CH582146A5 - 2,2,6,6-Tetramethyl-4-oxo-piperidine prepn. - by acid catalyst treatment of 2,2,4,4,6-pentamethyl 2,3,4,5-tetrahydro-pyrimidine - Google Patents

Abstract

is prepd. from 2,2,4,4,6-pentametyl-2,3,4,5-tetrahydro-pyrimidine ("acetonine") by treating the acetonine with 0.2-12 mole % of an acid catalyst based on the amt. of acetonine either (a) in anhydrous medium or with less than an equimolar amt. of water based on the amt. of acetonine and in the presence of acetone and/or diacetone alcohol or (b) with at least an equimolar amt. of water. The reaction is pref. carried out in the presence of a solvent or mixt. of solvents e.g. ketones other than acetone, their auto-condensation prods. with acids, diacetone-amine, mesityl oxide, diacetonyl alcohol, triacetone diamine or phorone at -15 to +40 degrees C and a press. of 1-30 atmos., pref. 1-3 atmos. The acid catalyst may be an ammonium or organic N-contg. base salt of a protonic acid e.g. a mineral, sulphonic or carboxylic acid.

Description

  

  
 



      The main patent No. 574 relates to a process for the preparation of 2,2,6,6-tetramethyl-4oxopiperidine from 2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine hydrate, in the presence of an organic one Solvent, characterized in that the reaction is carried out in at least 1.5 moles of acetone per mole of pyrimidine starting material in the presence of 0.2-7 mole percent, based on pyrimidine starting material, of a Lewis or protic acid catalyst
Temperatures between 40 and 65 "C performs.



   The present invention la relates to an extension de.



   in the main patent no. 574411 protected process, characterized in that 2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine with 0.2 to 12 mol percent, based on the acetonin starting material , an acidic catalyst behang delt, wherein a) anhydrous or with less than the equimolar amount of water based on the acetone, and in the presence of acetone and / or diacetone alcohol, or b) with at least the equimolar amount of water based on acetone works, with the exception of what is protected in the patent claim of the main patent no. 574411.



   The reaction is optionally carried out in the presence of diacetonamine, triacetonediamine and / or another acidic condensation product of acetone as diacetone alcohol, and / or in case b), also of acetone and / or diacetone alcohol.



   An acid condensation product of acetone is e.g. Phoron and especially mesityl oxide and especially diacetone alcohol.



   It is advantageous to use an organic solvent or an additional organic solvent.



   Organic solvents which are particularly suitable for the process according to the invention are e.g. Hydrocarbons such as aromatics e.g. Benzene, toluene and xylene, and aliphatics, such as hexane, heptane and cyclohexane, and chlorinated hydrocarbons, such as methylene chloride, trichloroethane, carbon tetrachloride, chloroform, ethylene chloride and chlorobenzene, and ethers, such as tetrahydrofuran, dioxane and acetonitrile, such as nitrile, and also aprotic polar solvents such as sulfolane, nitromethane, dimethylformamide, dimethylacetamide, tetramethylurea, hexamethylphosphoric acid amide and dimethyl sulfoxide, and particularly preferably alcohols such as mono- or polyfunctional, unsubstituted or substituted aliphatic alcohols, for example

  Lower alkanols such as methanol, ethanol, propanol, isopropanol and tert-butanol, and cyclohexanol, benzyl alcohol, ethylene glycol monomethyl ether, glycol and propanol -1,3-diol, and ketones such as acetone, methyl ethyl ketone and cyclohexanone. A C1-C4 alcohol, such as methanol, as well as acetone, diacetone alcohol, Phoron, diacetonamine, triacetonediamine and mesityl oxide is particularly suitable. Mixtures of the above solvents are also suitable.



   The catalysts which can be used in the present invention are Lewis acid catalysts, e.g. Zinc chloride, tin chloride, aluminum chloride and boron trifluoride or protic acids.



   Catalysts are also salts of protic acids with ammonia or organic bases. Organic bases are above all organic nitrogen bases, in particular primary, secondary or tertiary nitrogen bases. Examples of such protic acids or of acid components in salts used as acidic catalysts are in particular:
Mineral acids such as hydrochloric acid, boric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid and phosphoric acid, as well as sulfonic acids such as aliphatic or aromatic sulfonic acids, e.g. Methanesulphonic acid, benzenesulphonic acid, p-toluenesulphonic acid or naphthalenesulphonic acid, phosphoric acids and phosphinic acids such as aliphatic or aromatic, e.g.

  Methyl, benzyl or phenylphosphonic acid or dimethyl, diethyl or diphenylphosphinic acid, and
Carboxylic acids such as monobasic, dibasic or tribasic aliphatic or aromatic carboxylic acids, e.g. ge saturated or unsaturated monobasic aliphatic carboxylic acids with 1-18 carbon atoms, such as formic acid, acetic acid,
Chloroacetic acid, dichloroacetic acid, trichloroacetic acid, cyano acetic acid, propionic acid, butyric acid, lauric acid, palmitic acid, stearic acid, acrylic acid, methacrylic acid and cinnamic acid, saturated and unsaturated dibasic aliphatic acids
Carboxylic acids, such as oxalic acid, malonic acid, succinic acid,
Adipic acid, sebacic acid, tartaric acid, malic acid, fumaric acid and maleic acid, tribasic aliphatic carboxylic acids such as citric acid, monobasic aromatic carboxylic acid such as optionally substituted benzoic acid and naphthoic acid,

   and dibasic aromatic carboxylic acids such as
Phthalic acid and terephthalic acid. Monobasic and dibasic aliphatic or aromatic carboxylic acids and monobasic aromatic sulfonic acids, such as acetic acid, succinic acid, maleic acid, benzoic acid, m-methylbenzoic acid, p-tert-butylbenzoic acid, p-toluenesulfonic acid and cinnamon acid are preferred. Suitable organic bases are: aliphatic, aly cyclic and aromatic, primary, secondary and tertiary amines, saturated and unsaturated nitrogen bases, urea, thiourea and basic ion exchange resins. So aliphatic primary amines are e.g. Methylamine, ethylamine, n-butylamine, octylamine, dodecylamine and hexamethylene diamine, aliphatic secondary amines e.g.

  Dimethylamine, diethylamine, di-n-propylamine and di-isobutylamine, aliphatic tertiary amines e.g. Triethylamine, alicyclic primary amines e.g. Cyclohexylamine, aromatic primary amines e.g.



  Aniline, toluidine, naphthylamine and benzidine, aromatic secondary amines e.g. N-methylaniline and diphenylamine, aromatic tertiary amines e.g. N, N-diethylaniline, saturated and unsaturated nitrogen bases e.g. heterocyclic bases, e.g. Pyrrolidine, piperidine, N-methyl-2-pyrrolidone, pyrazolidine, piperazine, pyridine, picoline, indole, quinuclidine, morpholine, N-methylmorpholine, 1,4-diazobicyclo [2,2,2] octane and triacetonamine, urea, thiourea and strong and weakly basic ion exchange resins. Acetonine and diacetonamine and triacetonamine are also preferred.

  Examples of preferred salts are: cyclohexylamine formate, pyridine formate,
Pyridine p-toluenesulfonate, di-n-butylamine acetate, di-n-butyl amine benzoate, morpholine succinate, morpholine maleate, triethylamine acetate, triethylamine succinate, triethylamine maleate, aniline acetate, triacetonamine p-toluenesulfone and hydrochloride.



   Mixtures of acidic catalysts or, in addition, co-catalysts different therefrom, in particular in amounts of 0.01-0.5 mol%, based on acetone, can be used.



   Possible mixture components or co-catalysts are:
Potassium iodide, sodium iodide, lithium bromide, lithium iodide, lithium rhodanide, ammonium rhodanide, lithium cyanide, lithium nitrate, ammonium sulfide, bromine, iodine, or a bromide, iodide, nitrate, methanesulfonate, benzenesulfonate or p toluenesulfonate of ammonia, triethylamine, urea.

 

   Preferred catalysts are ammonium chloride, ammonium bromide, ammonium nitrate and boron trifluoride. The amount of catalyst used is between 0.2 and
12 mol. XO, based on PySmidine starting material and is preferably between 0.2 and 7, in particular between 2 and 4 mol%. The reaction is carried out in particular between 40 and 1200 ° C., preferably between 50 and 100 ° C.

  In the presence of acetone, the preferred reaction temperature is 40-65 "C, in particular 50-55" C, in the presence of diacetone alcohol or mesityl oxide 90-100 ° C, without the addition of coreactants, preferably 50-100 "C. If ketones other than acetone or its is used acidic self-condensation products, the reaction temperature is advantageously -15 "C to + 400C. Finally, it is also advantageous to work under pressure, e.g. at 1-30, especially 1-10, especially 1-3 atmospheres overpressure.



   The reaction time is preferably ¸-15 hours, with acetone as the coreactant preferably 7-14, in particular 8-12 hours, and with diacetone alcohol as the coreactant preferably 1/2-2, especially 1-1 hours.



   The amount of acetone, diacetonamine, triacetonediamine or acidic acetone condensation product is generally at least 1.5 moles per mole of pyrimidine starting material, but can be up to 10 moles. As a practical matter, the preferred range is 2 to 6 moles, especially 3 to 4 moles. However, less than 1.5 mol of coreactant can also be used with advantage.



   The use of diacetone alcohol as a coreactant is particularly suitable, since the reaction can be carried out more quickly because of the possibility of increased reaction temperature.



   The work-up can be carried out in a manner known per se, e.g. by adding water and separating it off as a hydrate, or by adding acid, such as hydrochloric acid, sulfuric acid or oxalic acid and separating it off as a salt, or by adding an excess of alkali, in particular concentrated alkali, such as aqueous sodium hydroxide solution or potassium hydroxide, and separating it off as an organic layer , or in particular by distillation, optionally after neutralizing the catalyst by adding a base, such as sodium hydroxide, potassium hydroxide or sodium carbonate.



   It is advantageous to use some water in the reaction according to the invention, either as pyrimidine hydration water and / or as a small amount of added water. If a) is carried out in an anhydrous manner, the proton acid catalysts used are preferably weak acids or salts thereof, if b) is carried out in a water-containing manner, the protic acid catalysts used are preferably strong acids, such as mineral or sulfonic acids. A hydrate of a salt can also be used as a water supplier.



   The present invention is illustrated by the following examples:
example 1
10 g acetonine hydrate, 10 g diacetone alcohol and 0.3 g ammonium chloride are mixed, heated to about 100 ° C. The content of acetonine or triacetonamine in the reaction mixture is determined by gas chromatography at regular intervals. After 1 hour of reaction time at 90-1000 are less detectable as 5% of the original amount of acetonin, the remainder being rearranged to triacetonamine, which is isolated by fractional distillation.



   Example 2
10 g of acetone hydrate, 10 g of acetone and 0.3 g of ammonium chloride are heated to 550. The acetonine or triacetonamine content of the reaction mixture is determined by gas chromatography at regular intervals. After a reaction time of 12 hours at 55 ", less than 3% of the original amount of acetonin can be detected. The remainder has been rearranged to triacetonamine, which is isolated by fractional distillation.



   In this example, instead of 0.3 g of ammonium chloride, a mixture of 0.3 g of ammonium chloride and 0.1 mol%, calculated on acetonine hydrate, of one of the following cocatalysts is used: NH4, Br, NH4NO3, NH4J, LiBr, LiNO3, LiJ , NaJ, KJ, J2, urea nitrate, triethylammonium p-toluenesulfonate, NH4SCN, LiSCN or (NH4) 2S so is the
Reaction with equally good yields ended after about 5 hours.



   Example 3
10 g acetonin hydrate, 10 g mesityl oxide and 0.3 g ammonium chloride are heated to about 100 ". In regular
The content of the reaction mixture in
Acetonine or triacetonamine be determined by gas chromatography. After a reaction time of 5 hours at 90-100, less than 5% of the original amount of acetonine can be detected. The resulting triacetonamine is fractionated by
Distillation isolated.



   Example 4
10 g acetonin hydrate, 5 g mesityl oxide, 2.6 acetone and 0.3 g ammonium chloride are heated to 550. In regular
The content of the reaction mixture is increased at intervals
Acetonine or triacetonamine be determined by gas chromatography. After a reaction time of 12 hours at 55 ", less than 5% of the original amount of acetonin can be detected
The rest is rearranged to triacetonamine, which is fractionated by
Distillation is isolated.



   Example 5
10 g of acetonin hydrate are heated to 100 "with 0.3 g of ammonium chloride. The
Acetonine or triacetone amine content of the reaction mixture determined by gas chromatography. After 3 hours of reaction time at 100 "is less than 5% of the original
Detectable amount of acetone. The rest is rearranged to triacetone amine, which is isolated by fractional distillation.



   Example 6
15.4 g of anhydrous acetonine, 20 g of acetone and 0.4 g of ammonium chloride are heated to 55 ° C. In regular
The content of the reaction mixture is increased at intervals
Acetonine or triacetonamine be determined by gas chromatography. After a reaction time of 15 hours at 55 ° C., at least 95% of triacetone amine, based on the amount of acetone used, was formed. The triacetone amine formed is isolated by fractional distillation after the catalyst has been neutralized with sodium hydroxide.



   If the same amount is used instead of acetone
Diacetone alcohol or a mixture of 20 g acetone and 0.9 g
Water and if the rest of the procedure is as described above, an approximately equally good rearrangement of the is obtained
Acetonins in Triacetonamine.



   Example 7
17.2 g of acetonin hydrate, 20 g of acetone and 0.5 g of acetic acid are heated to 55 ° C. The content of the reaction mixture of acetonin or acetonin is measured at regular intervals.



   Triacetonamine determined by gas chromatography. After 12
Hours of reaction time, the acetonin hydrate used is rearranged in at least 95% yield to triacetone amine, which is isolated by fractional distillation.

 

   If you use a corresponding amount of formic acid, benzoic acid, dichloroacetic acid instead of acetic acid,
Maleic acid, cinnamic acid, trichloroacetic acid, p-toluenesulfonic acid, methanesulfonic acid or an equivalent amount of a salt such as ammonium bromide, triethylamine-p-toluene sulfonate, pyridine formate, urea nitrate, triacetonamine hydrochloride, thiourea hydrochloride, ammonium acetate,
Triethylamine hydrochloride or ammonium tosylate, and if you proceed otherwise as described oden, you get that
Triacetonamine in similar good yields.



   Example 8
17.2 g acetonin hydrate, 50 g dimethylformamide and 0.5 g
Ammonium chloride are heated to 60 ° C. The content of acetonin or triacetonamine in the reaction mixture is determined by gas chromatography at regular intervals. After a reaction time of 15 hours, less than 5% of the original amount of acetonin can be detected fractional distillation is isolated.



   If, instead of dimethylformamide, 40 g of dioxane, 20 g of isopropanol, 15 g of ethylene glycol monomethyl ether or a mixture of 30 g of benzene and 20 g of acetone are used and the procedure is otherwise as described above, the triacetone amine is obtained in similarly good yields.



   Example 9
17.2 g of acetonin hydrate, 30 g of methyl ethyl ketone and 0.5 g of ammonium bromide are stirred at 40 ° C. for 24 hours.



  After this reaction time, as a gas chromatographic analysis shows, about 70% of the amount of acetonin used has been rearranged into triacetonamine, which is isolated by distillation.



      Example '10
17.2 g of acetonin hydrate, 20 g of acetone, 1.8 g of water and 0.4 g of ammonium chloride are heated to 55 ° C. After a reaction time of 12 hours, as a gas chromatographic analysis shows, at least 95% of the acetonin used has rearranged to triacetonamine, which is isolated by distillation.



   If instead of the 1.8 g of water, 3.6 g or 5.4 g of water are added to the above reaction mixture and the rest of the procedure as described there, the triacetone amine is obtained in practically the same good yields.



   Example 11 1712 g of acetonine hydrate, 3 g of methanol and 0.5 g of ammonium chloride are heated to 60 ° C. After a reaction time of 12 hours, as a gas chromatographic analysis shows, about 80% of the acetonine used has rearranged to triacetonamine, which is Distillation is isolated.

 

   If, instead of the 3 g of methanol, 2 g of water are added to the above reaction mixture and the rest of the procedure is as described there, the triacetone amine is obtained in practically the same yield.



   Example 12
17.2 g of acetonin hydrate, 30 g of acetone and 0.5 g of ammonium chloride are heated to 45 ° C. for 6 hours in the containment tube is isolated.

 

Claims (1)

PATENT CLAIM 1. Process for the preparation of 2,2,6,6-tetramethyl-4-oxopiperidine from 2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine, which is called acetonine below, characterized in that the acetonin is treated with 0.2 to 12 mole percent, based on acetone starting material, of an acidic catalyst, wherein a) anhydrous or with less than the equimolar amount of water, based on the acetonin, and in the presence of acetone and / or diacetone alcohol works, or b) works with at least the equimolar amount of water based on acetonine, with the exception of that protected in the patent claim of the main patent no. 574411. SUBCLAIMS 1. The method according to claim, characterized in that the solvent used is acetone, diacetone alcohol, mesityl oxide, diacetonamine, triacetone diamine, Phoron, a C1-C4 alcohol, ethylene glycol monomethyl ether or mixtures thereof. 2. The method according to claim, characterized in that the acidic catalyst used is a salt of a protic acid with ammonia or with an organic nitrogen base. 3. The method according to claim, characterized in that a mineral acid, sulfonic acid or carboxylic acid is used as the acidic catalyst. 4. The method according to claim, characterized in that ammonium chloride, ammonium bromide, ammonium iodide, ammonium nitrate, ammonium formate, ammonium tosylate, urea nitrate, urea tosylate, thiourea hydrochloride, hexamethylene diamine dihydrochloride or triacetonamine hydrochloride is used as the acid catalyst. 5. The method according to claim, characterized in that the acidic catalyst is a Lewis acid catalyst.