Process for preparing piperidine-4-carbothioamide hydrochloride

A process for preparing piperidine-4-carbothioamide hydrochloride of formula (I)

• wherein said process comprises reacting 4-cyanopiperidine hydrochloride of formula (II) with
• hydrogen sulfide (III)
• in the presence of a catalytic amount of a base of formula (IV)
• R1N(R2)R3 (IV),
• in which R1, R2, R3 are each independently hydrogen or C1-C20 alkyl,
• or in the presence of a catalytic amount of a heteroaromatic base from the group of picolines (V),
• wherein the catalytic amount of either the base of formula (IV) or the heteroaromatic base from the group of picolines (V) is between 0.1% and 20%, based on the amount of the piperidine-4-carbothioamide hydrochloride (I) to be produced,
• and
• in the presence of a solvent to give the compound of formula (I) wherein the solvent is a primary, secondary or tertiary alcohol or a mixture thereof, or a mixture of a primary, secondary and/or tertiary alcohol with one or more further solvents.