JPS6293275A - Production of 2,2,6,6-tetramenthyl-4-oxopiperidine - Google Patents

Abstract

PURPOSE:To obtain the titled substance which is a synthetic intermediate for light stabilizers of high polymeric materials, etc., in high yield in a short time, by using a specific compound as a catalyst in reacting aceton, etc., with 2,2,4,4,6- pentamethyl-2,3,4,5-terahydropyrimidine. CONSTITUTION:Aceton or an acidic condensate thereof in an equimolar amount or more, preferably 3-6mol based on 2,2,4,4,6-pentamethyl-2,3,4,5- tetrahydropyrimidine (hereinafter abbreviated to acetonin) is reacted with the acetonin in the presence of 2,4-dichloro-1,4-naphthoquinone as a catalyst at 0-100 deg.C, preferably 50-70 deg.C to afford the aimed compound. The amount of the 2,3-dichlore-1,4-naphthoquinone to be used as the catalyst is 0.001-1mol, preferably 0.005-0.05mol based on 1mol acetonin.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides 2,2,6,6-tetramethyl-4-
This invention relates to an improved method for producing oxopiperidine (hereinafter sometimes abbreviated as triacetonamine).

[Conventional technology]

2.2,4,4.6-pentamethyl-2,3°4.5-
Examples of methods for producing triacetone amine from tetrahydropyrimidine (hereinafter sometimes abbreviated as acetone) include: (1) A method of reacting holon, which is a condensation product of setone, with ammonia (-, Heitz, Ann, Chem.
ie,.

203, 336 (1880)) ■ A method of reacting acetone with ammonia gas in the presence of calcium chloride (11, Hall, J.

A.C.S., 79, 5444 (1957)
) ■ A method of reacting acetonin with a Lewis acid such as calcium chloride or zinc chloride in the presence of water (Japanese Patent Publication No. 44
(Japanese Patent Publication No. 58-30308, Japanese Patent Publication No. 58-30308, Japanese Patent Publication No. 58-30308, Japanese Patent Publication No. 58-30308)
9-6852), etc. are known.

[Problem that the invention seeks to solve]

However, according to the conventional methods, the use of acetone metal condensates is not practical; in either case, the reaction time is long, and reaction by-products such as resinous substances are produced during the reaction, resulting in the formation of a single target product. Complicated operations are required to separate. Moreover, the reaction yield is not fully satisfactory, and there are cases where it is necessary to add an excessive amount of catalyst.

[Means for solving problems]

The present inventors conducted intensive research to overcome the above-mentioned problems, and as a result, discovered a method for synthesizing triacetonamine with high yield and high purity, and completed the present invention.

That is, the present invention relates to acetone or an acidic condensate of acetone and 2,2,4,4,6-pentamethyl-2,3,4,5
- by reacting with tetrahydropyrimidine 2,2,6.
2. A method for producing 6-tetramethyl-4-oxopiperidine, characterized in that 2,3-dichloro-1,4-naphthoquinone is used as a catalyst.
6. The present invention relates to a method for producing 6-tetramethyl-4-oxopiperidine.

In the present invention, acidic condensates of acetone used alone or in combination with acetone include diacetone alcohol, mesityl oxide, holone, diacetone amine, triacetone diamine, etc. Among these, diacetone alcohol is preferred. The historical amount of acetone or an acidic condensate of acetone is equal to or more than the mole of acetonin used as the starting material. The reaction proceeds more quickly when a larger amount is used, but in practice, it is preferable to use 3 to 6 moles.

In the present invention, the amount of 2,3-dichloro-1,4-naphthoquinone used as a catalyst may be in the range of 0.001 to 1 mol, preferably 0.001 to 0.01 mol, per 1 mol of acetonin. 2 mol, more preferably 0.005~
It is 0.05 mole.

Furthermore, 2,3-dichloro-1,4-naphthoquinone can be used in combination with conventionally known Lewis acids, protonic acids, or salts of protonic acids and ammonia or nitrogen-containing organic bases. . Lewis acids include zinc chloride, tin chloride, aluminum chloride, iron chloride,
Examples include calcium chloride, potassium iodide, and boron trifluoride. Protonic acids include mineral acids such as hydrochloric acid,
Aliphatic or aromatic sulfonic acids such as nitric acid, sulfuric acid, phosphoric acid, hydrogen fluoride, hydrogen iodide, etc. Methanesulfonic acid,
Aliphatic or aromatic phosphonic acids such as benzenesulfone M, p-toluenesulfonic acid, naphthalenesulfonic acid, etc. Aliphatic or aromatic phosphonic acids such as methylphosphonic acid, benzylphosphonic acid, phenylphosphonic acid, etc. Aliphatic or aromatic phosphinic acids such as dimethylphosphinic acid, diethylphosphinic acid , diphenylphosphinic acid, etc. - basic aliphatic or aromatic carboxylic acids such as formic acid, acetic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, propionic acid, butyric acid, lauric acid, valmitic acid, stearic acid, acrylic acid, dibasic aliphatic or aromatic carboxylic acids such as methacrylic acid, cinnamic acid, naphthalic acid, etc., such as oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, tartaric acid, malic acid, fumaric acid, maleic acid , phthalic acid, terephthalic acid, etc. Examples of the ammonium salts of the protonic acids include ammonium salts of mineral acids such as ammonium chloride, ammonium bromide, ammonium iodide, ammonium nitrate, and ammonium borate; and ammonium salts of organic acids such as ammonium formate, ammonium acetate, and ammonium dichloroacetate. , ammonium trichloroacetate, ammonium trifluoroacetate, ammonium malonate, ammonium benzoate, ammonium p-toluenesulfonate, and the like. Further, as the organic base that forms a salt with the protic acid, aliphatic-class amines such as methylamine, ethylamine, n-butylamine, octylamine, dodecylamine, hexamethylene diamine, etc., aliphatic secondary amines such as dimethylamine, diethylamine, di-n-propylamine, di-isobutylamine, aliphatic tertiary amines such as triethylamine, alicyclic amines such as cyclohexylamine, aromatic-grade amines such as aniline, toluidine,
naphthylamine, benzidine, etc., aromatic secondary amines such as N-methylaniline, diphenylamine, etc., aromatic tertiary amines such as N-N-diethylaniline, heterocyclic bases such as pyrrolidine, piperidine, N-
Methyl-2-pyrrolidone, pyrazolidine, piperazine,
Pyridine, picoline, indoline, quinuclidine, morpholine, N-methylmorpholine, 1,4-diazabicyclo[2,2,2]octane, triacetonamine, etc.
Examples include saturated or unsaturated nitrogen-containing organic bases such as urea, diourea, strong bases or weakly basic ion exchange resins. The catalyst and cocatalyst to be used together are 0.001 to 0.1 mol, preferably 0.001 to 0.1 mol, preferably 0.
．． 0.005 to 0.01 mol, but it can be changed as appropriate depending on the type of catalyst.

The catalyst of the present invention can also be used in combination with magnesium chloride, sulfite, sulfites, hydrogen sulfites, pyrosulfites, phosphorus halides, sulfur halides, sulfamic acid or its salts, and the like.

During the reaction, a solvent is not particularly required, but by using an organic solvent, the reaction temperature can be controlled and the reaction can proceed smoothly. Organic solvents used include hexane, toluene, xylene, heptane, cyclohexane,
Methylene chloride, trichloroethane, dichloromethane, carbon tetrachloride, chloroform, ethylene chloride,
Benzene, chlorobenzene, tetrahydrofuran, dioxane, diethyl ether, acetone, acetonitrile, sulfolane, nitromethane, dimethylformamide, dimethylacetamide, tetramethylurea, hexamethylphosphoric acid amide, dimethyl sulfoxide, methanol, ethanol, propatool, isopropanol, t-
Examples include butyl alcohol, cyclohexyl alcohol, benzyl alcohol, ethylene glycol monomethyl ether, glycol, propane-1,3-diol, and the like.

As reaction conditions when carrying out the present invention, the reaction temperature is 0 to
A temperature of 100°C is suitable, but it is preferably carried out at a temperature of 50 to 70°C. The reaction time depends on the reaction conditions, the amount of catalyst used,
Although it varies depending on the type, it is usually carried out for 3 to 15 hours, more preferably 3 to 8 hours.

The desired triacetone amine can be extracted from the reaction solution obtained in this manner by any known method, such as by adding water to obtain a hydrate, or by adding an acid such as hydrochloric acid, sulfuric acid, or oxalic acid. A method for obtaining the product as a salt, or a method for obtaining the product by adding an excess amount of a concentrated alkaline solution such as sodium hydroxide or potassium hydroxide, removing the aqueous layer, and distilling the product is used.

C) Effects and Effects of the Invention) The method for producing triacetone amine of the present invention, as shown by the examples below, has: 1) a shorter reaction time, and 2) a lower amount of catalyst used than the conventional method as shown by the comparative experiments below. It has been found that it is extremely superior in that only a small amount is required, (1) the yield of triacetone amine is high, and no by-products are produced.

47.7g of acetonin (gas chromatography purity 9)
7%), 47 g of acetone, 5.4 g of water, and 4.8 g of ammonium chloride were charged and reacted at 60 to 64°C for 20 hours. The gas chromatography analysis value of acetonin was 5% or less, and the production rate of triacetonamine was 70%. there were.

As is clear from the above comparative experiment, the reaction time in the method of the present invention (for example, Example 1) is less than half that, the amount of catalyst used is as small as about 1/12, and the yield is very high. rate.

Furthermore, it has been found that since the amount of by-products is small, it has the advantage that the target product can be easily separated and purified.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 47.7 g of acetonin (gas chromatography purity 97%), 47 g of acetone, 5.4 g of water and 2.3-dichloro-1,4
- When 0.7 g of naphthoquinone was charged and reacted at 60 to 64° C. for 8 hours, the gas chromatography analysis value of acetonin was 5% or less, and the production rate of triacetonamine was 85%.

Example 2 47.7 g of acetonin (gas chromatography purity 97%), 47 g of acetone, 5.4 g of water and 2,3-dichloro-1,4
-Prepared 0.7g of naphthoquinone and heated to 60-64℃ for 15 minutes.
After the time reaction, the gas chromatography analysis value of acetonin was 5% or less, and the production rate of triacetonamine was 80%.

Example 3 47.7 g of acetonin (gas chromatography purity 97%), 47 g of acetone, 5.4 g of water, 1.7 g of 2,3-dichloro-1,4-naphthoquinone and 0.5 g of potassium iodide were added and heated at 60 to 64°C. After reacting for 5 hours, the gas chromatography analysis value of acetonin was less than 5%, and triacetonamine was 88%.
% production rate.

Example 4 47.7 g of acetonin (97% gas chromatography purity), 94 g of acetone, 5.4 g of water, and 2.3-dichloro-1,4
- When 1.7 g of naphthoquinone was charged and reacted at 60 to 64° C. for 7 hours, the gas chromatography analysis value of acetonin was 5% or less, and the production rate of triacetonamine was 87%.

Claims (1)

[Claims] Acetone or an acidic condensate of acetone and 2,2,4,
In a method for producing 2,26,6-tetramethyl-4-oxopiperidine by reacting with 4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine, 2,
2,2,6,6-tetramethyl-4 characterized by using 3-dichloro-1,4-naphthoquinone as a catalyst
- A method for producing oxopiperidine.