GB788301A - A process for the manufacture of 6, 10-dimethyl-undecanone-(2) - Google Patents

Abstract

6 : 10 - Dimethyl - undecanone - 2 is prepared by the catalytic hydrogenation of geranylacetone or tetra-hydro pseudoionone. A nickel or palladium catalyst may be used. The starting materials may be prepared by reacting 6-methyl-hepten-5-one-2 or 6-methyl-heptanone-2 with an alkali metal derivative of acetylene in liquid ammonia solution, treating the product with a non-alkaline hydrolysing agent, for example, water, a dilute aqueous acid or a nonalkaline ammonium salt as such or in aqueous solution, partially hydrogenating the resulting acetylenic carbinol in the presence of a palladium or nickel catalyst which selectively catalyses reduction of a triple bond to a double bond, reacting the ethylenic carbinol so formed with diketene and decarboxylating the resulting linalyl or di-hydro-linalyl acetoacetate by heating with elimination of carbon dioxide. The reaction with diketene is preferably effected in the presence of a weakly-acid agent such as a mixture of pyridine or choline and acetic acid; a solvent may be present. In examples: (1) a toluene solution of 6-methyl-hepten-5-one-2 is added dropwise to a liquid ammonia solution of sodium acetylide and the product is then stripped of the ammonia and treated with aqueous sulphuric acid; the resulting dehydrolinalool is hydrogenated in petroleum ether solution using a lead-poisoned palladium calcium carbonate catalyst to form linalool which is treated in toluene solution with diketene in the presence of some pyridine and acetic acid; the resulting linalyl acetoacetate is decarboxylated at 140-165 DEG C. to yield geranyl acetone; the latter is then hydrogenated at 95-100 DEG C. under 500 lb. hydrogen pressure using the above mentioned palladium catalyst yielding the desired 6 : 10-dimethyl undecanone-2; (2) using the same operations, 6-methyl-heptanone-2 is converted to the desired dimethyl undecanone. Specifications 788,302 and 788,303 are referred to.