Prey ether cleavage

What is Prey ether cleavage?

The Prey ether cleavage, a simple and convenient method for cleaving aliphatic-aromatic ethers by heating a mixture of the appropriate ether and pyridine hydrochloride, was first introduced by Klemenc in 1916 and further developed by Prey in 1941.

Prey ether cleavage has been used to remove methyl groups in several compounds, including anisole, phenetole, o-methoxyphenol, o-dimethoxybenzene, anisaldehyde, methoxy-illudinine, and 3,5-dichloro-2-methoxy-6-methylacetophenone. Additionally, this transformation has been used to prepare a series of phenol derivatives, such as p-pentadecylphenol, desoxymorphine, and β-dihydrothebainol. It is worth noting that phenyl ethyl ether can also be cleaved using this reaction, albeit at a slower rate.

Dry hydrogen chloride does not cleave the listed ethers under similar conditions; however, passing dry hydrogen chloride into the reaction system in the presence of a few percent of pyridine hydrochloride is sufficient to facilitate this reaction.

The Prey ether cleavage has been successfully employed to cleave both methyl aromatic ethers and phenoxy esters. Furthermore, this reaction has been utilized for accurate determination of methoxyl groups, with a precision of 1%, by converting pyridine hydrochloride to N-methylpyridinium chloride.


  • Klemenc, A., Ber., 1916, 49, 1371
  • Prey, V., Ber., 1941, 74, 1219
  • Prey, B., Ber., 1942, 75, 350
  • Prey, B., Ber., 1942, 75, 445
  • Prey, B., Ber., 1942, 75, 537
  • Prey, B. Ber., 1943, 76, 156