Process for preparing hindered amine light stabilizers

A process for preparing hindered amine light stabilizers by reacting (a) an alkyl substituted-4-hydroxypiperidine having the following general formula:

• ##STR3## where R' is hydrogen or methyl, with (b) a dicarboxylic acid ester of the formula:
• ##STR4## where R" and R"' are a C.sub.1 -C.sub.12 linear or branched alkyl, a C.sub.5 -C.sub.12 cycloalkyl, a C.sub.6 -C.sub.12 aryl or a C.sub.7 -C.sub.12 alkaryl or aralkyl and may be the same or different, and n is a number from 1-12, in the presence of a polar aprotic organic compound and basic inorganic compound catalyst system, wherein a 2:1 to 3.2:1 mole ratio of alkyl substituted-4-hydroxypiperidine to dicarboxylic acid ester is used, and said polar aprotic compound has sufficient polarity to dissolve the ingredients at the reaction temperature and is capable of complexation with the metal ion of said basic inorganic compound.