JPH03188065A - Production of 2,2,6,6-tetramethyl-4-oxopiperidine - Google Patents

Abstract

PURPOSE:To obtain the subject substance in high yield in a short time while producing little by-product by reacting acetone or an acidic condensate of acetone with 2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine in the presence of an iron carboxylic acid salt as a catalyst. CONSTITUTION:The subject substance can be produced by reacting acetone or an acidic condensate of acetone (e.g. diacetone alcohol) with a compound of formula at about 60 deg.C for 5-10hr in the presence of a carboxylic acid iron salt as the reaction catalyst. The carboxylic acid constituting the catalyst is preferably acetic acid, oxalic acid, lactic acid, citric acid, etc., and the amount of the catalyst is preferably 0.01-0.2mol per 1mol of the compound of formula. The above catalyst may be used in combination with a Lewis acid, protonic acid, etc. The subject substance useful as a photo-stabilizer for polymeric material or synthetic intermediate for pharmaceuticals, etc., can be produced in colorless state by the above process in high yield.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides 2,2.6.6-tetramethyl-4-
Oxopiperidine (hereinafter abbreviated as TAAM)
This relates to an improved manufacturing method.

[Prior art] 2.2,4,4.6-pentamethyl-2,3°4.5-
Examples of methods for producing TAAM from tetrahydropyrimidine (hereinafter abbreviated as ATN) include: (1) a method in which ATN is reacted with a Lewis acid such as calcium chloride or zinc chloride in the presence of water (Japanese Patent Publication No. 4412141); ■A method in which an acid catalyst such as ammonium chloride acts on ATN (Japanese Patent Publication No. 58-30308, Japanese Patent Publication No. 58-4
3392), etc. are known.

[Problems to be Solved by the Invention] However, the method (1) above has a maximum yield of about 60%, and also contains many reaction by-products derived from the catalyst, making the treatment complicated.

In addition, in method ① above, the yield can be improved if the catalyst is used in an amount equal to or more than the same mole relative to the raw material acetonin, but if it is used in an amount equal to or more than the same mole relative to the raw material acetonin, it should be considered as a reaction raw material rather than a catalyst. and is not practical.

[Means for Solving the Problems] As a result of intensive research to overcome the above problems, the present inventor has synthesized triacetonamine with high yield and high conversion rate of raw materials, and high purity. We have found a method to do this, and have completed the present invention.

That is, the present invention is directed to [acetone or an acidic condensate of acetone and 2°2.4
, 4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine to produce 2,2゜6,6-tetramethyl-4-oxopiperidine,
A method for producing 2,2,6,6-tetramethyl-4-oxopiperidine characterized by using an iron carboxylate as a catalyst.

It is a colorless or slightly yellow liquid represented by acetonate used as one of the raw materials of the present invention, such as R, B, Bra.
dbury et al., Journal of Chemical Society (J
,Chcv,! 1ioc,) No. 19471394.

In addition to the above, acetonin hydrate can also be used.

Acetone, one of the raw materials in the present invention, or an acidic condensate of acetone used in combination with acetone includes:
Examples include diacetone alcohol, mesityl oxide, holon, diacetone amine, and triacetone diamine, among which diacetone alcohol is particularly preferred.

The amount of acetone or the acidic condensate of acetone to be used is equal to or more than the equivalent mole relative to acetonin as the starting material, and the reaction proceeds more quickly when a larger amount is used, but it is practically preferable to use 3 to 6 moles.

In the present invention, the catalyst used is a salt of iron and carboxylic acid.

Carboxylic acids used to form such salts include -basic, dibasic and tribasic aliphatic and aromatic carboxylic acids. To illustrate, preferably saturated or unsaturated monobasic aliphatic carboxylic acids having 1 to 18 carbon atoms, such as formic acid, acetic acid, propionic acid, butyric acid, lauric acid, valmitic acid, stearic acid,
lactic acid, acrylic acid and methacrylic acid, preferably saturated or unsaturated dibasic aliphatic carboxylic acids having 2 to 12 carbon atoms, such as malonic acid, succinic acid, adipic acid,
Cepatic acid, tartaric acid, malic acid, fumaric acid, maleic acid; tribasic aliphatic carboxylic acids such as citric acid; optionally substituted monobasic aromatic carboxylic acids such as benzoic acid, toluic acid, cinnamic acid, Naphthoic acid; dibasic aromatic carboxylic acids, such as phthalic acid and terephthalic acid; and tribasic aromatic carboxylic acids, such as trimellitic acid.

Among these, particularly preferred carboxylic acids include acetic acid, oxalic acid, lactic acid, and citric acid.

It is also possible to use normal salts, acidic salts, basic salts, and hydrates of these salts.

Further, these catalysts can be used alone or in combination.

The catalyst used in the present invention is advantageous because it is produced industrially at low cost and is easily available.

There is no particular limitation on the amount of these catalysts to be used, and if a large amount is used, the reaction time will be shortened.

However, from the viewpoint of economy and workability, the amount is preferably 0.01 to 0.2 mol per 1 mol of acetonin used.

Furthermore, the catalyst of the present invention can be used in combination with conventionally known Lewis acids, protonic acids, or salts of protonic acids and ammonia or nitrogen-containing organic bases.

Examples of Lewis acids include zinc chloride, tin chloride, aluminum chloride, iron chloride, calcium chloride, potassium iodide, and boron trifluoride.

Examples of protonic acids include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrogen fluoride, and hydrogen iodide, aliphatic or aromatic acids such as methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and naphthalenesulfonic acid. aliphatic or aromatic phosphonic acids such as sulfonic acid, methylphosphonic acid, benzylphosphonic acid, phenylphosphonic acid, aliphatic or aromatic phosphinic acids such as dimethylphosphinic acid, diethylphosphinic acid, diphenylphosphinic acid, formic acid,
Monobasic aliphatic or aromatic acids such as acetic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, propionic acid, butyric acid, lauric acid, palmitic acid, stearic acid, lactic acid, acrylic acid, methacrylic acid, cinnamic acid, naphthalic acid, etc. Carboxylic acids, dibasic aliphatic or aromatic carboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, tartaric acid, malic acid, fumaric acid, maleic acid, phthalic acid, terephthalic acid, citric acid and tribasic aliphatic or aromatic carboxylic acids.

In addition, ammonium salts of the protonic acids include ammonium chloride, ammonium bromide, ammonium iodide,
Ammonium salts of inorganic acids such as ammonium nitrate and ammonium borate; organic acids such as ammonium formate, ammonium acetate, ammonium dichloroacetate, ammonium trichloroacetate, ammonium trifluoroacetate, ammonium malonate, ammonium benzoate, and ammonium 1)-toluenesulfonate; Examples include ammonium salts of acids.

Furthermore, examples of organic bases that form salts with the protonic acid include methylamine, ethylamine, N-butylamine,
Aliphatic amines such as octylamine, dodecylamine, hexamethylene diamine, aliphatic secondary amines such as dimethylamine, diethylamine, di-n-propylamine, di-isobutylamine, aliphatic tertiary amines such as triethylamine, Alicyclic amines such as cyclohexylamine, aniline, toluidine, naphthylamine,
Aromatic-class amines such as benzidine, aromatic secondary amines such as N-methylaniline, diphenylamine, N,N
- Aromatic tertiary amines such as diethylaniline, pyrrolidine, piperidine, N-methyl-2-pyrrolidone, pyrazolidine, piperazine, pyridine, picoline, indoline, quinuclidine, morpholine, N-methylmorpholine,
Heterocyclic bases such as 1,4-diazabicyclo[2.2.2]octane, triacetonamine, saturated or unsaturated nitrogen-containing organics such as urea, thiourea, strong bases or weakly basic ion exchange resins, etc. Examples include bases.

In carrying out the present invention, a solvent is not particularly required during the reaction, 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, isoproptool, t-butyl alcohol, cyclohexyl alcohol, benzyl alcohol, ethylene glycol monomethyl ether, glycol, Examples include propane-1,3-diol.

The outline of the reaction conditions is as follows.

In the reaction, acetone as a starting material or an acidic condensate of acetone used in combination with acetone, ATN, and a catalyst are prepared in a predetermined molar ratio, and the reaction temperature is around 60°C (reflux temperature in the case of acetone) for 5 to 50 minutes. Do it for 10 hours.

Since the catalyst is not dissolved but dispersed in the reaction raw material liquid, in order for the reaction to proceed efficiently, it is necessary to perform sufficient stirring to prevent the catalyst from precipitating.

The crude liquid after the completion of the reaction may be distilled as it is, or, for example, salting out may be performed using caustic soda, and the upper layer liquid separated into two layers may be distilled.

The desired product 2,2,6,6-tetramethyl-4-oxopiperidine (triacetonamine-TA
AM) is obtained.

[Action and Effect of the Invention] By the method of the present invention, 2,2,6,6-tetramethyl-
4-oxopiperidine (triacetonamine-TAAM
), the reaction time of (a) is shorter than that of conventional methods.

(b) The yield of triacetonamine is high without decreasing the conversion rate of acetonin.

(c) No coloring is observed and almost no reaction by-products such as resinous substances are produced.

(C) Also, due to the selection of the solvent or the catalyst used in combination, it does not contain halogen, which is advantageous in terms of equipment.

These advantages greatly facilitate the reaction and post-reaction processing.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but these examples are not intended to limit the present invention in any way.

Further, in this example, the concentration of 2,2,6,6-tetramethyl-4-oxopiperidine was measured using gas chromatography.

[Example] Example-1 A flask equipped with a reflux condenser was charged with 15.4 g of acetonin, 46.4 g of acetone, and 2.9 g of ferric acetate, and then stirred.

The reaction temperature was maintained at 60°C and the reaction was continued for 7 hours.

Thereafter, the mixture was cooled and left to stand, and the reaction solution was quantified by gas chromatography.

The quantitative value of triacetonamine was 18.9 g. A yield of 122.0% (based on acetonin) was obtained with an acetonin change rate of 99.5%.

Example-2 Acetonin 25 containing 40% acidic condensate of acetone such as diacetone alcohol instead of pure acetonin
．． 7g, acetone 34. og and ferric acetate 3.2g
Table 1 was carried out in the same manner as in Example-1 except that
The results shown are obtained.

Example 3 The same procedure as Example 2 was carried out except that 40 g of acetone and 1.6 g of ferric acetate were added, and the results shown in Table 1 were obtained.

Example 4 The same procedure as Example 2 was carried out except that 3.2 g of basic iron acetate (II) was charged, and the results shown in Table 1 were obtained.

Example 5 The same procedure as Example 2 was carried out except that 3.2 g of ferrous acetate was charged, and the results shown in Table 1 were obtained.

Example 6 The same procedure as Example 3 was carried out except that 3.2 g of ferric acetate and 3.2 g of acetic acid were charged, and the results shown in Table 1 were obtained.

Example 7 The same procedure as Example 2 was carried out except that 1.6 g of ferrous lactate was added, and the results shown in Table 1 were obtained.

Comparative Example 1 The same procedure as Example 1 was carried out except that 2.9 g of manganese acetate tetrahydrate was charged, and the results shown in Table 1 were obtained.

Comparative Example 2 The same procedure as Example 2 was carried out except that 1.6 g of acetic acid was charged, and the results shown in Table 1 were obtained.

Comparative Example 3 The same procedure as Example 2 was carried out except that 3.6 g of acetic acid was charged, and the results shown in Table 1 were obtained.

Comparative Example-4 Example-2 except that 3.6 g of ammonium acetate was charged.
The procedure was carried out in the same manner as above, and the results shown in Table 1 were obtained.

The conditions and results obtained in Examples 1 to 7 and Comparative Examples 1 to 4 are summarized in Table 1. (The following is a blank space) As is clear from the results shown in Table 1 (this invention 2
, 2,6.6-titramethyl-4-oxopiperidine, it is possible to obtain the desired product with both high yield and conversion rate.

On the other hand, the catalysts used in the comparative examples showed high values for both yield and conversion.

Claims (1)

[Claims] Acetone or an acidic condensate of acetone and 2,2,4,
In a method for producing 2,2,6,6-tetramethyl-4-oxopiperidine by reacting with 4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine, an iron carboxylate is used as a catalyst. 2 characterized by the use of
, 2,6,6-tetramethyl-4-oxopiperidine production method.