethylketene has been prepared by the treatment of a-bromoisobutyryl bromide with zinc,3 and by the pyrolysis of isobutyrylphthalimide,4 dimethylmalonic anhydride,6 or a-carbomethoxy-a,j3-dimethyl- -butyrolactone. Dimethylketene dimer has been prepared by heating isobutyryl chloride with a tertiary amine. Pyrolysis of the dimer yields dimethylketene.7... 

The method is apparently limited to the preparation of certain aryl and high-molecular-weight ketoketenes, which are relatively resistant to dimerization. Thus, the dehydrohalogenation of a low-molecular-weight acyl chloride such as isobutyryl chloride gives dimethyl ketene dimer (60%). It is quite possible that the tertiary amine salt catalyzes the dimerization. ... 

A soln. of 3 hydroxy-2,2,4-trimethyl-valeric acid in chloroform stirred with isobutyryl chloride for 1 hr. at 0-10° and 2 hrs. at room temp. -> a,a-dimethyl-/ -isopropyl-y -propiolactone. Y 81.4%. Also with other reagents... 

Preparation by reaction of isobutyryl chloride with 2-tert-butylhydroquinone dimethyl ether in the presence of aluminium chloride in carbon disulfide [7336]. 

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