Ciba-geigy Corporation

Ciba Specialty Chemicals Corporation

Walter Wolf

Hans Stephan

Rudolf Maul

Joachim Fries

Thomas Engert

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.

Process for the preparation of 4-hydroxy-1,2,2,6,6,-pentamethylpiperidine

A process is described for the preparation of hydroxybenzylphosphonates of the formula I ##STR1## which involves A) reacting a phenol of the formula II ##STR2## with an amine of the formula III ##STR3## formaldehyde or paraformaldehyde and a protonic acid H.sub.n A to give a salt of the formula IV ##STR4## B) distilling off the water of reaction which forms, and C) reacting the reaction mixture, or the salt IV isolated therefrom, with a trialkyl phosphite of the formula ##STR5## in which H.sub.n A is an organic or inorganic acid having n protons,

Process for the preparation of sterically hindered

A process for the production of alkyltin thiocarboxylic acid esters from alkyltin halides and thiocarboxylic acid esters in the presence of an acid acceptor, which process comprises carrying out the reaction continuously in a reaction system comprising 1 to 5 agitator vessels with an average dwell time of 1 to 60 minutes, at a constant pH value in the range from 3 to 8, and in a temperature range from 40.degree. to 80.degree. C. and separating the product drawn off from the reaction system from the aqueous phase and subsequently drying it. The alkyltin thiocarboxylic acid esters obtained by the process of the invention are used for stabilizing homo- and copolymers of vinyl chloride.

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Bensheim, Germany

Walter Wolf