Wax esters produced by solvent-free energy-efficient enzymatic synthesis and their applicability as wood coatings

The study aimed at developing a process for making a wood coating wax based on the principles of green chemistry. The research was conducted within the Swedish interdisciplinary research programme Greenchem. Wax esters are attractive since they are non-hazardous, biodegradable and can be produced in an atom-efficient process from building blocks obtained from renewable resources. Four wax esters were prepared in a solvent-free process using an immobilised lipase as catalyst. When the water was removed during the process from what was initially an equimolar mixture of the starting materials carboxylic acid and alcohol by a stream of dry air passed through the reactor, there was a 95–99% conversion to the ester. The enzymatic process consumed 34% less energy and generated less waste than chemical esterification using a strong acid as catalyst. Two of the esters worked well in the industrial wood coating equipment employed and produced surfaces resistant to water and somewhat less to fat stains.