' ADDITION TO A DOUBLE BOND 67Reversing the order of addition, or using an ether as a solvent, causes amarked retardation of the reaction, with subsequent sudden, uncon-trollable speed-up. Yields of about 80% are obtained and probablycan be improved by devices to minimize the mechanical losses.60The addition of hydrogen fluoride to stearolic acid in methylene chlo-ride solution to give 9,10-difluorostearic acid is cited in the patent litera-ture.46This claim should be verified, as either 9,9- or 10,10-difluoro-stearic acid or a mixture is much more likely to be the reaction product.ADDITIONTO ADOUBLEBONDHydrogen fluoride reacts with olefins to yield monofluoroalkanes,46-47but very few experimental details have been published. The reaction isreversible and is often accompanied by polymerization of the olefin,which is favored by excess hydrogen fluoride. The difficulties increaseif the product is a secondary and especially a tertiary fluoride. Concen-trated aqueous hydrofluoric acid does not react with olefins.
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