Rearrangement with change of an oxygen group

The conversion of epoxides into carbonyl compounds is an irreversible reaction. At 400° ethylene oxide (oxirane) passes into acetaldehyde, and at 500° propylene oxide (1-methyloxirane) gives a 2 1 mixture of propion- 

Rosowsky in A. Weissberger, Heterocyclic Compounds with Three- and Four-membered Rings, Interscience Publ., New York-London, 1964, Vol. 19, Part 1, pp. 230 to 270. 

Studies of the direction of ring opening have often been made more difficult by competition between hydride shift and alkyl shift this occurs particularly with epoxides derived from multiply branched olefins. Reactions involving hydride shift are the transformation of cis-2,3-epoxybutane into butanone,25 of l-oxospiro[2.7]decane (the epoxide from methylenecyclooctane) into cyclo-octanecarbaldehyde,26 and that of 1,2-epoxy-1-phenethylcyclohexane into 2-phenethylcyclohexanone described by Grewe27 as follows  

The epoxide (10 g), concentrated hydrochloric acid (10 g), and methanol (50 ml) are heated together under reflux for several hours, whereafter the ketonic product is precipitated by water, taken up in ether, and purified by distillation in a vacuum (yield 60 % b.p. 174°/12 mm). 

In more recent work alkaline catalysts have been applied for rearrangement of epoxides, e.g. 2S 29 

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