Hydroformylation with Recycled Rhodium Catalyst and One-Step Esterification-Acetalation: A Process for Methyl 9( 1O)-Methoxymethylenestearate from Oleic Acid

Previous studies on hydroformylation of methyl oleate with rhodium and triphenylphosphine or triphenylphosphite have led to a laboratory process for recycling the precious metal catalyst. Another catalyst recycling process has now been studied as the basis for converting commercially available oleic acid into the enol ether of methyl formylstearate. The process involves one-step esterification-acetalation of formylstearic acid made by hydroformylating oleic acid with rhodium and triphenylphosphine. Esterification-acetalation is done in a recycling system with methanol, an acid-exchange resin for catalysis, and molecular sieves to remove water from the reaction mixture. The dimethyl acetal methyl ester formed from formylstearic acid is thermally cracked and distilled in one pot to produce the enol ether, methyl methoxymethylenestearate. The soluble rhodium catalyst in the distillation residue is combined with the insoluble catalyst from filtration and recycled for hydroformylation. The product methoxymethylenestearate is a versatile and stable derivative for various potential industrial applications.