Chemistry of small ring compounds Part 15: The kinetics of the Cannizzaro reaction of cyclopropanecarbaldehyde

In aqueous sodium hydroxide, cyclopropanecarbaldehyde 1 disproportionates exclusively into cyclopropylmethanol 2 and cyclopropanecarboxylic acid 3 (Cannizzaro reaction). The reaction is second order in aldehyde and second order in base and shows a small positive salt effect. These results and the absence of deuterium incorporation in the alcohol 2, when the reaction is carried out in D2O, have been rationalized in scheme 1. The enthalpy and entropy of activation are found to be ΔH≠ = 11.7 ± 0.6 kcal/mole and ΔS≠ = −17.5 ± 1.0 e.u. (74°). The results of the crossed Cannizzaro reaction between benzaldehyde and cyclopropanecarbaldehyde suggests that cyclopropyl is a better electron-donating group than phenyl.