Concerning the stability of benzyl alcohol: formation of benzaldehyde dibenzyl acetal under aerobic conditions.

An impurity in benzyl alcohol was identified as benzaldehyde dibenzyl acetal (BDBA). The component BDBA is reversibly formed by the reaction of benzyl alcohol with benzaldehyde, an oxidative degradation product of benzyl alcohol. Whereas, BDBA is a known chemical entity, it is not typically controlled in commercial benzyl alcohol since it cannot be formed in the absence of benzaldehyde, which is itself generally controlled. However, once commercial benzyl alcohol is exposed to the atmosphere, formation of BDBA is possible. The synthesis and characterization of BDBA is reported. The ability of BDBA to react with alcohols to form other types of acetals, and the impact of low levels of BDBA on the quantitative analysis of pharmaceutical products, are considered.