KR960014351B1 - Processes for preparation of 2.2.6.6. -tetramethyl-4-ox0- piperidine - Google Patents

Abstract

The 2.2.6.6.-tetramethyl-4-oxopiperidine such as formula (II) is prepared by (a) reacting acetone with ammonia in presence of catalysts expressed as R1COOH-NH4, where R1 is C1-C2 aliphatic or aromatic compound, hydrogen, methyl, ethyl or phenyl or NH4-X1, where X1 is fluorine, chlorine, bromine or iodine, to convert acetonine expressed as the structural formula (II), (b) reacting the product solution containing acetonine at 50-70 deg.C for 5-6 hrs. in presence of catalysts expressed as M-X2, where M is sodium, potassium or lithium and X2 is fluorine, chlorine, bromine or iodine, (c) maintaining the product solution to less than 25 deg.C and adding 5-30 vol% peroxide expressed as R2-O-O-R3, where R2 and R3 are C1-C6 alkyl group, cyclohexyl, cycloalkyl, etc., respectively to the product solution.

Description

Method for preparing 2,2,6,6-tetramethyl-4-oxo-piperidine

In the present invention, acetone and ammonia are condensed using an organic or inorganic ammonium salt of the following general formula (III) or general formula (IV) as a catalyst so that the following structural formula (I) is 2,2,4,6,6-pentamethyl -2,3,4,5-tetrahydropyrimidine (acetonin), and the method of the following preparation by the hydrolysis reaction of the compound of formula (I) in an organic solvent. More specifically, a compound of the structural formula (I) is prepared in a high yield within a short time by using an inorganic ammonium salt organic or acetone and ammonia as a catalyst, and additionally, acetone is added to the prepared compound of the structural formula (I) without a separation process. In the preparation of the compound of formula (II) by carrying out the hydrolysis reaction using a promoter of formula (V), by adding a peroxide of formula (VI) to the reaction by-products generated during the reaction 2,2,6,6-tetramethyl-4-oxo-piperi, characterized in that the reaction by-products are converted into compounds represented by the structural formula (II) to increase the production and recovery of the structural formula (II) compounds. It relates to a process for preparing a dean.

Wherein R ₁ is an aliphatic or aromatic compound having 1 to 6 carbon atoms or is hydrogen, methyl, ethyl, phenyl, preferably hydrogen, methyl.

Wherein X 1 is fluorine, chlorine, bromine, iodine, preferably chlorine or bromine.

Wherein M is sodium, potassium, lithium, preferably sodium, potassium, and X ₂ is fluorine, chlorine, bromine, iodine, preferably bromine, iodine.

Wherein R ₂ and R ₃ are independently an alkyl group of C ₁ to C ₆ as t, hydrogen, methyl, ethyl, propyl, isopropyl, t-butyl, s-butyl, t-amyl or alkyl such as cyclohexyl , cycloalkyl such as l-methylcyclohexyl, l-methoxy cyclohexyl, and specifically hydrogen, methyl, ethyl, propyl, t-butyl, t-amyl, cyclohexyl, l-methylcyclohexyl, preferably Hydrogen, methyl, propyl, t-butyl, cyclohexyl.

The compound of formula (II) is an intermediate of the known light stabilizer for plastic addition, which is then used to synthesize the light stabilizer by converting it from keto to alcohol form through hydrogenation, and then by various ester and ester exchange reactions. It is a substance.

Looking at the prior art by condensation of acetone and ammonia using calcium chloride or zinc chloride [H. K. Hall; J.A.C.S., 79, 5444 (1975)], by condensation of phorone and ammonia [W. Heintz; ann. Chemine. 203, 336 (1880)] 2,2,6,6-tetramethyl-4-oxo-piperidine have been published, but these methods have a low yield by producing a large amount of by-products, There are problems that are very difficult.

The production of 2,2,6,6, -tetramethyl-4-oxopiperidine by the reaction of acetone with ammonia involves the production of various by-products.

That is, by-products such as diacetone alcohol by acetone condensation reaction, mesityl oxide by dehydration of diacetone alcohol, and diacetoneamine by addition of ammonia are produced in a large amount. Lowering the yield of and increasing the recovery of 2,2,6,6, -tetramethyl-4-oxopiperidine is a major challenge in this area.

Many studies have been conducted to solve these problems. For example, United States Patent Nos. 3,959,298, 3,960,875, 3,963,730, Korean Patent Publication Nos. 78-745, British Patent No. 1,461,701, and British Patent No. 1,461,702. to be.

These are new technologies that complement the problems of previous technologies, but have their advantages, but not enough.

U.S. Patent No. 3,963,730 uses reaction starting materials using 2,2,4,4,6-pentamenyl-2,3,4,5-tetrahydro pyrimidine (hereinafter referred to as acetonin) rather than acetone and ammonia. 2,2,6,6-tetramethyl-4-oxo-piperidine was added to 91.1% by replacing the existing catalyst with ammonium salt to proceed with the reaction, and then extracting the solvent, removing water, and distilling the obtained reaction mixture. Announced yield.

However, when 2,2,6,6-tetramethyl-4-oxo-piperidine is prepared by this process, 2,2,6,6-tetramethyl-4-oxo-piperidine from acetonin The recovery rate of 2,2,6,6-tetramethyl-4-oxo-piperidine per unit time is lowered because the hydrolysis process for producing the reaction usually exceeds 10 hours, and the reaction mixture is colored due to the long time reaction. As a result, the 2,2,6,6-tetramethyl-4-oxo-piperidine, which is not easily removed after the post-treatment process, is severely discolored, which greatly affects the reaction.

In terms of raw material use, acetone, which is a reaction raw material, is added in excess of 200 mole% compared to acetonin, which is an economically disadvantageous method because it is more than twice as large as acetone for preparing initial acetonin.

In addition, Korean Patent Publication No. 78-754, British Patent No. 1,461,702, and US Patent No. 3,960,875 use boron tetrafluoride as a reaction catalyst with acetonine as a starting material, 2,2,6,6-tetramethyl-4- Oxo-piperidine was prepared. In this case, an additional amount of reactant acetone is 150 mole% or more and the reaction time also requires a long time of 12 hours or more. In the case of US Pat. No. 3,959,298, p-toluene is added to acetonin. 2,2,6,6-tetramethyl-4-oxo-piperidine was prepared by adding sulfonic acid to prepare a salt of acetonin and p-toluene sulfonic acid, and then hydrolyzing by adding water thereto. In this case, since p-toluene sulfonic acid is used in the same amount or more with respect to acetonin, the additional economic cost is increased, and the additional acetone is 150 mole% or more, similar to the techniques mentioned previously. There is a problem using the quantity.

In addition, Japanese Laid-Open Patent Publication No. 62-174049 has almost no modification of the reactants when the hydrogen peroxide solution is added to acetonin, stirred at 10-20 ° C. for 1 hour, and then heated to 50 ° C. for 2.5 hours. After claiming that there was a shortening effect, the present inventors found that the resultant reaction was carried out in the same manner, and the result was a very bad result in which the amount of the by-product in question reached 70% of the total reaction solution.

Therefore, in the present invention, when preparing a compound of formula (II) using acetone and ammonia to solve the above problems, the compound of formula (I), which is an intermediate of the compound of formula (II), continues without separation during the reaction Discoloration of the reactants is delayed by reducing the reaction time by advancing the reaction, avoiding excessive use of acetone in the middle stage, and reducing the economic loss, and adding the peroxide to the reaction mixture at the end of the reaction and stirring at low temperature It is an object of the present invention to provide a process for producing an industrially advantageous compound of formula (II), which can significantly improve the conversion and yield of phosphorus (II) compounds.

The present inventors conducted extensive research in order to achieve the above object, and as a result, the conversion rate of the compound of formula (II) is excellent due to the excellent ability to convert the by-products generated during the reaction into the compound of formula (II) as the final reaction product. It was found that after the peroxide treatment, the compound of formula (II) was recovered with high recovery by purifying with an aqueous sodium hydroxide solution and an alkane series organic solvent, and the present invention was completed based on this finding.

The present invention is to prepare a compound of formula (I) in a high yield in a short time with ammonia acetone as an organic or ammonium salt catalyst, and further added acetone without separating the compound of formula (I) as a solid, In preparing the compound of formula (II) by performing a hydrolysis reaction using a promoter of formula (V), the peroxide same as the formula (VI) is added and stirred to the reaction mixture during the reaction. It relates to a method for producing 2,2,6,6, -tetramethyl-4-oxo-piperidine characterized by increasing the production rate and recovery rate of the compound of formula (II) as a product.

[Formula 1]

[Formula 2]

[Formula 3]

R ₁ here is an aliphatic having 1 to 6 carbon atoms is an aromatic compound or is hydrogen, methyl, ethyl phenyl, preferably hydrogen, methyl.

[Formula 4]

NH ₄ -X ₁ (IV)

Wherein X 1 is fluorine, chlorine, bromine, iodine, preferably chlorine or bromine.

[Formula 5]

MX ₂ (V)

Wherein M is sodium, potassium, lithium, preferably sodium, potassium, and X ₂ is fluorine, chlorine, bromine, iodine, preferably bromine, iodine.

[Formula 6]

R ₂ -OOR ₃ (VI)

Wherein R ₂ and R ₃ are independently of each other an alkyl group of C ₁ to C ₆ , hydrogen, methyl, ethyl, propyl, isopropyl, t-butyl, s-butyl, t-amyl, or cyclohexyl, cycloalkyl such as l-methylcyclohexyl, l-methoxy cyclohexyl and the like, specifically hydrogen, methyl, ethyl, propyl, t-butyl, t-amyl, cyclohexyl, l-methylcyclohexyl, preferably hydrogen, Methyl, propyl, t-butyl, cyclohexyl.

Hereinafter, the manufacturing method of the present invention will be described in more detail.

The present invention relates to a compound of formula (I) when acetone and ammonia are prepared using a organic or inorganic ammonium salt to prepare a compound of formula (I), and then a compound of formula (II) is prepared from the compound of formula (I). The overall reaction time can be considerably reduced while increasing the production rate of the compound of formula (II), and the by-products generated during the reaction are converted back to the compound of the formula (II) to increase the overall recovery rate, and the catalyst removal process and the product recovery process are performed simultaneously. It is very economical in terms of time and manufacturing cost.

More specifically, the method of the present invention will be described in the reaction by blowing anhydrous ammonia gas into the acetone solution in which the ammonium salt is dispersed, the temperature and pressure is -20 so that the ammonia gas used as a reactant can be saturated in the acetone solution Maintain ˜30 ° C. and 760 to 1520 mm Hg, preferably −10 to 20 ° C. and 760 to 1140 mm Hg.

The ammonium salt used is 0.2 mol% to 20 mol% for shortening the reaction time and avoiding overuse, preferably 1 mol% to 15 mol%, and the optimum amount is 2.5 mol% to 10 mol%.

As ammonia is dissolved in the gas reaction solution, the temperature of the whole reaction solution increases, so the temperature of the reaction solution should be controlled so that the temperature of the reaction solution does not exceed 20 ° C using an ice bath. Particular attention should be paid to reaction temperature control as the formation of s increases and affects subsequent reactions.

The progress of the reaction is determined by gas chromatography and usually takes 90 to 150 minutes.

In the reaction mixture thus obtained, a promoter of the general formula (V) is added in an amount of 0.01 mol% to 5 mol%, preferably 0.05 mol% to 2.5 mol%, based on the initial acetone consumption. If the rate is significantly reduced and more than 2.5 mol% is added, discoloration of the reaction solution may occur severely.

After adding the cocatalyst to the reaction solution, acetone is additionally added by 10 vol% to 100 vol% of the initial use, preferably 25 vol% to 75 vol%.

After the addition of acetone, the reaction solution is well stirred and the temperature is raised to 50 ° C. to proceed with the reaction. The faster the temperature rise, the faster the reaction proceeds, so it is advantageous to raise the temperature as quickly as possible, and the temperature of the reaction solution is 70%. Beyond ℃, discoloration of the reaction solution occurs, so care must be taken in temperature control.

The progress of the reaction is determined by gas chromatography and the presence of byproducts and products (2,2,6,6-tetramethyl-4-oxo-piperidine) produced after about 6 hours as the reaction proceeds. The ratio is about 3: 7, and the reaction solution is cooled and then peroxide is added.

The temperature at the time of addition should be maintained at 0 ° C to 40 ° C, preferably 5 ° C to 25 ° C, and the amount of peroxide added is 2vol% to 50vol% compared to the amount of acetone used initially, preferably at 5vol%. Add 30vol%.

The peroxide was added, the reaction proceeded with continuous stirring, and gas chromatography confirmed the reduction of by-products, and the solution was stirred by adding an aqueous sodium hydroxide solution. Thus, the concentration of the sodium hydroxide solution added to remove the catalyst and the added peroxide was 15% to 50%. %, Preferably 20% to 40% aqueous solution is added and 25% to 250%, preferably 50% to 150% relative to the amount of acetone used initially.

Since it is recommended to use an alkane-based solvent for the solidification of the compound of formula (II), n-hexane, n-heptane, in particular n-hexane are preferable.

Through the following examples, the present invention will be described in more detail with respect to the manufacturing method and its effects, but it does not limit the present invention. % Means vol% unless otherwise specified.

Example 1

A well-dried 2,000 ml four-necked flask is equipped with a coil-type condenser, thermometer, stirrer, and gas injector bubbler, and nitrogen gas is flown into the flask to remove any water or air present.

This operation is continued for about 30 minutes, then 640 ml acetone, 64 ml methanol and 24 g ammonium chloride are added and the flask is cooled to 5 ° C. with a cooling solution consisting of dry ice and acetone.

When the reaction solution reaches 5 ° C, anhydrous ammonia gas is injected through the flask's bubbler and the reaction proceeds with vigorous stirring.After about 2 hours, ammonia gas injection stops and additional 320 ml of acetone and 2.7 g of sodium iodide are added. After doing this, the mixture is heated to 50 ° C. with vigorous stirring.

When the reaction solution reached 50 ° C, the temperature was maintained and stirring was continued for 6 hours. As a result, the composition of the reaction solution was determined by gas chromatography, and the composition of the by-product was 14% and the detected acetonin was less than 5%.

At this time, the reaction solution was cooled to 0 ° C., and when the reaction solution reached 0 ° C., 100 ml of 30% hydrogen peroxide aqueous solution was added and stirred vigorously. After stirring for 1 hour at 0 ° C., the composition of the reaction solution was analyzed with a gas chromatograph. As a result, the composition of a by-product previously present was detected at 3% or less, and acetonin was less than 2%.

Example 2

Example 1 was carried out in the same manner as in Example 1, except that 100 ml of 30% hydrogen peroxide was used instead of 200 ml. The composition of the by-products remaining in the reaction solution was less than 2%, and the amount of acetonin present was less than 3%.

Example 3

The same procedure as in Example 1 was conducted except that 100 ml of tertiary butyl peroxide was used instead of 100 ml of 30% hydrogen peroxide solution. The remaining byproducts in the reaction solution and the amount of acetonin present were less than 2%, respectively.

Comparative Example 1

Acetone production process is the same as in Example 1.

Once acetonin is produced, 307 ml of 30% hydrogen peroxide solution is added and the temperature of the reaction solution is adjusted to 10 ° C. and stirred for 1 hour. When the reaction solution was heated to 50 ° C. and stirred for 2.5 hours, the reaction progress was analyzed by gas chromatography. As a result, it was found that the composition of the by-products was 70% or more of the total reaction solution. , 6,6-tetramethyl-4-oxo-piperidine produced less than 20%.

Claims (5)

The acetone and ammonia are reacted in the presence of a catalyst represented by the following general formula (III) or (IV) to convert to acetonine represented by the following structural formula (I), and from the reaction solution containing acetonine, the following structural formula In the method for producing 2,2,6,6-tetramethyl-4-oxopiperidine represented by (II), the reaction solution containing acetonin is subjected to a temperature of 50 to 70 ° C and the following general formula (V After reacting with acetone for 5 to 6 hours in the presence of a catalyst represented by), the temperature of the reaction solution is maintained at 25 ° C. or lower and peroxide represented by the general formula (VI) is added thereto to reduce the temperature of the reaction solution to 25 ° C. or less. A method of preparing 2,2,6,6-tetramethyl-oxopiperidine by further reacting for about 1 hour while maintaining the same. Wherein R ₁ is an aliphatic or aromatic compound having 1 to 6 carbon atoms or is hydrogen, methyl, ethyl, phenyl, preferably hydrogen, methyl. NH ₄ -X ₁ (IV) Wherein X ₁ is fluorine, chlorine, bromine, iodine, preferably chlorine or bromine. MX ₂ (V) Wherein M is sodium, potassium, lithium, preferably sodium, potassium, and X ₂ is fluorine, chlorine, bromine, iodine, preferably bromine, iodine. R ₂ -OOR ₃ (VI) Wherein R ₂ and R ₃ are independently of each other an alkyl group of C ₁ to C ₆ , hydrogen, methyl, ethyl, propyl, isopropyl, t-butyl, s-butyl, t-amyl, or cyclohexyl, cycloalkyl such as l-methylcyclohexyl, l-methoxy cyclohexyl, and specifically, hydrogen, methyl, ethyl, propyl, t-butyl, t-amyl, cyclohexyl, l-methylcyclohexyl, preferably hydrogen , Methyl, propyl, t-butyl, cyclohexyl. The method for preparing 2,2,6,6-tetramethyl-4-oxo-piperidine according to claim 1, wherein 5 to 30 vol% of the acetone used amount of the peroxide is used. The method for preparing 2,2,6,6-tetramethyl-4-oxo-piperidine according to claim 1, wherein the peroxide is a 30% aqueous solution. The 2,2,6,6-tetramethyl-4-oxo-piperidine according to claim 1, wherein an amount of the compound of the general formula (III) or (IV) is added in an amount of 1 to 15 mol% based on the initially added acetone. Manufacturing method. The method for producing 2,2,6,6-tetramethyl-4-oxo-piperidine according to claim 1, wherein the amount of the compound of the general formula (V) is added in an amount of 0.05 to 2.5 mol% based on the initially added acetone.