Destabilisation of a carbocation by α-oxygen substitution: the hydrolysis of orthocarbonates

Abstract

Tetraphenyl orthocarbonate is hydrolysed by general acids 10¹-fold slower than triphenyl orthoformate, whilst tetrakis(p-methoxyphenyl) orthocarbonate is hydrolysed 10¹-fold faster than tetraphenyl orthocarbonate, with a Brønsted α-value closer to triphenyl orthoformate than tetraphenyl orthocarbonate, indicating that cation stability, not an early transition state, is the cause of the lower rate of the orthocarbonate.