Mineral Oil/Methanol : a Cheap Biphasic Reaction Medium with Thermomorphic Properties and Its Application to the Palladium-Catalyzed Carbonylation of Nitrobenzene to Methyl Phenylcarbamate

We developed the methanol/mineral oil system as a new thermomorphic solvent mixture that allows homogeneous catalyst recovery without the use of water or fluorinated solvents. Mineral oil (nujol) is cheap and shows a very limited miscibility with methanol at room temperature but becomes completely miscible at high temperatures. Here we report the synthesis of some phenanthrolines substituted with long-chain alkyl groups, which render them soluble in hydrocarbons and insoluble in methanol, and their application to the palladiumcatalyzed carbonylation of nitrobenzene to methyl phenylcarbamate. Both the reagents and products of the catalytic reaction are much more soluble in methanol than in hydrocarbons, so an easy separation of the catalyst is possible.