JPH07330707A - Production of aryl cyanate - Google Patents

Abstract

PURPOSE: To simply obtain the subject compound continuously without danger by using a cooled tubular reactor to effect the reaction under specific conditions in the production of an aryl cyanate by reaction of a phenol compound with cyanogen chloride in the presence of a tertiary amine.

CONSTITUTION: In this process, a phenol compound of formula I [(a) n=0-20; A is a direct bond, O, S, an alkan-diyl, an alicyclic group; (b) in the case of n=0, A is formula II (Q is a direct bond, alkan-diyl; X is CN); R₁-R₁₁ are each H, a halogen, an alkoxy, an alkylthio] is allowed to react with cyanogen chloride to give an aryl cyanate of formula III. In this case, at least one of the raw materials is dissolved in an organic solvent, this raw material (the molar ratio of cyanogen chloride to the OH of the phenol compound is 1.0-1.2) is simultaneously together with others and continuously fed to a tubular reactor so that the reaction components may be diluted with the reaction mixture circulating in the reactor before these reactants come into contact with each other, while the reaction mixture is taken out from the reaction system simultaneously.

COPYRIGHT: (C)1995,JPO

Description

Detailed Description of the Invention

The present invention relates to a process for continuously producing polyhydric aryl cyanates from the corresponding phenols and cyanogen chloride.

Aryl cyanates, or phenolic esters of cyanic acid, are important building blocks for synthetic resins (see, for example, DE-OS 1720663). Aryl cyanates are usually prepared from the corresponding phenols and cyanogen chloride, with the hydrogen chloride formed as a by-product being bound by a base as a salt (DE-A).
S 1195764). Since cyanogen chloride is considered to be the chloride of cyanic acid, this reaction corresponds formally to the reaction of producing the ester from the corresponding alcohol and the corresponding acid chloride. However, since both cyanogen chloride and the corresponding aryl cyanate are highly reactive compounds, in order to obtain a product with satisfactory yield and sufficient purity, side reaction and continuous reaction should be performed in strict adherence to strictly defined reaction conditions. The reaction must be suppressed. This criterion is particularly important for such aryl cyanates, which cannot be purified by distillation or crystallization. Known processes for the production of pure aryl cyanates (DE-OS 24460)
04,2507671,2507705,252948
6,2529487) is a discontinuous process or requires a water-organic two-phase system. Moreover, the discontinuous process requires an excess amount of cyanogen chloride, which presents safety concerns in mass production (cyanide chloride is very toxic).

The object of the present invention is to provide a continuous process which is suitable for the mass production of high-purity aryl cyanates and which is simple and can be carried out without risk.

This problem is solved according to the invention by the method of claim 1.

The polyvalent aryl cyanates which can be produced according to the present invention have the general formula

[0006]

[Chemical 4]

It is represented by Here, n is an integer of 0 to 20, preferably 0 to 10. Therefore, both divalent aryl cyanates and polyvalent (oligomeric) aryl cyanates are included in formula I. The polyhydric aryl cyanate is derived from, for example, a novolac type polyhydric phenol.

A may be a direct chemical bond or a divalent group. Possible divalent groups are oxygen, sulfur, sulfonyl, carbonyl and carbonyldioxy (-
O-C (= O) -O-). Similarly, a linear or branched C ₁ -C ₁₀ alkanediyl group, which may optionally be fully or partially substituted with fluorine, optionally one or more C ₁ -C ₄ alkyl groups. And / or a divalent monocyclic or polycyclic aromatic group which may be substituted with one or more halogen atoms, or optionally substituted with one or more C ₁ -C ₄ alkyl groups. Divalent monocyclic or polycyclic cycloaliphatic radicals which are possible are also possible. Moreover, A may be a divalent group composed of two or more of the above divalent groups.
When n is 1 or more and therefore there are many divalent groups, these groups may be the same or different. However, it is preferred that the groups A are the same.

If n is 0, A is of the formula

[0010]

[Chemical 5]

It may be a group of Here, Q may be a direct chemical bond or a divalent group. Possible 2
The valent group may be a straight or branched C ₁ -C _{1-, which} may be fully or partially substituted with fluorine.
A C ₁₀ alkanediyl group, optionally one or more C ₁ -C
₄ Divalent monocyclic or polycyclic aromatic groups which may be substituted by alkyl groups and / or one or more halogen atoms, or divalent groups composed of two or more of the above groups It may be a group of. X is -C in this case
It means N.

The aromatic ring bearing a cyanate group can additionally carry substituents R _{1 to} R ₁₁ on the "vacant" carbon. The substituents R _{1 to} R ₁₁ may be the same or different, and in addition to hydrogen, halogen, C _{1 to} C ₄ alkoxy, C _{1 to} C ₄ alkylthio, C _{1 to} C ₄ alkoxycarbonyl, or each of them. It may also be C ₁ -C ₄ alkyl, which may be fully or partially substituted with fluorine. The divalent groups A and Q also have the substituent R
_{1 to} R ₁₁ can each also be in the ortho, meta or para position relative to the cyanate group, the substitution formula for the individual aromatic rings being either intramolecular, molecular-to-molecular or identical. Or may be different.

The term "alkanediyl group" as used herein and in the following description, is a group whose free valences are derived from the same carbon atom, such as methylene, ethylidene or 1-methylethylidene (= isopropylidene), And radicals whose free valences originate from different carbon atoms, such as 1,2-ethanediyl (= ethylene) or 1,3-propanediyl (= trimethylene).

An example of a fluorine-substituted alkanediyl group is 1- (trifluoromethyl) -2,2,2-trifluoroethylidene.

"Polycyclic" here and in the following description means all cyclic structures having at least two rings. This includes easily linked rings such as biphenyl, spiro compounds, fused ring systems such as naphthalene, or bridged ring systems such as norbornane.

Divalent aromatic radicals are, for example, o-, m- and p-phenylene and the various isomeric naphthylenes and biphenylenes. In a divalent cycloaliphatic radical, both free valences are derived from the same carbon atom, such as cyclohexylidene, or, for example, octahydro-4,7-methanoindenediyl,
It can be derived from different carbon atoms.

The constituted divalent group is represented by, for example, the formula

[0018]

[Chemical 6]

Or

[0020]

[Chemical 7]

It is the base of

The polyvalent aryl cyanates are according to the invention
In the presence of a tertiary amine, the general formula

[0023]

[Chemical 8]

It is prepared from the corresponding polyhydric phenol of and cyanogen chloride.

Index n and groups A, R _{1 to} R ₁₁ and
When present, Q has the same meaning as product (I), while X represents hydrogen when present.

According to the invention, these three components are reacted with one another in a cooled annular reactor. The term "annular reactor" is used herein only to mean a functional principle, not a specific structural form. In the simplest case, the annular reactor consists of a ring-shaped closed tube (ring) in which the rolling pump is installed. The cooling required due to the exothermicity of the reaction and the low reaction temperature is achieved, for example, by a cooling jacket extending over almost the entire length of the tube or by a heat exchanger of conventional structure incorporated in the annulus at any position. can do. The ring has at least one connection for withdrawing the reaction mixture, and many, preferably three, connections for supplying the reaction components. Since the reaction of phenol (II) with cyanogen chloride takes place in solution, at least one of the three components to be fed must be in dissolved form. Since phenol is usually a solid at the reaction temperature,
Phenol is used as a solution in organic solvent. Of course, cyanogen chloride and / or tertiary amines can also be added in dissolved or diluted form. The reaction components can be fed into the annular reactor essentially simultaneously and sequentially. That is, the supply of the reaction components in the reaction mixture is not interrupted for a long time or the molar ratio thereof does not fluctuate greatly. For example, slight fluctuations due to pulsation of piston or thin film pumps can be ignored.

Furthermore, the reaction components are fed into the annular reactor in such a way that they only come into contact with each other after they have been diluted by the initially circulating reaction mixture. This is achieved by properly arranging the feed locations and taking into account the flow ratio in the annulus. However, it is not necessary to force an ideal mix. Simultaneously with the supply of the reaction components, the flow of the reaction mixture corresponding to the supplied amount is taken out from the annular reactor and separated. This condition is automatically satisfied if the ring is always completely filled.

The reaction temperature is preferably −20 ° C. to 0 ° C., in which case it is advantageous to cool the reaction components to be fed in advance. If cyanogen chloride is supplied in pure form, i.e. not as a solution, it should be taken into account that the temperature range in which this substance is present in the liquid is narrow (-6 to + 14 ° C).

The molar ratio of cyanogen chloride to phenolic reactive hydroxy groups is advantageously 1.0 to 1.2, preferably 1.0 to 1.1. These values are related to the feed rate, and the proportion virtually present in the reaction mixture may then differ to some extent.

The tertiary amine has the general formula RR'R "
It is preferable to use a trialkylamine of N (in the formula, R, R ′ and R ″ may be the same or different and each represents a linear or branched C _{1 to} C ₆ alkyl group). It is advantageous.

As the solvent for carrying out the reaction, it is basically possible to use all solvents in which the reaction components are sufficiently soluble and which do not react with cyanogen chloride or other components. Particularly suitable for this are esters such as ethyl acetate or butyl acetate, ethers such as tetrahydrofuran, ketones such as acetone, or halogenated hydrocarbons such as dichloromethane.

For the separation treatment, it is advantageous to use a solvent in which the product is soluble but the tertiary ammonium chloride formed as a by-product is insoluble or sparingly soluble. The by-product thereby precipitates and can be completely or partly removed by filtration or centrifugation.
It is also possible to carry out the reaction and the separation process in different solvents, in which case the solvent of the reaction mixture, for example taken out of the ring reactor, is distilled off and replaced by another solvent.

Furthermore, it is advantageous to use a solvent which has little or no miscibility with water and to extract the reaction mixture with water in order to separate off the tertiary ammonium chloride. This is especially important when producing aryl cyanates which cannot be purified by crystallization or by distillation.

Subsequent processing is carried out in a manner known per se and depends essentially on the physical properties of the individual products. The crystallizable product is advantageously concentrated in solution and then crystallized, filtered or centrifuged and finally dried. For products that do not crystallize, the solution is completely distilled off, optionally followed by a second distillation to separate easily volatile by-products.

The method of the present invention is suitable, for example, for producing the following compounds. 4,4'-thiodiphenyl cyanate of the following formula

[0036]

[Chemical 9]

4,4'-methylenebis (2,6-
Dimethylphenyl cyanate)

[0038]

[Chemical 10]

Aryl cyanate of the formula

[0040]

[Chemical 11]

4,4'-ethylidene diphenyl cyanate of the following formula

[0042]

[Chemical 12]

2,2-bis (4-cyanatophenyl) propane of the following formula

[0044]

[Chemical 13]

4,4'-bis (trifluoromethyl) methylenediphenyl cyanate of the following formula

[0046]

[Chemical 14]

Aryl cyanate of the formula

[0048]

[Chemical 15]

4,4 '-(1,3-phenylenediisopropylidene) diphenyl cyanate of the following formula

[0050]

[Chemical 16]

Phosphoric acid tri (4- (1- (4-cyanatophenyl) -1-methylethyl) phenyl ester) of the formula

[0052]

[Chemical 17]

The present invention is illustrated by the accompanying drawings and examples, which do not limit the invention.

The phenol solution is supplied from the stirring storage container 1 through a metering pump 5 to a reaction ring equipped with a rolling pump 3 and a heat exchanger 2. At the same time, the tertiary amine is likewise fed from the storage container 6 through the metering pump 4 and also through the pipe 7 with cyanide chloride. The reaction mixture is continuously fed through a pipe (upper part of the drawing) to a filtration device 8 from which the filtrate is further led to a liquid-liquid extractor 9 where it is extracted with water in countercurrent. The extracted water is subjected to dehydration treatment. For the production of amorphous aryl cyanate, the product solution is treated with solvent in the first distillation apparatus 10,
By-products and contaminants that are easily volatilized in the second distillation apparatus 11 are removed. The pure product 12 is obtained from the liquid container of the second distillation apparatus.

Solvent distillation apparatus 1 is used for the production of crystalline products.
The concentrated product solution from the 0 liquid container is sent to the crystallizer 13. The dispersion liquid of the crystals formed there is sent to the filter device 14, the filter cake is sent to the dryer 15,
The final product 16 is taken from there.

[0056]

EXAMPLE Preparation of 2,2-bis (4-cyanatophenyl) propane (bisphenol A-dicyanate) A 15 liter volume annular reactor cooled to an internal temperature of −10 ° C. was passed simultaneously with a metering pump and Individually 1
00 kg / h of 15% bisphenol A in acetone,
And 13.6 kg / h of triethylamine were fed.
At the same time, 8.5 kg / h of cyanogen chloride (molar ratio 1: 1.0
2: 1.05) was introduced. The reaction mixture was circulated through a rolling pump in a ring and fed into a collection tank.

Therefore, in order to prevent the deposited triethylammonium chloride from being deposited, the mixture was first stirred and then flowed in stages through a filter funnel. The filter cake was washed with acetone and further processed to recover triethylamine. The filtrate was concentrated and about 80% of the solvent was distilled off. The concentrated product solution thus obtained is
At a temperature of ~ 70 ° C, it was placed in water at about 10 ° C with vigorous stirring. The precipitated product was centrifuged, washed twice with water and dried in a turbine dryer at 50 ° C. and about 50 mbar for 24 hours.

The purity of the final product is 97.5-99.5%
And the yield is about 90% (based on bisphenol A).
Met.

[Brief description of drawings]

FIG. 1 is a flowchart showing the configuration of an apparatus for carrying out the manufacturing method of the present invention.

[Explanation of symbols]

 1,6 Storage container 2 Heat exchanger 3 Rolling pump 4,5 Dispensing pump 7 Pipe 8 Filtration device 9 Liquid-liquid extractor 10 First distillation device 11 Second distillation device 12 Product 13 Crystallization device 14 Filtration device 15 Dryer 16 Final product

Claims (7)

[Claims] 1. A general formula: [Wherein a) n is an integer from 0 to 20, A is a direct bond, or is substituted with oxygen, sulfur, sulfonyl, carbonyl, carbonyldioxy, optionally completely or partially with fluorine. A straight or branched chain C ₁ -C ₁₀ alkanediyl group, a divalent monocyclic or polycyclic aromatic group optionally substituted with C ₁ -C ₄ alkyl and / or halogen, optionally It is a C ₁ -C ₄ alkyl-substituted divalent monocyclic or polycyclic cycloaliphatic group, or a divalent group composed of two or more of the above groups, and n is 1 or more. In each case, the groups represented by the symbol A may be the same or different, and b) when n is 0, A is represented by the formula: Where Q is a direct bond or is a straight or branched chain C optionally or fully or partially substituted with fluorine.
₁ -C ₁₀ alkanediyl group, optionally C ₁ -C ₄ alkyl group and (or) a divalent monocyclic or polycyclic aromatic group substituted with a halogen atom or a group described above,
X is -CN, which is a divalent group composed of one or more groups. ), R _{1 to} R ₁₁ are the same or different and each is hydrogen, halogen, C ₁
-C ₄ alkoxy, means a C ₁ -C ₄ alkylthio, C ₁ -C ₄ alkoxycarbonyl, or fully or partially C ₁ -C ₄ alkyl substituted with fluorine, if desired. ] Of the aryl cyanate in the presence of a tertiary amine of the general formula: [In the formula, n, A, Q and R _{1 to} R ₁₁ have the meanings described above, and X is hydrogen. ] In the method for producing by converting the phenol of the above with cyanogen chloride, phenol,
Using at least one of an amine and cyanogen chloride as a solution in an organic solvent, the phenol, the amine and the cyanogen chloride are essentially simultaneously and successively -20
In a cooled cyclic reactor at a temperature of ℃ to 0 ℃ and a molar ratio of cyanogen chloride to reactive hydroxy groups of phenol to 1.0 to 1.2, before the reaction components come into contact with each other. Diluted by the reaction mixture circulating in
At the same time, a method is provided in which a flow of the reaction mixture corresponding to the amount of the reaction components fed is fed in such a way that it is withdrawn from the circulation path. 2. The method according to claim 1, wherein the molar ratio of cyanogen chloride to reactive hydroxy groups of phenol is 1.0 to 1.1. 3. The tertiary amine, as the tertiary amine, has the formula RR′R ″ N.
[Wherein R, R ′ and R ″ are the same or different and each is a straight chain or branched chain C ₁ to
It represents a C ₆ alkyl group. ] The method of claim 1 or 2, wherein the trialkylamine of 4. The method according to claim 3, wherein triethylamine is used as the tertiary amine. 5. The method according to claim 1, wherein an organic solvent in which the produced tertiary ammonium chloride is sparingly soluble is used. 6. The process of claim 5, wherein the tertiary ammonium chloride is completely or partially removed from the reaction mixture by filtration or centrifugation. 7. A solvent immiscible with water is used, the reaction mixture optionally after filtration or centrifugation,
Extracting with water, The method in any one of Claims 1-6 characterized by the above-mentioned.