PRODUCTION OF TERPENEDIOL

PURPOSE:To obtain the titled compound useful as an intermediate of squalane, economically, by adding a terpene ketone corresponding to the objective compound to a tetrahydrofuran solution of tetramethylene dimagnesium chloride at a specific temperature to effect the reaction of the components. CONSTITUTION:The compound of formula I (R is saturated or unsaturated hydrocarbon group having the carbon skeleton of formula II), e.g. 6,10-dimethylundeca-5,9-dien-2-one, 6,10-dimethylundecan-2-one or 6,10-dimethylundeca-6,9-dien- 2-one, is added to a tetrahydrofuran solution of tetramethylene dimagnesium chloride [ClMg(CH2)4MgCl] at 10-70 deg.C, especially preferably at 20-80 deg.C to effect the reaction of both components. The objective compound of formula IIIwhich is an intermediate of squalane useful as a cosmetic base, etc. can be produced economically with simple procedure from a raw material available industrially in a mass.