Process for producing 2-ethylheptanoic acid

A process for producing 2-ethylheptanoic acid, the process comprising:

• (i) reacting 3,6-diethyltetrahydro-2H-pyran-2-one of formula (I) with hydrogen to obtain 2-ethylheptanoic acid of formula (II) in the presence of a heterogeneous catalyst,
• wherein the heterogeneous catalyst is a bifunctional catalyst or a catalyst mixture of at least two catalyst components,
• the bifunctional catalyst or one catalyst component of the catalyst mixture has an acidically acting component, and
• the acidically acting component comprises a solid oxidic acid which has an alkylation index below 100.