JPS6127383B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for producing organic isocyanates. More specifically, the present invention relates to a method for safely producing various organic isocyanates useful as synthetic intermediates for pharmaceuticals, agricultural chemicals, dyes, polymer raw materials, etc., which is characterized by photolyzing N-acylsulfoylimines. Conventionally, organic isocyanates have been obtained through reactions such as alkyl calcium sulfate and potassium cyanate, alkyl iodide and silver cyanate, arylamine hydrochloride and phosgene, and the thermal decomposition of acid azides, but all of them are extremely difficult to obtain. It is necessary to use isocyanates, phosgene, sodium azide, etc., which are toxic or dangerous to handle, and it is difficult to obtain starting materials.
Only a limited number of isocyanates can be synthesized in limited locations, and a safe and general method for synthesizing isocyanates has been desired. The present inventors have conducted various studies on the photodecomposition of N-acyl-S.S-diarylsulfoylimines, and have discovered that organic isocyanates can be synthesized in a short time and in high yields, and have completed the present invention. did. That is, the present invention has the following formula: (In the formula, R represents a lower alkyl group, a phenyl-substituted lower alkyl group, or a phenyl group.) The present invention relates to a method for producing organic isocyanates represented by R-NCO (wherein R is the same as above). Examples of N-acyl-S.S-diarylsulfyl imines include N-acetyl-S.S.
-diphenylsulfuimine, N-phenylacetyl-S.S-diphenylsulfuimine,
N-p-tolylacetyl-S・S-diphenylsulfuimine, N-2-phenylpropionyl-S・S-diphenylsulfuimine, N-3
-Phenylpropionyl-S.S-diphenylsulfuilimine, N-cyclopropylcarbonyl-S.S-diphenylsulfuimine, N-cyclohexylcarbonyl-S.S-diphenylsulfuimine, N-benzoyl- Examples include S.S-diphenylsulfilimine. The solvent used in the present invention is N-acyl-S.
It is preferable to use a substance that dissolves S-diarylsulfuimines, but any substance that does not react with the isocyanates produced is acceptable, and N-acyl-
They are appropriately selected depending on the type of S.S-diarylsulfoylimines and isocyanates, and may be used alone or in combination. Isocyanates are generally very active and cannot be used in solvents with polymerizable double bonds or active hydrogen, such as water, alcohol,
Amines, organic acids, acrylonitrile, etc. are not preferred. Examples of the solvent used in the present invention include benzene, toluene, xylene, ethylbenzene, anisole, n-hexane, cyclohexane, methylene chloride, chloroform, ethylene chloride, chlorobenzene, ether, isopropyl ether, n-hexyl ether, - 4-dioxane, furan, tetrahydrofuran, ethylene glycol diethyl ether, diethylene glycol diethylene ether, acetonitrile, etc. As a light source for photolysis, one having a wavelength of 200 to 400 m[mu] is usually used, and examples thereof include a carbon arc lamp, a xenon arc lamp, a mercury lamp, and the like. The reaction is carried out, for example, by dissolving N-acyl-S.S-diarylsulfuimines in an appropriate solvent and irradiating with light with or without inert gas substitution. The irradiation time varies depending on the N-acyl-S.S-diarylsulfoylimine, but a few minutes to about 4 or 5 hours is sufficient. The reaction is usually carried out at around room temperature, but may be cooled or heated if necessary. After the reaction is completed, the product is separated by a conventional method such as distillation or extraction. In addition, the generated isocyanates are reacted with acidic sulfites, aromatic amines, alcohols, amides, phenols, lactams, heterocyclic compounds, hydrocyanic acid, sulfites, etc. to produce so-called isocyanate regenerants or to decompose the generated isocyanates. It may be separated as an amine derivative, a urea derivative, etc. by dimerization. The diarylsulfide obtained by photolysis is recovered and converted into diarylsulfyl imine.
It can also be used in circulation. N-acyl-S.S-diarylsulfyl imines are diarylsulfyl imines and common acylating agents such as carboxylic acid anhydrides, carboxylic acid halides, carboxylic acids, carboxylic acid esters, carboxylic acid thioesters, lactones, and ketenes. It can be obtained in high yield at room temperature by reaction with Diarylsulfuimine can be easily synthesized by the method invented by the present inventors. or,
N-acyl-S.S-diarylsulfyl imine can also be synthesized under cooling by reaction of diarylsulfide, t-butylhypochlorite, and an alkali salt of an acid amide. As described above, by using the method of the present invention, the isocyanate derivative of the acylating agent used can be easily obtained in high yield. The method of the present invention can produce a wide variety of organic isocyanates without using any chemicals that are toxic or dangerous to handle, and thus greatly contributes to this industry. Reference examples and examples will be described below. Parts in Reference Examples and Examples indicate parts by weight. Reference example 1 100 parts of diphenylsulfoylimine/benzene
115 parts benzoic anhydride/900 parts benzene in 900 parts solution
Part solution was added dropwise and stirred at room temperature for 10 minutes. After washing the reaction solution with water, it was dried, the benzene was distilled off, and N
150.6 parts (yield 99%) of -benzoyl-S.S-diphenylsulfilimine are obtained. Recrystallize from ethyl alcohol. mp124~124.5℃. less than
Shows the results of IR and elemental analysis. IR; νmax (KBr) = 1595, 1550, 805cm ^-1 Elemental analysis C ₁₉ H ₁₅ ONS Mw30540

[Table] Reference example 2 Diphenylsulfoylimine 100 parts/benzene
A solution of 52.1 parts of acetic anhydride/500 parts of benzene was added dropwise to the 900 parts solution, and 118.5 parts of N-acetyl-S.S-diphenylsulfimine was obtained (yield 98%) in the same manner as in Reference Example 1. Recrystallize from ethyl alcohol. mp87-89℃ The results of IR and elemental analysis are shown below. IR; νmax (KBr) = 1575, 1590, 800cm ^-1 Elemental analysis C ₁₄ H ₁₃ ONS Mw243.33

[Table] Reference example 3 Diphenylsulfoylimine 50 parts/benzene
47 parts p-toluoyl chloride in 450 parts solution/
A solution of 450 parts of benzene was added dropwise, and the mixture was stirred at room temperature for 1 hour. After adding a dilute aqueous alkali solution to the reaction solution, it was extracted with benzene, and after drying, the benzene was distilled off, and N
-p-Toluyl-S.S-diphenylsulfoylimine 75.3 parts (95% yield, white prismatic crystals)
get. Recrystallize from benzene-hexane.
mp119~120℃. The results of IR, NMR, and elemental analysis are shown below. IR; νmax (KBr) = 1590, 1545, 1330 cm ^-1 NMR; δ (CDCl ₃ ) = 8.28-7.14 (m, 14H),
2.32 (S, 3H) Elemental analysis C ₂₀ H ₁₇ NSO Mw319.43

[Table] Reference example 4 Diphenylsulfoylimine 50 parts/benzene
Cyclopropionyl chloride in 450 parts solution
A solution of 40 parts/400 parts of benzene was added dropwise in the same manner as in Reference Example 3 to obtain 61.5 parts of N-cyclopropionyl-S.S-diphenylsulfimine (yield: 92%). Recrystallize from benzene-hexane.
mp90.5~91℃. The results of IR, NMR, and elemental analysis are shown below. IR; νmax (KBr) = 1590, 1570, 1390, 1220cm
^-1 NMR; δ (CDCl ₃ ) = 7.9 to 7.3 (m, 10H), 2.0
(m, 1H), 1.0~0.9 (m, 4H) Elemental analysis C ₁₆ H ₁₅ NSO Mw269.37

[Table] Reference example 5 Diphenylsulfoylimine 50 parts/benzene
A solution of 49 parts of α-phenylpropionyl chloride/450 parts of benzene was added dropwise to the 450 parts solution, and N-α-phenylpropionyl-
78.6 parts of S.S-diphenylsulfilimine (yield 95%) are obtained. Recrystallized from benzene-hexane. mp93~94℃. The results of IR, NMR, and elemental analysis are shown below. IR; νmax (KBr) = 1595, 1565, 1325, 1225cm
^-1 NMR; δ (CDCl ₃ ) = 7.8-7.1 (m, 5H), 4.02
(q, 1H), 1.56 (d, 3H) Elemental analysis C ₂₁ H ₁₉ NSO Mw333.46

[Table] Reference Example 6 α-phenylpropionic acid is optically resolved with strychnine to obtain (+)-α-phenylpropionic acid. (+)-α-phenylpropionic acid 52.6 parts/
59.5 parts of thionyl chloride/500 parts of methylene chloride were added dropwise to 500 parts of methylene chloride, and the mixture was stirred at 30 to 50°C for 3 hours. After the reaction, 54.3 parts (yield 92%) of (+)-α-phenylpropionyl chloride was obtained by distillation. bp56℃/1mmHg, [α]+87.8゜(C=
2.86; in benzene). Diphenylsulfuimine and (+)-α-phenylpropionyl chloride were reacted in the same manner as in Reference Example 5, and the reaction solution was filtered to form (-)-N-α-phenylpropionyl-
77.74 parts of S.S-diphenylsulfilimine (yield 94%) are obtained. mp93~95℃ [α] -36.5゜ (C=1.17, in benzene) Example 1 150 parts of N-benzoyl-S.S-diphenylsulfimine was dissolved in 2400 parts of benzene, and the solution was placed in a quartz glass container under argon gas. 3 at room temperature under gas exchange
Irradiate with a low-pressure mercury lamp for an hour. After irradiation, the solvent was distilled off and phenyl isocyanate (bp55
℃/13 mmHg) (yield 74%). Phenyl isocyanate was identified by gas chromatography (SE-30, 2m, 100°C). The distillation residue was subjected to column chromatography [filling material: silica gel, developing solvent: benzene-hexane (19:1)]
10.7 parts of N·N'-diphenylurea (yield 20.5%) was obtained. mp238°C Example 2 150 parts of N-benzoyl-S.S-diphenylsulfilimine was dissolved in 2400 parts of tetrahydrofuran and irradiated with a low-pressure mercury lamp for 3 hours at room temperature under nitrogen gas substitution in a quartz glass container. In the same manner as in Example 1, 35.11 parts of phenyl isocyanate (yield
60%), N・N'-diphenylurea 18.26 parts (yield
35%). Example 3 150 parts of N-p-tolyl-S.S-diphenylsulfyl imine was dissolved in 2400 parts of benzene and irradiated with a low-pressure mercury lamp for 3 hours under argon gas substitution in a quartz glass container. After irradiation, the solvent was distilled off and p-tolyl isocyanate (bp68-72℃/
100 mmHg) 38.9 parts (yield 62%) are obtained. p-Tolyl isocyanate was identified by gas chromatography (SE-30, 2m, 100°C). The distillation residue was subjected to column chromatography [filling material: silica gel, developing solvent: benzene-hexane (19:1)]
N・N′-di-P-toluylurea
17.5 parts (31% yield) are obtained. Recrystallize from benzene-hexane-methanol to obtain white prismatic crystals (mp 243°C). The results of IR, NMR, and elemental analysis of N·N'-di-p-tolylurea are shown below. IR; νmax (KBr) = 3280, 1630 cm ^-1 NMR; δ (CD ₃ OD) = 7.5 to 7.0 (m, 10H), 2.30
(S, 6H) Elemental analysis C ₁₅ H ₁₆ N ₂ O Mw240.309

[Table] Example 4 100 parts of N-acetyl-S.S-diphenylsulfilimine was dissolved in 1,800 parts of benzene and irradiated with a low-pressure mercury lamp for 3 hours under argon gas substitution in a quartz glass container. After irradiation, 15.3 parts (65% yield) of methyl isocyanate (bp 37-39°C) are obtained by distillation. Methyl isocyanate was identified by gas chromatography (SE-30, 2m, 30°C). Example 5 100 parts of N-acetyl-S.S-diphenylsulfilimine was dissolved in 1800 parts of tetrahydrofuran and irradiated with a low-pressure mercury lamp for 3 hours at room temperature in a quartz glass container under nitrogen gas substitution. After irradiation, 40 parts of aniline was added to the reaction solution, and 12.9 parts of methyl isocyanate (bp 37-39℃) was obtained by distillation (yield 55%).
get. The distillation residue was separated by column chromatography [filling material: silica gel, developing solvent: benzene-hexane (19:1)], and N-methyl-
9.0 parts of N'-phenylurea (yield 14.6%) is obtained. Recrystallize from benzene-hexane-methanol to obtain white prismatic crystals (mp 145-146°C). Below, N-methyl-N'-phenylurea
Shows the results of IR, NMR, and elemental analysis. IR; νmax (KBr) = 3350, 3300, 1645 cm ^-1 NMR; δ (CD ₃ OD) = 7.5-6.8 (m, 7H), 2.66
(S, 3H) Elemental analysis C ₈ H ₁₀ N ₂ O Mw150.18

[Table] Example 6 60 parts of N-cyclopropionyl-S.S-diphenylsulfilimine was dissolved in 1000 parts of benzene and irradiated with a low-pressure mercury lamp for 3 hours at room temperature under argon gas substitution in a quartz glass container. . Add 21 parts of aniline to the reaction solution and separate by column chromatography [filling material: silica gel, developing solvent benzene-hexane (19:1)] to obtain N-cyclopropyl-
3.0 parts of N'-phenylurea (yield 17.3%) is obtained. Recrystallize from benzene-hexane-methanol to obtain white prismatic crystals (mp 154-155°C). The IR and NMR results are shown below. IR; νmax (KBr) = 3325, 3250, 1635 cm ^-1 NMR; δ (CD ₃ OD) = 7.5 ~ 6.6 (m, 7H), 2.8 ~
2.4 (m, 1H), 1.0-0.3 (m, 4H) Example 7 75 parts of N-α-phenylpropionyl-S.S-diphenylsulfimine was dissolved in 1300 parts of benzene, and in a quartz glass container, Irradiate with a low-pressure mercury lamp for 3 hours at room temperature under argon gas substitution. The solvent was distilled off and gas chromatography (SE-
30, 2m, 100°C) to obtain 16.2 parts of N-α-phenylethyl isocyanate (yield 49%). The results of IR and elemental analysis are shown below. IR; νmax (film) = 2260cm ^-1 Elemental analysis C ₉ H ₉ NO, Mw 147.18

[Table] Example 8 After adding 21 parts of aniline to the reaction solution that was irradiated with light in the same manner as in Example 7, the reaction rate (based on gas chromatography) was α-phenethylisocyanate.
37.0%, N-phenethyl-N'-phenylurea
It was 14.0%. After adding aniline, column chromatography [filling material: silica gel, developing solvent;
Separate with benzene-hexane (19:1)]
Phenethyl-N'-phenylurea 5.9 parts (yield 11
%). Recrystallized from benzene-hexane-methanol to give white prismatic crystals (mp150-151
℃) is obtained. The results of IR, NMR, and elemental analysis are shown below. IR; νmax (KBr) = 3290, 1625 cm ^-1 NMR; δ (CD ₃ OD) = 7.4-6.8 (m, 2H), 4.85
(q, 1H), 1.46 (d, 3H) Elemental analysis C ₁₅ H ₁₆ N ₂ O, Mw240.31

[Table] Reference example 7 (-)-N-α-phenylpropionyl-S.
75 parts of S-diphenylsulfoylimine in benzene
Dissolve in 1300 parts and irradiate with a low-pressure mercury lamp for 3 hours at room temperature in a quartz glass container under argon gas substitution. The solvent was distilled off and 15.6 parts (yield: 47%) of (-)-α-phenylethyl isocyanate was obtained by gas chromatography (SE-30, 2m, 100°C). [α]-17.4° (C=1.38 in benzene) 15 parts of (-)-α-phenethylisocyanate are poured into 50 parts of concentrated hydrochloric acid and stirred at -5 to -10°C for 3 hours. The reaction solution was neutralized with dilute alkali, extracted with benzene, and after drying, the benzene was distilled off.
(-)-α-phenethylamine 9.2 parts (yield 75%)
get. [α] −33.9° (C = 2.64 in benzene),
Optical yield 98.0%

Claims (1)

[Claims] 1 formula (In the formula, R represents a lower alkyl group, a phenyl-substituted lower alkyl group, or a phenyl group.) A method for producing an organic isocyanate represented by R-NCO (wherein R is the same as above).