# Transformation of an epoxido-carboxylic acid to an aldehyde [duplicate]

This question already has an answer here:

So I am battling with the last part of this transformation and was hoping someone could explain this mechanism to me so that I can confirm my answer.

Treating an alcohol with a strong hydrohalic acid results in the formation of alkyl halide and proceeds through an SN1 mechanism. (Protonation of alcohol on the carboxylic acid, then loss of $\ce{H2O}$ to form a carbocation) But $\ce{HCl}$ is supposed to give a substitution reaction and not an elimination reaction. So I am unsure how the final product is formed.

## marked as duplicate by Mithoron, Gaurang Tandon, Todd Minehardt, Community♦Mar 24 '18 at 7:06

• Looking at the product, we can see there's a decarboxylation here due to the "heat". I bet the $\ce{HCl}$ is only to perform acidic cleavage of the epoxide. Though I am unsure how to knit both of them together. – Gaurang Tandon Mar 23 '18 at 11:34