Ciba Specialty Chemicals Corporation

Joachim Fries

Walter Wolf

Karl Stephan Nitsche

A process for the preparation of 4-hydroxy-1,2,2,6,6-pentamethylpiperidine (HPMP) from 4-oxo-2,2,6,6-tetramethylpiperidine (TAA) is described, in which TAA is first reduced to 4-hydroxy-2,2,6,6-tetramethylpiperidine (HTMP) by means of catalytic hydrogenation in water, the resulting crude solution, if desired after concentration by distillation, is reacted with formaldehyde or paraformaldehyde in at least 20% molar excess, and with formic acid, and the crude product melt separated from the reaction mixture is worked up by distillation.

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Bensheim, Germany

Joachim Fries