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AssigneeCiba-Geigy Corporation
InventorsHeinz Issler, Siegfried Kintopf, Lutz Konig, Hans Stephan
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There is disclosed a process for the preparation of 1-(2-hydroxyethyl-2,2,6,6-tetramethyl-4-piperidinol from triacetoneamine, which comprises first reducing triacetoneamine in water and/or a polar organic solvent by catalytic hydrogenation to 2,2,6,6-tetramethyl-4-piperidinol, and adding a catalytic amount of acid to the resultant solution, without isolation of the intermediate, after optional concentration of the solution by distillation, and subsequently reacting the 2,2,6,6-tetramethyl-4-piperidinol with ethylene oxide. 1-(2-Hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol is a useful light and heat stabilizer for plastics and is, in addition, a valuable intermediate for the synthesis of further light stabilizer additives.
In the process for the preparation of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol by reducing triacetoneamine by catalytic hydrogenation in water or in a polar organic solvent, or in a mixture thereof, and subsequently reacting the resulting 2,2,6,6-tetramethyl-4-piperidinol with excess ethylene oxide, the improvements which comprise (i) adding, prior to the reaction with the ethylene oxide, a catalytic amount of an inorganic or organic acid to the solution of 2,2,6,6-tetramethyl-4-piperidinol or to said solution concentrated by distillation with the proviso that, if the solution is concentrated, the acid is added before or after distillation, (ii) adding the ethylene oxide in a molar excess of 1-35%, and (iii) maintaining the temperature of the reaction with the ethylene oxide in a range from 60.degree. to 170.degree. C.
Dependencies are inferred from the claim text.