Abstract: A process for preparing triacetonamine characterized in that acetonine is reacted with water in the presence of at least 12.5 mole % based on acetonine of an acid catalyst.Triacetonamine is used as an intermediate for light stabilizer for synthetic polymers.

Abstract: Piperidine derivatives having the formula ##SPC1##WhereinR' represents an alkyl group, a substituted alkyl group, an acyl group, an alkoxycarbonyl group, a substituted alkoxycarbonyl group, an amino group, a substituted amino group, or nitroso group;X represents oxygen atom or sulfur atom;Y represents oxygen atom, sulfur atom or a group of the formula = N -- R" in which R" is hydrogen atom, an alkyl group or a substituted alkyl group;Z represents oxygen atom or a group of the formula >N -- R'" in which R'" is hydrogen atom, an alkyl group or a substituted alkyl group;n is an integer of 1 through 4 inclusive; andR represents, when n is 1, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, a cycloalkyl group, an alkoxycarbonyl group, a substituted alkoxycarbonyl group, a substituted phosphino group or a substituted phosphinyl group, when n is 2, an alkylene group, an alkenylene group, an arylene group, a substituted arylene group, an aralkylene group; an alkylenediphenylene g

Abstract: Piperidine derivatives having the formula ##SPC1##WhereinR' represents an alkylene group which may be interrupted with an oxygen or sulfur atom, an alkenylene group, an alkynylene group, an aralkylene group, an aliphatic diacyl group, a group of the formula ##EQU1## IN WHICH N IS AN INTEGER OF 1 OR 2 AND X is an alkylene group, or o-, m- or p-phenylene group or the carbon atoms of CO groups may be directly joined in the absence of X or a group of the formula ##EQU2## in which Y is an alkylene group or O-, m- or p-phenylene group; R represents hydrogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, an aryl group, an alkoxycarbonylalkenyl group, an aliphatic, aromatic or heterocyclic monoacyl group, a N-substituted carbamoyl group, a N-substituted thiocarbamoyl group or a monovalent radical derived from an oxoacid;R.sub.1 and R.sub.2 individually represent a lower alkyl group or they jointly represent, together with the oxygen atoms, a group of the formula ##SPC2##In which R.sub.