During the Scientific Update conference 'Organic Process Research and Development' in Cologne in September, amongst the many great talks was a tip I had not previously come across. Thomas Allmendinger (Novartis) was describing efforts to scale-up the hydrogenolysis of the benzylic hydroxyl by first forming the carbonate with methyl chloroformate. A really interesting talk within which was a single slide describing how they used a simple colour test to monitor for residual methyl chloroformate. The reaction is shown below. They could calibrate the colour of test solutions with the residual chloroformate and although on this occasion they had to use visual comparison, in principle at least a photometric method of analysis is feasible.