JP2002512626A - Method for producing carbamates - Google Patents

Abstract

  (57) [Summary] A method for producing carbamates by reacting an aromatic amine with an organic carbonate in the presence of a metal-based catalyst on an inert support.

Description

The present invention relates to a method for producing carbamates by reacting aromatic amines with organic carbonates using a catalyst on an inert carrier. It is known to react amines with organic carbonates to obtain carbamates. U.S. Patent Application No.5.347.034 discloses the reaction of the corresponding amines and dialkyl carbonates in the presence of a catalyst such that the formed poly (o-alkyl urethanes) crystallize in a very high purity form upon cooling. A method for producing a diphenylmethane-based poly (o-alkyl urethane) by reacting the same is disclosed. EP 391.473 discloses that an amine is first reacted with a (cyclo) alkyl carbonate in the presence of a carbamate catalyst to produce a mixture of carbamate and urea, and urea is produced to produce the corresponding carbamate. A method for producing carbamate using a small amount of catalyst by further reacting with carbonate and finally recovering the carbamate from the reaction mixture is described. DE-A 3.202.690 describes a process for producing aromatic urethanes by reacting aromatic amines and alkyl carbonates in the presence of an alkali metal or alkaline earth metal alcoholate. I have. U.S. Patent Application No. 4.268.684 discloses a process for preparing carbamates by reacting an organic carbonate with an aromatic amine in the presence of certain zinc, tin or cobalt salts that are only active at a temperature of at least 200 ° C. However, U.S. Patent Application No. 4.26 8.683 uses a zinc or tin salt that is soluble in the reaction mixture at room temperature conditions. European Patent Application No. 48.371 describes an N, O-diamine by reacting primary amines with dialkyl carbonates in the presence of neutral or basic inorganic or organic lead, titanium, zinc or zirconium compounds. The production of substituted urethanes is disclosed. Japanese Patent Application No. 07.328.435 uses a catalyst containing an oxide composition containing Zr and Si to produce carbamates from diester carbonates and aliphatic amines in a liquid phase. An improved method for producing carbamates by reacting aromatic amines with organic carbonates was discovered. Thus, the present invention relates to a process for producing carbamates by reacting aromatic amines with organic carbonates in the presence of a metal-based catalyst on an inert carrier support. Since the catalyst can be easily recovered by the present method, this step can be economically and environmentally improved. In yet another aspect, the invention relates to a catalyst comprising an organometallic salt on an inert support. Such catalysts have improved processability of converting aromatic amines to carbamates by reaction with organic carbonates. Aromatic amine compounds that can be used in the present method include mono-, di- or polyamines. Suitable amines in the method of the present invention include, for example, phenylamine, 4-chlorophenylamine, 2-fluorophenylamine, 3,4-dichlorophenylamine, aniline, tolylamine, diisopropylphenylamine, 2,4′-diaminodiphenylmethane 4,4'-diaminodiphenylmethane, 2,2'-diaminodiphenylmethane and higher homologs (polyaminopolyphenylmethanes), 2,4-toluenediamine, 2,6-toluenediamine, m-phenylenediamine, 1,5 -Naphthylenediamine and mixtures thereof. Aromatic di- or polyamines such as toluenediamines, diaminodiphenylmethanes or polyaminopolyphenylmethanes or any mixtures thereof are preferred. Suitable organic carbonates include cyclic or acyclic carbonates such as ethylene carbonate, propylene carbonate, styrene carbonate, diphenyl carbonate, methylphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, dihexyl carbonate. , Methyl ethyl carbonate, methyl butyl carbonate and the like. Organic or inorganic salts that can be used include, for example, acetate, chloride, nitrate, sulfonate, propionate, isopropanoate, butanoate, butanoate, 2-ethylhexanoate, n- octoate, isononanoic acid salt (isonona noate), benzoate, chlorobenzoate, naphthenate, stearate, itaconate, pivalate, phenolates, acetylacetonate, alkoxide, C ₁₆ / C ₁₈ -alkenyl succinoate (ASA), C ₁₂ -alkenyl succinoate (DSA) and the like. Alkanoates having 1 to 15 carbon atoms are preferred. Suitable catalysts include, for example, zinc catalysts such as zinc chloride, zinc acetate, zinc propionate, zinc octoate, zinc benzoate, zinc p-chlorobenzoate, zinc naphthenate, zinc stearate, zinc itaconate, Examples include lead catalysts such as zinc pivalate, zinc phenolate, zinc acetylacetonate, zinc methoxide, lead acetate and lead octoate, and tin catalysts such as stannous chloride, tin octoate and mixtures thereof. The metal in the catalyst is preferably selected from the group consisting of Ti, Zr, Zn, Sn and Pb. Heterogeneous metal-based catalysts on supports can be prepared by impregnating the support with the catalyst or by precipitating the catalyst on the support. Suitable inert carrier such as oxides, e.g., alumina, silica, etc. TiO _2, MgO, clay, zeolite, polymeric support, resins, graphite and carbon. Carrier preferably comprises TiO _2, alumina or silica. The supported catalyst is usually used in an amount of 10 ^{-3 to} 20 mol% based on the amount of amine used. The polyamines and organic carbonates can be reacted in stoichiometric amounts. However, it is preferred to use an excess of organic carbonates. Reaction conditions are highly dependent on the type of reactants used. The method can be performed at atmospheric pressure or overpressure. The pressure is preferably at most 20 bar. The reaction time depends on the temperature and the type and amount of the carbamate compound, but is usually 0.5 to 6 hours. Reaction times of less than 3 hours are common, but reaction times of less than 2.5 hours performed without any problems. Generally, the reaction temperature is between 50 and 300C. The process according to the invention is preferably carried out at a temperature between 100 and 250 ° C. A solvent is not required, but can be added if it does not adversely affect the reaction. Any solvent or mixture of solvents that is inert to the reactants under the reaction conditions can be used. Suitable solvents that can be used include aromatic hydrocarbons, such as benzene; halogenated aromatic hydrocarbons, such as monochlorobenzene, ortho-dichlorobenzene, trichlorobenzene or 1-chloronaphthalene; alkylated aromatic hydrocarbons Hydrogens such as toluene, xylene, ethylbenzene, cumene or tetrahydronaphthalene; other functionalized aromatic hydrocarbons such as anisole, diphenylether, ethoxybenzene, benzonitrile, 2-fluoroanisole, 2,3-dimethylanisole Or trifluorotoluene; alkanes such as n-pentane, n-hexane, n-heptane or higher or branched alkanes; cyclic alkanes such as cyclopentane, cyclohexane or derivatives thereof; halogenated alkanes such as , Chloroform, dichloromethane, carbon tetrachloride; alkanes having and other functional groups, for example, diethyl ether, acetonitrile, dioxane or the like mixtures thereof. Of these, inert aromatic solvents are preferred. The method can be carried out, if necessary, on any device which can be equipped with stirring means and heating and / or cooling means for maintaining the temperature in the desired range. The process according to the invention can be carried out batchwise or in a semi-continuous or continuous manner. One type of continuous operation is performed in a fluidized bed reactor in which the catalyst is introduced into the reactor as a slurry in one or more reactants. Another method which is carried out continuously is carried out in a moving bed reactor in which the catalyst bed and the reactants pass cocurrently or countercurrently to one another. However, a preferred type of continuous process is in a fixed bed reactor where the reactants pass over a catalyst bed. During the reaction, alcohols are formed as by-products. For example, they can be removed from the reaction mixture continuously during the reaction or after completion of the reaction, such as by distillation. The present invention will be described by the following examples, which do not limit the present invention. EXAMPLES Example 1 To a suspension of ₂ g of TiO _{2 in} 100 ml of acetone was added 0.308 g of zinc octoate (6 wt% of Zn in mineral terpentine oil) and the mixture was purged with Ar gas for 5 minutes. The flask was placed in an ultrasonic bath (frequency: 20 MHz) containing water at room temperature for 1 hour. After sonication, the solvent was removed under reduced pressure and the solid was finally dried under reduced pressure at 70 ° C. for 1 hour. The solid thus obtained was used as such for the production of carbamates. Isolated yield: 2.2 g. To 100ml steel autoclave, 4,4'-diaminodiphenylmethane 2.0 g (10 mmol l), dimethyl carbonate 42.7 g (0.47 mol) and the TiO ₂ supported zinc octoate 0.18 g (Ti O ₂ was supported on 2-ethylhexanoic acid Zinc salt (20% by weight) was added. The mixture was purged with nitrogen. The reaction mixture was then heated at 180 C for 2 hours. After the reaction was completed, the autoclave was cooled to room temperature, the crude product was evaporated to dryness, redissolved in dichloromethane and finally filtered to separate the catalyst. The filtrate thus obtained was evaporated to dryness under reduced pressure to give a crystalline solid. The amine conversion was 100% based on the starting material. Urethane selectivity was 96.3% based on quantitative HPLC. Example 2 100 ml steel autoclave, 4,4'-diaminodiphenylmethane 2.0 g (10 mmol l), dimethyl carbonate 25.5 g (0.28 mol), was carried on toluene 16ml and TiO ₂ supported zinc octoate 0.18 g (TiO ₂ 2 -Zinc salt of ethylhexanoic acid (20% by weight). The mixture was purged with nitrogen. The reaction mixture was then heated at 180 C for 2 hours. After the reaction was completed, the autoclave was cooled to room temperature, the crude product was evaporated to dryness, redissolved in dichloromethane and finally filtered to separate the catalyst. The filtrate thus obtained was evaporated to dryness under reduced pressure to give a crystalline solid. The amine conversion was 100% based on the starting material. Urethane selectivity was 98% based on quantitative HPLC. Example 3 100 ml steel autoclave, polymeric diaminodiphenylmethane 2.0 g (8 mmol), dimethyl carbonate 42.7 g (0.47 mol) and TiO ₂ supported zinc octoate 0. 18 g (0.1 mmol active catalyst) (was supported on TiO ₂ 2- (A zinc salt of ethylhexanoic acid 20% by weight) was added. The mixture was purged with nitrogen. The reaction mixture was then heated at 180 C for 2 hours. After completion of the reaction, the autoclave was cooled to room temperature, and the catalyst was separated by filtration. The filtrate thus obtained was evaporated to dryness under reduced pressure to produce a solid. Amine conversion was> 98% based on starting material. Urethane selectivity was 89-92% based on IR and ¹³ C NMR. Example 4 1.22 g (10 mmol) of 2,4-diaminotoluene, 42.7 g (0.47 mol) of dimethyl carbonate and 0.18 g of zinc octoate supported on TiO ₂ (0.1 mmol active catalyst) (2-ethylhexanoic acid supported on TiO ₂ Was charged to a 100 ml autoclave and purged with nitrogen. The reaction mixture was then heated at 180 C for 2 hours. After completion of the reaction, the autoclave was cooled to room temperature, and an equal volume of dichloromethane was added to dissolve 2,4-bis (methoxycarbonylamino) toluene partially precipitated. Then the mixture was filtered off to separate the catalyst. The filtrate thus obtained was evaporated to dryness under reduced pressure to give crystalline yellow solid 2,4-bis (methoxycarbonylamino) toluene. Amine conversion and urethane selectivity were 100% and 92%, respectively, by quantitative HPLC. Example 5 To a suspension of 2 g of Al ₂ O _{3 in} 40 ml of acetone was added 1.2 g of zinc octoate (6% by weight of Zn in mineral turpentine oil) and the mixture was purged with Ar gas for 5 minutes. The flask was placed in an ultrasonic bath (frequency: 20 MHz) containing water at room temperature for 1 hour. After sonication, the solvent was removed under reduced pressure and the solid was finally dried under reduced pressure at 70 ° C. for 1 hour. The solid thus obtained was used as such for the production of carbamates. Isolated yield: 2.8g. To 100ml steel autoclave, polymeric diaminodiphenylmethane 20 g (10 mol), dimethyl carbonate 42.7 g (0.47 mol) and Al ₂ O ₃ supported zinc octoate 0. 212g (0.12 mmol active catalyst) (was supported on Al ₂ O ₃ 2- Ethylhexanoic acid zinc salt (20% by weight) was added. The mixture was purged with nitrogen. The reaction mixture was then heated at 180 C for 2 hours. After the reaction was completed, the autoclave was cooled to room temperature, the crude product was evaporated to dryness, redissolved in dichloromethane and finally filtered to separate the catalyst. The filtrate thus obtained was evaporated to dryness under reduced pressure to give a crystalline solid. The amine conversion was 100% based on the starting material. Urethane selectivity was 91% based on HPLC. Example 6 In a 100 ml steel autoclave, 2.0 g (8 mmol) of polymeric diaminodiphenylmethane, 42.7 g (0.47 mol) of dimethyl carbonate and 0.212 g of zinc octoate on Al ₂ O ₃ (0.12 mmol active catalyst) (on Al ₂ O ₃ ) The supported zinc salt of 2-ethylhexanoic acid (20% by weight) was added. The mixture was purged with nitrogen. The reaction mixture was then heated at 180 C for 2 hours. After the reaction was completed, the autoclave was cooled to room temperature, and the crude product was filtered to separate the catalyst. The filtrate thus obtained was evaporated to dryness under reduced pressure to give a crystalline solid. The amine conversion was 98% based on the starting material. Urethane selectivity was 84-92% based on IR and ¹³ C NMR. Example 7 To a suspension of 2 g of silica (silica gel for column chromatography, 200-300 mesh) in 40 ml of acetone, 1.2 g of zinc octoate (6% by weight of Zn in mineral turpentine oil) were added and the mixture was treated with Ar. Purge with gas for 5 minutes. The flask was placed in an ultrasonic bath (frequency: 20 MHz) containing water at room temperature for 1 hour. After sonication, the solvent was removed under reduced pressure and the solid was finally dried under reduced pressure at 70 ° C. for 1 hour. The solid thus obtained was used as such for the production of carbamates. Isolated yield: 2.4g. In a 100 ml steel autoclave, 4,4′-diaminodiphenylmethane 2.0 g (10 mmol), dimethyl carbonate 42.8 g (0.47 mol) and silica-supported zinc octanoate 0.216 g (2-ethylhexanoic acid zinc salt supported on silica gel 20 Wt%) was added. The mixture was purged with nitrogen for 5-10 minutes. The reaction mixture was then heated at 180 C for 2 hours. After the reaction was completed, the autoclave was cooled to room temperature, the crude product was evaporated to dryness, redissolved in dichloromethane and finally filtered to separate the catalyst. The filtrate thus obtained was evaporated to dryness under reduced pressure to give a crystalline solid. The amine conversion was 100% based on the starting material. Urethane selectivity was 81.8% based on quantitative HPLC. Example 8 In a 100 ml steel autoclave, 2.0 g (8 mmol) of polymeric diaminodiphenylmethane, 42.7 g (0.47 mol) of dimethyl carbonate and 0.216 g of zinc octoate supported on acidic silica (0.12 mmol active catalyst) (2-ethylhexane supported on silica gel) Acid zinc salt (20% by weight) was added. The mixture was purged with nitrogen. The reaction mixture was then heated at 180 ° C. for 2 hours. After the reaction was completed, the autoclave was cooled to room temperature, and the crude product was filtered to separate the catalyst. The filtrate thus obtained was evaporated to dryness under reduced pressure to give a crystalline solid. The amine conversion was 97% based on the starting material. Urethane selectivity was 81-83% based on IR and ¹³ C NMR.

────────────────────────────────────────────────── ─── Continuation of front page    (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, L S, MW, SD, SZ, UG, ZW), EA (AM, AZ , BY, KG, KZ, MD, RU, TJ, TM), AL , AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, E E, ES, FI, GB, GE, GH, GM, GW, HU , ID, IL, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, M D, MG, MK, MN, MW, MX, NO, NZ, PL , PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, UZ, V N, YU, ZW

Claims (1)

[Claims] 1. A method for producing carbamates by reacting an aromatic amine with an organic carbonate in the presence of a metal-based catalyst on an inert support. 2. The method of claim 1, wherein the catalyst comprises a metal selected from the group consisting of Ti, Zr, Zn, Sn and Pb. 3. The method of claim 1 or 2, wherein the catalyst comprises an alkanoate having 1 to 15 carbon atoms. 4. Wherein said carrier, TiO _2, containing alumina or silica, the method according to any one of claims 1 to 3. 5. The method according to any one of claims 1 to 4, wherein the reaction is performed at a temperature of 100 to 250C. 6. The method according to any one of claims 1 to 5, wherein the aromatic amine is selected from the group consisting of toluenediamines, diaminodiphenylmethanes or polyaminopolyphenylmethanes or mixtures thereof. 7. The method according to any one of claims 1 to 6, wherein the reaction is performed at a pressure of 20 bar or less. 8. The method according to any one of claims 1 to 7, wherein the method is performed in the presence of an inert aromatic solvent. 9. The process according to any one of the preceding claims, wherein the process is performed with a reaction time of less than 2.5 hours. 10. A catalyst comprising an organometallic salt on an inert support. 11. The catalyst according to claim 10, wherein the metal is selected from the group consisting of Ti, Zr, Zn, Sn and Pb. 12. The catalyst according to claim 10 or 11, wherein the organic salt is an alkanoate having 1 to 15 carbon atoms. 13. Wherein said carrier TiO _2, containing alumina or silica, the catalyst according to any one of claims 10 to 12.