JP4298995B2 - Method for producing carbamate and method for producing isocyanate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a carbamate, and a method for producing an isocyanate using a carbamate obtained by the method for producing a carbamate.
[0002]
[Prior art]
Conventionally, alkyl carbamate is a useful organic compound as a raw material for pharmaceuticals, agricultural chemicals and the like, as a raw material for various fine chemicals, and as an industrial raw material having a wide range of uses as an analytical reagent for alcohols.
[0003]
As a method for producing such an alkyl carbamate, (1) a method of reacting isocyanate and alcohol, (2) a method of reacting chloroformate and amine in the presence of a base, (3) phosgene and alcohol and A method of reacting amine, (4) a method of reacting urea and alcohol, (5) a method of reacting dimethyl carbonate and formamide, and (6) a method of reacting dialkyl carbonate and amine (for example, Patent Documents 1 to Various methods are known, such as 5).
[0004]
In recent years, various studies have been made on using such alkyl carbamates as raw materials for producing isocyanates that do not use phosgene.
[0005]
That is, isocyanate is an organic compound containing an isocyanate group, and is widely used as a raw material for polyurethane. Industrially, it is produced by a reaction between an amine and phosgene (phosgene method). However, phosgene is highly toxic and corrosive, and is inconvenient to handle. Therefore, in recent years, as an economical method for producing isocyanates instead of the phosgene method, an amine is carbamated with a dialkyl carbonate. Various proposals have been made to produce isocyanates by decomposing (see, for example, Patent Documents 6 to 8).
[0006]
[Patent Document 1]
Japanese Patent Publication No.51-33095
[Patent Document 2]
JP-A-57-82361
[Patent Document 3]
U.S. Pat. No. 4,395,565
[Patent Document 4]
JP-A 64-85956
[Patent Document 5]
JP-A-6-128215
[Patent Document 6]
JP-A-7-165696
[Patent Document 7]
JP-A-6-172292
[Patent Document 8]
JP-A-9-249633
[Problems to be solved by the invention]
However, in the method for producing an alkyl carbamate described above, the method (1) requires handling an irritating isocyanate as a raw material, which is cumbersome. In the method (2), an equimolar or more base is used. It is necessary to use, in the method of (3), the toxicity and corrosiveness of phosgene is strong, and it is necessary to use a base for the reaction. In the methods of (4) and (5), the temperature is high. Or, each has a defect, such as the need to carry out the reaction at high pressure.
[0007]
In the method (6), a method using dimethyl carbonate as a dialkyl carbonate is well known (for example, see Patent Documents 1 to 3). In this method, dimethyl carbonate and amine are reacted in the presence of a Lewis acid catalyst, a lead, titanium or zirconium catalyst, an alkali metal or alkaline earth metal alcoholate catalyst, etc. In addition, the reaction rate is low and the N-methyl compound is easily produced as a by-product, so that the space-time yield of carbamate cannot be improved.
[0008]
On the other hand, for example, Patent Document 4 describes a method of adding an amine and an alkali metal or alkaline earth metal alcohol catalyst so as to prevent the N-methylation reaction from occurring continuously or intermittently. .
[0009]
However, in this method, in order to obtain a carbamate in a high yield, it is necessary to use a large amount of an alcoholate catalyst with respect to the amine, and an increase in cost is unavoidable, and since the catalyst is neutralized, A large amount of salt is produced, causing problems such as a heavy load on the recovery and purification of carbamate.
[0010]
Furthermore, as another method using a carbonate, for example, Patent Document 5 describes a method for producing an alkyl carbamate from an alkyl aryl carbonate and an aromatic amine. However, although this method uses a nitrogen-containing heterocyclic compound as a catalyst, there are problems that a large amount of catalyst is required and the yield cannot be improved.
[0011]
In the above-described method for producing isocyanate, the carbamate obtained is pyrolyzed after the amine is carbamated with dialkyl carbonate. For example, although an example is described in Patent Document 4, when the basic catalyst is heated together with the carbamate, the carbamate is further changed to change to an undesired high-boiling point, so that the neutralization step is performed. In fact, before the carbamate thermal decomposition step, the basic catalyst remaining in the carbamate is always neutralized with phosphoric acid, and the excessively added phosphoric acid is washed with water and removed.
[0012]
The present invention has been made in view of such problems, and the object thereof is a method for producing a carbamate capable of obtaining a carbamate with high selectivity and high yield at a low cost by a simple method, And it is providing the manufacturing method of the isocyanate which can manufacture the isocyanate used industrially using the carbamate obtained by the manufacturing method of the carbamate.
[0013]
[Means for Solving the Problems]
  In order to achieve the above object, the method for producing a carbamate of the present invention comprises an aliphatic group.TheAmine, alicyclicTheAmines and araliphaticTheNon-aromatic selected from the group consisting of aminesTheAn amine and an alkylaryl carbonate represented by the following general formula (1):The alkylaryl carbonate is charged so as to be 1.01 to 30 times mol of the amino group of the non-aromatic diamine,It is characterized by reacting.
[0014]
R¹OCOOR²                    (1)
(In the formula, R1 represents an alkyl group, and R2 represents an aryl group which may have a substituent.)
In the carbamate production method of the present invention, the alkylaryl carbonate is preferably methylphenyl carbonate. As the alkylaryl carbonate, a crude material containing 1% by weight or more of alkylaryl carbonate obtained by transesterification of dialkyl carbonate and phenol or a derivative thereof can be used.
[0015]
  Also non-aromaticTheThe amine is 1,6-hexamethylenediamine, isophoronediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 4,4′-methylenebis (cyclohexaneamine), 2,5. -Bis (aminomethyl) bicyclo [2,2,1] heptane, 2,6-bis (aminomethyl) bicyclo [2,2,1] heptane, 1,3-bis (aminomethyl) benzene, 1,4- It is preferably at least one selected from the group consisting of bis (aminomethyl) benzene.
[0016]
Furthermore, the present invention also includes a method for producing an isocyanate, comprising the steps of producing a carbamate by the above-described method for producing a carbamate and a step of producing an isocyanate by thermally decomposing the obtained carbamate. .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
  First, the manufacturing method of the carbamate (carbamic acid ester) of this invention is explained in full detail. The method for producing a carbamate of the present invention comprises an aliphatic group.TheAmine, alicyclicTheAmines and araliphaticTheNon-aromatic selected from the group consisting of aminesTheAn amine is reacted with an alkylaryl carbonate represented by the following general formula (1).
[0018]
                            R¹OCOOR²      (1)
(In the formula, R1 represents an alkyl group, and R2 represents an aryl group which may have a substituent.)
  Non-aromatic used in the present inventionTheAmines have primary or secondary amino groupsTwoAn amino group-containing organic compound having and having no amino group directly bonded to an aromatic ring, which is aliphaticTheAmine, alicyclicTheAmines and araliphaticTheSelected from amines. Such an amino group-containing organic compound may contain a stable bond or a functional group such as an ether bond, a thioether bond, an ester bond, a sulfone group, a carbonyl group, or a halogen atom in the molecular skeleton. Good.
[0019]
  AliphaticTheAs an amine, ExampleFor example, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-monohexamethylenediamine, 1,7-diaminoheptane, 1,8-diamino Octane, 1,9-diaminononane, 1,10-diaminodecane, 1,12-diaminododecane, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, tetramethylenediamine1, 2-bis (aminoethylthio) ethaneWhoBe mentioned.
[0020]
  Also aliphaticTheExamples of the amine include amino group-containing polyoxyalkylene compounds such as polyoxypropylene diamine and amino group-containing polysiloxane compounds.
[0021]
  AlicyclicTheAs an amine, ExampleFor example, diaminocyclobutane, isophoronediamine (3-aminomethyl-3,5,5-trimethylcyclohexylamine), 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,3 -Bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 4,4'-methylenebis (cyclohexaneamine), 2,5-bis (aminomethyl) bicyclo [2,2,1] Such as heptane, 2,6-bis (aminomethyl) bicyclo [2,2,1] heptane, hydrogenated 2,4-toluenediamine, hydrogenated 2,6-toluenediamine.WhoBe mentioned.
[0022]
  Aromatic aliphaticTheAs an amine, ExampleFor example, 1,3-bis (aminomethyl) benzene and 1,4-bis (aminomethyl) benzene.WhoBe mentioned.
[0023]
  These non-aromaticTheAmong amines, diamines that are precursors of poly (di) isocyanates used industrially, such as 1,6-hexamethylenediamine, isophoronediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4- Bis (aminomethyl) cyclohexane, 4,4′-methylenebis (cyclohexaneamine), 2,5-bis (aminomethyl) bicyclo [2,2,1] heptane, 2,6-bis (aminomethyl) bicyclo [2, 2,1] heptane, 1,3-bis (aminomethyl) benzene, and 1,4-bis (aminomethyl) benzene are preferably used.
[0024]
  Such non-aromaticTheYou may use an amine individually or in combination of 2 or more types.
[0025]
The alkylaryl carbonate used in the present invention is represented by the following general formula (1).
[0026]
R¹OCOOR²                    (1)
(In the formula, R1 represents an alkyl group, and R2 represents an aryl group which may have a substituent.)
In the above formula (1), examples of the alkyl group represented by R1 include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, hexyl, C1-C8 linear or branched saturated hydrocarbon groups such as heptyl, octyl, isooctyl and 2-ethylhexyl, for example, alicyclic saturated hydrocarbon groups having 5 to 10 carbon atoms such as cyclohexyl and cyclododecyl Etc.
[0027]
In the above formula (1), the aryl group which may have a substituent represented by R2 is, for example, an aryl group having 6 to 18 carbon atoms such as phenyl, tolyl, xylyl, biphenyl, naphthyl, anthryl, phenanthryl. Is mentioned. Examples of the substituent include a hydroxyl group, a halogen atom (eg, chlorine, fluorine, bromine and iodine), a cyano group, an amino group, a carboxyl group, an alkoxy group (eg, methoxy, ethoxy, propoxy, butoxy, etc.) An alkoxy group having 1 to 4 carbon atoms, an aryloxy group (for example, phenoxy group, etc.), an alkylthio group (for example, an alkylthio group having 1 to 4 carbon atoms such as methylthio, ethylthio, propylthio, butylthio, etc.) (For example, a phenylthio group etc.) etc. are mentioned. These substituents may be the same or different and may be substituted by 1 to 5, preferably 1 to 3.
[0028]
More specifically, methylphenyl carbonate is preferably used as such an alkylaryl carbonate.
[0029]
In addition, the above-described alkylaryl carbonate can be easily produced by various known methods. That is, for example, a method for producing by transesterification from a dialkyl carbonate and phenol or a derivative thereof described in Japanese Patent No. 1519075; Org. Chem. 57, 3237 (1992), a method of producing from an aryl chlorocarbonate and an alkyl alcohol is used.
[0030]
In the present invention, for example, the reaction solution obtained by the production method as described above is used as it is or without high-level purification such as recrystallization or rectification without using purified alkylaryl carbonate. A crude material containing an alkylaryl carbonate can be used.
[0031]
That is, for example, when an alkylaryl carbonate is produced from a dialkyl carbonate and phenol or a derivative thereof, the alkylaryl carbonate obtained by a transesterification reaction between the dialkyl carbonate and phenol or a derivative thereof is preferably 1% by weight or more, preferably , 10 to 100% by weight of the crude material can be used as the alkyl aryl carbonate in this production method.
[0032]
As mentioned above, alkylphenyl carbonate is produced by the reaction of dialkyl carbonate and phenol. For example, amine is added in the presence of dialkyl carbonate and phenol, or dialkyl carbonate, phenol, and amine are mixed. By doing so, it is also conceivable to produce carbamate by the method described later.
[0033]
  And, in the method for producing carbamate of the present invention, the above-mentioned non-aromaticsTheThe amine is reacted with the alkyl aryl carbonate described above. Non-aromaticTheThe reaction of an amine with an alkylaryl carbonate can be carried out, for example, in a reaction vessel with a non-aromaticTheAn amine and an alkylaryl carbonate are charged in a predetermined ratio described below, and a reaction solvent is added if necessary, and the reaction is carried out under very mild conditions.
[0034]
  Alkyl aryl carbonate charge is non-aromaticTheAgainst the amino group of the amine1.01 timesMore than moleAndTherefore, the alkyl aryl carbonate itself can also be used as a reaction solvent in this reaction. More specifically, the amount of alkylaryl carbonate charged is non-aromatic.TheFor the amino group of the amineAnd1.01 to 30 times moleGoodPreferably, it is about 1.02 to 15 times mole. When the amount of the alkylaryl carbonate charged is larger than this, a great amount of energy is consumed in the separation step or the purification step after the reaction, which is not suitable for industrial production. On the other hand, when the amount of alkylaryl carbonate charged is less than this, the reaction rate decreases as the reaction proceeds.
[0035]
  In this reaction, a reaction solvent is not necessarily required, but the operability can be improved by blending the reaction solvent. Such reaction solvents are non-aromaticTheIt is not particularly limited as long as it is inert or poorly reactive with amines and alkylaryl carbonates. For example, aliphatic alcohols (for example, methanol, ethanol, n-propanol, iso-propanol) , N-butanol, iso-butanol, etc.), aliphatic hydrocarbons (eg, hexane, pentane, petroleum ether, ligroin, cyclododecane, decalins, etc.), aromatic hydrocarbons (eg, benzene, toluene, xylene, Ethylbenzene, isopropylbenzene, butylbenzene, cyclohexylbenzene, tetralin, chlorobenzene, o-dichlorobenzene, methylnaphthalene, chloronaphthalene, dibenzyltoluene, triphenylmethane, phenylnaphthalene, biphenyl, diethyl Phenyl, triethylbiphenyl, etc.), ethers (eg, diethyl ether, diisopropyl ether, dibutyl ether, anisole, diphenyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, etc.), Esters (eg, ethyl acetate, butyl acetate, amyl acetate, dioctyl phthalate, didecyl phthalate, didodecyl phthalate, etc.), nitriles (eg, acetonitrile, propionitrile, adiponitrile, benzonitrile, etc.), aliphatic halogenated Hydrocarbons (eg, methylene chloride, chloroform, 1,2-dichloroethane, 1, -Dichloropropane, 1,4-dichlorobutane etc.), amides (eg dimethylformamide, dimethylacetamide etc.), nitro compounds (eg nitromethane, nitrobenzene etc.), phenol or derivatives thereof (eg phenol, cresol etc.) , Carbonates (for example, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, etc.), commonly used heat transfer oil (for example, THERM S 200S, 300, 600, 700, 800, 900, 1000S manufactured by Nippon Steel Chemical Co., Ltd.) Yakken Chemical Co., Ltd. NeoSK-OIL1300, 1400, 170, 240, 330, KSK-OIL260, 280, etc.), N-methylpyrrolidinone, N, N-dimethylimidazolidinone, dimethylsulfoxide, water and the like are used.
[0036]
Among these reaction solvents, aliphatic alcohols, aliphatic hydrocarbons, aromatic hydrocarbons, phenols, and carbonates are preferably used in consideration of economy and operability. Moreover, you may use such a reaction solvent individually or in combination of 2 or more types.
[0037]
  The amount of the reaction solvent used is not particularly limited as long as the carbamate of the reaction product is dissolved, but industrially, it is necessary to recover the reaction solvent from the reaction solution. If the energy consumed for the recovery is reduced as much as possible and the amount used is large, the reaction substrate concentration decreases and the reaction rate slows down. More specifically, non-aromaticTheThe amount is usually 0.01 to 50 parts by weight, preferably 0.1 to 10 parts by weight, based on 1 part by weight of the amine.
[0038]
  In this reaction, the reaction temperature is the raw material, that is, non-aromatic.TheAlthough it varies depending on the type of amine, alkylaryl carbonate, reaction solvent, etc., for example, it is in the range of 0 to 200 ° C, preferably 20 to 150 ° C, and more preferably 30 to 100 ° C. In addition, the reaction pressure may be any atmosphere of normal pressure, pressurization, or reduced pressure, and is not particularly limited.
[0039]
  This reaction proceeds in the absence of a catalyst.The
[0040]
  And this reaction is carried out in the reaction vessel under the above-mentioned conditions, and is non-aromatic.TheThe amine and the alkylaryl carbonate may be stirred or mixed. More specifically, for example, non-aromatic in alkylaryl carbonateTheAn amine may be added dropwise and stirred. As a result, an alkyl carbamate is produced with high selectivity and high yield under mild conditions. As a result, this reaction,NothingReact under catalystTheThe reaction solution after completion of the reaction includes an excess (unreacted) alkylaryl carbonate, a reaction solvent, a carbamate represented by the following general formula (2) as a reaction product, and
                        (R¹OCONH) ₂ R³      (2)
(Wherein R1 has the same meaning as R1 in formula (1) above, and R3 is non-aromatic.TheAmine residueShowThe )
An aryl alcohol represented by the following general formula (3), which is a by-product, is included.
[0041]
R²-OH (3)
(In the formula, R2 has the same meaning as R2 in the above formula (1).)
Then, by recovering these excess (unreacted) alkylaryl carbonate, reaction solvent, and aryl alcohol by distillation separation or the like, the produced carbamate can be easily separated. In this reaction, post-treatment steps such as catalyst separation are not usually required, and the obtained carbamate is further purified by washing, neutralization, recrystallization, distillation, sublimation, column chromatography, or the like, if necessary. be able to.
[0042]
  Therefore, according to such a manufacturing method, with a simple equipment, substantially non-aromaticTheAlkyl carbamate can be obtained with high selectivity and high yield only by blending amine and alkyl aryl carbonate, and a complicated post-treatment step is not required, so that carbamate can be produced efficiently at low cost. be able to.
[0043]
And this invention includes the manufacturing method of isocyanate which thermally decomposes the carbamate obtained by the manufacturing method of the above-mentioned carbamate, and manufactures isocyanate.
[0044]
  That is, in such an isocyanate production method, the carbamate obtained by the above-described carbamate production method is thermally decomposed, and the above-mentioned non-aromatics are obtained.TheAn isocyanate represented by the following general formula (4) corresponding to an amine; and
                          R³-(NCO) ₂       (4)
(Wherein R3 has the same meaning as R3 in formula (2) above)ShowThe )
An alkyl alcohol represented by the following general formula (5) as a by-product is produced.
[0045]
R¹-OH (5)
(Wherein R1 has the same meaning as R1 in formula (1)).
This thermal decomposition is not particularly limited, and for example, a known decomposition method such as a liquid phase method or a gas phase method can be used. Preferably, it is preferably carried out by a liquid phase method, more specifically, a reactive distillation method in which alkyl alcohol produced as a by-product in this thermal decomposition is separated out of the system.
[0046]
The thermal decomposition temperature is usually 350 ° C. or lower, preferably 80 to 350 ° C., more preferably 100 to 300 ° C. When it is lower than 80 ° C., a practical reaction rate may not be obtained, and when it exceeds 350 ° C., undesirable side reactions such as polymerization of isocyanate may occur. Further, the pressure during the pyrolysis reaction is preferably a pressure at which the generated alkyl alcohol can be vaporized with respect to the above-mentioned pyrolysis reaction temperature. It is preferable that it is -90kPa.
[0047]
The carbamate used for the thermal decomposition may be purified, or may be subsequently subjected to thermal decomposition using the carbamate crude material separated by recovering the aryl alcohol after completion of the reaction.
[0048]
Further, if necessary, a catalyst and an inert solvent may be added. These catalysts and inert solvents may be added to the carbamate reaction, either before or after the distillation separation after the reaction, or before or after the carbamate separation.
[0049]
As a catalyst used for thermal decomposition, one or more kinds selected from Sn, Sb, Fe, Co, Ni, Cu, Cr, Ti, Pb, Mo, Mn, etc., used for urethanization reaction of isocyanate and hydroxyl group Metal compounds such as simple metals or oxides thereof, halides, carboxylates, phosphates and organometallic compounds are used. Among these, in this thermal decomposition, Fe, Sn, Co, Sb, and Mn are preferably used because they exhibit the effect of making it difficult to generate by-products.
[0050]
Examples of the Sn metal catalyst include tin oxide, tin chloride, tin bromide, tin iodide, tin formate, tin acetate, tin oxalate, tin octylate, tin stearate, tin oleate, tin phosphate, Examples include dibutyltin chloride, dibutyltin dilaurate, 1,1,3,3-tetrabutyl-1,3-dilauryloxydistanoxane.
[0051]
Examples of the metal catalyst of Fe, Co, Sb, and Mn include acetates, benzoates, naphthenates, and acetylacetonates.
[0052]
In addition, the usage-amount of a catalyst is 0.0001-5 weight% with respect to the reaction liquid as a metal single-piece | unit or its compound, Preferably, it is the range of 0.001-1 weight%.
[0053]
Moreover, the inert solvent is inert to at least carbamate and isocyanate, and in order to efficiently perform the thermal decomposition reaction, it is desirable that the inert solvent has a higher boiling point than the generated isocyanate. Examples of such inert solvents include esters such as dioctyl phthalate, didecyl phthalate, and didodecyl phthalate, such as dibenzyltoluene, triphenylmethane, phenylnaphthalene, biphenyl, diethylbiphenyl, and triethylbiphenyl. Aromatic hydrocarbons and aliphatic hydrocarbons that are commonly used as media. The amount of the inert solvent used is in the range of 0.001 to 100 parts by weight, preferably 0.01 to 80 parts by weight, more preferably 0.1 to 50 parts by weight with respect to 1 part by weight of the carbamate. is there.
[0054]
This thermal decomposition reaction can be carried out either as a batch reaction in which carbamate, a catalyst and an inert solvent are charged in a batch, or a continuous reaction in which carbamate is charged under reduced pressure in an inert solvent containing a catalyst. it can.
[0055]
  In this thermal decomposition reaction, the carbamate obtained above is thermally decomposed, and as described above, non-aromaticTheSince an isocyanate corresponding to an amine can be obtained, for example, a polyisocyanate used industrially as a raw material for polyurethane can be easily and efficiently produced.
[0056]
Although the carbamate production method and the isocyanate production method have been described above, in the production method of the present invention, a pretreatment step such as a dehydration step, an intermediate step, or a post-treatment step such as a purification step and a recovery step, etc. A known process may be included.
[0057]
【Example】
EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.
[0058]
Example 1
A 200 mL glass four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen blowing nozzle, a dropping funnel and a stirrer was purged with nitrogen, and then 45.6 g (0.30 mol) of methylphenyl carbonate was added to the flask. And 58.8 g of methanol were added, and 11.6 g (0.10 mol) of 1,6-hexamethylenediamine was added dropwise with stirring at room temperature. Then, after making it react at 50 degreeC for 3 hours, a part of reaction liquid was sampled and potentiometric titration was performed with 1N hydrochloric acid. As a result, the conversion of 1,6-hexamethylenediamine was 99.5% or more. Further, as a result of quantitative analysis of the reaction solution by gas chromatography, it was confirmed that 1,6-bis (methoxycarbonylamino) hexane was produced in a yield of 99.9%.
[0059]
Subsequently, the reaction solution was transferred to a 200 mL flask equipped with a capillary, a thermometer, and a distillation tube, and the flask was heated under reduced pressure (0.67 kPa) to evaporate the evaporated component. As a result, 1,6-bis (methoxy Carbonylamino) hexane crude crystals remained in the 23.2 g flask. The crude crystals were dissolved in a small amount of methanol, 90 g of diethyl ether was added and mixed well, and the precipitated crystals were separated by filtration. The weight after drying was 22.6 g (isolated yield 97.7%).
[0060]
The isolated crystals were subjected to FT-IR, MS spectrum and¹Identified by 1 H-NMR. In IR spectrum, NH stretching 3335 cm^-1, C = O stretch 1686cm^-1, N-H deflection angle 1530cm^-1Was observed. In the MS spectrum, (M +) = 232 was observed. Also,¹The spectrum of H-NMR is shown below.
[0061]
¹H-NMR spectrum (CDCl₃, TMS; ppm)
1.35 (t, 4H)
1.50 (m, 4H)
3.15 (m, 4H)
3.70 (s, 6H)
4.65 to 4.85 (b, 2H)
Example 2
A 200 mL glass four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen blowing nozzle, a dropping funnel and a stirrer was purged with nitrogen, and then the crude methylphenyl carbonate (dimethyl carbonate and phenol and The reaction mixture was synthesized by a transesterification reaction and was simply distilled, and the composition ratio by gas chromatography analysis was 76.1 g (a mixture of 60 parts by weight of methylphenyl carbonate, 26 parts by weight of phenol, and 9 parts by weight of dimethyl carbonate). 30 mol) and 28.5 g of methanol were charged, and 11.6 g (0.10 mol) of 1,6-hexamethylenediamine was added dropwise with stirring at room temperature. Then, after making it react at 50 degreeC for 4 hours, a part of reaction liquid was sampled and potentiometric titration was performed with 1N hydrochloric acid. As a result, the conversion of 1,6-hexamethylenediamine was 99.5% or more. Further, as a result of quantitative analysis of the reaction solution by gas chromatography, it was confirmed that 1,6-bis (methoxycarbonylamino) hexane was produced in a yield of 99.9%.
[0062]
Example 3
A 200 mL glass four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen blowing nozzle, a dropping funnel and a stirrer was purged with nitrogen, and then 45.6 g (0.30 mol) of methylphenyl carbonate was added to the flask. ) And 63.3 g of methanol, and 13.6 g (0.10 mol) of 1,3-bis (aminomethyl) benzene were added dropwise with stirring at room temperature. Then, after making it react at 60 degreeC for 10 hours, a part of reaction liquid was sampled and potentiometric titration was performed with 1N hydrochloric acid. As a result, the conversion of 1,3-bis (aminomethyl) benzene was 99.0% or more. Further, as a result of quantitative analysis of the reaction solution by gas chromatography, it was confirmed that 1,3-bis (methoxycarbonylaminomethyl) benzene was produced in a yield of 99.7%.
[0063]
Example 4
A 200 mL glass four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen blowing nozzle, a dropping funnel and a stirrer was purged with nitrogen, and then 45.6 g (0.30 mol) of methylphenyl carbonate was added to the flask. ) And 68.1 g of methanol, and 14.2 g (0.10 mol) of 1,3-bis (aminomethyl) cyclohexane was added dropwise with stirring at room temperature. Then, after making it react at 60 degreeC for 8 hours, a part of reaction liquid was sampled and potentiometric titration was performed with 1N hydrochloric acid. As a result, the conversion rate of 1,3-bis (aminomethyl) cyclohexane was 99.0% or more. Further, as a result of quantitative analysis of the reaction solution by gas chromatography, it was confirmed that 1,3-bis (methoxycarbonylaminomethyl) cyclohexane was produced in a yield of 99.9%.
[0064]
Example 5
A 200 mL glass four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen blowing nozzle, a dropping funnel and a stirrer was purged with nitrogen, and then 82.2 g (0.54 mol) of methylphenyl carbonate was added to the flask. ) And 17.0 g (0.10 mol) of isophoronediamine was added dropwise with stirring at room temperature. Then, after making it react at 60 degreeC for 6 hours, a part of reaction liquid was sampled and potentiometric titration was performed with 1N hydrochloric acid. As a result, the conversion rate of isophoronediamine was 99.0% or more. As a result of quantitative analysis of the reaction solution by gas chromatography, it was confirmed that isophorone dimethyl carbamate was produced in a yield of 99.8%.
[0066]
    Example6
  A 200 mL glass four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen blowing nozzle, a dropping funnel, and a stirring device was purged with nitrogen, and then 80.2 g (0.53 mol) of methylphenyl carbonate was added to the flask. ), And 18.0 g (0.10 mol) of 1,2-bis (2-aminoethylthio) ethane was added dropwise with stirring at room temperature. Then, after making it react at 60 degreeC for 5 hours, a part of reaction liquid was sampled and potentiometric titration was performed with 1N hydrochloric acid. As a result, the conversion rate of 1,2-bis (2-aminoethylthio) ethane was 99.0% or more. As a result of quantitative analysis of the reaction solution by gas chromatography, it was confirmed that 1,2-bis (2-methoxycarbonylaminoethylthio) ethane was produced in a yield of 99.0%.
[0070]
Comparative Example 1
A 200 mL glass four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen blowing nozzle, a dropping funnel, and a stirring device was purged with nitrogen, and then 54.0 g (0.60 mol) of dimethyl carbonate was added to the flask. And 18.8 g (0.10 mol) of 1,6-hexamethylenediamine were added dropwise with stirring at room temperature. Then, after making it react at 70 degreeC for 16 hours, a part of reaction liquid was sampled and potentiometric titration was performed with 1N hydrochloric acid. As a result, the conversion of 1,6-hexamethylenediamine was 71.9%. As a result of quantitative analysis of the reaction solution by gas chromatography, the yield of 1,6-bis (methoxycarbonylamino) hexane was 41.6%. Moreover, the production | generation of 5.6% of N-methyl body was confirmed.
[0071]
    Example7
  A 500 mL flask equipped with a rectifying column equipped with a condenser, a capillary and a thermometer was used as a reactor. Hot water at 60 ° C. was passed through the cooler, and the receiver was connected to a vacuum line through a cold trap cooled with cold ethanol. The reaction solution of 1,6-bis (methoxycarbonylamino) hexane obtained in Example 1 was transferred to a flask and placed in an oil bath. The inside of the flask was decompressed to 0.67 kPa, and the oil bath was heated to 90 ° C. to distill off the evaporated components such as unreacted methylphenyl carbonate and by-product phenol.
[0072]
Next, the reaction system was returned to normal pressure, and 100 g of THERM S 1000S (manufactured by Nippon Steel Chemical Co., Ltd.) and 0.15 g of dibutyltin dilaurate were charged into the flask, and the reaction system was purged with nitrogen. The oil bath was heated to 250 ° C. and reacted (decomposed) for 1 hour. After completion of the reaction, the reaction liquid (distilled portion) collected in the receiver was quantitatively analyzed by gas chromatography. As a result, 12.5 g (74.1%) of 1,6-hexamethylene diisocyanate and 4.6 g of monoisocyanate (23.23%) were obtained. 0%) was confirmed.
[0073]
    Example8
  Example7The 1,6-bis (methoxycarbonylamino) hexane obtained in Example 2 was subjected to a thermal decomposition reaction in the same manner as in Example 1 to obtain 12.6 g (74.9%) of 1,6-hexamethylene diisocyanate and monoisocyanate. 4.4 g (22.0%) were obtained.
[0074]
    Example9
  Example7In the same manner as described above, the thermal decomposition reaction of 1,3-bis (methoxycarbonylaminomethyl) cyclohexane obtained in Example 4 was carried out to give 14.2 g (73.1) of 1,3-bis (isocyanatomethyl) cyclohexane. %) And 4.7 g (20.9%) of monoisocyanate.
[0075]
Comparative Example 2
A glass four-necked flask having an internal volume of 300 mL equipped with a reflux condenser, a thermometer, a nitrogen blowing nozzle, a dropping funnel and a stirring device was purged with nitrogen, and then 11.6 g of 1,6-hexamethylenediamine was added to the flask. (0.10 mol) and 72.0 g (0.80 mol) of dimethyl carbonate were charged, and the temperature was raised to 70 ° C. with stirring. Next, 1.5 g of a 28% methanol solution of sodium methylate was added in portions over 30 minutes. Furthermore, after making it react at 70 degreeC for 1 hour, a part of reaction liquid was sampled and potentiometric titration was performed with 1N-hydrochloric acid. As a result, the conversion of 1,6-hexamethylenediamine was 99.5% or more. Further, as a result of quantitative analysis of the reaction solution by gas chromatography, it was confirmed that 1,6-bis (methoxycarbonylamino) hexane was produced in a yield of 99.5%.
[0076]
Then, the obtained 1,6-bis (methoxycarbonylamino) hexane was thermally decomposed by the following method. That is, in this method, a 500 mL flask equipped with a rectifying column equipped with a cooling tube, a capillary, and a thermometer was used as a reactor. Hot water at 60 ° C. was passed through the cooler, and the receiver was connected to a vacuum line through a cold trap cooled with cold ethanol. The reaction liquid of 1,6-bis (methoxycarbonylamino) hexane obtained above was transferred to a flask and placed in an oil bath. The inside of the flask was decompressed to 0.67 kPa, and the oil bath was heated to 90 ° C., and evaporated components such as unreacted dimethyl carbonate and by-product methanol were distilled off.
[0077]
Next, the reaction system was returned to normal pressure, and 100 g of THERM S 1000S (manufactured by Nippon Steel Chemical Co., Ltd.) and 0.15 g of dibutyltin dilaurate were charged into the flask, and the reaction system was purged with nitrogen. The oil bath was heated to 250 ° C. Although this state was maintained for 1 hour, 1,6-hexamethylene diisocyanate was not distilled. At this time, solid matter was generated in the flask.
[0078]
【The invention's effect】
  According to the method for producing a carbamate of the present invention, it is substantially non-aromatic by simple equipment.TheAlkyl carbamate can be obtained with high selectivity and high yield only by blending amine and alkyl aryl carbonate, and a complicated post-treatment step is not required, so that carbamate can be produced efficiently at low cost. be able to. In this production method, a raw material containing an alkylaryl carbonate can be used as it is as the alkylaryl carbonate.
[0079]
Moreover, according to the isocyanate production method of the present invention, a polyisocyanate that is industrially used as a raw material for polyurethane can be produced simply and efficiently.

Claims (5)

Aliphatic di-amine, and aromatic di amine selected from the group consisting of cycloaliphatic di- amine and araliphatic di-amine, and the alkyl aryl carbonate represented by the following general formula (1), the alkyl aryl carbonate, a non A method for producing a carbamate , which is prepared so as to be 1.01 to 30 times the mole of an amino group of an aromatic diamine and to react them in the absence of a catalyst .
R ¹ OCOOR ² (1)
(In the formula, R1 represents an alkyl group, and R2 represents an aryl group which may have a substituent.)   The method for producing a carbamate according to claim 1, wherein the alkylaryl carbonate is methylphenyl carbonate.   The carbamate according to claim 1 or 2, wherein a crude raw material containing 1% by weight or more of alkylaryl carbonate obtained by transesterification of dialkyl carbonate and phenol or a derivative thereof is used as alkylaryl carbonate. Production method. Aromatic di-amine, 1,6-hexamethylenediamine, isophoronediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 4,4'-methylenebis (cyclohexanamine) 2,5-bis (aminomethyl) bicyclo [2,2,1] heptane, 2,6-bis (aminomethyl) bicyclo [2,2,1] heptane, 1,3-bis (aminomethyl) benzene, The method for producing a carbamate according to any one of claims 1 to 3, wherein the carbamate is at least one selected from the group consisting of 1,4-bis (aminomethyl) benzene. An isocyanate comprising: a process for producing a carbamate by a method for producing a carbamate according to any one of claims 1 to 4 ; and a process for producing an isocyanate by thermally decomposing the obtained carbamate. Manufacturing method.