摘要:
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.
摘要翻译:在酸性催化剂存在下,由丙酮和氨制备2,2,6,6-四甲基-4-氧代哌啶。 合适的催化剂是路易斯酸,丙酸及其与氨或有机碱的盐,例如BF 3,NH 4 Cl或H 2 SO 4。 加入醇如甲醇以及助催化剂的使用可能促进反应。 该方法可以在两个步骤中进行,其中第一步将温度保持在35℃以下。在第二步中,加入另外量的丙酮,将温度升至约40℃至65℃。
摘要:
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.
摘要:
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.
摘要:
Derivatives of sterically hindered 4-aminopiperidines are effective as light-stabilizers for organic polymers, especially for polyolefins. The piperidine ring is substituted with at least five alkyl groups, preferably methyl and ethyl groups. The 4-amino group is substituted with mono- or divalent acyl groups. The nitrogen in 1-position may also be substituted with a monovalent organic substituent. The compounds can be synthesized starting from higher homologs of acetone in sequence of several reaction steps.
摘要:
Polymers, both natural and synthetic, are stabilized against the deterioration resulting from heat and/or light by the incorporation of certain 2,2,6,6-tetra-substituted-4-piperidinol derivatives which additionally have an alkyl, alkenyl, alkynyl or aralkyl substituent at one or both of the 3- and 5- positions.
摘要:
Polymers, both natural and synthetic, are stabilized against the deterioration resulting from heat and/or light by the incorporation of certain 2,2,6,6-tetra-substituted-4-piperidinol derivatives which additionally have an alkyl, alkenyl, alkynyl or aralkyl substituent at one or both of the 3- and 5- positions.
摘要:
Novel 7,7,9,9-tetra-substituted-1,3,8-triazaspiro�4.5!decane-2,4-diones having an alkyl or allyl group at either the 6- or the 10- position are useful for the stabilization of polymers against photo- and thermal- deterioration.
摘要:
Cyclic ketals of sterically hindered 4-oxopiperidines are effective light-stabilizers for organic polymers. These compounds have at least five alkyl groups in ring positions 2,3,5 and 6 and four alkyl groups in ring positions 2 and 6, preferably methyl and ethyl groups. The ring nitrogen may be unsubstituted or substituted with a monvalent substitutent. The new compounds can be synthesized by ketalization of the corresponding 4-oxopiperidines with diols, triols or tetrols. Using triols the obtained ketals possess hydroxyl groups which may be esterified or etherified in a subsequent reaction step. Ketalization with tetrols yields cyclic bis-ketals.
摘要:
Sterically hindered piperidines having at least 5 alkyl groups in ring positions 2,3,5 and 6 are usable as light-stabilizers for organic polymers. The nitrogen may be unsubstituted or may bear a mono- to tetravalent substituent. The compounds can be synthesized by a Wolf-Kishner reduction of polyalkyl 4-oxopiperidines optionally followed by a N-substitution reaction in a second step.The stabilizers are added to the polymers in an amount of from 0.01 to 5% by weight. Preferred is the stabilization of polyolefins, styrene polymers, polyamides and polyurethanes.
摘要:
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.