Method for preparing amidines from n-(alkyl lactams)

A method for preparing amidines or derivatives thereof of formula

• starting from a compound of formula:
• wherein
• R1 is H or an aliphatic hydrocarbon group, optionally substituted, having from 1 to 5 carbon atoms, and is more preferably H;
• R2 is H or an aliphatic hydrocarbon group, optionally substituted, having from 1 to 5 carbon atoms, and is more preferably H;
• R3 is H or an aliphatic hydrocarbon group, optionally substituted, having from 1 to 5 carbon atoms, and is more preferably H;
• R4 is H or an aliphatic hydrocarbon group, optionally substituted, having from 1 to 5 carbon atoms, and is more preferably H;
• R5 is H or an aliphatic hydrocarbon group, optionally substituted, having from 1 to 5 carbon atoms, and is more preferably H;
• m is an integer from 3 to 7,
• wherein said process comprises a step of subjecting said compound of formula to dehydration in the presence of an acid catalyst,
• wherein the acid catalyst is selected from heterogeneous acid catalysts based on, or comprising, one or more compounds selected from the group consisting of:
• cerium oxide (ceria) and/or salts thereof, preferably phosphates;
• boron phosphate;
• phosphotungstic acid;
• zirconium salts, preferably phosphates, and/or modified zirconium oxides, preferably zirconium oxide sulfated.