Process for the preparation of ketones

A process for the preparation of one or more ketones corresponding to Formula I

• 7
• in which
• R1 and R2 may be the same or different and each may be hydrogen, a saturated C1-C20 alkyl radical which may be substituted with oxygen-containing groups and may be branched or unbranched, or a C1-C20 alkylaryl radical, wherein the radicals R1 and R2 may form a 5- or 6-membered ring;
• R3 and R5 may be the same or different and each may be hydrogen or a C1 to C4-alkyl radical;
• and
• R4 may be a hydrogen or a C1 to C4 alkyl radical;
• by a two-stage reaction which comprises:
• (1) reacting at least one propargyl alcohol corresponding to Formula II in the presence of an acid catalyst,
• 8
• in which
• R6 and R7 may be the same or different and each may be hydrogen, a C1-C20 alkyl radical which may be substituted with oxygen-containing groups and may be saturated or unsaturated, branched or unbranched, or a C1-C20 alkylaryl radical, wherein the radicals R6 and R7 may form a 5- or 6-membered ring, with at least one enol ether corresponding to Formula III
• 9
• in which
• R8 may be a C1- to C4-alkyl radical;
• to obtain a mixture comprising one or more β,γ,δ-allenic, di-unsaturated ketones corresponding to Formula IV A and one or more α,β,γ,δ-conjugated, di-unsaturated ketones corresponding to Formula IV B
• 10
• followed by
• (2) hydrogenating the mixture of β,γ,δ-allenic, di-unsaturated ketones and α,β,γ,δ-conjugated, di-unsaturated ketones in the presence of a noble metal catalyst;
• wherein the di-unsaturated ketones may be hydrogenated to one or more ketones of Formula I without purification by distillation.