JPS5872552A - Condensation of n-phenylcarbamic acid ester - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as a raw material for polyurethane, etc. in high selectivity industrially advantageously, by reacting an N- phenylcarbamic acid ester with an agent to introduce methylene in the presence of an inorganic oxide linked with a sulfonic group-containing organic residue, etc. CONSTITUTION:For example, in reacting an N-phenylcarbamic acid ester shown by the formulaI(R<1> is aliphatic or aromatic group, etc., R<2> is H, alkyl, halogen, nitro, etc.; r is 0-4) with an agent to introduce methylene (e.g., formaldehyde, trioxane, paraformaldehyde, etc.), an inorganic oxide linked with an organic residue or an organometallic compound residue containing a sulfonic group shown by the formula II (R is bifunctional organic residue organometallic compound residue) is used as a catalyst to carry out the reaction. The catalyst has industrially advantageous points wherein corrosion will not occur, whereas it takes place in the case of a liquid acid catalyst, the catalyst is easily separated from a reaction solution component, the reaction is continuously carried out easily, an aqueous solution of waste acid is not produced, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for condensing unexploded 11-,N-phenylcarbamate through a methylene bond. When reacting and condensing,
The present invention relates to an industrially advantageous method for obtaining methylene-bis-(4-phenylcarbamate) with high selectivity.

This methylene-bis-(4-phenylcarbamate ester) is used as a precursor of 4,4'-diphenylmethane diincyanate (so-called pure MDI). , general 1NHC00R1 (wherein R1 is an alkyl group, an aromatic group, or an alicyclic group,
n represents an integer from 1 to 4] The mixture with polymethylene polyphenylcarbamine ester is a substance useful as a precursor of so-called crude MDI. These incyanates are extremely important industrially as additives for polyurethane.
Pure MDI is used as a raw material for polyurethane elastomers, spandex, coating materials for artificial leather, etc.
Second, demand has increased rapidly in recent years. Therefore, it is desired to develop an industrially advantageous method for producing polymethylene polyphenylcarbamate esters containing a large amount of lumethylene/-bis-(4-phenylcarbamate ester), which can be used as a raw material.

Conventionally, as a method for producing methylene-bis-(4-phenylcarbamate) using N-phenylcarbamate as a starting material.

A method of reacting formalin or paraformalde with do or trioxa/ as a condensing agent in an aqueous medium with a mineral acid such as hydrochloric acid, sulfuric acid, or phosphoric acid as a catalyst, or a method of reacting in an organic solvent with an organic sulfonic acid as a catalyst. Methods are known.

However, these methods produce a large amount of by-products, resulting in low yields of the target methylene-bis-(4-phenylcarbamate ester), and the isolation of the target product is time-consuming. It has its flaws and is not satisfactory. For example, in a reaction in an aqueous medium, nitrogen formation in N-phenylcarbamate esters is involved, resulting in formation of N-(alkoxycarbonyl)phenylaminomethylphenyl compounds and dimers and dimers of these substances. N
- A considerable amount of benzyl compounds are produced, and even in the reaction in an organic solvent using an organic sulfonic acid as a catalyst, a considerable amount of polymethylene polyphenylcarbamate ester, which is a polynuclear substance containing three or more benzene rings, is produced. By-product in quantity 1
2. Target selectivity is not very high.

Furthermore, when using the liquid acid catalyst described above, the equipment is highly corroded and the separation and recovery of the catalyst requires a great deal of expense. Furthermore, it has various drawbacks, such as the need to dispose of waste acid.

Furthermore, a method using a strongly acidic ion exchange resin has been proposed in order to avoid the disadvantages that inevitably accompany the use of a liquid acid as a catalyst. However, (1) when a commonly known ion exchange resin is used as a catalyst, the swelling of the ion exchange resin is significant under the reaction conditions (1) the mechanical strength is reduced, and the preferred reaction temperature may be lower than the heat resistance temperature of the resin. It has disadvantages such as high cost and practically unusable. In addition, since the methylene condensate of N-phenylcarbamate ester, which is the product, has a relatively high molecular weight and high polarity, it is presumed that this is adsorbed to the resin and covers the acid groups. The activity of this catalyst decreases significantly over time, so it cannot be used as an industrial catalyst.

Therefore, the present inventors have conducted extensive research into an effective method for condensing N-phenylcarbamate esters via methylene bonds to overcome these drawbacks.
By using as a catalyst a compound in which an organic residue having a sulfonic acid group or an organometallic compound residue is bonded to an inorganic oxide.

It has been discovered that the various drawbacks mentioned above can be solved and methylene-bis-(4-phenylcarbamate ester) can be produced with high selectivity, and the present invention has been completed based on this knowledge.

Namely, according to the present invention, In,N-7 enyl carbamate is reacted with a methylenating agent using an inorganic oxide bonded with an organic residue having a sulfonic acid group or an organometallic compound residue as a catalyst. N-phenylcarbamate can be condensed via a methylene bond.

The catalyst used in the present invention is an inorganic oxide bonded with a group represented by the general formula % (1) (in which R is a divalent organic residue or an organometallic compound residue). , R in this formula preferably has 30 or less carbon atoms, particularly 20 or less carbon atoms. As such organic residues.

For example, aliphatic, aromatic, aliphatic-aromatic saturated or unsaturated hydrocarbon groups, at the ends or in the main chain of these hydrocarbon groups,
Ether bond, thioether bond a1 sulfone bond, carbonyl bond, ester bond.

Examples include those containing an amide bond, an imino bond, and a heterocyclic moiety, and examples of organometallic compound residues include those in which a metallic element is bonded to the terminal or main chain of the above-mentioned organic residue. This organometallic compound residue or group may be an organosilicon compound residue having a silicon atom at the terminal, for example, a halosilyl group or an alkoxysilyl group at the terminal, since it is particularly easy to prepare and forms a stable bond with an inorganic oxide. Preference is given to organosilicon compound residues having the like.

The organic residues or organometallic compound residues described above have some of the hydrogen atoms present therein, as well as halogen atoms such as fluorine, chlorine, and bromine, alkyl groups, alkoxy groups, aryl groups, aryloxy groups, and hydroxyl groups. It may be substituted with a group such as a nitrile group, a nitrile group, an alkoxycarbonyl group, a carboxyl group, or a sulfonic acid group. Examples of inorganic oxides to which the group -R-5o3I of general formula (1) is bonded include silica, silica-alumina, alumina, titania, zirconia, magnesia, zeolite, diatomaceous earth, clay materials, glass, titania-alumina, Oxides having hydroxyl groups on the surface, such as silica-titania and silica-zirconia, are suitable.Particularly preferred are silica, porous glass, and silica-alumina.The forms of such inorganic oxides include powders and beads. ,
It can be anything such as pellets or balls.

The catalyst used in the present invention, in which an inorganic oxide and a group represented by formula Preferred is a method of introducing -R-8o3H using -R-8o3H.

(Inorganic oxide) -OH+X-R-8o3H--→(Inorganic oxide)-0-R-5O3H (In the above formula,
When R is a plated residue or an organometallic compound residue having a metal in the main chain.

For example, a halogen atom or a hydroxyl group.

Further, when R is an organometallic compound residue having a metal at the end of the main chain, it is, for example, a halogen atom or an alkoxy group. ) Or (inorganic oxide) -OH-1-5OOz2-m-→(inorganic oxide') --at 10 so2 + HC1 (inorganic oxide HO
6-)-Y-R-5O3H-m-→(inorganic oxide)-R
-S O3H + Y cz (In the above formula, Y is, for example, amine, 7 group, hydroxyl group, alkali metal, -MgB
Represents a group such as r. ) The catalyst used in the present invention as described above may of course be made by a method of bonding an organic residue or organometallic compound residue not containing a sulfonic acid group with an inorganic oxide and then introducing a sulfonic acid group. However, after bonding an inorganic oxide with an organic residue or an organometallic compound residue containing a moiety that becomes a sulfonic acid precursor, it may be converted into a sulfonic acid by a predetermined treatment.

The catalyst used in the method of the present invention prepared in this manner is an organic residue or an organometallic compound a residue in which R in the group represented by the above formula combined with an inorganic oxide has 30 or less carbon atoms. In particular, with relatively low molecular weight substances such as ordinary high molecular weight ion exchangers or ion exchange resins, there is virtually no swelling and associated decrease in physical strength, and methylene formation in the swollen state is not possible. It has been found that phenomena such as reduction in catalyst activity due to adhesion of products do not occur at all, or even if they occur, the extent of the decrease is extremely small.

The N-phenylcarbamate ester used in the present invention is a compound represented by the general formula (2), where R1 represents an aliphatic group, aromatic group, or alicyclic group, and R2 represents hydrogen or an alkyl group. , represents a substituent such as a halogen atom, nitro group, cyano group, alkoxy group, alicyclic group, etc., and these substituents are bonded to the ortho or meta position to the urethane group, and r is 0 to 4. represents an integer. Further, R1 where r is 2 or more may be the same or different substituents. Furthermore, R1 may have one or more hydrogen atoms substituted with the above-mentioned substituents.

Examples of the more specific N-phenylcarbamate esters include, for example, in the general formula (II), R1 is a methyl group, and an ethyl group a2,2.2''-F!Jchloroethyl group.

2.2.2-t') fluoroethyl group, propyl group (
n+, 1so-), butyl group (n- and various isomers),
Pentyl group (n- and various isomers), hexyl group, (n-
- and various isomers), or an alicyclic group such as a cyclopentyl group or a cyclohexyl group, or an aromatic group such as a phenyl group or a naphthyl group, and R2 is hydrogen or the alkyl group or alicyclic group mentioned above. Examples include N-phenylcarbamate esters, which are halogen atoms such as fluorine, chlorine, bromine, and iodine, or nitro groups, cyano groups, or alkoxy groups whose constituent components are the alkyl groups mentioned above.

Preferred is methyl N-phenylcarbamate, N-
Ethyl phenylcarbamate, N-phenylcarbamate fil n -propyl, N-phenylcarbamate 1
80-7'lopyl, n-butyl N-phenylcarbamate, BeC-butyl N-phenylcarbamate, N-phenylcarbamate m1so-butyl, N-phenylcarbamine fli tart -7' f, pentyl N-phenylcarbamate , N-phenylcarbamate hexyl, N-phenylcarno(cyclohexyl mate, N
-Phenylcarbamic acid 2.2.2-) ') Chloroethyl, N-phenylcarbamic acid 2,2.2-) Lifluoroethyl, N-〇 or ham-) Methyl lylcarbamate, N-o -Ethyl tolylcarbamate, N-
2,2.2-trifluoroethyl 0 or m-tolylcarbamate, N-0 or m-propyl tolylcarbamate (each isomer), N-o or m-tolylbutylcarbamate (each isomer) a” or m-methyl chlorophenylcarbamate & N-0 or ethyl m-chlorophenylcarbamate % N-0 or um-10 propyl lophenylcarbamate (each isomer), N-o or ham-chlorophenylcarbamate 7 'Th, Ru (each isomer K), N-0-cross m-chlorophenylcarbamate 2,2.2-trifluoroethyl%N-2,6-dimethylphenylcarbamate methyl, N-2,6-dimethyl Ethyl phenylcarbamate.

N-2,6-dimethylcarbamate furovir (each isomer), N-2,b-dimethylcarbamate (each isomer) N 2+6-dimethylcarbamate 2
, 2.2-trifluoroethyl, methyl N-2,6-dibromophenylcarbamate, ethyl N-2,6-dibromophenylcarbamate%N-propyl 2,6-dibromophenylcarbamate (each isomer) %N-2
．． Butyl 6-dibromophenylcarbamate (each isomer), N-2,6-dibromophenylcarbamate 2,2
．． 2-) Lifluoroethyl (7)N-phenylcarbamate esters are used.

Examples of the methylenating agent used in the present invention include formaldehyde, paraformaldehyde, trioxane, tetraoxane, dialkoxymethane, cyasyloxymethane, 1,3-dioquinrane, 1,3-dioxane% 1,
Examples include 3-dithiane, 1,3-oxathiane, hexamethylenetetramine, and the like, and among these methylenating agents, formaldehyde and paraformaldehyde are particularly preferred.

Trioxane and dialkoxymethanes having a lower alkyl group having 1 to 6 carbon atoms, such as dimethoxymethane, jetoxymethane, dipropoxymethane, dipentoxymethane, dihexyloxymethane and diacetoxymethane,
These include siasiloxymethane having a lower carboxyl group such as diacetoxymethane, and these may be used alone or in a mixture of two or more.

Although the method of the present invention can be carried out without a solvent, it can also be carried out in a suitable solvent if necessary. Examples of such solvents include aliphatic or alicyclic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane, -n-hexadecane, cyclopentane, and cyclohexane, chloroform, methylene chloride, carbon tetrachloride, Halocarbons such as dichloroethane, trichloroethane, and tetrachloroethane; alcohols such as methanol, ethanol, propatool, and butanol.

Benzene, toluene, xylene, ethylbenzene.

Monochlorobenzene, dichlorobenzene, bromonaphthalene, nitrobenzene, 〇-um4. Hp-=aromatic compounds such as trotoluene, diethyl ether% 1
, 4-dioxane, tetrahydrofura/etc., esters such as methyl acetate, ethyl acetate, methyl formate, and sulfolane.

Sulfolanes such as 3-methylsulfolane and 2,4-dimethylsulfolane, acetic acid, propionic acid, monochloroacetic acid, dichloroacetic acid, and trichloroacetic acid.

Carboxylic acids such as trifluoroacetic acid, methanesulfo/
Examples include acids, sulfonic acids such as trichloromethanesulfonic acid and trifluoromethanesulfonic acid, and acetic acid.

In carrying out the method of the present invention, the molar ratio of methylene and other agents to N-phenylcarbamate is not particularly limited, but is usually 0.01 to 1 mole of N-phenylcarbamate. It is preferably used in a range of 10 to 10 moles, more preferably 0.05 to 5 moles. If the amount of methylenating agent used is too small, the residual rate of unreacted N-phenylcarbamate ester will be large.

On the other hand, if the amount is too large, the proportion of polymethylene polyphenyl carbamate esters that are polynuclear bodies having three or more phenyl groups will increase, which is not preferable.

The catalyst still used in the process of the invention is used in an amount in the range corresponding to 10 to 10 molar equivalents of sulfonic acid groups per mole of N-phenylcarbamate ester, in particular 5 x 10 to 5 molar equivalents of sulfonic acid groups. A range of molar equivalents is desirable. If the amount of catalyst is less than 10 molar equivalents, the reaction will be substantially slow. On the other hand, even if it is used in an amount of 10 molar equivalents or more, it is not industrially advantageous because no particular effect is observed.

The reaction of the present invention is carried out at a temperature of 250C or less, preferably 10 to 200C.
It is carried out at a temperature of 80 to 1
It is in the range of 80C.

Furthermore, although the method of the present invention is usually carried out under normal pressure or increased pressure, it can also be carried out under reduced pressure if necessary.

The reaction time varies depending on other reaction conditions such as reaction temperature, type and amount of catalyst, presence or absence and amount of solvent, raw material composition, reaction method, etc., but is usually from several minutes to several hours.

In addition, the reaction method of the present invention and 1. Teke, there are no particular restrictions 1
For example, there are a method in which a catalyst prepared by combining #i of -R-8o3H with an inorganic oxide is suspended in the reaction mixture, a method in which a fixed bed is used, and the like. Further, it may be carried out batchwise or continuously.

Since the catalyst of the present invention is a solid, it does not corrode equipment unlike ordinary liquid acid catalysts such as hydrochloric acid and sulfuric acid, and it is easy to separate and recover from one reaction liquid acid and continue the reaction. It has extremely industrial advantages such as not emitting an aqueous solution.

Furthermore, when the catalyst of the present invention is used as a reaction catalyst for N-phenylcarbamate and a methylenating agent, methylene-bis-(4-phenylcarbamate) can be obtained with high selectivity.

Next, the present invention will be explained in more detail with reference to Examples.
The invention is not limited to this example.

In addition, the reaction product was analyzed using high performance liquid chromatography.

Example 1 Silica gel (10fil) was suspended in toluene (30mi) and 3-chloropropyltrimethoxysilane (g
ig) was added and the mixture was then stirred and reacted at reflux temperature for 5 hours under nitrogen atmosphere. Sort the reaction products by day,
It was subjected to Soxhlet extraction with methanol for 15 hours and dried under vacuum. A saturated aqueous solution of sodium sulfite (100 ml) was added to the chloropropyl silica, and the mixture was stirred under reflux and nitrogen atmosphere for 24 hours. After cooling, the silica product was separated and washed with distilled water to remove residual sulfite.

This silica product was then acidified with IN nitric acid and then
Wash with distilled water and vacuum dry. This silica product I
It contained 0.9% by weight of sulfur and yellow (hereinafter, this product will be referred to as sulfopropyl silica).

This sulfopropyl silica 29% ethyl N-phenylcarbamate 8.257 and dimethoxymethane 1.9
1 and sulfolane 89ml 1. put it in an autoclave,
The reaction was carried out at 120 t:' for 2 hours. After the reaction, the five reaction solutions were analyzed, and the reaction rate of ethyl N-phenylcarbamate was 63%, the yield of methylene-bis-(ethyl 4-phenylcarbamate) was 44%, and the selectivity thereof was 70%. Moreover, polymethylene polyphenylcarbamate ethyl having trinuclear or more bodies was formed with a selectivity of 18.

1. Separate and recover from the reaction solution after the reaction by filtration.

When the same reaction was repeated using sulfopropyl silica, the reaction rate for ethyl N-phenylcarnocmate was 62%, and the selectivity for methylene-bis-(ethyl 4-phenylcarbamate) was 72%. , the selectivity of polymethylene polyphenyl ethyl carbamate was 15%, substantially the same results were obtained, and no decrease in catalytic ability was observed.

Example 2 Silica gel was heated under reflux in 2N HCt for 4 hours, then filtered, washed with water and acetone, and then heated at 200C.
I let it dry for a day and night. This pretreated silica gel (5P) and 2-phenylethyltrichlorosilane (2f
After reacting with reflux in anhydrous dioxane (100 mg) for 4 hours, the mixture was filtered, washed successively with dioxane and acetone, and then dried. This product is 2
After heating under reflux for 3 hours in trchloroform (100IIIJ) containing 0 vol % chlorosulfonic acid, the solid acid catalyst having 0.6 meq/fI of sulfonic acid groups was prepared by washing and drying. Obtained.

Fill the column with this catalyst 1. A nitrobenzene solution containing 10 wt% of methyl N-phenylcarbamate and 70.5 wt% of trioxa was injected from the bottom of the column at a flow rate of 20 ml/hr. After maintaining this column at 110C and reaching a steady state, the product solution was analyzed and the reaction rate of methyl N-phenylcarbamate was 45%, and the selectivity of methylene-bis-(4-phenylmethylcarbamate) was 45%. The selectivity of methyl polymethylene polyphenyl carbamate was 13%, and the remaining residue was a dimer containing 2,4' monomer.

Example 3 Silica gel (5?) subjected to the same pretreatment as in Example 2
After reacting for 7 hours under reflux of an excess amount of thionyl chloride, unreacted substances and adsorbed substances were removed under reduced pressure at 1801:'. In this way, chlorinated silica containing about 1.7 milliequivalents of chlorine was obtained. This chlorinated silica was reacted with benzyllithium in anhydrous tetrahydrofuran to obtain benzylated silica. Next, this was added to 35 g of oleum and heated at room temperature for 5 g.
Allowed time to react. After washing with water, it was dried at 120C for one day and night to obtain sulfopropyl silica having a sulfonic acid group of about 1.2 milliequivalents/P.

This catalyst was packed into a stainless steel column with an inner diameter of 12 m and a length of 20 cm. A sulfolane solution containing N-phenylcarno (13 wt% ethyl mate and 2 wt% jetoxymethane) was injected at the bottom of the column at a rate of 39 Ill/hr. The column was maintained at 120 C and after reaching a steady state. , Results obtained by analyzing the product solution. The anti-EJu of ethyl N-phenylcarbamate is 43%, the selectivity of methylene-bis-(ethyl 4-phenylcarbamate) is 73es, and the selectivity of methyl N-phenylcarbamate is 73es. was 10%.This condensation reaction was 10%.
After that time, the results were almost the same.

Comparative Example 1 A reaction was carried out under the same conditions as in Example 3 using a commercially available MR type strongly acidic ion exchange resin based on a crosslinked polymer of styrene-divinylbenzene. The reaction rate of phenylcarbamate ester is 4
At 0%, the selectivity of methylene-bis-(ethyl 4-phenylcarbamate) was 60%, but after 1 to 3 hours, the reaction rate decreased to 25%, and the selectivity of methylene-bis-(ethyl 4-phenylcarbamate) was 60%. The selectivity also decreased to 48%, which was 1-.After 10 hours, it further decreased, and the reaction rate was 10%, and the selectivity was 20%.

Example 4 Silica alumina (Si/At=674) was pretreated in the same manner as in Example 2, reacted with a supercharged amount of thionyl chloride under reflux for 7 hours, and then heated at 160 to 180 C under reduced pressure.
Unreacted substances and adsorbed substances were removed. In this way, about 1
．． A chlorinated silica alumina containing 2 meq. of chlorine was obtained. 2-sulfoethyl aminated silica alumina (1 meq/1) was obtained by reacting this chlorinated silica alumina and 2-aminoethanesulfonic acid at a temperature of 80 to 100 C for 10 hours in anhydrous dioxane.

This catalyst was packed into a stainless steel column with an inner diameter of 12w and a length of 20cm. Ethyl N-phenylcarbamate 16
wt% and an acetic acid-sulfolane (10/90 volume ratio) solution containing 1 wt% trioxane.

It was injected down the column at 15 ml/hr. After maintaining this column at 110C and reaching a steady state, the product solution was analyzed and the reaction rate of ethyl N-phenylcarbamate was 48%, with a selectivity of methylene-bis-(ethyl 4-phenylcarbamate). was 73%, and the selectivity for polymethylene polyphenyl ethyl carbamate was 15%.

Example 5 Water glass 10? Add 26 mg of a 0.5 trihydrium hydroxide aqueous solution of phenyltrimethoxysilane No. 11 to 100 iJ of an aqueous solution in which 11 is dissolved, and stir to make a homogeneous aqueous solution.
A cooled 5% sulfuric acid aqueous solution was gradually added to this while stirring thoroughly to adjust the pH to 6. This solution was left to gel, and after about 5 hours, this gel-like substance was thoroughly washed with ion-exchanged water and then dried at a temperature of 150C for 5 hours. The obtained phenylated silica was added to chloroform containing 20% (by volume) chlorosulfonic acid, and reacted under reflux for 5 hours. After filtering, washing and drying, sulfophenyl silica (1.1 meq/?) was obtained.

3fi', N-phenylcarbamate ethyl 8
．． 25 f,) Put 1.35 P of rioxane and 50 P of nitrobenzene into an autoclave and heat at 130C for 1
Allowed time to react. After the reaction, the reaction solution was analyzed and found to be N-
The reaction rate of ethyl phenylcarbamate was 85%, the selectivity of methylene-bis-(4-phenylethylcarbamate) was 75%, and the selectivity of ethyl polymethylene polyphenylcarbamate was 17%.

Patent applicant: Asahi Kasei Industries, Ltd. Agent Akira Agata

Claims (1)

[Claims] ■ A method characterized by reacting an N-phenylcarbamate and a methylenating agent in the presence of an inorganic oxide bound to an organic residue having a sulfonic acid group or an organometallic compound residue. A method for condensing N-phenylcarbamate ester. 2. The condensation method according to claim 1, wherein the inorganic oxide is silica. 3. The condensation method according to claim 1, wherein the organic residue or organic/organometallic compound residue has 30 or less carbon atoms.