Water the key to green pharmaceutical manufacturing
drug considerably more "green", according to research in
Angewandte Chemie.
In the journal Professor's Vigalok and Shapiro, researchers at Tel Aviv University, claim to have found a technique for replacing some chemical solvents with water. Implementation of this method could reduce the environmental impact of the pharmaceutical manufacturing industry, which Vigalok said can use 100kg of solvents and materials to produce 1kg of medicine. Vigalok added: "Ten to twenty chemical reactions may be done to make a single medicine, and in each step organic solvents are used. "If we can cut out their use by applying water instead, this could amount to a substantial advance." The process works by mixing water with aldehydes, a group of organic compounds. The aldehydes float on the surface of the water where the reaction takes place and are oxidized to produce carboxylic acid. Oxygen for the reaction is consumed directly from the air, which the paper refers to as "the ultimate 'green' oxidant". The water, having not mixed with the reactants, can then be removed and easily recycled. The researchers scaled up the process to laboratory scale, 50 mmol, without being detrimental to the efficiency of the reaction. In addition they used the methodology to perform consecutive organic reactions "on water" with hydrophobic organic compounds. Vigalok believes this method could have a positive impact on the environmental credentials of a few key stages in the reaction process. The industrial process for aldehyde oxidation reactions is mostly performed in bulk liquid aldehyde or organic solvents, to which various additives are introduced. Examining the chemistry behind these reactions the researchers hypothesized that the solvent is at best unnecessary and may even be detrimental to oxidation. Further research is necessary but "on water" is nonetheless another advance in the field of "Green chemistry" which Vigalok believes should play a more significant role in industry. He said: "The plastics industry, the oil refinery business, every drug we take - they're all parts of the chemical industry, the biggest industry in the world by far. "In making certain steps of the chemical process greener, we may not have an enormous impact on the environment at present, but we certainly challenge chemists to rethink methods used in traditional chemistry."
