Ammonium salts of .alpha.-ketocarboxylic acids

A process for producing ammonium salts of .alpha.-ketocarboxylic acids corresponding to the following general formula:

• ##STR8## wherein n represents an integer of from about 1 to 4,
• A and B are the same or different and represent hydrogen, an optionally branched and/or halogen- or methoxy-substituted C.sub.1 -C.sub.10 -alkyl radical, a C.sub.5 -C.sub.15 -cycloalkyl radical, a C.sub.6 -C.sub.15 -aryl radical which may optionally be substituted by --OH, --R, --OR, --SR, halogen, --NO.sub.2, --COR, --COOH, --CN, COOR, --CONH.sub.2, --OR', --SR' or --COR', a C.sub.4 -C.sub.10 -heterocyclic radical containing oxygen, sulphur and/or nitrogen as a hetero atom or A and B together represent a 5-membered or 6-membered cycloaliphatic ring optionally containing oxygen or nitrogen as a hetero atom, and
• D represents hydrogen, halogen, --OH, --COOH, --COOR, --CH, --COOH, --OR, --COR, --COR', --CCL.sub.3, an optionally branched C.sub.1 -C.sub.10 -alkyl radical, a C.sub.4 -C.sub.15 -cycloalkyl radical, a C.sub.6 -C.sub.15 -aryl radical which may optionally be substituted by --OH, --R, --OR, --SR, halogen, --NO.sub.2, --COR, --COOH, --CN, --COOR, --CONH.sub.2, OR', --SR', or --COR' or a C.sub.4 -C.sub.10 -heterocyclic radical containing oxygen and/or nitrogen as a hetero atom,
• wherein
• R represents an optionally halogen-substituted alkyl group containing from about 1 to 6 carbon atoms and
• R' represents an aryl group containing from about 6 to 12 carbon atoms
• comprising reacting .alpha.-ketocarboxylic acids of the formula I with an amine component having a molecular weight between about 31 to 500 at temperatures in the range of from about -20.degree. to +50.degree. C.

In a process for coating substrates with coating compositions based on polyurethane or epoxide precursors which harden in the presence of amines, the improvement wherein said compositions contain from about 0.1 to 40% by weight, based on the solids content, of ammonium salts of .alpha.-ketocarboxylic acids corresponding to the following general formula:

• ##STR9## wherein n represents an integer of from about 1 to 4,
• A and B are the same or different and represent hydrogen, an optionally branched and/or halogen- or methoxy-substituted C.sub.1-C.sub.10 -alkyl radical, a C.sub.5 -C.sub.15 -cycloalkyl radical a C.sub.6 -C.sub.15- aryl radical which may optionally be substituted by --OH, --R, --OR, --SR, halogen, --NO.sub.2, --COR, --COOH, --CN, COOR, --CONH.sub.2, --OR', --SR' or --COR', a C.sub.4 -C.sub.10 -heterocyclic radical containing oxygen, sulphur and/or nitrogen as a hetero atom or A and B together represent a 5-membered or 6 membered cycloaliphatic ring optionally containing oxygen or nitrogen as a hetero atom, and
• D represents hydrogen, halogen, --OH, --COOH, --COOR, --CH, --COOH, --OR, --COR, --COR', --CCl.sub.3, an optionally branched C.sub.1 -C.sub.10 -alkyl radical, a C.sub.4 --C.sub.15 -cycloalkyl radical, a C.sub.6 -C.sub.15 -aryl radical which may optionally be substituted by --OH, --R, --OR, --SR, halogen, --NO.sub.2, --COR, --COOH, --CN, --COOR, --CONH.sub.2, --OR', --SR', or --COR' or a C.sub.4 -C.sub.10 -heterocyclic radical containing oxygen and/or nitrogen as a hetero atom,
• wherein
• R represents an optionally halogen-substituted alkyl group containing from about 1 to 6 carbon atoms and
• R' represents an aryl group containing from about 6 to 12 carbon atoms
• and said composition is irradiated with light having a wavelength of from about 250 to 500 nm.