JP5615644B2 - Method for producing N-unsubstituted carbamic acid ester and method for producing isocyanate - Google Patents

Description

  The present invention relates to a method for producing an N-unsubstituted carbamic acid ester, an N-unsubstituted carbamic acid ester obtained by the method for producing an N-unsubstituted carbamic acid ester, and an isocyanate in which the N-unsubstituted carbamic acid ester is used. The present invention relates to a production method and an isocyanate obtained by the production method of the isocyanate.

  N-unsubstituted carbamic acid ester is a basic organic compound, and is widely known industrially as, for example, a solubilizer in water, a raw material for pharmaceuticals, agricultural chemicals and the like, and a raw material for production of isocyanate and the like.

  For example, in the production of isocyanate, as a method not using toxic phosgene, N-unsubstituted carbamic acid ester, amine and alcohol are reacted to produce carbamate (urea method), and the resulting carbamate is heated. Methods are known for producing isocyanates by decomposition.

  Various methods for producing such an N-unsubstituted carbamic acid ester have been studied. Examples of such a method include urea and various alcohols in the presence of a catalyst composed of tin tetrachloride and the like. A method of reacting has been proposed (for example, see Patent Document 1).

German open patent 753127

  However, as described in Patent Document 1, when urea and alcohol are reacted in the presence of tin tetrachloride, N-unsubstituted carbamic acid ester is obtained, and various biuret derivatives are used as by-products. More specifically, for example, alkyl allophanate and dialkyl iminobisformate are produced.

  If the N-unsubstituted carbamic acid ester contains a large amount of such biuret derivatives, it may cause deterioration in quality and production efficiency in the production of various industrial products. For example, when such a N-unsubstituted carbamic acid ester is used in the urea method described above to produce a carbamate, by-products such as amino-methyl-tetrahydroquinazoline-dione (benzoylene urea derivative, AMQ) and In some cases, dialkyl carbonate (DAC) is produced.

  And when these by-products are thermally decomposed to produce isocyanate, there is a problem in that the isocyanate production apparatus and the like are blocked (fouling) and the production efficiency of isocyanate is reduced.

  An object of the present invention is to provide a method for producing an N-unsubstituted carbamic acid ester capable of reducing the formation of by-products, an N-unsubstituted carbamic acid ester obtained by the production method, and an N-unsubstituted carbamic acid ester thereof. It is in providing the isocyanate obtained by the manufacturing method of isocyanate for manufacturing isocyanate using this, and the manufacturing method of the isocyanate.

  In order to achieve the above object, the method for producing an N-unsubstituted carbamic acid ester of the present invention comprises reacting urea with an alcohol in the presence of a compound containing a non-coordinating anion and a metal atom. It is said.

  In the method for producing an N-unsubstituted carbamic acid ester of the present invention, it is preferable that the urea is added in portions or continuously in the reaction.

  In the method for producing an N-unsubstituted carbamic acid ester of the present invention, it is preferable that the alcohol is represented by the following general formula (1) and the compound is represented by the following general formula (2).

R ¹ —OH (1)
(In the formula, R ¹ represents an aliphatic hydrocarbon group having ^{1 to} 16 carbon atoms in total or an aromatic hydrocarbon group having 6 to 16 carbon atoms in total.)
MX ¹ mX ² nm (2)
(In the formula, M represents a metal atom of Groups ¹ to 16 of the periodic table, X ¹ represents a non-coordinating anion, X ² represents a ligand, m represents an integer of 1 to n, n represents the valence of M.)
In the method for producing an N-unsubstituted carbamic acid ester of the present invention, in the general formula (2), X ¹ is preferably a non-coordinating anion represented by the following general formula (3). .

R ² SO ₃ ^- ₍₃₎
(In the formula, R ² represents a substituent having a substituent constant σ in the range of −0.1 to +0.7.)
Further, in the method for producing an N-unsubstituted carbamic acid ester of the present invention, in the general formula (3), R ² contains at least one fluorine atom and has 1 to 16 carbon atoms in total. Or an aromatic hydrocarbon group having 6 to 16 carbon atoms in total.

  In the method for producing an N-unsubstituted carbamic acid ester of the present invention, the biuret derivative by-produced by the reaction is preferably 3 mol or less with respect to 100 mol of the N-unsubstituted carbamic acid ester. .

  The present invention also includes a step of producing an N-unsubstituted carbamic acid ester by the above-described method for producing an N-unsubstituted carbamic acid ester, and the obtained N-unsubstituted carbamic acid ester and a primary amine. It also includes a method for producing an isocyanate, which comprises a step of producing a urethane compound by reacting at least and a step of producing an isocyanate by thermally decomposing the obtained urethane compound.

  The present invention also includes an N-unsubstituted carbamic acid ester obtained by the above-described method for producing an N-unsubstituted carbamic acid ester.

  The present invention also includes an N-unsubstituted carbamic acid ester containing 3 moles or less of a biuret derivative with respect to 100 moles of the N-unsubstituted carbamic acid ester.

  Moreover, this invention also contains the isocyanate obtained by the manufacturing method of an above-described isocyanate.

  According to the method for producing an N-unsubstituted carbamic acid ester of the present invention, since a compound containing a non-coordinating anion and a metal atom is used as a catalyst, the production of by-products is reduced, and N-unsubstituted Carbamates can be produced with excellent efficiency.

  Moreover, in the N-unsubstituted carbamic acid ester of the present invention obtained by the method for producing the N-unsubstituted carbamic acid ester of the present invention, the content of the biuret derivative as a by-product is reduced. Therefore, in the isocyanate production method of the present invention, it is possible to suppress the generation of a substance that causes fouling by the reaction of such a biuret derivative.

  As a result, according to the method for producing an isocyanate of the present invention, it is possible to produce an isocyanate with an excellent yield while suppressing blockage of the apparatus.

  First, the method for producing the N-unsubstituted carbamic acid ester of the present invention will be described in detail.

  In the method for producing an N-unsubstituted carbamic acid ester of the present invention, urea and alcohol are reacted in the presence of a compound (catalyst) described later.

  The alcohol used in the present invention is, for example, a 1-3 grade monovalent alcohol, and is represented by, for example, the following formula (1).

R ¹ —OH (1)
(In the formula, R ¹ represents an aliphatic hydrocarbon group having ^{1 to} 16 carbon atoms in total or an aromatic hydrocarbon group having 6 to 16 carbon atoms in total.)
In the above formula (1), in R ¹ , examples of the aliphatic hydrocarbon group having 1 to 16 carbon atoms include an alkyl group having 1 to 16 carbon atoms.

  Examples of the alkyl group include methyl, ethyl, propyl, iso-propyl, butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, iso-pentyl, sec-pentyl, hexyl, heptyl, octyl, 2-ethylhexyl. , Nonyl, decyl, isodecyl, dodecyl, tetradecyl, hexadecyl, cyclohexyl, cyclododecyl and the like.

In the above formula (1), examples of the alcohol in which R ¹ is an aliphatic hydrocarbon group having ¹ to 16 carbon atoms include methanol, ethanol, propanol, iso-propanol, butanol (1-butanol), and iso-butanol. , Sec-butanol, tert-butanol, pentanol, iso-pentanol, sec-pentanol, hexanol, heptanol, octanol (1-octanol), 2-ethylhexanol, nonanol, decanol, isodecanol, dodecanol, tetradecanol, Examples include hexadecanol, cyclohexanol, and cyclododecanol.

In the above formula (1), in R ¹ , examples of the aromatic hydrocarbon group having 6 to 16 carbon atoms include an aryl group having 6 to 16 carbon atoms.

  Examples of the aryl group include phenyl, tolyl, xylyl, biphenyl, naphthyl, anthryl, phenanthryl and the like.

In the above formula (1), examples of the alcohol in which R ¹ is an aromatic hydrocarbon group having 6 to 16 carbon atoms include, for example, phenol, hydroxytoluene, hydroxyxylene, biphenyl alcohol, naphthalenol, anthracenol, phenanthrenol Etc.

  These alcohols can be used alone or in combination of two or more.

As the alcohol, preferably, in the above formula (1), R ¹ is an alcohol having an aliphatic hydrocarbon group having ¹ to 16 carbon atoms, more preferably, R ¹ is an aliphatic hydrocarbon group having 2 to 12 carbon atoms. Some alcohols are mentioned.

  The compound used in the present invention contains a non-coordinating anion and a metal atom, and is represented by, for example, the following formula (2).

MX ¹ mX ² nm (2)
(In the formula, M represents a metal atom of Groups ¹ to 16 of the periodic table, X ¹ represents a non-coordinating anion, X ² represents a ligand, m represents an integer of 1 to n, n represents the valence of M.)
In the above formula (2), M includes a metal atom of the periodic table group 1 to 16 (IUPAC Periodic Table of the Elements (version date 22 June 2007), the same shall apply hereinafter).

  The metal atom is preferably a metal atom of Groups 4 and 11 to 14 of the periodic table, more preferably a metal atom of Groups 4 and 12 of the periodic table.

  Moreover, as a metal atom, Preferably, the metal atom of a periodic table 3rd-6th period among the above-mentioned metal atoms, Preferably, the metal atom of a 4th-6th period of a periodic table is mentioned.

  More specifically, as such metal atoms, for example, titanium, zirconium, hafnium (above, Group 4 to 6 of the periodic table), copper, silver, gold (above, Group 11 of the periodic table) 4th to 6th cycle), zinc, cadmium, mercury (above, periodic table group 12 group 4-6 cycle), aluminum, gallium, indium, thallium (above, periodic table group 13 group 3-6 cycle) , Tin, lead (above, Periodic Table Group 14 Group 5-6) and the like.

  Preferred examples of the metal atom include titanium, zirconium, hafnium (above, Group 4 to 6 periods of periodic table), zinc, cadmium, and mercury (above, Group 12 to 6 periods of periodic table). More preferably, titanium, hafnium, or zinc is used.

In the above formula (2), in X ¹ , the non-coordinating anion is defined as an anion that does not coordinate to a cation described later or is slightly coordinated to the extent that it is replaced by a neutral Lewis base. .

  Examples of such non-coordinating anions include non-coordinating sulfur-containing anions, oxygen-containing anions, boron-containing anions, and phosphorus atom-containing anions.

  As a sulfur containing anion, the non-coordinating anion shown by following General formula (3) is mentioned, for example.

R ² SO ₃ ^- ₍₃₎
(In the formula, R ² represents a substituent having a substituent constant σ in the range of −0.1 to +0.7.)
In the above formula (3), the substituent constant σ is a constant (Charton, M. Prog. Phys. Org) indicating the strength of electron withdrawing of a substituent, defined and extended from Hammett's substituent constant by Charton. Chem., 1981, 13, 119), which is a dimensionless numerical value unique to the substituent.

Examples of the substituent R ² having a substituent constant σ in the range of −0.1 to +0.7 include, for example, CH ₃ —, C ₂ H ₅ —, C ₃ H ₇ —, iso-C ₃ H ₇ —. _{, C 4 H 9 -, iso} -C 4 H 9 -, sec-C 4 H 9 -, tert-C 4 H 9 -, C 5 H 11 -, iso-C 5 H 11 -, sec-C 5 H _{11 -, C 6 H 13 -} , C 7 H 15 -, C 8 H 17 -, C 9 H 19 -, C 10 H 21 -, C 11 H 23 -, C 12 H 25 -, C 13 H 27 - _{, C 14 H 29 -, C} 15 H 31 -, C 16 H 33 -, C 6 H 5 -, 2- (CH 3) C 6 H 4 -, 3- (CH 3) C 6 H 4 -, 4 _{- (CH 3) C 6 H} 4 -, 2,3- (CH 3) 2 C 6 H 3 -, 2,4- (CH 3) 2 C 6 H 3 -, 2 _{, 5- (CH 3) 2 C} 6 H 3 -, 2,6- (CH 3) 2 C 6 H 3 -, 3,4- (CH 3) 2 C 6 H 3 -, 3,5- (CH ₃ ) ₂ C ₆ H ₃ —, 3,6- (CH ₃ ) ₂ C ₆ H ₃ — and the like.

As the substituent R ² having a substituent constant σ in the range of −0.1 to +0.7, preferably, the substituent R ² described above contains at least one fluorine atom and has a total number of carbon atoms of 1 to 1. 16 aliphatic hydrocarbon groups or aromatic hydrocarbon groups having 6 to 16 carbon atoms in total, for example, CH ₂ F—, CHF ₂ —, CF ₃ —, CH ₂ FCH ₂ —, CHF ₂ CH _{2 -, CF 3 CH 2 -} , CH 3 CHF-, CH 3 CF 2 -, CH 2 FCHF-, CHF 2 CHF-, CF 3 CHF-, CH 2 FCF 2 -, CHF 2 CF 2 -, C 2 F _{5 -, C 3 F 7 -} , C 4 F 9 -, iso-C 4 F 9 -, sec-C 4 F 9 -, tert-C 4 F 9 -, C 5 F 11 -, iso-C 5 F _{11 -, sec-C 5 F} 11 -, C 6 F 13 _{-, C 7 F 15 -,} C 8 F 17 -, C 9 F 19 -, C 10 F 21 -, C 11 F 23 -, C 12 F 25 -, C 13 F 27 -, C 14 F 29 -, _{C 15 F 31 -, C 16} F 33 -, 2-F-C 6 H 4 -, 3-F-C 6 H 4 -, 4-F-C 6 H 4 -, C 6 F 5 -, 2- _{(CF 3) C 6 H 4} -, 3- (CF 3) C 6 H 4 -, 4- (CF 3) C 6 H 4 -, 2,3- (CF 3) 2 C 6 H 3 -, 2 _{, 4- (CF 3) 2 C} 6 H 3 -, 2,5- (CF 3) 2 C 6 H 3 -, 2,6- (CF 3) 2 C 6 H 3 -, 3,4- (CF _{3) 2 C 6 H 3 -} , 3,5- (CF 3) 2 C 6 H 3 -, 3,6- (CF 3) 2 C 6 H 3 - , and the like.

More specifically, as the sulfur-containing anion, for example, a perfluoroalkylsulfonate anion (for example, OSO ₂ CF ₃ ⁻ (hereinafter sometimes abbreviated as OTf ⁻ ), OSO ₂ C ₂ F ₅ ⁻ , OSO ₂ ). ^{_{C 3 F 7 -, OSO 2}} C 4 F 9 - , etc.), an aryl sulfonate anion ^{_{(OSO 2 C 6 H 4 CH}} 3 -, OSO 2 C 6 H 5 - , etc.) and the like.

Examples of the oxygen-containing anion include perchlorate anion (ClO ₄ ⁻ ).

Examples of the phosphorus atom-containing anion include hexafluorophosphate anion (PF ₆ ⁻ ).

Examples of the boron-containing anion include tetrafluoroborate anion (BF ₄ ⁻ ), tetraphenylborate anion, tetra (p-tolyl) borate anion, tetra (o-tolyl) borate anion, tetrakis (o, p-dimethylphenyl). Borate anion, tetrakis (m, m-dimethylphenyl) borate anion, tetrakis [p- (trifluoromethyl) phenyl] borate anion, tetrakis (pentafluorophenyl) borate (B (C ₆ F ₅ ) ₄ ⁻ ) anion, tetrakis And [3,5-bis (trifluoromethyl) phenyl] borate anion (B [3,5- (CF ₃ ) ₂ C ₆ H ₃ ] ₄ ⁻ ).

  As the non-coordinating anion, preferably a perfluoroalkyl sulfonate anion, an aryl sulfonate anion, a hexafluorophosphate anion, a tetrafluoroborate anion, a tetrakis (pentafluorophenyl) borate anion, tetrakis [3,5-bis (trifluoromethyl) ) Phenyl] borate anion, more preferably an aryl sulfonate anion.

In the above formula (2), in X ² , the ligand is an atomic group coordinated to the above metal atom, and more specifically, for example, an alkyl group (for example, CH ₃ —, C ₂ H _{5 -, C 3 H 7 -} , iso-C 3 H 7 -, C 4 H 9 -, iso-C 4 H 9 -, sec-C 4 H 9 -, tert-C 4 H 9 -, C 5 H ₁₁ − ₋ etc.), an alkoxy group (for example, CH ₃ O—, C ₂ H ₅ O—, C ₃ H ₇ O—, iso-C ₃ H ₇ O—, C ₄ H ₉ O—, iso-C _{4). H 9 O-, sec-C 4} H 9 O-, tert-C 4 H 9 O-, C 5 H 11 O- - etc.), primary amino groups _(NH 2 -), 2 amino groups (e.g., _{CH 3 NH-, C 2 H 5} NH-, C 3 H 7 NH-, iso-C 3 H 7 NH-, C 4 H 9 NH-, iso- _{4 H 9 NH-, sec-C} 4 H 9 NH-, tert-C 4 H 9 NH-, C 5 H 11 NH- - etc.), tertiary amino groups _{(e.g., (CH 3)} 2 N -, ( _{C 2 H 5) 2 N -} , (C 3 H 7) 2 N -, (C 4 H 9) 2 N -, (C 5 H 11) 2 N- , etc.), an acyloxy group _(e.g., CH 3 COO- _{, C 2 H 5 COO-, C} 3 H 7 COO-, iso-C 3 H 7 COO-, C 4 H 9 COO-, iso-C 4 H 9 COO-, sec-C 4 H 9 COO-, tert _{-C 4 H 9 COO-, C 5} H 11 COO-, C 6 H 13 COO-, C 7 H 15 COO-, C 8 H 17 COO-, C 9 H 19 COO-, C 10 H 21 COO-, _{C 11 H 23 COO-, C 12} H 25 COO-, C 13 H _{7 COO-, C 14 H 29 COO-} , C 15 H 31 COO-, C 16 H 33 COO-, C 17 H 35 COO-, C 18 H 37 COO-, C 6 H 5 COO- , etc.), acetylacetonates Nato, halogen atom (eg, fluorine, chlorine, bromine, iodine, etc.), sulfate ion (SO ₄ ²⁻ ), oxide ion (O ²⁻ ), amide ligand (eg, [N (SiMe ₃ ) ₂ ] Etc.).

  In said formula (2), m shows the integer of 1-n and n shows the valence of M.

In the above formula (2), when m is 2 or more (that is, when X ¹ for one M is 2 or more), each X ¹ is the same as or different from each other. Also good.

Further, in the above formula (2), when nm is 2 or more (that is, when X ² for one M is 2 or more), even if each X ² is the same, Each may be different.

In the above formula (2), when m = n (when the valence of M and the number of X ¹ are the same), the compound of the above formula (2) is a ligand (X ² ). It is formed from a cation of a metal atom (M) and a non-coordinating anion (X ¹ ).

More specifically, as such a compound, for example, Zn (OTf) ₂ (another notation: Zn (OSO ₂ CF ₃ ) ₂ , zinc trifluoromethanesulfonate), Zn (OSO ₂ C ₂ F ₅ ) ₂ , Zn (OSO ₂ C ₃ F ₇ ) ₂ , Zn (OSO ₂ C ₄ F ₉ ) ₂ , Zn (OSO ₂ C ₆ H ₄ CH ₃ ) ₂ (zinc paratoluenesulfonate), Zn (OSO ₂ C ₆ H ₅ ) ₂ , Zn (BF ₄ ) ₂ , Zn (PF ₆ ) ₂ , Hf (OTf) ₄ (hafnium trifluoromethanesulfonate), Sn (OTf) ₂ , Al (OTf) ₃ , Cu (OTf) _{2 and the} like. It is done.

In the above formula (2), when m <n (when the number of X ¹ is less than the valence of M), the compound of the above formula (2) has a metal atom (M), It is formed from a non-coordinating anion (X ¹ ) and a ligand (X ² ).

In such a case, the compound of the above formula (2) is formed as a compound having 1 to (n−1) ligands (X ² ) with respect to the metal atom (M) having a valence of n. Is done. Specifically, for example, when the valence of the metal atom (M) is 4, the compound of the above formula ( ² ) has 1 to 3 ligands (X ² ).

In the case where m <n, in the compound of the above formula (2), the cation that electrically attracts the non-coordinating anion (X ¹ ) is the metal atom (M) and the coordination coordinated thereto. And a child (X ² ).

That is, when m <n, the compound of the above formula (2) is a cation (eg, complex ion) formed by coordination of the ligand (X ² ) to the metal atom (M). And a non-coordinating anion (X ¹ ).

  Such a compound can be formed, for example, by mixing a metal compound and a compound that generates a non-coordinating anion.

More specifically, such a compound includes, for example, a metal compound (MX ² n) composed of a metal atom (M) coordinated with n ligands (X ² ) and a non-coordinating anion (X ¹ )) (for example, a compound having a non-coordinating anion as a conjugate base (HX ¹ ), etc.) can be mixed to form a product.

That is, when these metal compounds (MX ² n) and a compound that generates a non-coordinating anion (for example, HX ¹ ) are mixed in, for example, water or an organic solvent, A part of the ligand (X ² ) in the metal compound (MX ² n) and the non-coordinating anion (X ¹ ) are substituted to form the compound of the above formula (2).

More specifically, for example, by mixing titanium tetrachloride (TiCl ₄ ) and trifluoromethanesulfonic acid (HOTf), some chlorine anions (Cl ⁻ ) in titanium tetrachloride and triflate anions ( A non-coordinating anion, OTf ⁻ ) is substituted, and as the compound of the above formula (2), a compound in which 1 to 3 triflate anions and a chlorine anion are substituted, for example, TiCl (OTf) ₃ , TiCl ₂ ( OTf) ₂ , TiCl ₃ (OTf), etc. are formed.

In such a mixture, all the ligands (X ² ) in the metal compound (MX ² n) and the non-coordinating anion (X ¹ ) are substituted, and n non-coordinating properties are obtained. A compound having an anion (X ¹ ) may be formed.

As the compound of the above formula (2), preferably, Zn (OTf) ₂ (zinc trifluoromethanesulfonate), Zn (OSO ₂ C ₆ H ₄ CH ₃ ) ₂ (zinc paratoluenesulfonate), Hf (OTf) ₄ (Hafnium trifluoromethanesulfonate), a mixture of titanium tetrachloride (TiCl ₄ ) and trifluoromethanesulfonic acid (HOTf) (TiCl (OTf) ₃ , TiCl ₂ (OTf) ₂ , TiCl ₃ (OTf)).

  These compounds can be used alone or in combination of two or more.

  And in the manufacturing method of N-unsubstituted carbamic acid ester of this invention, urea and alcohol are mix | blended and it is made to react preferably in a liquid phase in presence of an above described compound (catalyst).

  The blending ratio of urea and alcohol is not particularly limited and can be appropriately selected within a relatively wide range.

  Usually, it is sufficient that the blending amount of alcohol is equimolar or more with respect to urea. Therefore, urea or alcohol itself can be used as a reaction solvent in this reaction.

  In addition, when urea or alcohol is also used as a reaction solvent, an excessive amount of urea or alcohol is used as necessary, but if the excessive amount is large, energy consumption in the separation step after the reaction increases, Not suitable for industrial production.

  Therefore, the blending amount of the alcohol is 1 to 50 times mol, preferably 1 to 20 times mol, more preferably 1 to 1 mol, with respect to urea, from the viewpoint of improving the yield of N-unsubstituted carbamic acid ester. 10 moles.

  Moreover, the compounding quantity of a compound (catalyst) is 0.000001-0.1 mol with respect to 1 mol of urea, Preferably, it is 0.00005-0.05 mol. Even if the amount of the catalyst is larger than this, no further significant reaction promoting effect is observed, but the cost may increase due to an increase in the amount of the catalyst. On the other hand, if the blending amount is less than this, the reaction promoting effect may not be obtained.

  In this reaction, a reaction solvent is not always necessary. For example, when the reaction raw material is solid or a reaction product is precipitated, the operability can be improved by blending the reaction solvent.

  Such reaction solvents are particularly limited as long as they are inert or poorly reactive with urea and alcohol as reaction raw materials and N-unsubstituted carbamic acid ester as a reaction product. For example, aliphatic hydrocarbons (for example, hexane, pentane, petroleum ether, ligroin, cyclododecane, decalins, etc.), aromatic hydrocarbons (for example, benzene, toluene, xylene, ethylbenzene, isopropylbenzene, Butylbenzene, cyclohexylbenzene, tetralin, chlorobenzene, o-dichlorobenzene, methylnaphthalene, chloronaphthalene, dibenzyltoluene, triphenylmethane, phenylnaphthalene, biphenyl, diethylbiphenyl, triethylbiphenyl, etc.), ethers (for example, die 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.), nitriles (for example, acetonitrile, propionitrile, adiponitrile, Benzonitrile, etc.), aliphatic halogenated hydrocarbons (eg, methylene chloride, chloroform, 1,2-dichloroethane, 1,2-dichloropropane, 1,4-dichlorobutane, etc.), amides (eg, dimethylformamide, Dimethylacetamide), nitro compounds (eg, nitromethane, nitrobenzene, etc.), N Methylpyrrolidinone, N, N-dimethylimidazolidinone, and dimethyl sulfoxide.

  Of these reaction solvents, aliphatic hydrocarbons and aromatic hydrocarbons are preferably used in view of economy and operability. Moreover, such a reaction solvent can be used individually or in combination of 2 or more types.

  The amount of the reaction solvent is not particularly limited as long as the N-unsubstituted carbamic acid ester of the target product is dissolved, but industrially, the reaction solvent is recovered from the reaction solution. Therefore, if the energy consumed for the recovery is reduced as much as possible and the amount is large, the reaction substrate concentration decreases and the reaction rate becomes slow. More specifically, it is generally used in the range of 0 to 10 parts by mass, preferably 0 to 5 parts by mass with respect to 1 part by mass of urea.

  Moreover, in this reaction, reaction temperature is suitably selected, for example in the range of 120-260 degreeC, Preferably it is 140-240 degreeC. If the reaction temperature is lower than this, the reaction rate may decrease. On the other hand, if the reaction temperature is higher than this, the side reaction may increase and the yield of the target product N-unsubstituted carbamic acid ester may decrease. is there.

  The reaction pressure is usually atmospheric pressure, but may be increased when the boiling point of the component in the reaction solution is lower than the reaction temperature, and further reduced as necessary.

  Moreover, reaction time is 0.1 to 20 hours, for example, Preferably, it is 0.5 to 10 hours. If the reaction time is shorter than this, the yield of the target product, N-unsubstituted carbamic acid ester, may decrease. On the other hand, if it is longer than this, it is unsuitable for industrial production.

  In this reaction, for example, alcohol, a catalyst, and, if necessary, a reaction solvent are charged in a reaction vessel under the above-described conditions, and urea is added in portions, or is continuously added thereto, or Urea and alcohol, a catalyst, and, if necessary, a reaction solvent may be charged all at once and stirred or mixed.

  From the viewpoint of suppressing by-products, it is particularly preferable to add urea in divided portions or continuously, more preferably continuous addition (continuous feed). Divided addition refers to a method in which the urea to be reacted is divided into two or more times, and the divided urea is charged at different times during the reaction, and continuous addition (continuous feed) refers to a metering pump or feeder. The method is not limited as long as it is a method that feeds quantitatively and can control the amount charged per unit time.

  Then, for example, the reaction represented by the following general formula (4) proceeds, ammonia is produced as a by-product, and an N-unsubstituted carbamic acid ester represented by the following general formula (5) corresponding to the alcohol is generated. To do.

NH ₂ CONH ₂ + R ¹ —OH → NH ₂ COOR ¹ + NH ₃ (4)
(Wherein, ^{R 1} represents the same meaning as ^{R 1} in the formula (1).)
NH ₂ COOR ¹ (5)
(Wherein, ^{R 1} represents the same meaning as ^{R 1} in the formula (1).)
In the above formula (5), ^{R 1} represents the same meaning as ^{R 1} in the formula (1), that is, aliphatic hydrocarbon group having a total carbon number of 1 to 16 or a total aromatic carbon atoms 6 to 16 Represents a hydrocarbon group.

In the above formula (5), examples of the N-unsubstituted carbamic acid ester in which R ¹ is an aliphatic hydrocarbon group having ¹ to 16 carbon atoms include, for example, methyl carbamate, ethyl carbamate, n-propyl carbamate, Iso-propyl carbamate, n-butyl carbamate, iso-butyl carbamate, sec-butyl carbamate, tert-butyl carbamate, pentyl carbamate, hexyl carbamate, heptyl carbamate, octyl carbamate, iso carbamate Saturated hydrocarbon N-unsubstituted carbamic acid esters such as octyl and 2-ethylhexyl carbamate, for example, alicyclic saturated hydrocarbon N-unsubstituted carbamic acid esters such as cyclohexyl carbamate and cyclododecyl carbamate It is done.

In the above formula (5), examples of the N-unsubstituted carbamic acid ester, which is an aromatic hydrocarbon group having 6 to 16 carbon atoms in total in which R ¹ may have a substituent, include phenyl carbamate. And aromatic hydrocarbon N-unsubstituted carbamic acid esters such as tolyl carbamate, xylyl carbamate, biphenyl carbamate, naphthyl carbamate, anthryl carbamate, phenanthryl carbamate, and the like.

  In this reaction, for example, a biuret derivative is by-produced.

  Examples of the biuret derivative include alkyl allophanate, aryl allophanate, dialkyl iminobisformate, diaryl iminobisformate and the like, but in a narrow sense, alkyl allophanate, aryl allophanate, dialkyl iminobisformate and diaryl iminobisformate.

  The alkyl allophanate and aryl allophanate correspond to the above-mentioned alcohol, and are represented by, for example, the following general formula (6).

(Wherein, ^{R 1} represents the same meaning as ^{R 1} in the formula (1).)
In the reaction of urea and alcohol, the alkyl allophanate and / or aryl allophanate are produced according to various reaction routes. For example, it produces | generates according to the reaction pathway shown by the following general formula (7) and the following general formula (8).

(Wherein, ^{R 1} represents the same meaning as ^{R 1} in the formula (1).)
Further, dialkyl iminobisformate and diaryliminobisformate correspond to the above-mentioned alcohols, and are represented by, for example, the following general formula (9).

(Wherein, ^{R 1} represents the same meaning as ^{R 1} in the formula (1).)
In the reaction of urea and alcohol, the dialkyl iminobisformate and / or diaryliminobisformate is produced, for example, from the alkyl allophanate and / or aryl allophanate according to the reaction route represented by the following general formula (10). .

(Wherein, ^{R 1} represents the same meaning as ^{R 1} in the formula (1).)
As for the content ratio of these biuret derivatives, the biuret derivative (total amount) is, for example, 3 mol or less, preferably 1 mol or less with respect to 100 mol of the N-unsubstituted carbamic acid ester.

  If the content ratio of the biuret derivative is not more than the above upper limit, when using an N-unsubstituted carbamic acid ester, for example, when producing an isocyanate using an N-unsubstituted carbamic acid ester, as described later, Generation of a substance that causes a ring can be suppressed.

  Further, in this reaction, other by-products such as carbonate (for example, dialkyl carbonate, diaryl carbonate, alkylaryl carbonate, etc.) and derivatives thereof may be generated. Carbonates are produced, for example, by alcohol addition and deammonification of N-unsubstituted carbamic acid esters.

  In this reaction, either a batch type or a continuous type can be adopted as the reaction type.

  In addition, this reaction is preferably carried out while allowing ammonia produced as a by-product to flow out of the system.

  Thereby, the production | generation of the N-unsubstituted carbamic acid ester which is a target product can be accelerated | stimulated, and the yield can be improved further.

  When the obtained N-unsubstituted carbamic acid ester is isolated, for example, excess (unreacted) urea and alcohol, catalyst, N-unsubstituted carbamic acid ester, reaction solvent, by-product ammonia, What is necessary is just to isolate | separate N-unsubstituted carbamic acid ester from the reaction liquid containing the biuret derivative byproduced, the carbonate byproduced, etc. by the well-known separation purification method.

  According to such a method for producing an N-unsubstituted carbamic acid ester, since a compound containing a non-coordinating anion and a metal atom is used as a catalyst, the production of by-products is reduced, and N- Unsubstituted carbamic acid esters can be produced with excellent efficiency.

  Moreover, in the N-unsubstituted carbamic acid ester obtained by such a method for producing an N-unsubstituted carbamic acid ester, the content of the biuret derivative as a by-product is reduced. Therefore, such an N-unsubstituted carbamic acid ester is a basic organic compound, and can be suitably used in a raw material such as a solubilizer in water, a medicine, and an agricultural chemical, and further in the production of isocyanate. In particular, in the production of isocyanate, it is possible to suppress the formation of a substance that causes fouling by the reaction of such a biuret derivative.

  And this invention includes the manufacturing method of the isocyanate which manufactures isocyanate using the N-unsubstituted carbamic acid ester obtained by the manufacturing method of the above-mentioned N-unsubstituted carbamic acid ester.

  That is, in such a method for producing isocyanate, first, a urethane compound (carbamate) is produced using the N-unsubstituted carbamic acid ester obtained by the above-described method for producing N-unsubstituted carbamic acid ester, The obtained urethane compound is pyrolyzed to produce isocyanate.

  In the step of producing a urethane compound, the above-described N-unsubstituted carbamic acid ester and at least a primary amine are reacted.

    The primary amine is an amino group-containing organic compound having one or more primary amino groups, and is represented by, for example, the following general formula (11).

_{^{R 4 - (NH 2) n}} (11)
(In the formula, R ⁴ represents an alicyclic non-aliphatic hydrocarbon group having 1 to 15 carbon atoms, an alicyclic aliphatic hydrocarbon group having 3 to 15 carbon atoms, or 6 to 15 carbon atoms in total. (In the aromatic ring-containing hydrocarbon group, n represents an integer of 1 to 6.)
In the above formula (11), R ⁴ is an alicyclic non-aliphatic hydrocarbon group having 1 to 15 carbon atoms, an alicyclic aliphatic hydrocarbon group having 3 to 15 carbon atoms, and 6 carbon atoms. Selected from ˜15 aromatic ring-containing hydrocarbon groups. R ⁴ may include a stable bond such as an ether bond, a thioether bond, or an ester bond in the hydrocarbon group, or may be substituted with a stable functional group (described later). Good.

In R ⁴ , the alicyclic non-aliphatic hydrocarbon group having 1 to 15 carbon atoms is, for example, a 1 to 6-valent linear or branched alicyclic non-aliphatic fatty acid having 1 to 15 total carbon atoms. Group hydrocarbon group and the like.

In the above formula (11), examples of the primary amine in which R ⁴ is an alicyclic non-aliphatic hydrocarbon group having 1 to 15 carbon atoms include aliphatic amines having 1 to 15 carbon atoms. .

  Examples of such aliphatic amines include methylamine, ethylamine, n-propylamine, iso-propylamine, butylamine, pentylamine, hexylamine, n-octylamine, 2-ethylhexylamine, decylamine, dodecylamine, tetra Linear or branched aliphatic primary monoamines such as decylamine, such as 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane (1,4-tetramethylenediamine), 1 , 5-diaminopentane (1,5-pentamethylenediamine), 1,6-diaminohexane (1,6-hexamethylenediamine), 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane 1,10-diaminodecane, 1,12-diaminododecane, , 2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, aliphatic primary diamine such as tetramethylenediamine, for example, 1,2,3-triaminopropane, triaminohexane, triamino Nonane, triaminododecane, 1,8-diamino-4-aminomethyloctane, 1,3,6-triaminohexane, 1,6,11-triaminoundecane, 3-aminomethyl-1,6-diaminohexane, etc. And aliphatic primary triamines.

In R ⁴ , examples of the alicyclic hydrocarbon group having 3 to 15 carbon atoms include 1 to 6 valent alicyclic hydrocarbon groups having 3 to 15 carbon atoms.

  The alicyclic-containing aliphatic hydrocarbon group only needs to contain one or more alicyclic hydrocarbons in the hydrocarbon group. For example, the alicyclic hydrocarbon includes, for example, an alicyclic non-cyclic group. An aliphatic hydrocarbon group or the like may be bonded. In such a case, the amino group in the primary amine may be directly bonded to the alicyclic hydrocarbon, or may be bonded to the alicyclic non-aliphatic hydrocarbon group bonded to the alicyclic hydrocarbon. Or both of them.

In the above formula (11), examples of the primary amine in which R ⁴ is an alicyclic-containing aliphatic hydrocarbon group having 3 to 15 carbon atoms include alicyclic amines having 3 to 15 carbon atoms. .

  Examples of such alicyclic amines include alicyclic primary monoamines such as cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, and hydrogenated toluidine, such as 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 (cyclohexylamine), 2,5-bis (aminomethyl) bicyclo [2,2,1] heptane, 2,6-bis (aminomethyl) bicyclo [ 2,2,1] heptane, hydrogenated 2,4-tolylenediamine, water Alicyclic primary diamines, such as 2,6-tolylenediamine, for example, an alicyclic primary triamine such as triamino-cyclohexane.

In R ⁴ , examples of the aromatic ring-containing hydrocarbon group having 6 to 15 carbon atoms include 1 to 6-valent aromatic ring-containing hydrocarbon groups having 6 to 15 carbon atoms in total.

  The aromatic ring-containing hydrocarbon group only needs to contain one or more aromatic hydrocarbons in the hydrocarbon group. For example, the aromatic hydrocarbon includes, for example, an alicyclic non-aliphatic aliphatic carbonization. A hydrogen group or the like may be bonded. In such a case, the amino group in the primary amine may be directly bonded to the aromatic hydrocarbon, or may be bonded to the alicyclic non-aliphatic aliphatic hydrocarbon group bonded to the aromatic hydrocarbon. Or both.

In the above formula (11), examples of the primary amine in which R ⁴ is an aromatic ring-containing hydrocarbon group having 6 to 15 carbon atoms include aromatic amines having 6 to 15 carbon atoms and 6 to 15 carbon atoms. And araliphatic amines.

  Examples of such aromatic amines include aniline, o-toluidine (2-methylaniline), m-toluidine (3-methylaniline), p-toluidine (4-methylaniline), 2,3-xylidine (2 , 3-dimethylaniline), 2,4-xylidine (2,4-dimethylaniline), 2,5-xylidine (2,5-dimethylaniline), 2,6-xylidine (2,6-dimethylaniline), 3 Aromatic primary monoamines such as 1,4-xylidine (3,4-dimethylaniline), 3,5-xylidine (3,5-dimethylaniline), 1-naphthylamine, 2-naphthylamine, for example, 2,4-tolylene Amine (2,4-diaminotoluene), 2,6-tolylenediamine (2,6-diaminotoluene), 4,4'-diphenylmethane dia 2,4′-diphenylmethanediamine, 2,2′-diphenylmethanediamine, 4,4′-diphenyletherdiamine, 2-nitrodiphenyl-4,4′-diamine, 2,2′-diphenylpropane-4,4′- Diamine, 3,3′-dimethyldiphenylmethane-4,4′-diamine, 4,4′-diphenylpropanediamine, m-phenylenediamine, p-phenylenediamine, naphthylene-1,4-diamine, naphthylene-1,5- Examples include diamines and aromatic primary diamines such as 3,3′-dimethoxydiphenyl-4,4′-diamine.

  Examples of such araliphatic amines include araliphatic primary monoamines such as benzylamine, such as 1,3-bis (aminomethyl) benzene, 1,4-bis (aminomethyl) benzene, 1,3. -Tetramethylxylylenediamine (1,3-di (2-amino-2-methylethyl) benzene), 1,4-tetramethylxylylenediamine (1,4-bis (2-amino-2-methylethyl) And aromatic aliphatic primary diamines such as benzene).

In the above formula (11), examples of the functional group which may be substituted with R ⁴ include a nitro group, a hydroxyl group, a mercapto group, an oxo group, a thioxo group, a cyano group, a carboxy group, and an alkoxy-carbonyl group (for example, Methoxycarbonyl group, alkoxycarbonyl group having 2 to 4 total carbon atoms such as ethoxycarbonyl group), sulfo group, halogen atom (for example, fluorine, chlorine, bromine, iodine, etc.), lower alkoxy group (for example, methoxy group, ethoxy group) , Propoxy group, butoxy group, iso-butoxy group, sec-butoxy group, tert-butoxy group, etc.), aryloxy group (for example, phenoxy group), halogenophenoxy group (for example, o-, m-, or p-chloro) Phenoxy group, o-, m- or p-bromophenoxy group, etc.), lower alkylthio group ( For example, a methylthio group, an ethylthio group, an n-propylthio group, an iso-propylthio group, an n-butylthio group, a tert-butylthio group, an arylthio group (for example, a phenylthio group), a lower alkylsulfinyl group (for example, a methylsulfinyl group) , Ethylsulfinyl group etc.), lower alkylsulfonyl group (eg methylsulfonyl group, ethylsulfonyl group etc.), arylsulfonyl group (eg phenylsulfonyl etc.), lower acyl group (eg formyl group, acetyl group etc.), aryl Examples thereof include a carbonyl group (for example, a benzoyl group).

In the above formula (11), a plurality of these functional groups may be substituted with R ^4, and when the functional group is substituted with R ⁴ , each functional group may be the same as each other. , Each may be different.

  In the above formula (11), n represents, for example, an integer of 1 to 6, preferably 1 or 2, and more preferably 2.

  These amines can be used alone or in combination of two or more.

As the amine, preferably, the equation (11) Oite, primary amine, the aromatic ring of ^{R 4} total carbon number 6 to 15 ^{wherein R 4} is an alicyclic-containing aliphatic hydrocarbon group having a total carbon number of 3 to 15 Primary amine which is a hydrocarbon group to be included, and more specifically, an alicyclic amine having 3 to 15 carbon atoms, an aromatic amine having 6 to 15 carbon atoms, and a fragrance having 6 to 15 carbon atoms. Aliphatic amines are mentioned.

  Moreover, what becomes a manufacturing raw material of the isocyanate (after-mentioned) used industrially as an amine is also preferable, As such a primary amine, 1, 5- diamino pentane, 1, 6- diamino hexane, isophorone diamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 4,4′-methylenebis (cyclohexylamine), 2,5-bis (aminomethyl) bicyclo [2,2 , 1] heptane, 2,6-bis (aminomethyl) bicyclo [2,2,1] heptane, 2,4-tolylenediamine (2,4-diaminotoluene), 2,6-tolylenediamine (2, 6-diaminotoluene), 4,4'-diphenylmethanediamine, 2,4'-diphenylmethanediamine, 2,2'-diphenylmethanedia , Naphthylene-1,5-diamine, 1,3-bis (aminomethyl) benzene, 1,4-bis (aminomethyl) benzene, 1,3-tetramethylxylylenediamine, 1,4-tetramethylxylylenediamine And particularly preferably 1,5-diaminopentane, isophoronediamine, 2,4-tolylenediamine (2,4-diaminotoluene), 2,6-tolylenediamine (2,6-diaminotoluene) ), 4,4′-diphenylmethanediamine, 2,4′-diphenylmethanediamine, 2,2′-diphenylmethanediamine, naphthylene-1,5-diamine, 1,3-bis (aminomethyl) benzene, 1,4-bis (Aminomethyl) benzene, 1,3-tetramethylxylylenediamine, 1,4-tetramethylxylylenediamine Min, and the like.

  In this reaction, in order to stabilize the N-unsubstituted carbamic acid ester, an alcohol can be further blended if necessary.

  As alcohol, the alcohol shown by said Formula (1) etc. are mentioned, for example.

  And in the manufacturing process of a urethane compound, above-mentioned primary amine, N-unsubstituted carbamic acid ester, and also alcohol are mix | blended as needed, Preferably it is made to react in a liquid phase.

  The mixing ratio of the primary amine and the N-unsubstituted carbamic acid ester is not particularly limited and can be appropriately selected within a relatively wide range.

  Usually, the compounding amount of N-unsubstituted carbamic acid ester should be equimolar or more with respect to the amino group of the primary amine. Therefore, N-unsubstituted carbamic acid ester should be used as a reaction solvent in this reaction. You can also.

  In addition, when N-unsubstituted carbamic acid ester is also used as a reaction solvent, an excessive amount of N-unsubstituted carbamic acid ester is used as necessary. However, if the excessive amount is large, in the separation step after the reaction, As the energy consumption increases, it becomes unsuitable for industrial production.

  Therefore, the blending amount of the N-unsubstituted carbamic acid ester is 0.5 to 20 times mol, preferably 1 to 1 amino group of the primary amine, from the viewpoint of improving the yield of the urethane compound. 1-10 times mol, More preferably, it is about 1-5 times mol, and the compounding quantity of alcohol is 0.5-100 times mol with respect to one amino group of primary amine, Preferably, It is about 20 times mole, more preferably about 1 to 10 times mole.

  Moreover, when alcohol is blended, the blending ratio is not particularly limited, and is appropriately set according to the purpose and application.

  In this step, a catalyst can be further blended.

  Examples of the catalyst include a catalyst represented by the above formula (2).

  Moreover, the compounding quantity of a catalyst is 0.000001-0.1 mol with respect to 1 mol of primary amines, Preferably, it is 0.00005-0.05 mol. Even if the amount of the catalyst is larger than this, no further significant reaction promoting effect is observed, but the cost may increase due to an increase in the amount of the catalyst. On the other hand, if the blending amount is less than this, the reaction promoting effect may not be obtained.

  In addition, the addition method of a catalyst does not affect reaction activity in any addition method of lump addition, continuous addition, and a plurality of intermittent additions, and is not particularly limited.

  In this reaction, a reaction solvent is not always necessary. For example, when the reaction raw material is solid or a reaction product is precipitated, the operability can be improved by blending the reaction solvent.

  Such a reaction solvent is inactive or reactive with a primary amine as a reaction raw material, an N-unsubstituted carbamic acid ester, an alcohol blended as necessary, and a urethane compound as a reaction product. It is not particularly limited as long as it has poor properties. For example, the above-mentioned aliphatic hydrocarbons, the above-mentioned aromatic hydrocarbons, the above-mentioned ethers, the above-mentioned nitriles, the above-mentioned aliphatic halogenation Examples include hydrocarbons, the above nitro compounds, N-methylpyrrolidinone, N, N-dimethylimidazolidinone, dimethyl sulfoxide and the like.

  Of these reaction solvents, aliphatic hydrocarbons and aromatic hydrocarbons are preferably used in view of economy and operability. Moreover, such a reaction solvent can be used individually or in combination of 2 or more types.

  Further, the amount of the reaction solvent is not particularly limited as long as the urethane compound of the target product is dissolved, but industrially, it is necessary to recover the reaction solvent from the reaction solution. When the amount of energy consumed for the recovery is reduced as much as possible and the blending amount is large, the reaction substrate concentration decreases and the reaction rate becomes slow. More specifically, it is used in the range of usually 0.1 to 500 parts by mass, preferably 1 to 100 parts by mass with respect to 1 part by mass of the primary amine.

  In this reaction, the reaction temperature is appropriately selected, for example, in the range of 100 to 350 ° C, preferably 150 to 300 ° C. When the reaction temperature is lower than this, the reaction rate may decrease. On the other hand, when the reaction temperature is higher than this, side reactions may increase and the yield of the urethane compound as the target product may decrease.

  The reaction pressure is usually atmospheric pressure, but may be increased when the boiling point of the component in the reaction solution is lower than the reaction temperature, and further reduced as necessary.

  Moreover, reaction time is 0.1 to 20 hours, for example, Preferably, it is 0.5 to 10 hours. When reaction time is shorter than this, the yield of the urethane compound which is a target product may fall. On the other hand, if it is longer than this, it is unsuitable for industrial production.

  For this reaction, for example, a primary amine, an N-unsubstituted carbamic acid ester, and, if necessary, an alcohol, a catalyst, and a reaction solvent may be charged in a reaction vessel and stirred or mixed under the above-described conditions. Then, according to the reaction route represented by the following general formula (12), for example, the urethane compound which is the target product represented by the following general formula (13) is produced in a short time, at low cost and in a high yield under mild conditions. Generate.

(In the formula, ^{R 1,} the same meanings as ^{R 1} above formula (1), ^{R 4} is the same meaning as ^{R 4} in the formula (11), n is the same as n in the formula (11) Shows significance.)
(R < ¹ > OCONH) n-R < ⁴ > (13)
(In the formula, ^{R 1,} the same meanings as ^{R 1} above formula (1), ^{R 4} is the same meaning as ^{R 4} in the formula (11), n is the same as n in the formula (11) Shows significance.)
In this reaction, ammonia is by-produced, and in some cases, a single or multiple polycondensate of a urethane compound (for example, a benzoylene urea derivative or the like) is by-produced.

  In this reaction, either a batch type or a continuous type can be adopted as the reaction type.

  In addition, this reaction is preferably carried out while allowing ammonia produced as a by-product to flow out of the system.

  Thereby, the production | generation of the urethane compound which is a target product can be accelerated | stimulated, and the yield can be improved further.

  When the obtained urethane compound is isolated, for example, excess (unreacted) urea and N-unsubstituted carbamic acid ester, alcohol, catalyst, urethane compound, reaction solvent, by-product ammonia, urethane compound A urethane compound may be separated from a reaction solution containing a polycondensate of the above by a known separation and purification method.

  And in this method, the urethane compound obtained in the manufacturing process of the urethane compound described above is thermally decomposed to produce isocyanate.

That is, in such an isocyanate production method, the urethane compound obtained by the above-described urethane compound production method is thermally decomposed, and the isocyanate represented by the following general formula (14) corresponding to the above-mentioned primary amine, and
^{R 4 - (NCO) n (} 14)
(Wherein R ⁴ has the same meaning as R ^{4 in} formula (11), and n has the same meaning as n in formula (11).)
An alcohol represented by the following general formula (15), which is a by-product, is generated.

R ¹ —OH (15)
(Wherein, ^{R 1} represents the same meaning as ^{R 1} in the 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.

  In the gas phase process, the isocyanate and alcohol produced by pyrolysis can be separated from the gaseous product mixture by fractional condensation. In the liquid phase method, isocyanate and alcohol produced by thermal decomposition can be separated by using, for example, distillation or a solvent and / or an inert gas as a support material.

  The thermal decomposition is preferably a liquid phase method from the viewpoint of workability.

  Since the thermal decomposition reaction of the urethane compound in the liquid phase method is a reversible reaction, the reverse reaction of the thermal decomposition reaction (that is, the isocyanate represented by the general formula (14) and the general formula (15) are preferable. In order to suppress the urethanation reaction with the alcohol), the urethane compound is thermally decomposed, and the isocyanate represented by the general formula (14) and / or the alcohol represented by the general formula (15) is removed from the reaction mixture. For example, it is extracted as gas and separated.

  As the reaction conditions for the thermal decomposition reaction, preferably, the urethane compound can be thermally decomposed satisfactorily, and the isocyanate (the general formula (14)) and the alcohol (the general formula (15)) generated in the thermal decomposition are evaporated. As a result, the carbamate and the isocyanate are not brought into an equilibrium state, and further, there are conditions under which side reactions such as polymerization of the isocyanate are suppressed.

  More specifically, as such reaction conditions, 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. In addition, the pressure during the pyrolysis reaction is preferably a pressure at which the generated alcohol can be vaporized with respect to the above pyrolysis reaction temperature. It is preferably 90 kPa.

  The urethane compound used for the thermal decomposition may be purified, but the above reaction (that is, the reaction between a primary amine, an N-unsubstituted carbamic acid ester, and an alcohol blended as necessary). After the completion of the step, excess (unreacted) N-unsubstituted carbamic acid ester, alcohol, catalyst, reaction solvent, and by-product ammonia are recovered and subsequently thermally decomposed using a crude raw material of urethane compound separated. Also good.

  Further, if necessary, a catalyst and an inert solvent may be added. Although these catalysts and inert solvents differ depending on their kind, they may be added to the reaction, before or after distillation separation after the reaction, or before or after the separation of the urethane compound.

  As a catalyst used for thermal decomposition, one kind selected from Sn, Sb, Fe, Co, Ni, Cu, Zn, Cr, Ti, Pb, Mo, Mn, etc., used for the urethanization reaction between isocyanate and hydroxyl group The metal simple substance or its oxides, halides, carboxylates, phosphates, organometallic compounds and the like 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.

  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.

  Examples of the metal catalyst of Fe, Co, Sb, and Mn include acetates, benzoates, naphthenates, and acetylacetonates.

  In addition, the compounding quantity of a catalyst is 0.0001-5 mass% with respect to the reaction liquid as a metal simple substance or its compound, Preferably, it is the range of 0.001-1 mass%.

  The inert solvent is not particularly limited as long as it dissolves at least the urethane compound, is inert to the urethane compound and isocyanate, and is stable at the temperature in thermal decomposition, but the thermal decomposition reaction is efficiently performed. In order to carry out, it is preferable that it is a boiling point higher than the isocyanate to produce | generate. 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 inert solvent is also available as a commercial product. For example, barrel process oil B-01 (aromatic hydrocarbons, boiling point: 176 ° C.), barrel process oil B-03 (aromatic hydrocarbons, Boiling point: 280 ° C.), barrel process oil B-04AB (aromatic hydrocarbons, boiling point: 294 ° C.), barrel process oil B-05 (aromatic hydrocarbons, boiling point: 302 ° C.), barrel process oil B-27 (Aromatic hydrocarbons, boiling point: 380 ° C.), barrel process oil B-28AN (aromatic hydrocarbons, boiling point: 430 ° C.), barrel process oil B-30 (aromatic hydrocarbons, boiling point: 380 ° C.) , Barrel therm 200 (aromatic hydrocarbons, boiling point: 382 ° C.), barrel therm 300 (aromatic hydrocarbons, boiling point: 344 ° C.), barrel therm 400 (aromatic hydrocarbons) , Boiling point: 390 ° C.), barrel therm 1H (aromatic hydrocarbons, boiling point: 215 ° C.), barrel therm 2H (aromatic hydrocarbons, boiling point: 294 ° C.), barrel therm 350 (aromatic hydrocarbons, boiling point) : 302 ° C.), Barrel Therm 470 (aromatic hydrocarbons, boiling point: 310 ° C.), Barrel Therm PA (aromatic hydrocarbons, boiling point: 176 ° C.), Barrel Therm 330 (aromatic hydrocarbons, boiling point: 257) ° C), Barrel Therm 430 (aromatic hydrocarbons, boiling point: 291 ° C), (Made by Matsumura Oil Co., Ltd.), NeoSK-OIL1400 (aromatic hydrocarbons, boiling point: 391 ° C), NeoSK-OIL1300 (aromatic) Hydrocarbons, boiling point: 291 ° C), NeoSK-OIL330 (aromatic hydrocarbons, boiling point: 331 ° C), NeoSK-OIL170 (aromatic Hydrocarbons, boiling point: 176 ° C), NeoSK-OIL240 (aromatic hydrocarbons, boiling point: 244 ° C), KSK-OIL260 (aromatic hydrocarbons, boiling point: 266 ° C), KSK-OIL280 (aromatic hydrocarbons) , Boiling point: 303 ° C.) (above, manufactured by Soken Technics).

  The compounding quantity of an inert solvent is the range of 0.001-100 mass parts with respect to 1 mass part of urethane compounds, Preferably, it is 0.01-80 mass parts, More preferably, it is the range of 0.1-50 mass parts. It is.

  In addition, this thermal decomposition reaction is carried out either as a batch reaction in which a urethane compound, a catalyst and an inert solvent are charged in a batch, or as a continuous reaction in which a urethane compound is charged in an inert solvent containing a catalyst under reduced pressure. be able to.

  In thermal decomposition, isocyanate and alcohol are produced, and side reactions may produce allophanate, amines, urea, carbonate, carbamate, carbon dioxide, etc. The isocyanate is purified by a known method.

  In such a thermal decomposition reaction, the urethane compound obtained above is thermally decomposed, so that an isocyanate corresponding to the primary amine can be obtained as described above. The polyisocyanate used in the above can be easily and efficiently produced.

  And in this manufacturing method of isocyanate, said N- unsubstituted carbamic acid ester in which content of the biuret derivative which is a by-product is reduced is used. Therefore, in this isocyanate manufacturing method, it can suppress that the substance which causes a fouling is produced | generated by reaction of such a biuret derivative.

  As a result, according to such a method for producing an isocyanate, it is possible to produce an isocyanate with an excellent yield while suppressing clogging of the apparatus.

  In addition, although the manufacturing method of N-unsubstituted carbamic acid ester and the manufacturing method of isocyanate have been described above, in the manufacturing method of the present invention, a pretreatment process such as a dehydration process, an intermediate process, or a purification process and a recovery process. A known process such as a post-treatment process may be included.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not limited to an Example and a comparative example at all. In the following Examples and Comparative Examples, liquid chromatographs (UV detector (254 nm) and RI detector) were used for quantification of reaction products.

Example 1
<Synthesis of butyl carbamate>
In a 1 L internal volume SUS autoclave equipped with a pressure control valve, a reflux condenser, a gas-liquid separator and a stirrer, urea (111 g: 1.84 mol) and 1-butanol (341 g: 4.61 mol), p as a catalyst -Zinc toluene sulfonate (0.94 g: 2.31 mmol) was charged, and the internal pressure was adjusted with a pressure control valve so as to keep the reaction temperature at 180 ° C. while stirring at 500 rpm at a flow rate of 300 mL per minute for 4 hours. Reaction was performed to obtain 408 g of a reaction solution.

  When a part of the reaction solution was collected and quantified, it was confirmed that butyl carbamate was produced in a yield of 90.4 mol% with respect to the charged urea. It was also confirmed that dibutyl carbonate was produced in a yield of 9.35 mol% and iminobisformate dibutyl in a yield of 0.12 mol%. On the other hand, since butyl allophanate was below the detection limit (0.1 mol%), the total of biuret derivatives was 0.12 mol% (0.14 mol relative to 100 mol of butyl carbamate).

  Next, 1-butanol was distilled off by simple distillation from 402 g of the obtained reaction solution, and further supplied to a distiller having a packing equivalent to 20 theoretical plates, and dibutyl carbonate was distilled off under a pressure of 20 mmHg. As a result, 145 g of butyl carbamate having a purity of 99.0% by weight was obtained.

Further, the same operation was repeated 3 batches to obtain 580 g of butyl carbamate having a purity of 99.0% by weight.
<Synthesis of 2,4-bis (butyloxycarbonylamino) toluene>
A 1-liter SUS autoclave equipped with a pressure control valve, a reflux condenser, a gas-liquid separator, and a stirrer was mixed with butyl carbamate (220 g: 1.88 mol) obtained in the above step, 2,4-diaminotoluene. (80.5 g: 0.659 mol) and a mixture of 1-butanol (139 g: 1.88 mol), and further, zinc paratoluenesulfonate (0.638 g: 1.56 mmol) as a catalyst was added. While stirring at 500 rpm for 1 minute, the reaction was carried out for 10 hours while adjusting the internal pressure with a pressure control valve so as to keep the reaction temperature at 200 ° C., to obtain 410 g as a carbamate reaction solution.

When a part of the carbamate reaction liquid was collected and quantified, 2,4-bis (butyloxycarbonylamino) toluene was produced in a yield of 96.7 mol% with respect to the charged 2,4-diaminotoluene. It was confirmed. It was also confirmed that mono (butyloxycarbonylamino) aminotoluene was produced in a yield of 0.5 mol% and a benzoylene urea derivative in a yield of 0.4 mol%.
<Synthesis of 2,4-tolylene diisocyanate>
[Low-boiling vacuum distillation]
A glass flask having an internal volume of 500 mL equipped with a stirrer and a condenser is charged with 403 g of the carbamation reaction solution obtained by the synthesis of 2,4-bis (butyloxycarbonylamino) toluene and stirred at 200 rpm. The inside of the container was depressurized to 2 kPa with a vacuum pump. With the circulating water of 25 ° C. flowing through the cooling pipe, the temperature in the container was raised to 100 ° C. to distill off the low boiling point, and the carbamation reaction solution was concentrated. Subsequently, the circulating water temperature was set to 70 ° C., the temperature in the container was raised to 180 ° C., the low boiling point was distilled off, the carbamate reaction liquid was concentrated, and finally 170 g of a brown concentrated liquid was obtained. .

  As a result of analyzing the low boiling point by liquid chromatography and gas chromatography, it was confirmed that the main components were butanol and butyl carbamate, and no compound derived from 2,4-diaminotoluene was present.

  From this result, it is assumed that a derivative (including 2,4-bis (butyloxycarbonylamino) toluene) of 0.648 mol (= 0.659 mol × (403 g / 410 g)) of 2,4-diaminotoluene is present in 170 g of the concentrated liquid. It was.

  Subsequently, the above operation was repeated two more batches to obtain 510 g of a brown concentrated liquid composed of a derivative of 1.94 mol of 2,4-diaminotoluene.

[Thermal decomposition reaction of concentrate]
It is equipped with a thermometer, a stirring device, a rectifying column with a reflux tube at the top, and a device equipped with a raw material supply container and a liquid feed pump, and is made of glass with an internal capacity of 1 liter with an extraction cock at the bottom. In a separable flask, 50 g of the concentrated liquid obtained above (corresponding to 0.190 mol (= 1.94 mol × 50 g / 510 g) as 2,4-diaminotoluene) and barrel process oil B-05 (manufactured by Matsumura Oil Co., Ltd.) as a solvent ) 117 g was charged and the inside of the container was depressurized to 10 kPa with a vacuum pump while stirring at 300 rpm. When heating was started with circulating water at 90 ° C. flowing in the reflux tube, the tower top temperature rose around 220 ° C., and tolylene diisocyanate began to condense in the reflux tube, so that the reflux ratio was 5 (= reflux 10 seconds). / Distillation 2 seconds) and tolylene diisocyanate was distilled off. 2 hours after the start of distillation, a raw material supply container charged with 340 g of concentrated liquid (corresponding to 1.29 mol (= 1.94 mol × 340 g / 510 g) as 2,4-diaminotoluene) and 793 g of barrel process oil B-05 Then, the mixture was supplied to the reaction vessel at a rate of 72 g / h using a liquid feed pump, and further reacted for 14 hours.

  During the reaction, in order to keep the liquid level of the reaction vessel constant, the reaction solution was extracted from the extraction cock at the bottom every 2 hours from the start of the raw material supply.

  Since the distillate amount became stable 7 hours after the start of the distillation, the composition of the distillate and the reaction liquid extracted from the bottom was measured from 7 hours to 14 hours after the start of the distillation using a liquid chromatograph. The mol yield of 2,4-tolylene diisocyanate relative to 2,4-diaminotoluene was calculated.

Tolylene diisocyanate yield (mol% / diaminotoluene) =
Tolylene diisocyanate (mol) distilled from 7 hours to 14 hours after the start of distillation / (Diaminotoluene (mol) supplied from 7 hours to 14 hours after the start of distillation)-after 7 hours from the start of distillation The total of 2,4-bis (butyloxycarbonylamino) toluene, mono (butyloxycarbonylamino) aminotoluene, and tolylene diisocyanate (mol) extracted from the reaction solution after 14 hours)
The yield of 2,4-tolylene diisocyanate based on 2,4-diaminotoluene determined by the above calculation was 90.9 mol%.

  Since the yield of 2,4-bis (butyloxycarbonylamino) toluene relative to 2,4-diaminotoluene in the synthesis of 2,4-bis (butyloxycarbonylamino) toluene was 96.7 mol%, This indicates that 94.0% of 2,4-bis (butyloxycarbonylamino) toluene becomes 2,4-tolylene diisocyanate in the thermal decomposition reaction.

Example 2
Into a 500 ml glass flask equipped with a reflux condenser, a screw feeder, and a stirrer, 1-octanol (338 g: 2.60 mol) and zinc p-toluenesulfonate (0.14 g: 0.35 mmol) as a catalyst The internal temperature was raised to 180 ° C. while stirring at 300 rpm with a nitrogen gas flow of 200 ml per minute. Thereafter, urea (28.9 g: 0.48 mol) was charged over 1 hour using a screw feeder, and after completion of the charging, the reaction was further continued for 3 hours to obtain 355 g of a reaction solution.

  When a part of the reaction solution was collected and quantified, it was confirmed that octyl carbamate was produced in a yield of 95.2 mol% with respect to the charged urea. In addition, it was confirmed that dioctyl carbonate was produced in a yield of 4.73 mol%, and dioctyl iminobisformate was produced in a yield of 0.02 mol%. On the other hand, since butyl allophanate was below the detection limit, the total of biuret derivatives was 0.02 mol% (0.02 mol with respect to 100 mol of octyl carbamate).

Example 3
A 300-ml glass flask equipped with a reflux condenser and a stirrer was charged with 1-octanol (156 g: 1.20 mol) and zinc p-toluenesulfonate (0.14 g: 0.34 mmol) as a catalyst. The internal temperature was raised to 170 ° C. while stirring the gas at a flow rate of 200 ml per minute at 300 rpm. Thereafter, urea (12.0 g: 0.20 mol) was charged and reacted for 4 hours to obtain 163 g of a reaction solution.

  When a part of the reaction solution was collected and quantified, it was confirmed that octyl carbamate was produced in a yield of 92.9 mol% with respect to the charged urea. Moreover, the dioctyl carbonate was 7.21 mol%. On the other hand, octyl allophanate and dioctyl iminobisformate (detection limit 0.1 mol%) were not detected.

Example 4
The reaction was conducted in the same manner as in Example 3 except that zinc trifluoromethanesulfonate (0.058 g: 0.16 mmol) was used in place of zinc p-toluenesulfonate as a catalyst to obtain 161 g of a reaction solution. It was.

  When a part of the reaction solution was collected and quantified, it was confirmed that octyl carbamate was produced in a yield of 90.6 mol% with respect to the charged urea. It was also confirmed that dioctyl carbonate was produced in a yield of 6.51 mol%, octyl allophanate was produced in a yield of 0.46 mol%, and dioctyl iminobisformate was produced in a yield of 0.26 mol%. For this reason, the total of biuret derivatives was 0.72 mol% (0.79 mol with respect to 100 mol of octyl carbamate).

Comparative Example 1
1-octanol (157 g: 1.21 mol) was charged into a 300 ml glass flask equipped with a reflux condenser and a stirrer, and the internal temperature was 170 ° C. while stirring at 300 rpm with a nitrogen gas flow of 200 ml per minute. The temperature was raised to. Thereafter, urea (12.1 g: 0.20 mol) was charged and reacted for 4 hours to obtain 163 g of a reaction solution.

  When a part of the reaction solution was collected and quantified, it was confirmed that octyl carbamate was produced in a yield of 82.5 mol% with respect to the charged urea. It was also confirmed that dioctyl carbonate was produced in a yield of detection limit (0.1 mol%) or less, octyl allophanate in 1.33 mol%, and dioctyl iminobisformate in 7.41 mol%. For this reason, the sum total of biuret derivatives was 8.74 mol% (10.6 mol with respect to 100 mol of octyl carbamate).

Comparative Example 2
1-octanol (156 g: 1.20 mol) and tin tetrachloride (0.056 g: 0.16 mmol) as a catalyst were charged in a 300 ml glass flask equipped with a reflux condenser and a stirrer, and nitrogen gas was added every time. The internal temperature was raised to 170 ° C. while stirring at 200 rpm for 300 minutes. Thereafter, urea (12.0 g: 0.20 mol) was charged and reacted for 4 hours to obtain 164 g of a reaction solution.

  When a part of the reaction solution was collected and quantified, it was confirmed that octyl carbamate was produced in a yield of 89.5 mol% with respect to the charged urea. Further, it was confirmed that dioctyl carbonate was produced in a yield of 0.56 mol%, octyl allophanate was produced in a yield of 0.86 mol%, and dioctyl iminobisformate was produced in a yield of 2.18 mol%. Therefore, the total of biuret derivatives was 3.04 mol% (3.40 mol with respect to 100 mol of octyl carbamate).

  The results of each Example and each Comparative Example are shown in Table 1.

Claims (5)

Urea and alcohol,
A method for producing an N-unsubstituted carbamic acid ester which is reacted in the presence of a compound containing a non-coordinating anion and a metal atom,
The method for producing an N-unsubstituted carbamic acid ester, wherein the compound is zinc p-toluenesulfonate or zinc trifluoromethanesulfonate .   2. The method for producing an N-unsubstituted carbamic acid ester according to claim 1, wherein in the reaction, the urea is added in portions or continuously. 3. The method for producing an N-unsubstituted carbamic acid ester according to claim 1 or 2, wherein the alcohol is represented by the following general formula (1).
R ¹ —OH (1)
(In the formula, R ¹ represents an aliphatic hydrocarbon group having ^{1 to} 16 carbon atoms in total or an aromatic hydrocarbon group having 6 to 16 carbon atoms in total.) The biuret derivative by-produced by the reaction is 3 mol or less with respect to 100 mol of the N-unsubstituted carbamic acid ester, according to any one of claims 1 to 3. A method for producing a substituted carbamic acid ester. The process of manufacturing N-unsubstituted carbamic acid ester by the manufacturing method of N-unsubstituted carbamic acid ester as described in any one of Claims 1-4 ,
A step of producing a urethane compound by reacting at least the obtained N-unsubstituted carbamic acid ester with a primary amine;
A process for producing an isocyanate by thermally decomposing the obtained urethane compound.