JPH0313229B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved process for producing monothio-bisphenols, particularly by reacting an alkylated hydroxybenzene with sulfur dichloride in the presence of a carboxamide to produce monothio-bisphenols. Relating to a method of manufacturing.

Generally, thio-bisphenols are made by condensing phenol and sulfur dichloride. 3-Methyl-6-t-butylphenol (i.e. monobutyl-metacresol) in an organic solvent.
4,4'-thio-bis-3-methyl-6-t-butylphenol is produced by condensing the compound with sulfur dichloride ( _SCl2 ). According to past experience,
The preferred solvent for carrying out this reaction is an aliphatic hydrocarbon solvent, with expected yields in the range of 65-70% of theoretical yield. 4,4'-thio-bis-3-methyl-6-tert-butylphenol is a well-known and useful antioxidant for rubbers and plastics.

The inventors have surprisingly found that by adding a catalytic amount of N,N-dialkylcarboxamide to the reaction charge of alkylated hydroxybenzene and sulfur dichloride, the product quality is not adversely affected. It has been found that the yield of desired monothio-bis-phenols can be improved.

According to the method of the invention, alkylated hydroxybenzene is reacted with sulfur dichloride in an inert liquid solvent in the presence of 0.1 to 10% carboxamide, based on the amount of alkylated hydroxybenzene. Using 3-methyl-6-t-butylphenol as the starting material, this reaction can be illustrated by the following equation.

A wide range of hydroxybenzenes can be used as starting materials, such as cresol and resorcinol and their alkylated derivatives. Typical examples of products produced include the following.

(a) When the starting material is a monoalkylphenol: In the formula, the position of R attached to the benzene ring and the bonding position of sulfur between the phenol groups are shown at unspecified positions, R is an alkyl group bonded to alkylated hydroxybenzene, and the actual R
The position of is determined by the position of R in the starting material.

(b) When the starting material is dialkylphenol: Representative examples of bisphenols that can be produced include the following compounds.

4,4'-thio-bis(2,6-di-tert-butylphenol) 4,4'-thio-bis(2,6-di-sec-butylphenol) 4,4'-thio-bis(6 -tert-butyl-metacresol) 2,2'-thio-bis(6-tert-butyl-4-
ethylphenol) (c) If the starting material is an alkylated resorcinol: N, N, which is an additive used in the method of the present invention
-Dialkylcarboxamides are known compounds that are commercially available and can be easily produced by known methods, and are represented by the following structural formula.

In the formula, R ₁ is a group selected from the group consisting of hydrogen, an alkyl group, a cycloalkyl group, an aralkyl group, a lower alkoxy group and a lower dialkylamino group,
R ₂ and R ₃ are groups selected from the group consisting of alkyl groups and aralkyl groups, and R ₁ , R ₂ and R ₃ are also
Pairs may be taken together to represent a common member of a heterocycle containing a carboxamide nitrogen atom.

Preferred catalysts are N,N-substituted carboxylic acid amides. Amides of this type can be derived from lower fatty acids such as formic acid and acetic acid, and can also be derived from higher fatty acids such as lauric acid. Of course,
Amides of fatty acids having a suitable number of carbon atoms, for example up to 7 carbon atoms, are also suitable. Among fatty acid amides, fatty acid amides derived from fatty acids having four or fewer carbon atoms generally give the best results. In addition to fatty acid amides, aryl-substituted aliphatic carboxylic acids such as phenyl acetic acid
acids) can also be used. It is also possible to use amides of alicyclic carboxylic acids such as hexahydrobenzoic acid.

Suitable compounds can also be derived from aliphatic and aryl-substituted aliphatic amines and polymethyleneimines. Among the alkyl-substituted amines, amines having a substituent having 4 or less carbon atoms, particularly amines having an ethyl group or a methyl group, are preferred. As used herein, the term "lower alkyl group" means
It means an alkyl group having 4 or less carbon atoms. Acid amides derived from alicyclic imines having 5- to 7-membered rings are also suitable as catalysts.

Lactams such as pyrrolidone, caprolactam and enantactic lactams, which are substituted in the N position by lower alkyl groups, especially ethyl or methyl groups, can also be used as catalysts. Alkyl-substituted compounds, especially lower alkyl group-substituted compounds are preferred.

In general, catalysts derived from formic acid and lower aliphatic secondary amines, or catalysts derived from formic acid and 5- to 6-membered lower alicyclic imines, and lactams N-substituted with lower alkyl groups. gives the best results.

Examples of suitable catalysts include N,N-dimethylformamide, N,N-diethylformamide,
N,N-dibutylformamide, N-formylpiperidine, N,N-diethylacetamide, N-acetylpyrrolidine, N,N-dimethylpropionamide, N,N-dimethylstearamide,
N-methylpyrrolidone, N-ethylcaprolactam, N,N-dimethylbenzamide, N-formylpyrrolidone, N-formylhexamethyleneimine, N,N'-diformylpiperazine, N,N-
Mention may be made of dicyclohexylformamide, piperidine butyrate, dipropyl butyrate, diethyl isobutyrate, dimethyl hexahydrobenzoate, dimethyl laurate and N-cyclohexylpyrrolidone.

The amount of catalytic N,N-dialkylcarboxamide used can vary within the range of 0.1% to 10% relative to the weight of hydroxybenzene. If the amount of carboxamide is less than 0.1%, there will be no appreciable effect. Even if the amount of carboxamide exceeds 10%, the improvement in yield is not significant. The preferred amount of carboxamide used is based on the weight of cresol,
Approximately 0.2% to 2.0% by weight.

This reaction proceeds in a liquid medium. Examples of organic solvents commonly used to dissolve hydroxybenzene and catalyst include aliphatic hydrocarbons such as butane, pentane, hexane, isohexane, heptane, isoheptane, octane, isooctane, and cyclopentane, cyclohexane,
Alicyclic hydrocarbons such as methylcyclohexane can be mentioned. Solvent mixtures are also suitable for use.
Halogenated hydrocarbons, aromatic hydrocarbons, ethers and esters can also be used, provided they are inert to the sulfur dichloride and carboxamide catalysts. The amount of solvent used is usually 1/2 to 10 parts by volume, preferably 2 to 5 parts by volume per 1 part by weight of hydroxybenzene.

Preferably, stoichiometric amounts of reactants are used, taking into account that 1 mole of sulfur dichloride reacts with 2 moles of hydroxybenzene, but sulfur dichloride to 2 moles of hydroxybenzene is preferably used. The amount used can vary between 0.8 and 1.2 moles.

The reaction between sulfur dichloride and hydroxybenzene is an exothermic reaction. Temperature can be easily controlled by mixing of the reactants, dilution of the reactants, gradual addition of sulfur dichloride, external cooling, etc. Under a wide range of temperatures and pressures, e.g. under atmospheric pressure
The reaction can be carried out at a temperature of 0° to 85°C, preferably 25°C to 45°C.

Pressure has little effect other than potentially interfering with HCl removal. Lower temperatures will of course slow down the reaction rate, but lower temperatures provide better selectivity of the reaction, and higher temperatures will result in undesirable side reactions. Preferably, the reaction is run at 15° to 25°C under atmospheric pressure until the reaction is nearly complete, and then, if desired, the reactants are heated to reflux and kept under reflux conditions until no more HCl is evolved. to continue the reaction.

Preferably, the raw materials are charged into the reactor in the following order. Sulfur dichloride dissolved in an organic solvent is added dropwise at a controlled rate to a solution of cresol and carboxamide catalyst dissolved in an organic solvent such that hydrogen chloride gas is constantly evolved as a result of the reaction.

After the reaction is complete, the reactants are cooled to a temperature between 0° and 25°C. The precipitate consisting of thio-bisphenol is generally separated by filtration, washed with an organic solvent and, if desired, further washed with water and finally dried.

The present invention will be further explained below with reference to Examples.

Example 1 Stirrer, thermometer, reflux condenser and 500ml
In a 2-volume flask with a 633-volume dropping funnel,
212 g (1.24 mol) dissolved in g of n-hexane
3-methyl-6-tert-butylphenol, a commercially available product (96%), and 1.1 g of N-N-dimethylformamide (0.5% relative to the weight of the alkylated phenol) as catalyst were introduced. Set the reaction temperature to 20°~
96 in 159 g of n-hexane while maintaining at 25°C.
A solution of 68 g (0.63 moles) of % sulfur dichloride was added dropwise to the stirred contents of the flask over 1 2/3 hours. Hydrogen chloride gas evolved as soon as the sulfur dichloride addition began. Reaction mixture 20-25
The mixture was stirred at ℃ for 2 hours and hydrogen chloride was driven off with nitrogen gas. The reaction mixture was heated to reflux temperature (63°C) and refluxed for 1 2/3 hours to complete the condensation reaction. The mixture was then cooled to 20°-25°C and filtered. 282 g of the residue was washed with 1128 g of n-hexane and filtered. The residue was washed again with 1000 g of n-hexane, spread on paper and air-dried.
166 g (75.1% of theoretical yield) of 4,4'-thio-bis-3-methyl-6-tert-butylphenol was obtained, which had a capillary melting point of 160 DEG C. and an off-white color.

Example 2 In a 500 ml flask equipped with a thermometer, stirrer, addition funnel and reflux condenser, 33.3 g (0.2 mol) of commercially available 3-methyl-6-tert-butylphenol (purity: 97%) were added. 150 ml of n-hexane and 3.0 g (9% by weight relative to the weight of alkylated phenol) of N,N-dimethylformamide were charged. While stirring the above solution, add 10.8g
(0.1 mol) of commercially available sulfur dichloride (purity: 95%)
When sulfur dichloride was added dropwise over 85 minutes at 19° to 25°C, hydrogen chloride was generated immediately after the start of dropping sulfur dichloride. The stirred reaction mixture was held at room temperature for an additional 68 minutes, then held at 24°-46°C for 167 minutes before being cooled to 25°C and filtered. 50 solid product
After washing with 50 ml of n-hexane and 50 ml of water and drying, a gray-white 4,4'-thio-bis-
3-methyl-6-tert-butylphenol 29.1g
(81.3% of the theoretical yield) was obtained.

Example 3 The procedure of Example 2 was repeated, except that the catalyst was changed. 0.7 g (0.2% by weight, based on the weight of the alkylated phenol) of N,N-dimethylacetamide was used instead of N,N-dimethylformamide. The crude product was washed with n-hexane,
Dried, crude off-white 4,4'-thio-bis-
3-methyl-6-tert-butylphenol 31.8g
(88.8% of theoretical yield).

Example 4 To a slurry made by adding 133.2 g (0.6 mol) of 4,6-tert-butylresorcinol to 500 ml of n-heptane, 2.7 g of N,N was added with stirring.
- Dimethylformamide (0.2% by weight relative to dibutylresorcinol) was added. A solution of 34.5 g (0.3 mol) of 75% sulfur dichloride dissolved in 100 ml of n-heptane was added over 75 minutes, and the reaction was maintained at 21° to 25° C. (a cold water bath was used to maintain this temperature). temperature). The reaction mixture was continued to be stirred for an additional 20 hours at 24°C, and less hydrogen chloride evolution occurred. At this point, a slow stream of nitrogen was introduced into the reactor to aid in HCl removal. Furthermore, 25° ~ 26
After holding at ℃ for 1.5 hours, the slurry was strained.
The filter cake was washed twice with 50 ml of n-heptane and dried at approximately 100°C/50 Torr (mmHg). 2,2'-thio-bis-4, melting point 217-218°C
86 g (yield: 62%) of 6-di-tert-butylresorcinol was obtained.

Claims (1)

[Claims] 1. In the presence of 0.1 to 10% carboxamide based on the amount of alkylated hydroxybenzene,
A method for producing monothiobisphenols, which comprises reacting alkylated hydroxybenzene with sulfur dichloride in an inert liquid solvent. 2. The method according to claim 1, wherein the alkylated hydroxybenzene is an alkylated phenol. 3. The method according to claim 1, wherein the alkylated hydroxybenzene is an alkylated resorcinol. 4. The method according to claim 1, wherein the carboxamide is a compound represented by the following formula: (In the formula, R ₁ is a group selected from the group consisting of hydrogen, an alkyl group, a cycloalkyl group, an aralkyl group, a lower alkoxy group, and a lower dialkylamino group, R ₂
and R ₃ are groups selected from the group consisting of alkyl groups and aralkyl groups, and R ₁ , R ₂ and R ₃ are also
Pairs may be taken together to represent a common member of a heterocycle containing a carboxamide nitrogen atom. ) 5. The reaction is carried out in a liquid solvent which at least partially dissolves the starting materials, alkylated hydroxybenzene and carboxamide, and which is inert towards sulfur dichloride. the method of. 6. React 3-methyl-6-tert-butylphenol with sulfur dichloride in hexane in the presence of N,N-dimethylformamide until the evolution of by-product hydrogen chloride stops, cool the reaction mixture,
4,4'-thio-bis-3-methyl-6- precipitates
2. Process according to claim 1, characterized in that tert-butylphenol is separated from the reaction mixture. 7. React 3-methyl-6-tert-butylphenol with sulfur dichloride in hexane in the presence of N,N-dimethylacetamide until the evolution of by-product hydrogen chloride stops, cool the reaction mixture,
4,4'-thio-bis-3-methyl-6- precipitates
2. Process according to claim 1, characterized in that tert-butylphenol is separated from the reaction mixture. 8. 4,6-di-tert-butylresorcinol is reacted with sulfur dichloride in heptane in the presence of N,N-dimethylformamide until the evolution of the by-product hydrogen chloride stops, and then the product 2,2 2. Process according to claim 1, characterized in that '-thio-bis-di-tert-butylresorcinol is separated from the reaction mixture.