JPH0242825B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing diphenylmethane dicarbamates, and more specifically, the present invention relates to a method for producing diphenylmethane dicarbamates, and more specifically, the present invention relates to a method for producing diphenylmethane dicarbamates, and more specifically, at least one methylene amino bond (

The present invention relates to a method for producing diphenylmethane dicarbamates by reacting polycarbamates having the formula [formula]) with N-phenyl carbamates. Diphenylmethane dicarbamates are useful materials as precursors for the production of diphenylmethane diisocyanate (MDI) without the use of phosgene. In particular, its 4,4'-isomer 4,
Demand for 4'-diphenylmethane diisocyanate (so-called pure MDI) has increased rapidly in recent years as a raw material for polyurethane elastomers, spandex, coating materials for artificial leather, etc. Therefore, it is desired to develop an industrially advantageous method for producing diphenylmethane dicarbamates that can be used as raw materials. Conventionally, the method for producing diphenylmethane dicarbamates includes, for example, mixing N-phenyl carbamate and a condensing agent such as formaldehyde, paraformaldehyde, methylal, trioxane, etc. with a mineral acid, an organic sulfonic acid, a solid acid, etc. A method of reacting in the presence of an acid is known. In this case, if the reaction is carried out under relatively harsh conditions such as using a large amount of strong acid, increasing the reaction temperature, or prolonging the reaction time, other than the desired diphenylmethanedicarbamate, for example, the general formula () It is also known that a polymethylene polyphenyl carbamate of a polynuclear body represented by the formula (wherein R ² is an alkyl group, an aromatic group, or an alicyclic group, and z represents an integer of 1 or more) is produced in considerable amounts. ing. On the other hand, under relatively mild conditions, the methylene group contains a methylene amino bond (-CH ₂ -N) bonded to the nitrogen atom of the carbamate group, and a dinuclear or trinuclear body having two or more benzene rings is formed. It is also known that a large number of polynuclear bodies larger than the body are produced as by-products. Compounds with this methylene amino bond do not give isocyanate even when thermally decomposed, so
It is desired to reduce its abundance as much as possible. One method is to react these compounds under substantially anhydrous conditions in the presence of a brotic or Lewis acid with a strength of at least 75% sulfuric acid at a temperature of 50 to 170°C. Therefore, a method of rearrangement reaction for bonding a methylene group bonded to a nitrogen atom with a benzene ring has been proposed (Japanese Patent Application Laid-open No. 59264/1983). However, in this method, a polymethylene polyphenyl carbamate of a polynuclear body is still produced from a polynuclear body of trinuclear bodies or more containing a methylene amino bond. Therefore, the present inventors have conducted extensive studies on the reactivity of trinuclear or higher polynuclear bodies containing methylene amino bonds, and have surprisingly found that diphenylmethane dicarbamates can be produced from these polynuclear bodies. They discovered this and completed the present invention. That is, the present invention provides a method for reducing pKa in an aqueous solution at 25°C.
In the presence of one or more acids selected from organic carboxylic acids having a value of 4 or less or zeolites as inorganic cation exchangers, A, B, C, D, E
Compounds having and mixtures thereof A[-B]- _l [-C]- _n [-D]- _o E () A=H, or

[Formula] Also teeth

【formula】

【formula】

【formula】

[expression] or

[Formula] (In the formula, l, m, and n each represent an integer greater than or equal to 0, and in the case of n=0, if A is H, l+m≧
2 and if A is another group, l+m≧1
shall be satisfied. In addition, R ¹ represents hydrogen or a substituent such as an alkyl group, a halogen atom, a nitro group, a cyano group, an alkoxy group, or an alicyclic group, and x represents an integer of 0 to 4, and when x is 2 or more,
R ¹ may be the same or different substituents. R ² represents an alkyl group, aromatic group or alicyclic group, and R ² may have one or more hydrogens substituted with the above-mentioned substituents. ) and the general expression () (In the formula, R ³ represents hydrogen or a substituent such as an alkyl group, a halogen atom, a nitro group, a cyano group, an alkoxy group, an alicyclic group, etc., y represents an integer of 0 to 4, and when y is 2 or more, , R ³ may be the same or different substituents. ^{R 4}
represents an alkyl group, aromatic group or alicyclic group, and R ⁴ may be one in which one or more hydrogen atoms are substituted with the above-mentioned substituent. Also,
R ³ may be the same as R ¹ , y may be the same as x, and R ⁴ may be the same as R ² . ) General formula () characterized by reacting with N-phenyl carbamate represented by The present invention provides a method for producing diphenylmethane dicarbamates represented by: The method of the present invention can be applied to three compounds containing a methylene amino bond.
A more easily understood example using the reaction in the case of a nuclear body can be expressed as follows. (For simplicity, let R ¹ = R ³ = H, R ² = R ^4. ) For example, or for example, or for example, As described above, the method of the present invention can produce diphenylmethane dicarbamates with good selectivity from trinuclear or more polynuclear bodies having methylene amino bonds, which could only be converted into polymethylene polyphenyl carbamates using conventional techniques. It is characterized by Furthermore, in the prior art (Japanese Unexamined Patent Publication No. 54-59264), in order to carry out the rearrangement reaction, it is necessary to use a protic acid having a strong acid strength of 75% sulfuric acid or more under substantially anhydrous conditions. , it is necessary to use a strongly acidic Lewis acid such as antimony pentafluoride or boron trifluoride, but unlike that, in the method of the present invention, a polynuclear body of trinuclear bodies or more having a methylene amino bond and N -Because the intermolecular reaction with phenyl carbamate is carried out, the reaction can proceed quantitatively even in the presence of organic carboxylic acids such as trifluoroacetic acid, which are much weaker acids than 75% sulfuric acid. It is characterized by being able to produce diphenylmethane dicarbamates with good selectivity. The trinuclear or higher polynuclear body having a methylene amino bond used in the present invention has the general formula () A[-B]- _l [-C]- _n [-D]- _o E () (in the formula, A, B, C, D, E and l, m, n
is as described above), and these compounds may be produced by any method, but the general formula () (wherein R ¹ , R ² and x are as described above), formaldehyde, paraformaldehyde, trioxane,
One of the preferred methods is to use a product produced when reacting and condensing with a methylenating agent such as methylal or acyral. By doing so, the yield of diphenylmethane dicarbamate can be improved. In this case, the compounds represented by the general formula () may be separated and then reacted with the N-phenyl carbamate represented by the general formula (), or diphenyl carbamate, which is a condensation reaction product having no methylene amino bond, may be separated. Enylmethane dicarbamates, polymethylene polyphenyl carbamates, or 2 containing a methylene amino bond
General formulas () and () that are nuclear bodies The method of the present invention may be carried out in a system in which a compound represented by the formula (wherein R ¹ , R ² and x are as described above) coexists. Compounds of formulas () and () are converted to diphenylmethane dicarbamate by a similar reaction under the conditions of the present invention. Another raw material used in the present invention, N-
Phenyl carbamate has the general formula () (wherein R ³ , R ⁴ and y are as described above), for example, in the above general formula (), R ⁴ is a methyl group, an ethyl group, 2,
2,2-trichloroethyl group, 2,2,2-trifluoroethyl group, propyl group (n-, iso-),
Alkyl groups such as butyl group (n- and various isomers), bentyl group (n- and various isomers), hexyl group (n- and various isomers), or alicyclic groups such as cyclopentyl group and cyclohexyl group,
or an aromatic group such as a phenyl group or a naphthyl group, and R ³ is hydrogen, the above-mentioned alkyl group, an alicyclic group, a halogen atom such as fluorine, chlorine, bromine, or iodine, a nitro group, a cyano group, or the above-mentioned alkyl group or alicyclic group; Examples include N-phenyl carbamates such as an alkoxy group having an alkyl group as a constituent component. Preferred are methyl N-phenylcarbamate, ethyl N-phenylcarbamate, n-propyl N-phenylcarbamate, iso-propyl N-phenylcarbamate, n-butyl N-phenylcarbamate, N-phenylcarbamic acid
sec-butyl, iso-butyl N-phenylcarbamate, tert-butyl N-phenylcarbamate,
Pentyl N-phenylcarbamate, hexyl N-phenylcarbamate, cyclohexyl N-phenylcarbamate, 2,2,2-trichloroethyl N-phenylcarbamate, 2,2,2 N-phenylcarbamate -trifluoroethyl, N
-o or m-tolylmethylcarbamate, N-
o- or m-tolylcarbamate ethyl, N-o
or 2,2,2-trifluoroethyl m-tolylcarbamate, N-o or propyl m-tolylcarbamate (each isomer), N-o or m-
Butyl tolylcarbamate (each isomer), N-o
or methyl m-chlorophenylcarbamate,
No- or m-ethyl chlorphenylcarbamate, No- or m-propyl chlorphenylcarbamate (each isomer), No- or m-butyl chlorphenylcarbamate (each isomer),
2,2,2-trifluoroethyl N-o or m-chlorophenylcarbamate, N-2,6-
Methyl dimethylphenylcarbamate, N-2,
Ethyl 6-dimethylphenylcarbamate, N-
Propyl 2,6-dimethylphenylcarbamate (each isomer), Butyl N-2,6-dimethylphenylcarbamate (each isomer), 2,2,2 N-2,6-dimethylphenylcarbamate -trifluoroethyl, methyl N-2,6-dibromphenylcarbamate, ethyl N-2,6-dibromphenylcarbamate, propyl N-2,6-dibromphenylcarbamate (each isomer ), N-2,
N- such as butyl 6-dibromphenylcarbamate (each isomer), 2,2,2-trifluoroethyl N-2,6-dibromphenylcarbamate, etc.
Phenyl carbamates are used. In these N-phenyl carbamates (general formula ()), R ³ is R ¹ , y is x, and R ⁴ is R ²
Those which are the same as are particularly preferably used. pKa in aqueous solution at 25°C used in the present invention
Examples of organic carboxylic acids having a value of 4 or less include:
Formic acid, oxalic acid, fluoroacetic acid (mono-di-tri),
Chloroacetic acid (mono.di.tri), bromoacetic acid (mono.di.tri), cyanoacetic acid, α-fluoropropionic acid, α,α-dichlorobutyric acid, etc., and among these, preferred are It is an organic carboxylic acid containing fluorine, chlorine or cyano group.
Particularly preferred are dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, and cyanoacetic acid. Moreover, various zeolites are used as the inorganic cation exchanger. Although the method of the present invention can be carried out without dissolution, it can also be carried out in a suitable solvent if necessary. Such solvents include, for example, pentane, hexane, heptane, octane, nonane, decane,
Aliphatic or alicyclic hydrocarbons such as n-hexadecane, cyclopentane, and cyclohexane, halogenated hydrocarbons such as chloroform, methylene chloride, carbon tetrachloride, dichloroethane, trichloroethane, and tetrachloroethane, methanol, ethanol, and propanol. , alcohols such as butanol, aromatic compounds such as benzene, toluene, xylene, ethylbenzene, monochlorobenzene, dichlorobenzene, bromnaphthalene, nitrobenzene, o- or m- or p-nitrotoluene, diethyl ether, 1,4- Ethers such as dioxane and tetrahydrofuran, esters such as methyl acetate, ethyl acetate, and methyl formate, sulfolane, 3-methylsulfolane, 2,4
-Sulfolanes such as dimethylsulfolane, water, and the like. Furthermore, carboxylic acids such as acetic acid, propionic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, methanesulfonic acid, trichloromethanesulfonic acid,
Acids such as sulfonic acids such as trifluoromethanesulfonic acid can also be used as solvents. In carrying out the method of the present invention, the quantitative ratio of the compound represented by the general formula () or a mixture thereof as a raw material to the N-phenyl carbamate represented by the general formula () may be arbitrary, but methylene in the raw material It is preferable to use N-phenyl carbamate in an amount equal to or more than the amino bond ( _-CH2 -N). Of course, even if the amount is smaller than that, the desired diphenylmethane dicarbamate can be obtained, but the yield will be lower. On the contrary, using more than the same amount of N-phenyl carbamate has the effect of accelerating the reaction rate and is a preferred method. The amount of acid used varies depending on the type of acid used, raw material composition, and other reaction conditions, but is usually 10 ^-5 to 10 ³ mol per 1 mol of the raw material represented by the general formula (). A range of is preferred. The reaction of the present invention is carried out at 250°C or lower, preferably at 10-200°C.
It is carried out at a temperature of °C. The reaction time varies depending on other reaction conditions such as reaction temperature, type and amount of acid, presence or absence and amount of solvent, raw material composition, reaction method, etc., but is usually from several minutes to several hours. The method of the present invention is usually carried out under normal pressure or increased pressure, but can also be carried out under reduced pressure if necessary. Further, the reaction method of the present invention is not particularly limited, and may be carried out batchwise or continuously. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. Note that the reaction product was analyzed using high performance liquid chromatography. Example 1 50 g of ethyl N-phenylcarbamate and 4.54 g of trioxane were reacted at 50°C for 3 minutes in the presence of 2.1 g of 98% sulfuric acid, and the product was separated by column chromatography to give the general formula () In, l
= m = x = 0, A = H, n = 1, R ² = C ₂ H ₅ . A compound containing an isomer represented by (hereinafter referred to as trinuclear N,
In the general formula (), m=n=x=0, A≠H, l=1,

[Formula] The following formula where R ² = C ₂ H ₅ A compound containing an isomer represented by (hereinafter referred to as trinuclear N-
A mixture consisting of 76% by weight was obtained. 2.03 g of this mixture and 3.3 g of ethyl N-phenylcarbamate were dissolved in 20 g of trifluoroacetic acid.
After reacting at 70°C for 20 minutes with stirring, trifluoroacetic acid was separated by simple distillation and the product was analyzed. As a result, the 3-nuclear N,N'-form and the 3-nuclear N-form were all consumed. 2.6 g of diethyl diphenylmethanedicarbamate was produced. As a by-product, in the general formula (), z = 1, R ² = C ₂ H ₅
0.1 g of triethyl dimethylenetriphenylcarbamate, a trinuclear substance represented by , was produced.
In addition, 2.7g of ethyl N-phenylcarbamate
Recovered. This indicates that 95% of the trinuclear N,N'-form and the trinuclear N-form reacted with ethyl N-phenylcarbamate and were converted to diethyl diphenylmethanedicarbamate. Triethyl dimethylenetriphenylcarbamate, which is a trinuclear substance, is formed by forming diethyl diphenylmethanedicarbamate into an unreacted trinuclear N,N'-
It is thought that the diphenylmethane dicarbamate was produced as a by-product while regenerating diethyl diphenylmethanedicarbamate by reacting with the trinuclear N-isomer and the trinuclear N-isomer. Comparative Example 1 2.03 g of a mixture of 3-nuclear N,N'-form and 3-nuclear N-form having the same composition as used in Example 1 was used, except that ethyl N-phenylcarbamate was not added. The reaction was carried out in exactly the same manner as in Example 1, except that 12% by weight of the trinuclear N,N'-isomer and the trinuclear N
Only a mixture consisting of 82% by weight of ethyl carbamate and 6% by weight of ethyl polymethylene polyphenylcarbamate having trinuclear or higher forms was obtained, and almost no diethyl diphenylmethanedicarbamate was produced. Examples 2 to 4 and Comparative Example 2 Condensation mixtures were obtained in the same manner as in Example 1 using ethyl N-phenylcarbamate and trioxane. After washing with water to remove sulfuric acid, thin film distillation is performed, and in the general formula (), x=0,
(N-ethoxycarbonyl)phenylaminomethylphenylcarbamate ethyl (hereinafter referred to as dinuclear N-form) 43% by weight, where R ² = C ₂ H ₅ , x = 0, R Bis− where ² = C ₂ H ₅
(N-ethoxycarbonylanilino)methane (hereinafter referred to as dinuclear N,N'-form) 26% by weight, trinuclear N
A mixture was obtained consisting of 22.3% by weight of -isomer and 8.7% by weight of trinuclear N,N'-isomer. 8 g of this mixture in 50 g of trifluoroacetic acid,
varying amounts of ethyl N-phenylcarbamate;
Table 1 shows the results of the reaction at 70°C for 10 minutes. Comparative Example 2 was obtained by carrying out the same operation without adding ethyl N-phenylcarbamate.

[Table] The results of Example 2 are as follows: dinuclear N-body and dinuclear N,
All of the N'-isomers react and convert to diethyl diphenylmethanedicarbamate (MDU), and the trinuclear N
26% of the -isomer and trinuclear N,N′-isomer reacted with ethyl N-phenylcarbamate to form MDU, and the remaining 74% was converted to triethyl dimethylenetriphenylcarbamate (DTT). In addition, the results of Example 3 show that dinuclear N-
All the bodies and the dinuclear N,N′- bodies react to form MDU
and the trinuclear N-form and the trinuclear N,N'-form
It shows that 78% reacted with ethyl N-phenylcarbamate to produce MDU, and the remaining 22% was converted to trinuclear DTT. It was found that when ethyl N-phenylcarbamate was not added, the reaction rate was slow and the yield of MDU was low. The recovered EPC in the comparative example is
It is a by-product of some reactions. Example 5 In Example 2, methyl N-phenylcarbamate (40.0 mmol) was used instead of ethyl N-phenylcarbamate, and the reaction was carried out in exactly the same manner as in Example 2. As a result, dinuclear N - body, 2 nuclei N, N'-
All three types of diphenylmethane dicarbamate, namely diethyl diphenylmethane dicarbamate (5.1 mmol), diphenylmethane dicarbamate, were consumed, including the trinuclear N-form and the trinuclear N,N′-form. Methyl carbamate (3.2 mmol) and mixed ester methylethyl diphenylmethanedicarbamate (16.1 mmol) and dimethylenetriphenylcarbamic acid triester (1.0 mmol, a mixture of methyl ester, ethyl ester, and methyl ethyl ester) were produced. 23.5 mmol of the added methyl N-phenylcarbamate has been consumed, and new ethyl N-phenylcarbamate has been added.
18.7 mmol was produced. Example 6 2 g of trinuclear N,N'-form and trinuclear N-form having the same composition as the raw materials used in Example 1 and 2.54 g of ethyl N-phenylcarbamate were added to trifluoroacetic acid.
As a result of reacting in 20g at 100℃ for 30 minutes, the trinuclear N,N'-form and the trinuclear N-form were all consumed, resulting in diethyl diphenylmethanedicarbamate.
2.45g was produced. As a by-product, 0.14 g of triethyl dimethylenetriphenylcarbamate, which is a trinuclear substance, was produced. Additionally, 1.95 g of ethyl N-phenylcarbamate was recovered. Example 7 7.3 g of the raw material mixture used in Example 2, 6.3 g of ethyl N-phenylcarbamate, and 30 g of sulfolane
In the presence of 4 g of SK-500 (manufactured by Union Carbide), a Y-type zeolite partially ion-exchanged with rare earth elements, the reaction was carried out at 80°C for 10 minutes, resulting in a dinuclear N-form and a trinuclear N-form. 90 each of N-bodies
%, and the total amounts of the di-nuclear N,N'-form and the tri-nuclear N,N'-form are reacted and consumed, resulting in 18.9 mmol of diethyl diphenylmethanedicarbamate and 1.6 mmol of triethyl dimethylenetriphenylcarbamate. mmol
2.5 mmol of ethyl N-phenylcarbamate was consumed. Diethyl diphenylmethanedicarbamate is 13.9 mmol from the dinuclear N-form and the dinuclear N,N'-form, and from the trinuclear N-form and the 3-nuclear N-form.
It is thought that 5 mmol each was produced from the nuclear N and N'-isomers. Example 8 and Comparative Example 3 Table 2 shows the results of carrying out the same reaction as in Example 8, except that cyanoacetic acid was used instead of SK-500. Further, Comparative Example 3 was prepared in which no acid was used.

【table】

Claims (1)

[Claims] 1. In the presence of one or more acids selected from organic carboxylic acids having a pKa value of 4 or less in an aqueous solution at 25°C or zeolites as an inorganic cation exchanger. Compounds having A, B, C, D, and E represented by the following formula () as structural units and mixtures thereof A[-B]- _l [-C]- _n [-D]- _o E () A= H, or [formula] or [formula] [formula] [formula] [Formula] or [Formula] (In the formula, l, m, and n each represent an integer greater than or equal to 0, and if n=0, if A is H, l+m≧
2 and if A is another group, l+m≧1
shall be satisfied. In addition, R ¹ represents hydrogen or a substituent such as an alkyl group, a halogen atom, a nitro group, a cyano group, an alkoxy group, or an alicyclic group, and x represents an integer of 0 to 4, and when x is 2 or more,
R ¹ may be the same or different substituents. R ² represents an alkyl group, aromatic group or alicyclic group, and R ² may have one or more hydrogens substituted with the above-mentioned substituents. ) and the general expression () (In the formula, R ³ represents hydrogen or a substituent such as an alkyl group, a halogen atom, a nitro group, a cyano group, an alkoxy group, an alicyclic group, etc., y represents an integer of 0 to 4, and when y is 2 or more, , R ³ may be the same or different substituents. ^{R 4}
represents an alkyl group, aromatic group or alicyclic group, and R ⁴ may be one in which one or more hydrogen atoms are substituted with the above-mentioned substituent. Further, R ³ may be the same as R ¹ , y may be the same as x, and R ⁴ may be the same as R ² . General formula () characterized by reacting with N-phenyl carbamate represented by A method for producing diphenylmethane dicarbamates represented by 2. Claim 1 in which dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, or cyanoacetic acid is used as the organic carboxylic acid with a pKa value of 4 or less.
The method described in section.