Process for the preparation of 2-methyl-1,3-propanediol

Claim 1

A continuous process for the preparation of 2-methyl-1,3-propanediol which comprises (a) reacting acrolein with a 1,3-aliphatic diol with 3 to 7 carbon atoms other than 2-methyl-1,3-propanediol under conventional conditions to prepare a cyclic acetal; (b) hydroformylating the cyclic acetal in the presence of a rhodium complex catalyst comprising rhodium carbonyl and a phosphite ligand of the formula ##STR5## wherein R 1 , R 2 and R 3 are the same or different phenyl, substituted phenyl or alkyl groups having 1 to 12 carbon atoms under conventional conditions to prepare the aldehyde of the cyclic acetal; (c) hydrogenating and hydrolyzing the aldehyde of the cyclic acetal in the presence of a hydrogenation catalyst and an ion exchange catalyst to prepare 1,4-butanediol and a mixture of diols; (d) separating the mixture of diols from 1,4-butanediol; (e) recycling said mixture back to step (a) to react with acrolein in place of the diol of (a) for a number of cycles until a product consisting of 1,4-butanediol and essentially 2-methyl-1,3-propanediol; and (f) separating and recovering the 2-methyl-1,3-propanediol.