JPH01186864A - Production of n-alkyl-substituted lactam - Google Patents

Abstract

PURPOSE:To obtain the title high-purity substance in high yield and recycle the eliminated alcohol through a process for preparing a secondary amine, by reacting a lactone compound with secondary amines in the presence of water in a specific amount and subjecting the resultant reaction product to dealcoholizing decomposition at a specific temperature. CONSTITUTION:A lactone compound (e.g., gamma-butyrolactone) is reacted with a secondary amine in the presence of water in a molar amount of 3-5 times based on the lactone compound and the resultant reaction product is then subjected to dealcoholizing decomposition at 240-265 deg.C to afford the title substance (e.g., N-alkyl-substituted 2-pyrrolidone). The eliminated alcohol can be then separated and recycled through a process for preparing the secondary amine. The selectivity for the lactam is high in the above-mentioned method with a low lactone content in the product and the lactam having excellent color tone is obtained. Availability is improved by changing a primary amine with the secondary amine. Since the boiling point is high, safety problems can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing N-alkyl substituted lactams.

More specifically, the present invention relates to an improvement in a method for producing N-alkyl-substituted lactams using a lactone and a secondary amine or an ammonium derivative thereof as starting materials.

Among the N-alkyl-substituted lactams targeted by the present invention, N-alkyl-2-pyrrolidone is particularly useful as a non-toxic solvent with excellent chemical and thermal stability, and as an intermediate for various organauric acids. Although they are useful, quality regulations and requirements are strict, and high quality products are desired.

[Prior Art] It has been known that N-alkyl-substituted lactams can be produced by various methods.

Listing them, i) Method by reaction of lactones with primary amines.

■) A method in which lactams and an alkylating reagent are reacted in the presence of a catalyst.

ii) Method by catalytic hydrogenation of cyclic dicarboxylic acid-N-substituted imides.

1v) A method of hydrogenolyzing a starting material compound that can be converted into an N-substituted lactam by hydrogenolysis, such as N-hydroxyalkyl-substituted lactams and N-vinyllactams, in the presence of a catalyst.

Among these, method i) is most commonly employed industrially.

In other words, this method is good in terms of reaction rate, reaction yield, and product quality, and it does not use corrosive raw materials or catalysts, making it extremely advantageous for industrialization. [Kirk Othmer (Ki
rk Otbmsr) Encyclopedia of Chemical Chikunoroshii (Encyclopedia)
of Chemical Technology), published by John Willy & Son (Job++ Wilsy
& 5ons) (104) Volume 19, Page 517 and Journal of the American Chemical Society (J
, A+++.

Chew, See, +) Volume 71, Page 897 (1
949)].

When a secondary amine is reacted with a lactone instead of a primary amine, an N,N-dialkyl-substituted ω-oxycarboxylic acid amide is produced, and lactam production is difficult because it is impossible to form a lactam ring by dehydration reaction. It was difficult.

However, according to Japanese Patent Publication No. 47-18751, γ
- N-methyltopyrrolidone is obtained by reacting butyrolactone with dimethylamine and trimethylamine at a temperature range of 270 to 290°C, but the yield per raw material lactone is as low as 80%, and the substituted alkyl of secondary amine Due to the low usage efficiency of the group, the manufacturing unit consumption of secondary amines is large, and only low-quality products with low purity and easily colored can be obtained, so this technology could not be adopted industrially.

[Problems to be Solved by the Invention] Primary amines used as starting materials in conventional production methods for N-alkyl-substituted lactams are produced by various methods, but most commonly lower alcohols, Reaction of raw materials such as halogenated hydrocarbons with ammonia, nitro compounds,
It is produced through a hydrogenation reaction of a nitrile compound or its precursor.

Normally, primary amines are produced by the reaction of alcohol and ammonia, but the reaction products in this case are not simple and usually have a thermodynamic equilibrium composition or a ratio close to that of primary, secondary, and tertiary amines. A product containing a mixture of grade amines is produced.

For example, in the simplest reaction between methanol and ammonia, monomethylamine, dimethylamine, and trimethylamine are produced, and in particular, monomethylamine and dimethylamine, which have many uses, are produced in large quantities, and trimethylamine, which has few uses, is produced in a low amount. Many efforts have been made to research and develop technologies related to catalysts, reaction conditions and processes [for example, Frank J. Weigert (Frx
nkJ, Weigert) Journal of Catalyst J, Cxtil) Volume 103, pages 20-29 (
1987), JP-A No. 61-254, JP-A-61
-256 Publication, Chemical Handbook Applied Actinic Ray I (106)
Chemical Society of Japan, page 547].

However, despite these efforts, it is substantially difficult to selectively produce only primary amines, which are effective in producing N-alkyl-substituted lactams, among various amines, and Distilling and separating only primary amines from a mixture of substituted amines requires a large energy load and increases costs.

Therefore, as the demand for N-alkyl-substituted lactams increases, a method for producing N-alkyl-substituted lactams that does not use primary amines has been desired.

In order to solve these problems, the present invention uses secondary amines, which have conventionally been disadvantageous in terms of quality and yield, to produce products with high quality and high yield comparable to those of primary amines. The object of the present invention is to provide a method for producing an N-alkyl-substituted lactam in which the production unit of secondary amine is improved.

[Means for Solving the Problems] The present inventors used a secondary amine in the reaction of producing an N-alkyl-substituted lactam by reacting a lactone with an amine to achieve good yield and product quality. In order to find a production method, we conducted intensive research on reaction conditions, used a specific temperature and a specific amount of water, and used by-products in a circular manner to solve the above problems, resulting in the present invention. Ta.

That is, the present invention provides a method for producing an N-alkyl-substituted lactam by reacting t) a lactone compound with a secondary amine in the presence of water to form an N,N-dialkyl-substituted -ω-hydroxycarboxylic acid amide. of N-alkyl-substituted lactam, characterized in that the molar ratio of water and lactone (water/lactone) is 3 to 5, and the reaction temperature is 240 to 265°C, and the N-alkyl-substituted lactam is dealcoholized to form a lactam ring. Production method and ii) A method for producing an N-alkyl-substituted lactam by reacting a lactone compound with a secondary amine in the presence of water to form an N,N-dialkyl-substituted -ω-hydroxycarboxylic acid amide. N, N-
Heating the dialkyl-substituted -ω-hydroxycarboxylic acid amide to a temperature of 240°C or higher to form a lactam ring through dealcolysis, separating the eliminated alcohol and recycling it to the secondary amine manufacturing process. A method for producing an N-alkyl-substituted lactam, characterized in that:

The lactone compound used in the production method of the present invention has, as a skeleton,
It is a compound having a 4- to 7-membered ring, and various alkyl and allyl substituted derivatives can be used.

Examples of these include propiolactone, γ-butyrolactone, plutarolactone, caprolactone, 7talide, toviron, coumarin, dihydroaconic acid derivatives, dihydrobenzofuranone, and various other compounds known to form lactam rings. can be mentioned.

As the amines used in the present invention, secondary amines having an alkyl group or an aralkyl group having a carbon number of about C8 to C8 can be widely used, but for the purpose of producing a single reaction product, nitrogen atoms and It is preferable that the two substituents to be bonded are the same, and common examples thereof include dimethylamine, diethylamine, dipropylamine, dibutylamine, dicyclohexylamine, diphenylamine, and the like.

In general, dialkylamines having a low boiling point are often treated as an aqueous solution, but they are dissolved in the aqueous solution as an aqueous dialkylammonium solution.

Such dialkylammonium derivatives can also be used as secondary amines in the present invention.

That is, in the production method of the present invention, N
, N-dialkyl-substituted-ω-oxycarboxylic acid amide can be formed and suitably used as a raw material for the production method of the present invention.

In the conventional method for producing N-alkyl-substituted lactams, the production process of N-alkyl-substituted lactams using a lactone compound and a primary amine as starting materials involves the production of N-alkyl-substituted -ω-hydroxycarboxylic acid amide as an intermediate. including,
It is known that lactams are produced by dehydration and ring closure.

γ-Butyrolactone and monoalkylamine (R-N H
Taking the reaction of z) as an example, it is as follows, that is, γ
N-alkyl-2-pyrrolidone can be produced from -butyrolactone via N-alkyl-γ-oxybutyric acid amide.

On the other hand, in the reaction of a lactone compound and a secondary amine used in the production method of the present invention, N, N-';
It is known to produce alkyl-substituted -ω-hydroxycarboxylic acid amides.

To illustrate this by taking the reaction of γ-butyrolactone and secondary amine (INH) as an example, it follows the following chemical equation.

In this case, an N,N-dialkyl-substituted-ω-hydroxycarboxylic acid amide is produced.

Although this product does not have NH bonds to be dehydrated, it is reported in Japanese Patent Publication No. 18751/1987 that it can be converted into an N-substituted lactam by heating.

In order to elucidate this reaction mechanism, the present inventors
-We have conducted detailed studies on the reactivity of dialkyl-substituted -ω-hydroxycarboxylic acid amide compounds, and have confirmed that alcohol is eliminated when heated to 250°C in the presence of water. Based on this, it was discovered that the dealcoholization shown in the following formula occurs and the ring closes to form a lactam ring.

This dealcoholization reaction proceeds in an aqueous solution, and although water has a catalytic effect, as shown in the reaction equation, water is not a stoichiometrically essential component for the reaction; The reaction can be carried out without a catalyst in a gas phase or in an inert solvent.

The dealcoholization reaction of the present invention is carried out at a reaction temperature of 240 to 265
It is preferable to carry out the test at ℃. If the reaction temperature is less than 240°C, the reaction will hardly proceed, and if it exceeds 265°C, by-products will be generated due to sequential reactions, resulting in a decrease in purity and coloring of the product.

In particular, regarding N-alkyl lactams that have strict requirements for coloring (APHA) stability, the preferred reaction temperature for the production method of the present invention is approximately 240 to 265°C, and the reaction is substantially carried out in the presence of water in a specific range. It is carried out without catalyst.

In the production method of the present invention, the intermediate N,N-dialkyl-substituted acid amide is usually thermally decomposed in an aqueous solution, which is produced by the reaction of a lactone and a secondary amine. Preferred embodiments include, for example, a method in which a reaction product of a lactone and a secondary amine is dissolved in water and then thermally decomposed, and an aqueous solution of a lactone and a secondary amine (
Ammonium ionized) is reacted with N,N-
A method of directly producing an aqueous solution of a dialkyl-substituted carboxylic acid amide and thermally decomposing it, or a method of implementing any of the above steps under thermal decomposition conditions, etc. can be carried out.

It is desirable that the alcohol produced in the dealcoholization reaction of the present invention be recycled and used in the process of producing amines by reaction with ammonia. This makes it possible to recover most of the loss of substituent components caused by the use of the secondary amine.

In the production method of the present invention, the N,N-dialkyl-substituted-ω-oxycarboxylic acid amide is thermally decomposed. A ring-opening addition reaction of the compound occurs.

In the present invention, this ring-opening addition reaction can be carried out directly in-line with the final reaction step to form the lactam "ring" or at a prior stage to the pyrolysis reaction.

Examples are shown below, taking the production reaction of N-methyl-2-pyrrolidone as an example, but the present invention is not limited thereto.

Many modifications to the conditions of pyrolysis are possible that will be obvious to those skilled in the art without going beyond the gist of the invention.

Example 1' 609 gamma-butyrolactone and 125.469 g of a 50% aqueous solution of dimethylamine were mixed at room temperature and reacted for 5 hours. At this time, the liquid temperature rose to 40°C due to reaction heat.

Excess dimethylamine and water were distilled off, and the resulting colorless residue was identified by H-NMR and C-NMR, and was found to be N,N-dimethyl-γ-hydroxybutyric acid amide HO-CHxCIlzCHi represented by the following formula. -C-NC (C1ls)
It was confirmed that s.

When this was charged into an autoclave and heated to a temperature of 255°C, it was confirmed that N-methyl-2-pyrrolidone and methyl alcohol were produced in 3 hours.

Although unreacted N,N-dimethyl remained in the reaction solution, it was also confirmed that a large amount of N-methyl-γ-oxybutyric acid amide and a small amount of 2-pyrrolidone were produced.

N-methyl-γ-oxybutyric acid amide is an intermediate compound for the production of N-methyltopyrrolidone, which is conventionally produced by the reaction of γ-butyrolactone and methylamine (-grade amine).

It is estimated that the decomposition of N,N-dimethyl to N-methyltopyrrolidone involves the following two reaction routes.

(Route 1) H8 (Route 2) [0-CII*-CHx-CHx-C-N(CHx)x
→HOC11zC11ICI! , -C-NHCH3+
The yield of CH,OHL N-methyl-2-pyrrolidone was 41.49.

Selection of γ-butyrolactone as an active ingredient containing N-methyl-2-pyrrolidone as the total content of N,N-dimethyl form and N-methyl form is an effective intermediate for the production of N-methyltopyrrolidone The rate was 99% or more on a molar basis, which was almost quantitative.

The color tone (A P HA) of the product after distillation purification was 10, which was good. (See Distillation Condition Comparative Example 2) Example 2 500ml! γ-butyrolactone in an autoclave
6 g and 97.29 g of a 50% aqueous solution of dimethylamine were charged, and the reaction was carried out for 3 hours while maintaining the temperature at 255° C. and the pressure at 52 and 9/cra”G.

The molar ratio of dimethylamine/lactone in this case is 1.1
5, and the water/lactone molar ratio is 2.7.

When the reaction product liquid was analyzed by liquid chromatography, it was found that N
-The yield of methyl-2-pyrrolidone is 59.59,
Amides of methanol, N-methyl form, and N,N-dimethyl form were detected, and the composition was almost the same as in Example 1. Product purity is 99.9%, color tone (A P HA
) was 10.

The content of γ-butyrolactone was 0.02%.

Comparative Example 1 By reaction of γ-butyrolactone and monomethylamine,
N-methyl-gamma-hydroxybutyric acid amide crystals were synthesized. 500m for 103g of this crystal! The mixture was charged into an autoclave and reacted for 3 hours at a temperature of 255°C.

The yield of N-methyl-2-pyrrolidone was 61.89, the conversion rate of N-methylamide was 75.4%, and the selectivity was 92.3 mol%.

In addition to unreacted N-methylamide and water, the reaction solution contained 4.0% by weight of γ-butyrolactone, 2-pyrrolidone 2
8.5 ppm was detected. Product color tone (A PRA
) was 10.

Comparative Example 2 N-methyl-2-pyrrolidone was produced in the same manner as in Example 2 of the present invention except that the reaction temperature was 270° C. (same temperature as in Example 1 described in Japanese Patent Publication No. 18751/1984).

The yield of the target product was 81.59, and it was confirmed that the amount of methanol in the reaction solution was higher than in Example 2, and the amount of residual amide was reduced, indicating that the reaction was proceeding.

The product liquid is deamined, dehydrated and purified using a combination of three Oldershaw distillation towers to obtain the product N-methyl-2.
- obtained pyrrolidone.

In the purification tower, the product was extracted from the middle stage, and the residue containing high-boiling components was regularly extracted from the system.

The chemical purity of the product was 98.5%, and its color (APHA) deteriorated to 20. The content of γ-butyrolactone in the product was 0.4%.

Comparative Example 3 5. γ-butyrolactone in OC autoclave 1.7
2&g (20moA), 30% aqueous solution of dimethylamine 3.24&y (23,1moQ) were charged, and the temperature was 255.
After reacting at °C for 3 hours, the reaction solution was distilled to purify N-
Methyltopyrrolidone was produced.

The molar ratio of dimethylamine/lactone in this case is 1.1
5, and the water/lactone molar ratio is 6.3.

Product chemical purity is 99.7%, color (APHA) is 10
However, the content of γ-butyrolactone was 0.23%
increased to

[Effects of the Invention] The present invention provides a novel method for producing lactams by the reaction of lactones with secondary amines, which requires specific reaction conditions compared to conventional techniques using reactions with secondary amines. By employing this method, a lactam with high selectivity to lactam, low lactone content in the product, and good color tone (A P HA) can be obtained.

Furthermore, by recycling the alcohol by-produced into the amine production process, an N-alkyl-substituted lactam can be produced without material loss of substituents due to the use of secondary amines.

By replacing the primary amine with a secondary amine, one of the raw materials, the amine, is easily available and has a high boiling point, so there is the advantage that safety issues can be largely resolved.

Patent applicant: Mitsubishi Chemical Industries, Ltd.

Claims (3)

[Claims] (1) In a method for producing an N-alkyl-substituted lactam by reacting a lactone compound with a secondary amine in the presence of water to form an N,N-dialkyl-substituted-ω-hydroxycarboxylic acid amide, the water and lactone N characterized by dealcoholization to form a lactam ring at a molar ratio of 3 to 5 and a reaction temperature of 240 to 265°C.
- A method for producing an alkyl-substituted lactam. (2) A method for producing an N-alkyl-substituted lactam by reacting a lactone compound with a secondary amine in the presence of water to form an N,N-dialkyl-substituted-ω-hydroxycarboxylic acid amide, the N, N-dialkyl substituted -ω-
A hydroxycarboxylic acid amide is heated to a temperature of 240° C. or higher to form a lactam ring by dealcoholization, and the eliminated alcohol is separated and recycled to the secondary amine production process. A method for producing an N-alkyl substituted lactam. (3) The lactone compound is γ-butyrolactone, and N
3. The production method according to claims 1 and 2, wherein the -alkyl-substituted lactam is N-alkyl-substituted-2-pyrrolidone.