The Catalytic Introduction of Deuterium Into Organic Compounds With Special Reference to the Sterols

Bloch and Rittenberg's preparation of deuterio cholesterol by an exchange reaction between the sterol and heavy water in the presence of a platinum catalyst has been repeated. The method has been extended to the preparation of deuterio ergost-erol and a comparison made of the extent of the exchange reactions of the two sterols under comparable conditions. Information on the influence of structure on extent of exchange has been obtained by a study of the exchange reactions of simpler compounds containing structural features of the sterols. The positions of the deuterium atoms have been located in one of these compounds, deuteriocyclohexene. The compounds undergoing maximum exchange were found to be those undergoing a disproportionation reaction in which the catalyst removed hydrogen from some molecules and donated hydrogen or deuterium to others. On re-examining the sterol deuteration problem in the light of these experiments on simpler compounds, the catalyst was observed to have the same function, the removal and addition of hydrogen and deuterium atoms to produce the deuterio sterol. In addition the removal of hydrogen atoms from one ring of the sterol molecule and the addition of deuterium or hydrogen atoms to another ring, manifested itself in the migration of carbon-carbon double bonds. Ergosterol B1 has been isolated in ergosterol deuteration and A 4 cholesten-3-one in cholesterol deuteration. These compounds contained deuterium atoms probably in specific positions, introduced by a reaction similar to the disproportionation reaction. In these exchange reactions the solvent was heavy water and acetic acid and the extent of deuteration of the methyl group of the acid was investigated over a wide range of exchange reactions. It seemed unlikely that the deuterio acid was an intermediary in sterol deuteration for attempted deuteration of sterols with glacial deuterio acetic acid, containing deuterium atoms in the methyl group, was unsuccessful. The acetic acid may however have a specific role, for attempted exchange reactions involving sulphuric acid, heavy water and a platinum catalyst gave a sterol product which did not contain deuterium. Additional Paper on the Combustion of Sulphur to Sulphur Dioxide This paper contains an account of the combustion of sulphur in the presence of phenol to inhibit formation of sulphur trioxide and to obtain the maximum yield of sulphur dioxide. A gravimetric method has been developed for estimating sulphites and consequently sulphur dioxide. Using this method of estimation, combustion of sulphur to sulphur dioxide resulted in ninety per cent conversion