JPS6024096B2 - Method for producing carbamate compounds - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing carbamates (urethanes).

Specifically, in producing the corresponding carbamate (urethane) by reacting a diaryl (a and 1) carbonate compound with an aromatic amine, a heterocyclic monocyclic tertiary amine is used alone or a metal chloride is added to the tertiary amine as desired. (hereinafter referred to as additives) in combination with 100 qo or less. It is generally known to react diphenyl carbonate and piperazine or polyphenyl carbonate and amines to produce corresponding carbamates. Among these, in the reaction of diphenyl carbonate and aliphatic amine, carbamate compounds are easily produced quantitatively and in high yield.

However, the reaction between diphenyl carbonate and aromatic amine is extremely difficult compared to the reaction with aliphatic amine, and there are only a few known examples.

For example, reports on the reaction of diphenyl carbonate and aniline in the presence of various Lewis acid catalysts (Bml, Wmi
am to F Qr. bifer, 2160111, 197
According to 2), the yield of carbamate compounds is at most 3
A low amount of about 6% and a large amount of diphenyl urea are created. Therefore, the present inventors conducted extensive research aimed at developing a method for producing a corresponding carbonate compound in high yield by reacting a diaryl carbonate compound with an aromatic amine.

As a result, the present invention was completed based on the knowledge that carbamate compounds can be efficiently produced by specifying additives and reaction temperatures as reaction conditions.

That is, in the present invention, when a diaryl carbonate compound and an aromatic amine are reacted, an Enomoto cyclic monocyclic tertiary amine alone or a metal chloride is optionally used in combination with the tertiary amine as an additive at 100°C or lower. The purpose is to produce carbamate compounds by reacting with

The sialyl carbonate compound in the present invention is represented by a general formula, in which R and R are aromatic groups that may have a substituent, and R and R' are aromatic groups that have a substituent. R and R' may be the same or different.

Substituents include alkyl groups, halogen groups and alkoxy groups, and diaryl carbonate compounds suitable for the purpose of the present invention include diphenyl carbonate, di○-tolyl carbonate, so-P-chlorophenyl carbonate di(2.6 -dimethylphenyl)carbonate p
-Methoxyphenyl carbonate is an example.

Preferred aromatic amines include aniline, toluidine, 4,4'-diaminodiphenylmethane, 4,4'-diaminosyphenyl ether, m-phenylene diamine, p-phenylene diamine, 2,4 -diaminotoluene, 2,6-diaminotoluene, 3,3'-dichloro-4,4-diaminodiphenylmethane, 3,3'-dimethoxy-4,4'-diami/
Examples include diphenylmethane.

Examples of the polycyclic monocyclic tertiary amines used as additives include pyridine, 2-hydroxypyridine, Q1, 31,
and y-picoline, imidazole, 2-methylimidazole, pyrazole, pyrazine, pyrimidine, pyridazine and the like.

Metal chlorides that may be used in combination with the tertiary amine include magnesium chloride, lithium chloride, nickel chloride, zinc chloride, cupric chloride, iron chloride, tin chloride, cobalt chloride, calcium chloride, etc. be. It was also found that the effect of adding additives was significantly influenced by the reaction temperature.

That is, when a diaryl carbonate compound and an aromatic amine are reacted in the presence of these additives, the reaction temperature is 1
When the temperature is higher than 0.03°C, the yield of carbamate compounds decreases significantly and a large amount of urea compounds are produced as by-products.

In order to reduce the production of urea compounds and increase the yield of the desired carbamate compound, the reaction temperature should be adjusted to 100%.
It was found that it is important to maintain the temperature below midnight.

The reaction temperature is 100 qo or less, preferably 30 qo to 80°C
It is desirable to keep the temperature as low as . As explained above, when reacting a diaryl carbonate compound with an aromatic amine, a carbamate compound can be obtained in a high yield if the additives and reaction temperature are carefully controlled. This is thought to be due to the catalytic effect of the additive. This carbamate compound is extremely useful for producing polyurethane by further reacting with various polyols. Certain carbamates are also useful compounds in the pharmaceutical and agrochemical fields. The advantages of the present invention are that the by-product of urea compounds can be reduced and carbamate compounds can be produced in high yield, and that monocyclic tertiary amines or tertiary amines and metal chlorides can be used as additives. The carbamate compound of the present invention can be used in combination to produce a carbamate compound at a low reaction temperature, and the carbamate compound of the present invention can be used as a useful raw material for producing polyurethane because it can produce a polyurethane compound by reacting with a polyol.

Embodiments of the present invention will be described below with reference to Examples and Comparative Examples.

In addition, % in an example is weight %. Examples 1-5 Diphenyl carbonate (0.01 mol), aniline (
0.01 mol), 2-hydroxypyridine (0.01 mol), and toluene (10%) as a solvent were placed in an eggplant-shaped flask and allowed to react at a predetermined temperature for a predetermined period of time.

After the reaction was completed, toluene was concentrated and removed, and the resulting carbamate was precipitated with a 20% aqueous ethanol solution, separated and dried. Table 1 shows the reaction temperature, reaction time, and the proportions (%) of unreacted carbonate, produced carbamate, and produced urea. Table-1 Temperature Time Unreacted production Production (°C) (hr) Carbonate or receipt Urea (scale) (Tsumi) (Akira) Example 140 16 39 61
0 Example 260 20 18 82 0 Example 360 40 13 87 0 Example 460 20 o loo 0 Example eave 8
0 20 13 79 8*: Example 4
So diphenyl carbonate (0.01 mol), aniline (0.015 mol), 2-hydroxypyridine (0.01 mol),
01 mole) and toluene (10 mole).

Structural formula of carbamate produced (diphenyl carbamate) Examples 6 to 9 Aromatic diamines such as 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ena, p-phenylenediamine, and 2,4-diaminotoluene The results of the reaction with diphenyl carbonate are shown in Table 2.

The reaction conditions were to place each diamine (0.01 mol), diphenyl carbonate (0.02 mol), 2-hydroxypyridine (0.01 mol), and toluene in an eggplant-shaped flask, and react at 60 mol for 2 feeding hours. I let it happen. After the reaction is completed, a biscarbamate compound corresponding to each of the raw material diamines used is precipitated, and this is separated and dried. Then convert this into zu-HC1 (100')
Remove unreacted diamine and monocarbamate.

Separate the precipitate, wash thoroughly with water, and dry. When 2,4-tolylene diamine is used, the produced biscarbamate dissolves in toluene, so it is concentrated to remove toluene and then precipitated with a 50% ethanol aqueous solution.

After separating the precipitate, the precipitate is thoroughly washed under CI (100 desk top) for one day to remove the formed monocarbamate and unreacted diamine. After separating out insoluble matter, it is dried.

Next, a small amount of benzene is added to this to form a slurry, and then 50' of n-hexane is added to form a precipitate, and unreacted diphenyl carbonate and formed phenol are removed.The precipitate is separated and dried. do. Table 2 Structural formula of carbamate produced Example 6: [4,4'-diphenylcarbamate-P·P-diphenylmethane] Example 7: [4,4'-diphenylcarbamate-P·P-diphenyl ether] Example 8: [1,4-phenylene-diphenylcarbamate] Example 9: [2,4-diphenylcarbamate-toluene] Examples 10 to 16 4,4'-diaminodiphenylmethane and Table 3 shows the results of reacting p-phenylene diamine with diphenyl carbonate.

The reaction was carried out using each diamine shown in Table 3 (0.01 mol),
Diphenyl carbonate (0.02 mol), pyridine y
- 0.01 mol each of picoline and imidazole,
Toluene was added as a solvent to an eggplant-shaped flask and reacted at 70°C for 1 hour. hiscarbamate. was purified using the same method as in Examples 6 and 8. Examples 16-18 p-methoxyphenyl carbonate (0.01 mol) and aniline (0.01 mol) in the ratio of tertiary amine (0.01 mol) - metal chloride (0.002 mol) The reaction was carried out at 80° C. for about 10 hours using toluene 10% Z as a solvent.

The results are shown in Table 4.

Table 4 Comparative examples of N-phenyl p-methoxyphenyl carbamate: N-phenyl p-methoxyphenyl car/diamate Comparative examples 1 to 7 Comparative examples of multihata cyclic monocyclic tertiary amines and the formation of this tertiary amine and gold layer chloride under high temperature We conducted an experiment to determine the effect of the addition.

The results are shown in Table-5.

The reaction involves diphenyl carbonate (0.01 mol), aniline (0.01 mol), 0.01 mol when a tertiary amine is used alone as an additive, and tertiary amine when used in combination with a tertiary amine-metal chloride. Amiso (0.01 mol) - metal chloride (0.002 mol) were used in the ratio, and 10 units of toluene was used as a solvent, and the reaction was carried out at 110 qo for 1 hour.

Table-5

Claims (1)

[Claims] 1. A diaryl carbonate compound and an aromatic amine are reacted at 100°C or lower in a multi-ring monocyclic tertiary amine alone or in a system in which a metal chloride is optionally added to the tertiary amine. A method for producing a carbamate compound.