JPH0687814A - Method for producing α- (3-isocyanatophenyl) ethyl isocyanate - Google Patents

Abstract

PURPOSE:To obtain alpha-(3-isocyanatophenyl)ethyl isocyanate in a high purity and in a high yield, while preventing the generation of by-products, by reacting alpha-(3-aminophenyl)ethylamine hydrochloride with phosgene in an acetic acid ester under heating. CONSTITUTION:A salt (e.g. hydrochloride) of alpha-(3-amicophenyl) ethylamine of formula I is reacted with phosgene in an acetic acid ester at 92-110 deg.C to produce alpha-(3-isocyanatophenyl)ethyl isocyanate of formula II. The method permits to prevent the generation of by-products such as a tarry substance and is thereby industrially highly useful. The compound of formula II can be used as a raw material for polyurethane resins or polyurea resins in many fields such as foams, elastomers, synthetic leathers, coatings, adhesives and films.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing α- (3-isocyanatophenyl) ethyl isocyanate. The diisocyanate produced by the method of the present invention can be used as a raw material for polyurethane resins and polyurea resins in various fields such as foams, elastic bodies, synthetic leather, paints, adhesives and films.

[0002]

2. Description of the Related Art Conventionally, as aromatic diisocyanates, tolylene diisocyanate and diphenylmethane diisocyanate have been industrially mass-produced and used in various fields as raw materials for polyurethane resins and polyurea resins. Naphthalene diisocyanate and tolidine diisocyanate are also used industrially. As the aliphatic diisocyanate, hexamethylene diisocyanate and xylylene diisocyanate are industrially used as a non-yellowing type and a yellowing-resistant type, respectively. Further, alicyclic diisocyanates include isophorone diisocyanate and di (isocyanatocyclohexyl) methane,
Both are industrially used as non-yellowing diisocyanates. However, these are all compounds having two isocyanate groups having the same reactivity.

The present inventors have previously proposed α- (3-isocyanatophenyl) ethyl isocyanate as a novel diisocyanate compound having a completely different structure, which does not belong to any of the above-mentioned prior arts ( JP-A-2-2708
54). This α- (3-isocyanatophenyl) ethyl isocyanate is a diisocyanate compound having both an isocyanate group directly connected to an aromatic ring and an isocyanate group directly connected to an aliphatic carbon. The reactivity of the isocyanate group directly bonded to the aromatic ring with the active hydrogen compound is much larger than the reactivity of the isocyanate group bonded to the aliphatic carbon with the active hydrogen compound. Many applications are expected to take advantage of the difference in reactivity of the groups. For example, an isocyanate group directly bonded to an aromatic ring can be reacted with an active hydrogen compound to form a prepolymer or an adduct having an isocyanate group bonded to an aliphatic carbon at a terminal. The resulting prepolymer or adduct is expected to be stable and to have yellowing or non-yellowing properties characteristic of aliphatic isocyanates. In addition, since this α- (3-isocyanatophenyl) ethyl isocyanate has a substituent at the meta position of the aromatic ring, the urethane resin using this as a raw material has appropriate mechanical strength, heat resistance, and It is expected to have UV resistance.

Therefore, the inventors of the present invention, as a method for producing α- (3-isocyanatophenyl) ethyl isocyanate, a cold two-stage phosgenation method diamine in which α- (3-aminophenyl) ethylamine is directly reacted with phosgene. There have been previously proposed two production methods of a phosgenation method of an amine hydrochloride in which a salt such as the hydrochloride salt of the above is previously synthesized, and this is suspended in an inert solvent and reacted with phosgene (JP-A-2-2708).
54). However, in the cold heat two-stage phosgenation method of α-α represented by the formula (III) (Chemical Formula 3) in the reaction product,
A chloride derivative such as (3-isocyanatophenyl) ethyl chloride is by-produced.

[0005]

[Chemical 3]

When such a chloride derivative is contained, it inhibits the reaction between the isocyanate group and the active hydrogen compound in the production of a urethane resin using this as a raw material and causes the physical properties of the urethane resin to deteriorate. Therefore, in order to obtain a highly pure target product, it is necessary to remove the by-product using a distillation apparatus having a high theoretical plate number, and as a result, the yield of the target product is correspondingly reduced. On the other hand, in the phosgenation method of the amine hydrochloride, a tar-like by-product is likely to be generated, and therefore the isolation yield is as low as 61.6%, which is not satisfactory. Therefore, both of the methods are economically disadvantageous for industrial implementation. Therefore, a production method of α- (3-isocyanatophenyl) ethylisocyanate that suppresses byproducts such as chloride derivatives and tar-like substances and is industrially efficient has been desired.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to suppress the formation of by-products such as chloride derivatives and tar-like substances, and to provide a high yield and high purity of α- (3-isocyanatophenyl). It is to provide a method for producing ethyl isocyanate.

[0008]

The inventors of the present invention have completed the present invention as a result of extensive studies to achieve the above object. That is, the present invention relates to α-represented by the formula (I).
A salt of (3-aminophenyl) ethylamine is reacted with phosgene in acetic acid ester at a reaction temperature of 92 to 110 ° C.
The present invention relates to a method for producing-(3-isocyanatophenyl) ethyl isocyanate.

[0009]

[Chemical 4]

The present invention has conducted a detailed study on the phosgenation method of amine hydrochloride, and as a result, α- (3
It has been found that by-products such as tar-like substances are extremely reduced by reacting a hydrochloride of -aminophenyl) ethylamine with phosgene at a reaction temperature of 92 to 110 ° C in acetic acid esters. Is a method for producing high-purity α- (3-isocyanatophenyl) ethyl isocyanate in high yield.

Examples of acetic acid esters used in the method of the present invention include n-amyl acetate, isoamyl acetate,
Isobutyl acetate, isopropyl acetate, ethyl acetate, 2-ethylhexyl acetate, 1-ethylpentyl acetate, n-acetate
-Octyl, cyclohexyl acetate, 1,3-dimethylbutyl acetate, cellosolve acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, tert-butyl acetate, acetic acid 2
Examples include -n-butoxyethyl, n-propyl acetate, isopropyl acetate, n-hexyl acetate, methyl acetate and 3-methylbutyl acetate. Preferably, n-butyl acetate and isoamyl acetate are used. These solvents may be used alone or in combination of two or more.

The amount of the solvent used in the method of the present invention is preferably in the range of 8 to 30 parts by weight per 1 part by weight of the starting amine. If it is 8 parts by weight or less, stirring becomes difficult. Further, even if it exceeds 30 parts by weight, the reaction is not affected, but it is economically disadvantageous because it causes a decrease in volumetric efficiency, deterioration of thermal efficiency and the like.

In the method of the present invention, the reaction is conducted at 92 ° C to 11 ° C.
Perform within the range of 0 ° C. When the reaction temperature is lower than 92 ° C, the reaction rate becomes extremely slow, and it takes a long time to complete the reaction. On the contrary, if the reaction temperature is higher than 110 ° C., a large amount of tar-like by-products are produced and the yield is greatly reduced.

In a general embodiment of the process of the invention, the diamine hydrochloride is first obtained and then reacted with phosgene. The hydrochloride of α- (3-aminophenyl) ethylamine is easily obtained by reacting α- (3-aminophenyl) ethylamine with hydrogen chloride in acetic acid esters. The temperature at this time is preferably 30 ° C. or lower. Above this range, impurities tend to be generated in the reaction product. Next, in the reactor, sufficient stirring is performed to disperse the diamine hydrochloride as much as possible, and phosgene is introduced and reacted while maintaining the temperature at 92 to 110 ° C. The progress of the reaction is judged by the amount of the generated hydrogen chloride gas and the disappearance of the diamine hydrochloride insoluble in the acetic acid esters to make the reaction liquid transparent and uniform. The generated hydrogen chloride and excess phosgene gas are discharged through a reflux condenser. After completion of the reaction, nitrogen gas is introduced into the reaction solution to remove dissolved phosgene. Then cooling,
After filtration, the acetic acid ester solvent is distilled off under reduced pressure, and further purified by distillation under reduced pressure to obtain the desired α- (3-isocyanatophenyl) ethyl isocyanate represented by the formula (II).

[0015]

EXAMPLES The present invention will be specifically described below with reference to examples. The present invention is not limited thereby. Example 1 A 3-liter reaction flask equipped with a stirrer, a thermometer, a phosgene gas introduction tube, a cooling tube, and a dropping funnel was charged with n-butyl acetate 9
After charging 50 g, the reaction flask was placed in an ice-water bath with stirring, and hydrogen chloride was blown into the solution for 30 minutes to dissolve it while keeping the internal temperature at 5 to 10 ° C. Then, while continuing stirring, cooling, and blowing of hydrogen chloride, α- (3-aminophenyl)
A solution prepared by dissolving 100 g (0.734 mol) of ethylamine in 950 g of n-butyl acetate was added dropwise over 2 hours. During the dropping, the liquid temperature rose due to the formation of hydrochloride, but was kept at 15 ° C. or lower by cooling. After the dropping was completed, the blowing of hydrogen chloride was continued for another 30 minutes. Next, the liquid temperature was raised to 95 ° C., and phosgene gas was blown in at a rate of 100 g / h. When blowing was continued for 7.5 hours while maintaining the temperature at 95 ° C, the diamine hydrochloride disappeared and the reaction solution became transparent and uniform. Stop blowing the phosgene gas and leave at 95 ° C for 2
Nitrogen gas was bubbled at a rate of 1 l / min for degassing for a period of time. After cooling and filtering the reaction solution after degassing, n-butyl acetate as a solvent was distilled off under reduced pressure, and further distilled under reduced pressure to obtain 126.8 g of α- (3-isocyanatophenyl) ethyl isocyanate. Got Yield 92.0%, boiling point 1
10-113 ° C / 4 torr. The purity of this substance measured by gas chromatography was 99.7%.
The O% was 44.65.

Example 2 Isoamyl acetate 4 was placed in a 2 liter reaction flask equipped with a stirrer, a thermometer, a phosgene gas introduction tube, a cooling tube, and a dropping funnel.
68 g was charged, the reaction flask was placed in an ice-water bath with stirring, and hydrogen chloride was blown thereinto for 30 minutes to dissolve it while keeping the internal temperature at 5 to 10 ° C. Then, while continuing stirring, cooling, and blowing of hydrogen chloride, α- (3-aminophenyl)
580 g of ethylamine 56.2 g (0.413 mol)
The solution dissolved in isoamyl acetate of was added dropwise over 1.5 hours. During the dropping, the liquid temperature rose due to the formation of hydrochloride, but was kept at 15 ° C. or lower by cooling. After the dropping was completed, the blowing of hydrogen chloride was continued for another 30 minutes. Next, set the liquid temperature to 110 ° C.
The temperature was raised to 100 g / h, and phosgene gas was blown in at a rate of 100 g / h. When blowing was continued for 4.5 hours while maintaining the temperature at 110 ° C., the diamine hydrochloride disappeared and the reaction solution became transparent and uniform. Stop blowing phosgene gas, 1
Bubbling nitrogen gas at a rate of 1 l / min for 2 hours at 10 ° C,
Degassing was performed. After cooling and filtering the reaction solution after degassing, the solvent isoamyl acetate was distilled off under reduced pressure, and further distilled under reduced pressure to obtain 71.2 g of α- (3-isocyanatophenyl) ethyl isocyanate. It was Yield 91.6
%, Boiling point 109 to 112 ° C./4 torr. The purity of this substance by gas chromatography was 99.8% and NCO% was 44.65.

Comparative Example 1 54.3 g (0.4 mol) of α- (3-aminophenyl) ethylamine was placed in a 3 liter reaction flask equipped with a stirrer, a thermometer, a phosgene gas introduction tube, a cooling tube and a dropping funnel.
A solution dissolved in 1555 g of ortho-dichlorobenzene was added, the temperature was raised to 145 to 167 ° C. with stirring, and then nitrogen gas was bubbled into the solution at a rate of 300 ml / min for 1.5 hours while bubbling. The water in the system was removed. Then, after cooling the temperature of the solution to 19 ° C., hydrogen chloride was bubbled into the solution with stirring to generate a hydrochloride. Although the liquid temperature increased as the hydrochloride salt was formed, it was cooled and maintained at 35 ° C or lower. After 1.5 hours, the introduction of hydrogen chloride was stopped. Phosgene gas was blown into the produced hydrochloride slurry at a rate of 50 g / h, and the temperature was raised to 120 ° C. over 2 hours. 120 ° C
Then, the phosgene blowing was continued for 2 hours. Since the reaction solution became almost transparent, phosgene blowing was stopped. Then
Degassing was performed by bubbling nitrogen gas at a rate of 300 ml / min for 2 hours at 120 ° C. After cooling and filtering the reaction solution after degassing, the solvent orthodichlorobenzene was distilled off under reduced pressure, and further distilled under reduced pressure to obtain 46.4 g of α- (3-isocyanatophenyl) ethyl isocyanate. Obtained. Yield 61.6%.

Comparative Example 2 Isoamyl acetate 73 was placed in a 3 liter reaction flask equipped with a stirrer, a thermometer, a phosgene gas introduction tube, a cooling tube and a dropping funnel.
0 g was charged, the reaction flask was placed in an ice-water bath with stirring,
While keeping the internal temperature at 5 to 10 ° C, hydrogen chloride was blown into the solution for 30 minutes to dissolve it. Then, while continuing stirring, cooling, and blowing of hydrogen chloride, a solution of 100 g (0.734 mol) of α- (3-aminophenyl) ethylamine dissolved in 700 g of isoamyl acetate was added dropwise over 2 hours. During the dropping, the liquid temperature rose due to the formation of hydrochloride, but was kept at 15 ° C. or lower by cooling. After the dropping was completed, the blowing of hydrogen chloride was continued for another 30 minutes. Next, the liquid temperature was raised to 130 ° C., and phosgene gas was blown at a rate of 75 g / h.
When blowing was continued for 5 hours while keeping the temperature at 130 ° C, the diamine hydrochloride disappeared and the reaction liquid became transparent blackish brown, so blowing of phosgene gas was stopped and nitrogen gas was added at a rate of 1 l / min for 2 hours at 130 ° C. It was vented with and degassed. After cooling and filtering the reaction solution after degassing, the solvent isoamyl acetate was distilled off under reduced pressure, and further distilled under reduced pressure to obtain 87.0 g of α- (3-isocyanatophenyl) ethyl isocyanate. . Yield 63.0%, boiling point 87-
90 ° C / 2 torr.

[0019]

The present invention provides α- (3-aminophenyl)
By reacting ethylamine hydrochloride with phosgene in acetic acid esters at a reaction temperature of 92 to 110 ° C., by-products such as tar-like substances are suppressed, and α- (3- The present invention provides an industrially extremely useful production method for obtaining isocyanatophenyl) ethyl isocyanate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryuji Haseyama Mitsui Toatsu Chemical Co., Ltd. 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa

Claims (1)

[Claims] 1. α- (3-represented by formula (I)
Aminophenyl) ethylamine embedded image Of the salt of acetic acid in the reaction temperature 92-110 ℃
With the formula (II) characterized by reacting with phosgene
Represented by (Chemical Formula 2) A method for producing α- (3-isocyanatophenyl) ethyl isocyanate.