Ciba-geigy Corporation

Hanns Lind

Jean Rody

Heimo Brunetti

Ivan Orban

Michael Rasberger

Haukur Kristinsson

Paul Moser

Rolf Hugi

Heimo Brunnetti

The invention relates to compounds of the general formula I ##STR1## wherein R.sub.1 and R.sub.2 independently of one another are C.sub.1 -C.sub.8 -alkyl, C.sub.5 -C.sub.8 -cycloalkyl or C.sub.7 -C.sub.9 -aralkyl,

New stabilizers

Process for the preparation of 2-phenyl-4-hydroxy-1,2,3-triazole-1-oxides of the formula ##STR1## from oxime-hydrazones of the formula ##STR2## in which formulae R stands for an unsubstituted or substituted phenyl group.

Process for the preparation of 2-phenyl-4-hydroxy-1,2,3-triazole-1-oxides

The new N-[3-(3-hydroxyaryl)-2-hydroxypropyl]-imides may be prepared by reacting 3-(3-hydroxyaryl)-propenoxides with cyclic imides. These hydroxy compounds as well as their esters with carboxylic acids are highly effective in the stabilization of polymers, preferably of polyolefins, against thermal-oxydative attack. The compounds themselves exhibit a good stability against discoloration by radiation or gas fading.

Hydroxyaryl hydantoins and their use as stabilizers

New substituted p-hydroxybenzoic acid phenyl esters are light protecting agents for polymers. They are prepared by acylation of a corrsponding phenol with an appropriate acid chloride.

Light protecting agents

A new process for the preparation of alkalimetal salts of 3,5-substituted 4-hydroxybenzoic acids and the free acids thereof, which comprises reacting a 2,6-disubstituted phenol in a mixture of water and a dipolar aprotic solvent with an alkalimetal hydroxide, removing the water, treating the reaction mixture with carbon dioxide and in case of preparing the free acids treating the reaction mixture with a mineral acid. The alkalimetal salts of 4-hydroxybenzoic acids and the free acids thereof are compounds which can be used as intermediates for stabilizers.

Process for the manufacture of alkali salts of 3,5-disubstituted

New thiaalkylphenols are used as stabilizers for organic material. They are prepared by reacting corresponding alkenephenols with mercaptans.

Thiaalkyl phenols

New 3,5-dialkyl-4-hydroxybenzyl-oxiranes and the corresponding thiiranes are used as stabilizers for polymers. The oxiranes are prepared from the corresponding olefins by reaction with percarboxylic acids or from alkali phenoxides and epichlorohydrines. The thiiranes are prepared from the oxiranes by the usual sulfidation methods.

3,5-DIALKYL-4-HYDROXYBENZYL-OXIRANES

2,2,6,6-Tetramethyl-4-oxopiperidine is prepared from 2,2,4,4,6-pentamethyl-2,3,4,5-tetramethylpyrimidine (acetonine) by heating in the presence of acetone, diacetone alcohol or water. These regents may be used in excess or an organic solvent is added. The preferred modification is the heating of acetonine hydrate in an excess of acetone or in an acetone-methanol mixture to about 40.degree. to 65.degree.C for several hours. The use of diacetone alcohol permits higher reaction temperatures leading to shorter reaction times.

Process for the preparation of 2,2,6,6-tetramethyl-4-oxopiperidine

2,2,6,6-Tetramethyl-4-oxopiperidine is prepared from acetone and ammonia in the presence of acidic catalysts. Suitable catalysts are Lewis acids, protionic acids and their salts with ammonia or with organic bases, as for example BF.sub.3, NH.sub.4 Cl or H.sub.2 SO.sub.4. The addition of an alcohol such as methanol as well as the use of a cocatalyst may promote the reaction. The process may be carried out in two steps, in the first of which the temperature is held below 35.degree.C. In the second step a further amount of acetone is added and the temperature is rised to about 40.degree. to 65.degree.C.

The new N-[3-(3-hydroxyaryl)-2-hydroxypropyl]-imides may be prepared by reacting 3-(3-hydroxyaryl)-propenoxides with cyclic imides. These hydroxy compounds as well as their esters with carboxylic acids are highly effective in the stabilisation of polymers, preferably of polyolefins, against thermal-oxydative attack. The compounds themselves exhibit a good stability against discoloration by radiation or gas fading.

N-(3-hydroxyaryl-propyl)-imides

2,2,6,6-Tetramethyl-4-oxopiperidine is prepared from 2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine by treatment with an acidic catalyst. Suitable catalysts are Lewis acids, protonic acids and their salts with ammonia or organic bases. The reaction may be carried out in organic solvents, preferably in acetone, by gentle heating, for example at 40.degree. to 65.degree.C. Yields of 95% are obtainable after a reaction of several hours.

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Liestal, Switzerland

Hanns Lind