Process for the preparation of 1,4-dialkyl-2,3-diol-1,4-butanedione

A process for the preparation of a compound of formula

• by aldol condensation, in an aqueous reaction medium, between a glyoxal of formula
• and an α-hydroxy ketone of formula
• wherein each R1 represents, simultaneously or independently from each other, a linear or branched C1 to C5 alkyl radical,
• with the aqueous reaction medium having a pH of between 0 and 6, and with the process carried out at a temperature of between 50° C. and the reflux temperature of the aqueous medium and in the absence of catalysts of formula FeX3 or MX2, wherein M is Zn2+, Mg2+, Cu2+, Fe2+ or Ca2+ and X is a C1-C7 carboxylate, a halide or an acetylacetonate derivative of formula [R2COCHCOR2]−, R2 representing a C1-C3 alkyl group or a phenyl group.

A process for the preparation of a furanone of formula

• which comprises:
• preparing a compound of formula (I)
• by aldol condensation, in an aqueous reaction medium, between a glyoxal of formula
• and an α-hydroxy ketone of formula
• wherein each R1 represents, simultaneously or independently from each other, a linear or branched C1 to C5 alkyl radical,
• with the aqueous reaction medium having a pH of between 0 and 6, and with the process carried out at a temperature of between 50° C. and the reflux temperature of the aqueous medium and in the absence of catalysts of formula FeX3 or MX2, wherein M is Zn2+, Mg2+, Cu2+, Fe2+ or Ca2+ and X is a C1-C7 carboxylate, a halide or an acetylacetonate derivative of formula [R2COCHCOR2]−, R2 representing a C1-C3 alkyl group or a phenyl group;
• and
• cyclizing the compound (I).