On the reaction of furan with bromine in aqueous solution. Observation of the slow hydration of malealdehyde

The rate of reaction of furan with bromine in aqueous solution has been measured and the rate constant obtained by Williamson and Coller is confirmed. However, it is now found that the reaction of bromine with furan in water has two distinct stages: attack of bromine leading to the formation of malealdehyde 3 and hydration of 3 to a 2:1 mixture of the geometrical isomers of its cyclic hydrate 4 . This second, slower process is observable by stopped-flow uv spectrophotometry occurring after the consumption of bromine. The observed kinetics are very similar to those recently found for the analogous hydration of phthalaldehyde by McDonald and Martin.