PROCESS FOR PRODUCING PIPERIDINE DERIVATIVES

Abstract: wherein R₁ is a hydrogen atom or an alkyl group having 1 to 13 carbon atoms; R₂ is a hydrogen atom or an alkyl group having 1 to 2 carbon atoms; and R₃ and R₄ is each independently an alkyl group having 1 to 12 carbon atoms, which process comprises reacting a piperidine represented by the general formula (I) wherein R₁ and R₂ are as defined above, with a ketone represented by the general formula (II) wherein R₃ and R₄ are as defined above, in the presence of chloroform and alkali and in the presence or absence of a phase transfer catalyst, and a stabilized resin composition comprising a resin, said piperidine derivative, a phenol-type antioxidant and a sulfur-­ containing antioxidant.

Description: This invention relates to a process for producing a piperidine derivative. More particularly, this invention relates to a process for producing a piperidine derivative represented by the general formula (III) wherein R₁ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; R₂ is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms; and R₃ and R₄ is each independently an alkyl group having 1 to 12 carbon atoms. The piperidine derivative represented by the above-mentioned general formula (III) is known to be useful as a light stabilizer for high molecular substances such as plastics, rubbers and fibers. There has already been known as a process for producing the piperidine derivative represented by the general formula (III) a process which comprises reacting 4-amino-2,2,6,6-tetramethylpiperidine (in the general formula (I) which will be shown later, R₁ and R₂ are each H) with α-bromo-α,α-dimethyl-N-2,2,6,6-tetramethyl-4-piperidinylacetamide (EP-A-0 062 322). However, the above known process requires an extremely special raw material, such as α-bromo-α,α-dimethyl-N-2,2,6,6-tetramethyl-4-piperidinylacetamide, and further gives a low yield of intended product as low as 69%, so that it can hardly be deemed as an industrially satisfactory process for production. Under these circumstances, the present inventors have made intensive studies to find an industrially advantageous process for producing the piperidine derivative represented by the general formula (III). As a result, it has been found that the intended product can be obtained selectively and without requiring the special raw material, α-bromo-α,α-dialkyl-N-2,2,6,6-tetramethyl-4-piperidinylacetamide, by reacting a piperidine represented by the general formula (I) shown later and a ketone in the presence of chloroform and alkali and thus the present invention has been accomplished. An object of this invention is to provide a process for producing a piperidine derivative represented by the above-mentioned general formula (III) in an industrially very advantageous way and at a low cost. According to this invention, there is provided an industrially extremely excellent process for producing a piperidine derivative represented by the general formula (III) wherein R₁ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; R₂ is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms; and R₃ and R₄ are each independently an alkyl group having 1 to 12 carbon atoms, which process comprises reacting a piperidine represented by the general formula (I) wherein R₁ and R₂ are as defined above, with a ketone represented by the general formula (II) wherein R₃ and R₄ are as defined above, the ketone(II) being used in an amount of 0.5 to 30 moles based on 1 mole of the piperidine (II), in the presence of 0.5 to 2 moles of chloroform and 1 to 4 moles of an alkali each based on 1 mole of the piperidine (I), and at a temperature of -30 to 60°C. The reaction can be conducted either in the presence or absence of a phase transfer catalyst. Specific examples of piperidines represented by the general formula (I) in this invention include 4-amino-2,2,6,6-tetramethylpiperidine, 4-amino-1,2,2,6,6-pentamethylpiperidine, 4-amino-1-ethyl-2,2,6,6-tetramethylpiperidine, 4-N-butylamino-2,2,6,6-tetramethylpiperidine, 4-N-butylamino-1,2,2,6,6-pentamethyipiperidine, 4-N-octylamino-2,2,6,6-tetramethylpiperidine, 4-N-octylamino-1,2,2,6,6-pentamethylpiperdine, 4-N-laurylamino-2,2,6,6-tetramethylpiperidine, and 4-N-laurylamino-1,2,2,6,6-pentamethylpiperidine. The reaction of the piperidines represented by the general formula (I) with the ketones represented by the general formula (II) in the presence of a phase transfer catalyst is conducted under the following conditions. Examples of ketones represented by the general formula (II) include acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, and 2-nonanone. These ketones are used in an amount of generally 0.5 to 2 moles, preferably 0.5 to 1 mole, relative to 1 mole of the piperidines represented by the general formula (I). The amount of chloroform used in this invention is usually 0.5 to 2 moles, relative to 1 mole of the piperidines represented by the general formula (I). Alkalis usable in this invention include hydroxide of alkali metals and alkaline earth metals. For example, sodium hydroxide, potassium hydroxide and calcium hydroxide are usually used. The amount of the alkalis to be used is usually 1 to 4 moles, preferably 1.5 to 3 moles, relative to 1 mole of the piperidines represented by the general formula (I). They can be used either as an aqueous solution or directly as a solid. There is no specific restriction as to the phase transfer catalysts, which include, for example, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylphosphonium chloride, trioctylmethylammonium chloride, and tetraphenylphosphonium bromide. The amount of said catalyst to be used is generally 0.0001 to 0.01 mole, preferably 0.001 to 0.005 mole, relative to 1 mole of the piperidines represented by the general formula (I). The reaction of the piperidines represented by the general formula (I) with the ketones represented by the general formula (II) in the absence of a phase transfer catalyst is conducted under the following conditions. Examples of ketones represented by the general formula (II) include acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, and 2-nonanone. These ketones are used in an amount of generally 0.5 to 30 moles, preferably 0.5 to 20 moles, relative to 1 mole of the piperidines represented by the general formula (I). The amount of chloroform used in this invention is usually 0.5 to 2 moles, preferably 0.5 to 1 mole, relative to 1 mole of the piperidines represented by the general formula (I). Alkalis usable in this invention include hydroxide of alkali metals and alkaline earth metals. For example, sodium hydroxide, potassium hydroxide and calcium hydroxide are usually used. The amount of the alkalis to be used is usually 1 to 4 moles, preferably 1.5 to 3 moles, relative to 1 mole of the piperidines represented by the general formula (I). They can be used either as an aqueous solution or directly as a solid. The reaction is usually conducted in the presence of excess chloroform or starting ketones at a temperature of -30 to 60°C, preferably -10 to 30°C. However, other solvents may be used as occasion demands. In such cases, examples of the other solvents include aliphatic hydrocarbons such as hexane and heptane; aromatic hydrocarbons such as benzene, toluene and xylene; water soluble polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide, dioxane, and sulfolane; alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, t-butanol, n-amyl alcohol, isoamyl alcohol, 2-ethylhexyl alcohol and cyclohexanol; and glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and ethylene glycol monobutyl ether. These are used each alone or in a combination of two or more thereof. Typical piperidine derivatives of this invention produced as mentioned above are shown in Table 1. In obtaining the stabilized resin composition, from the viewpoint of obtaining more excellent light stability, the substituent R₁ in the above-mentioned general formula (III) is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom; R₂ is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom; R₃ and R₄ are, each independently, preferably of 1 to 7 carbon atoms, more preferably a methyl group. This invention will be described in more detail below with reference to the Examples. Example 1 Preparation of compound No. III-1 Into a four-necked flask equipped with a thermometer and a stirrer, were placed 156 g of 4-amino-2,2,6,6-tetramethylpiperidine, 32 g of acetone, 239 g of chloroform and 0.4 g of benzyltrimethylammonium chloride, and the mixture was cooled down to 5°C with stirring. Then, 257.6 g of 50% aqueous potassium hydroxide solution was added dropwise thereto over a period of 1 hour while the inner temperature was maintained at 5 to 10°C, and the resulting mixture was allowed to react at a temperature of 5 to 10°C for 5 hours. After completion of the reaction, the reaction liquid was separated into two layers, the aqueous layer was discarded, and excess chloroform in the organic layer was distilled off to obtain 176 g of white crystals. Yield: 92.6%; m.p.: 127-128°C. Parent ion peak of 380 was confirmed by FD-mass analysis. Example 2 Preparation of compound No. III-2 Reaction and after-treatment were carried out in the same manner as in Example 1 except that 39.6 g of methyl ethyl ketone was used in place of acetone used in the Example to obtain 177 g of white crystals. Yield: 89.8%; m.p.: 108-109°C. Parent ion peak of 394 was confirmed by FD-mass analysis. Example 3 Preparation of compound No. III-3 Reaction was carried out in the same manner as in Example 1 except that 55 g of methyl isobutyl ketone was used in place of acetone used in the Example. After removing excess chloroform by distillation and recrystalized from n-hexane, 175 g of white crystals were obtained. Yield: 80.8%; m.p.: 109-110°C. Parent ion peak of 422 was confirmed by FD-mass analysis. Example 4 Preparation of compound No. III-4 Reaction and after-treatment were carried out in the same manner as in Example 1 except that 170 g of 4-amino-1,2,2,6,6-pentamethylpiperidine was used in place of the piperidine compound used in the Example to obtain 184 g of a viscous liquid in 90.2% yield. Parent ion peak of 408 was confirmed by FD-mass analysis. Example 5 Preparation of compound No. III-7 Reaction and after-treatment were carried out in the same manner as in Example 3 except that 78 g of 2-nonanone was used in place of methyl isobutyl ketone used in the Example to obtain 168 g of white crystals. Yield: 72.4%; m.p.: 100-101°C. Parent ion peak of 464 was confirmed by FD-mass analysis. Example 6 Preparation of compound No. III-1 Into a four-necked flask equipped with a thermometer and a stirrer, were placed 100 g of 4-amino-2,2,6,6-tetramethylpiperidine, 600 g of acetone and 54.5 g of chloroform, and the mixture was cooled down to 5°C with stirring. Then, 64 g of a solid potassium hydroxide was added little by little over a period of one hour, while the inner temperature was maintained at 5 to 10°C, and the resulting mixture was allowed to react at a temperature of 0 to 10°C for 4 hours. After completion of the reaction, potassium chloride formed was separated by filtration, and 500 g of acetone was distilled off from the filtrate (acetone solution). White crystals isolated from the concentrated acetone solution were filtered and dried to obtain 110 g of the product. Yield: 91%; m.p.: 127-128°C. Parent ion peak of 380 was confirmed by FD-mass analysis. Example 7 Preparation of compound No. III-2 Reaction and after-treatment were carried out in the same manner as in Example 6 except that methyl ethyl ketone was used in place of acetone to obtain 108 g of white crystals. Yield: 85.3%; m.p.: 108-109°C. Parent ion peak of 394 was confirmed by FD-mass analysis. Example 8 Preparation of compound No. III-3 Reaction and after-treatment were carried out in the same manner as in Example 6 except that methyl isobutyl ketone was used in place of acetone and the resulting product was recrystalized from n-hexane to obtain 107 g of white crystals. Yield: 76.3%; m.p.: 109-110°C. Parent ion peak of 422 was confirmed by FD-mass analysis. Example 9 Preparation of compound No. III-4 Reaction and after-treatment were carried out in the same manner as in Example 6 except that 109 g of 4-amino-1,2,2,6,6-pentamethylpiperidine was used in place of 100 g of 4-amino-2,2,6,6-tetramethylpiperidine to obtain 118 g of a viscous liquid. Yield: 90.2%. Parent ion peak of 408 was confirmed by FD-mass analysis. Example 10 Preparation of compound No. III-7 Reaction and after-treatment were carried out in the same manner as in Example 8 except that 2-nonane was used in place of methyl isobutyl ketone to obtain 116 g of white crystals. Yield: 78.2%; m.p.: 100-101°C. Parent ion peak of 464 was confirmed by FD-mass analysis.

Claims: A process for producing a piperidine derivative represented by the general formula (III) wherein R₁ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; R₂ is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms; and R₃ and R₄ are each independently an alkyl group having 1 to 12 carbon atoms, which process comprises reacting a piperidine represented by the general formula (I) wherein R₁ and R₂ are as defined above, with a ketone represented by the general formula (II) wherein R₃ and R₄ are as defined above, the ketone (II) being used in an amount of 0.5 to 30 moles based on 1 mole of the piperidine (I), in the presence of 0.5 to 2 moles of chloroform and 1 to 4 moles of an alkali each based on 1 mole of the piperidine (I), and at a temperature of -30 to 60°C. A process according to Claim 1, wherein the reaction is conducted in the presence of 0.0001 to 0.01 mole of a phase transfer catalyst and using 0.5 to 2 moles of the ketone (II) each based on 1 mole of the piperidine (I). A process according to Claim 1 or 2, wherein in the general formula (III), R₁ is a hydrogen atom or a methyl group; R₂ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and R₃ and R₄ are each independently an alkyl group having 1 to 7 carbon atoms. A process according to any preceding claim, wherein the alkali is a hydroxide of alkali metals or alkaline earth metals. A process according to Claim 4, wherein the alkali is sodium hydroxide or potassium hydroxide. A process according to any preceding claim, wherein the reaction is conducted in the presence of a phase transfer catalyst selected from benzyltrimethylammonium chloride, benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylphosphonium chloride, trioctylmethylammonium chloride and tetraphenylphosphonium bromide. A process according to any preceding claim, wherein the piperidine represented by the general formula (I) is 4-amino-2,2,6,6-tetramethylpiperidine, 4-amino-1,2,2,6,6-pentamethylpiperidine, 4-amino-1-ethyl-2,2,6,6-tetramethylpiperidine, 4-N-butylamino-2,2,6,6-tetramethylpiperidine, 4-N-butylamino-1,2,2,6,6-pentamethylpiperidine, 4-N-octylamino-2,2,6,6-tetramethylpiperidine, 4-N-octylamino-1,2,2,6,6-pentamethylpiperidine, 4-N-laurylamino-2,2,6,6-tetramethylpiperidine or 4-N-laurylamino-1,2,2,6,6-pentamethylpiperidine. A process according to any preceding claim, wherein the ketone represented by the general formula (II) is acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone or 2-nonanone. A process according to Claim 2, wherein the phase transfer catalyst is present in an amount of 0.001 to 0.005 mole based on 1 mole of the piperidine (I).

Inventors: FUJII, TAKEO, ISHII, TAMAKI, KANEOYA, TATSUO, MAEGAWA, YUZO, OKAMURA, HARUKI, OKINO, EIZO, TAKAHASHI, YUKOH, YACHIGO, SHINICHI
Applicants: SUMITOMO CHEMICAL COMPANY, LIMITED
Application year: 1985
Main classification: C07D211
IPC codes: C08K5, C07D211