JPH0429970A - Production of tartaric acid imides - Google Patents

Abstract

PURPOSE:To efficiently obtain the title compound useful as a monomer for improvement of heat resistance of polymer or for modification thereof by reacting tartaric acid with an amine in an organic solvent immiscible with water while distilling away water produced by the reaction out of the system. CONSTITUTION:Tartaric acid is subjected to cyclodehydration reaction with an amine expressed by the formula R-NH2 (R is H or 1-20C alkyl, 3-20C alkenyl, phenyl, benzyl, cycloalkyl, pyridyl or quinolyl, each of which may be replaced) at 60-250 deg.C, especially 100-200 deg.C in an organic solvent (e.g. benzene, xylenes or octane) of 2-10 times by wt., based on tartaric acid and immiscible with water while distilling away water produced by the reaction as an azeotropic mixture out of the reaction system to provide a tartaric acid imide expressed by the formula. The amine is preferably used at an amount of 0.5-1.5mol, especially 0.8-1.2mol, based on 1mol of tartaric acid.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing tartarimides, and more particularly to a method for efficiently producing tartarimides from tartaric acid and amines through a one-step reaction.

Tartarimides are compounds useful as monomers for improving or modifying the heat resistance of many polymers.

(Prior Art) It is no exaggeration to say that tartarimides are only known as N-phenyltartarimide, and very little detailed research has been conducted on their production methods.

Under these circumstances, F. Hello and R.
C. I. Kinson, “Journal of Chemical
Society J (F, Barrow & R.

G, Atkinson, J, Chem, Soc.
) 638 (1939) discloses a method for the synthesis of N-phenyltartarimide. According to this synthesis method,
Aniline was added to a slightly saturated aqueous solution of tartaric acid, cooled, and the produced aniline tartrate was filtered and dried by heating in air. The aniline tartrate was then heated at 140°C for 8 hours to perform a dehydration cyclization reaction. Then, crystals of N-phenyltartarimide are taken out from the resulting reaction product using glacial acetic acid.

This synthesis method involves two steps from tartaric acid and aniline to produce N.
This is a so-called two-step reaction method for producing phenyltartaric acid imi I. Moreover, many problems arise when implementing this synthetic method.

One of them is that the solubility of aniline tartrate in water is extremely high, and in order to obtain crystals by cooling, it is necessary to cool the salt to a considerably low temperature. Since the tartrate aniline salt is dissolved, the yield of the target N-phenyltartarimide is low.

In addition, in the dehydration cycloclosing reaction, both aniline tartrate and N-phenyltartarimide are lumpy solids at the reaction temperature, and not only is it difficult to stir the reaction system, but some of the water produced by the reaction is dissolves a portion of these aniline tartaric acid salts and N-phenyltartarimide, resulting in the formation of even larger lumps due to the fusion of solid crystals. As a result, heat transfer to the reaction system becomes uneven, leading to insufficient local heating, resulting in an increase in side reactions, and a decrease in the yield of the target N-phenyltartarimide. do.

In addition, local heating may cause decomposition, carbonization, and other phenomena, resulting in a large amount of scum in the reactor and high pressure, making it less safe to implement.

(Problems to be Solved by the Invention) As mentioned above, the conventionally known production methods for tartaric acid imides have complicated production processes, low yields, and extremely low safety, so it is difficult to implement them industrially. That was difficult.

Therefore, it has been desired to develop an industrial method for producing tartaric acid imides with high yield and safety through a simple process.

Therefore, an object of the present invention is to provide a method for producing tartaric acid imides safely in a high yield using a one-step process using tartaric acid and amines as starting materials.

(Means for Solving the Problems) The present inventors heated tartaric acid and amines in an organic solvent immiscible with water to perform dehydration and cyclization, and at the same time produced water produced by this dehydration and cyclization reaction. It was found that tartrate imides can be obtained in high yield by distilling the tartrate imide out of the reaction system as a mixture with the above-mentioned organic solvent, and based on this knowledge, the present invention was completed.

That is, the present invention combines tartaric acid and general formula (1):% formula%(
1) (wherein R is hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted pencil group, a substituted or unsubstituted pyridyl group, or a substituted or unsubstituted quinolyl group) When producing tartaric acid imides represented by the general formula (): (in the formula, R is the same as above), tartaric acid and amines are mixed with water. Tartaric acid characterized by heating in an immiscible organic solvent to perform dehydration and cyclization, and at the same time, by this dehydration and cyclization reaction, raw water is distilled out of the reaction system as a mixture with the organic solvent. This is a method of manufacturing products such as

The present invention will be explained in detail below.

In the above general formulas (1) and (II), R is hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and 3 to 20 carbon atoms.
20 substituted or unsubstituted alkenyl groups, substituted or unsubstituted phenyl groups, substituted or unsubstituted Hensyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted pyridyl groups, or substituted or unsubstituted quinolyl groups. Examples of the substituent include halogen, an alkyl group, an alkoxy group, a carboxyl group, and a di-lyl group.

Representative examples of amines represented by general formula (1) include ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, 5ec
-Butylamine, tert-butylamine, n-hexylamine, n-F decylamine, allylamine, hensylamine, cyclopentylamine, cyclohexylamine, aniline, nitroaniline, aminophenol, aminobenzoic acid, anisidine, ethoxyphenylamine, monochloroaniline, dichloroaniline , toluidine, xylidine, ethylaniline and the like.

The amount of the amine represented by the above general formula (1) to be used may be 0.5 to 1.5 mol, particularly preferably 0.8 to 1.2 mol, per 1 mol of tartaric acid. .

If the amount of amine used exceeds 1.5 mol, side reactions will increase, which is not preferable. On the other hand, if it is less than 0.5 mol, tartaric acid will be used in excess, which is economically unfavorable.

In method t of the present invention, the tartaric acid and amines are heated in an organic solvent immiscible with water to effect dehydration and cyclization.

The water-immiscible organic solvent is preferably an inert solvent that does not participate in the reaction, and representative examples include hensen, toluene, petroleum distillates with a boiling point of 50 to 120°C, xylenes, ethyl hensen, isobrovir hemhen Zen, Kumen,
Mesitylene, Broi I/cumene, octane, tert-
Butylhensen, trimethylhexane, tetrachloroethane, nonane, chlorhensen, ethylcyclohexane, petroleum distillate with a boiling point of 120-170°C, m-dichlorohensen, decane, p-cymene, 0-dichlorohensen, butylbenzene, thecahytronaphthalene, tetrahydro Examples include naphthalene, dodecane, naphthalene, cyclohexylbenzene, and petroleum fractions with a boiling point of 170 to 250°C.

The water-immiscible organic solvent to be used may be determined as appropriate, taking into consideration the temperature conditions, price, ease of handling, etc. when distilling off the water. In addition, if necessary, polar solvents such as dimethylformamide, dimethylsulfoxide, sulborane, and methylpyrrolidone may be used in combination.

The amount of the organic solvent used is 1 to 20 times the weight of tartaric acid, preferably 2 to 10 times the weight of tartaric acid.

A feature of the present invention is that the dehydration cyclization is carried out while the water produced by the dehydration cyclization reaction is distilled out of the reaction system as a mixture with the organic solvent. Therefore, the reaction temperature is determined by considering the boiling point of the organic solvent used, or is usually 60 to 250°C, particularly 100 to 200°C.
o0C is preferable, and considering the separation of tartaric acid imide, which is the target product after the reaction, from the remaining organic solvent, an organic solvent with a low boiling point is selected as the organic solvent, and the dehydration cyclization reaction is carried out under pressure. There are times when it is advantageous to do so.

Of course, the above dehydration cyclization reaction can also be carried out under normal pressure or reduced pressure.

In the method of the present invention, there is no particular restriction on the order of adding the starting materials. For example, tartaric acid and the above organic solvent are charged into a reaction vessel, and amines are added at the azeotropic point of water and the organic solvent while heating it. Alternatively, tartaric acid, amines, and organic solvent may be charged into a reactor all at once to carry out the reaction.

The reaction time varies depending on the type of target tartarimide and the reaction temperature, so it cannot be determined unambiguously, or heating is usually continued until no water is recognized to be produced.

The above dehydration cyclization reaction can be carried out in the presence of an acid catalyst. Examples of acid catalysts include sulfuric acid, sulfuric anhydride,
Orthophosphoric acid, p-)luenesulfonic acid, metaphosphoric acid,
Birophosphoric acid and the like can be used. The amount used is preferably in the range of 2 to 80 mol% based on the raw material tartaric acid.

In the dehydration cyclization reaction, the organic solvent distilled out of the reaction system as an azeotrope with water may be separated from water and then returned to the reaction system for reuse.

From the mixture of tartarimide and organic solvent thus obtained, the organic solvent is separated by a conventional method such as distillation or filtration to obtain the desired solid crystal of tartarimide.

Tartarimides obtained by the method of the present invention are particularly useful as raw materials for heat-resistant resins, and can be used, for example, as heat resistance improvers for epoxy resins, polyester resins, polyamide resins, polyurethane resins, phenolic resins, alkyd resins, etc. can.

(Effect of the invention) The main advantages of the present invention are as follows.

(a) Target tartaric acid imides can be easily produced by heating the starting materials tartaric acid and amines in an organic solvent.

(b) Since the reaction system is a uniform slurry-like solid-liquid dispersion system, the heat added to the reaction system is transmitted in a good manner. Therefore, side reactions are suppressed, and the target tartarimide can be obtained in high yield.

(c) Extremely safe as there is no decomposition due to local overheating.

(d) Target tartarimides can be produced safely and efficiently through a simple process.

(Example) Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 12 equipped with stirrer, thermometer, dropping funnel and fractionating tube
A flask was charged with 78.8 g of tartaric acid and 450 g of 0-xylene, heated to 80°C, 4.6.6 g of aniline was added dropwise, and the reaction was carried out at the same temperature for 1 hour. Next, the slurry of aniline tartrate and 0-xylene obtained by ζ-filtering was heated as it was roughly to 140 to 145° C., and heating was continued until no water was distilled out due to the dehydration cyclization reaction.

The time required during this period was 3 hours, and the distillation was completed.

The xylene was returned to the flask. Next, the contents were cooled to room temperature, and then the product was filtered and dried to obtain 110.8 g of a pale yellow powdery solid.

When analyzed by liquid chromatography, the purity of the target tartarimide was 81.0%, and the yield was 86.7 mol% based on the raw material amine.

Example 2 In Example 1, with 78.8 g of tartaric acid. -xylene 4
The reaction was carried out in the same manner as in Example 1, except that 50 g of aniline was heated and 46.6 g of aniline was added dropwise under reflux of 0-xylene to obtain the target tartaric acid imide.

The yield of tartaric acid imide is 87.3% based on the raw material amine.
Met.

Example 3 The reaction was carried out in the same manner as in Example 1, except that 49.6 g of cyclohexylamine was used instead of aniline, and the desired N-cyclohexyltartarimide was obtained.

The yield of N-cyclohexyltartarimide was 84.1 mol% based on the raw material amine.

Example 4 The reaction was carried out in the same manner as in Example 1, except that 36.6 g of n-butylamine was used instead of aniline, to obtain the target N-butyl tartrate.

The yield of N-butyltartarimide is 8% based on the raw material amine.
It was 2.0 mol%.

Comparative Example 75 g of tartaric acid and the same amount of water were placed in a 300 cc flask equipped with a stirrer, thermometer, and dropping funnel, and heated at 50°C.
After heating to , 46.6 g of aniline was added dropwise and reaction was carried out for 30 minutes. The contents were then cooled to 1°C and then dried to remove moisture. After finely pulverizing 109.6 g of aniline tartrate obtained by zeta-filtering,
The mixture was heated at 140'C for 8 hours to obtain 84.8 g of a lumpy brown solid with large discoloration, especially on the heated surface.

When this was analyzed in the same manner as in Example 1, the purity of N-phenyltartarimide was 71.9%, and the yield was 58.9% based on the raw material amine.

Claims (3)

[Claims] (1) Tartaric acid and general formula (I): R-NH_2 (wherein R is hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 3 to 20 carbon atoms, a substituted or unsubstituted phenyl group, substituted or unsubstituted benzyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted pyridyl group, or substituted or unsubstituted quinolyl group);
II): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ When producing tartarimides represented by (in the formula, R is the same as above), tartaric acid and amines are mixed with water and immiscible organic A method for producing tartaric acid imides, which comprises heating in a solvent to perform dehydration and cyclization, and at the same time distilling water produced by the dehydration and cyclization reaction out of the reaction system as a mixture with the organic solvent. (2) The amount of water-immiscible organic solvent used is 1 to 1 of tartaric acid.
The method for producing tartaric acid imides according to claim (1), wherein the amount is 20 times by weight. (3) The method for producing tartarimides according to claim (1), wherein the dehydration cyclization reaction is carried out by heating at 60 to 250°C.