DE2202064C3 - Process for the production of chlorinated, brominated and / or nitrated phenyl (meth) acrylates - Google Patents

Description

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It is known that phenyl acrylates and methacrylates can be ethylenically obtained by reacting the chlorides mentioned unsaturated acids with phenols in the presence of hydrochloric acid acceptors, e.g. B. triethylamine or To produce alkali carbonates in inert solvents (U.S. Patent 32 07 731). - The immediate esterification, i.e. H. the conversion of (meth) acrylic acid with phenols, in the presence of acidic catalysts leads to a low conversion only with weakly acidic phenols, while the more acidic chlorine- or bromine-substituted phenols practically do not react. Finally be on that Method of reacting (meth) acrylic anhydride with phenols in the presence of acidic or basic ones Catalysts pointed out - a process that is economical because of the use of expensive anhydrides has gained no meaning.

In J. allg. Chemie 26 [88], 1956, 1127-1130, J. A. Arbuzova et al. about the action of Thionyl chloride on a mixture of chlorophenol and methacrylic acid has been reported. While the implementation of 2,4,6-trichlorophenol and pentachlorophenol with methacrylic acid and thionyl chloride in yields of 61 and 59%, respectively, of the corresponding chlorophenyl methacrylates led, our own experiments with the conversion of 2,4,6-tribromophenol only resulted in a yield of around 12% on tribromophenyl methacrylate. Especially the bromine-substituted phenyl (meth) acrylates come, such as. B. in the already mentioned US-PS 32 07 731 is detailed, as a comonomer in the production or not flame-retardant polymerisation plastics are of considerable importance.

It has now been found that chlorinated, brominated and / or nitrated phenyl (meth) acrylates can be prepared by reacting the corresponding chlorine, bromine and / and nitrophenols with (meth) acrylic acid and thionyl chloride with yields improved compared to the known processes, if one or more of the phenols mentioned with thionyl chloride and an iron-containing Lewis acid in an inert diluent, eg. For example, benzene or cyclohexane, mixed into this mixture with stirring (meth) acrylic acid enters, at temperatures between 20 to 150 ⁰ C, conveniently at temperatures between 40 and 8O ⁰ C, allowed to react with each other and formed in the esterification volatile products HCI and SO2 is blown out during and / or after the reaction at a temperature below the boiling point of the phenyl ester formed using air or an inert gas

The isolation of the crude ester formed is done in such a way that the reaction mixture with a Washes alkaline solution, binds free hydrochloric acid, sulphurous acid and unreacted starting materials, the aqueous solution of the solution of the ester formed in the organic inert solvent through Phase formation separates and, optionally after previous Drying with z. B. sodium sulfate, the organic solvent is distilled off from the crude ester obtained can in a simple manner by recrystallization z. B. from a lower alcohol of the pure ester be won.

Iron (3) chloride, iron sulfate, iron acetate and iron (meth) acrylate are available as iron-containing Lewis acids Use. While mono- to pentachlorinated and brominated according to the process of the invention Phenols could be converted, for obvious reasons (risk of explosion) only the Produced mono- and dinitrophenyl methacrylates

Even if, according to previous knowledge, the substituted monophenols, especially the brominated ones Monophenols as a reaction component of the new process are of greater technical importance it deserves to be noted that also substituted di- and triphenols according to the present invention Invention can be esterified with (meth) acrylic acid. The resulting di- and trimethacrylates result in the copolymerization with other ethylenically unsaturated compounds crosslinked copolymers, in special cases instead of the common crosslinking agents such as divinylbenzene or ethylene glycol dimethacrylate, can be used.

In carrying out the process of the invention, especially in the esterification by heating the reaction mixture to temperatures from 40 to 8O ⁰ C, it is convenient or necessary to the polymerization of the free (meth) acrylic acid and / or from this resulting Phenyiesters by the addition of To prevent inhibiting agents of the type known per se. Such an inhibition can already be achieved, for example, by means of air blown through the reaction mixture.

example 1

In 250 ml of cyclohexane, 66.2 g (0.2 mol) of 2,4.6-tribromophenol, 25.0 g (0.21 mol) of thionyl chloride, 0.66 g of ferric chloride and 0.066 g of hydroquinone and heated to 40 ⁰ C. 17.2 g (0.2 mol) of methacrylic acid are added dropwise within 30 minutes with vigorous stirring. After addition was complete, air is passed through the reaction solution and the reaction mixture to 75 to 8O ⁰ C heated at this temperature is stirred for 2 hours After cooling to room temperature, the acidic components with 10% strength sodium hydroxide solution extracted is then washed with water until neutral , dried the organic phase with anhydrous sodium sulfate and stripped off the cyclohexane on a rotary evaporator. The yellow, oily crude ester obtained slowly crystallizes out at room temperature. By recrystallization from approximately the same amount

Methanol to obtain 65.4 g of the pure 2,4,6-Tribromphenylesters (yield 82% of theory -. M.p .: 64-65 ⁰ C).

The phenol can now be obtained from the alkaline washing water in a simple manner in such a way that the _{blow-off gases containing HCl s and SO 2} are introduced into the alkaline washing water, 2,4,6-tribromophenol precipitating as a sparingly water-soluble substance and recovering it by filtration can be. Recovery is recommended for both economic and wastewater hygiene reasons.

Example 2
2,4,6-tribromophenyl acrylate

In 1000 ml of cyclohexane, 331.0 g (1 mol) of 2,4,6-tribromophenoI, 119.0 g (IMoI) of thionyl chloride, 3.0 g of iron trichloride and 0.3 g of hydroquinone dissolved and heated to 45 ° C with vigorous stirring 72.0 g (1 mol) of acrylic acid were added dropwise over the course of 60 minutes The reaction solution is passed and the reaction mixture is heated to 60-65 "C. At this temperature, it is heated Stirred for 3 hours. After cooling to room temperature, the acidic constituents are treated with 10% strength Sodium hydroxide solution is extracted. Then it is washed with water until a neutral reaction occurs organic phase dried with anhydrous sodium sulfate and the cyclohexane on a rotary evaporator deducted. 328.0 g of 2,4,6-tribromophenyl acrylate are obtained (yield 85.2% of theory, melting point: 72 ° C.).

Example 3
2,4,6-trichlorophenyl methacrylate

In 500 ml of cyclohexane, 78.8 g (0.4 mol) of 2,4,6-trichlorophenol, 50 g (0.42 mol) of thionyl chloride dissolved 0.79 g of ferric chloride and 0.88 g of hydroquinone and ⁰ to 40 C heated with vigorous stirring within 10 minutes 34.4 g (0.4 mol) of methacrylic acid are added dropwise upon complete addition, air is passed through the reaction solution and the reaction mixture heated to 75-80 ⁰ C. at this temperature, stirred for 2 hours After cooling, the acidic constituents are extracted with 10% sodium hydroxide solution at room temperature. It is then washed with water until the reaction is neutral, the organic phase is dried with anhydrous sodium sulfate and the cyclohexane is stripped off on a rotary evaporator. 90.0 g of crude yield is worked up by distillation. 78.4 g of 2,4,6-trichlorophenyl methacrylate are obtained (yield 73.8% of theory, melting point: 35 ° -39 ° C., boiling point).

Example 4
Pentachlorophenyl methacrylate

In 250 ml of carbon tetrachloride 53.3 g (0.2 mol) of pentachlorophenol, 25.0 g (0.21 mol) of thionyl chloride, 0.53 g of ferric chloride and 0.05 g of hydroquinone and heated to 6O ⁰ C with vigorous stirring be within 20 minutes. 17.2 g (0.2 mol) of methacrylic acid was added dropwise upon complete addition, air is passed through the reaction solution and the reaction mixture to 7O ⁰ C erwännt at this temperature 2> / stirred for 2 hours After cooling to room temperature the acidic constituents are shaken out with 10% NaOH. Then it is washed with water until the reaction is neutral, the organic phase is dried with anhydrous sodium sulfate and the solvent is stripped off on a rotary evaporator. Recrystallization from three times the amount of ethanol gives 57.7 g of the pure pentachlorophenyl ester (yield 86.2% of theory, melting point: 89 ° C.).

Example 5
p-nitrophenyl methacrylate

55.6 g (0.4 mol) of p-nitrophenol, 50.0 g (0.42 mol) of thionyl chloride, 0.56 g of iron trichloride and 0.05 g of hydroquinone are dissolved in 500 ml of benzene and heated to 45 ° C. Unter vigorous stirring, 34.4 g (0.4 mol) of methacrylic acid are added dropwise within 45 minutes. After addition was complete, air is passed through the reaction solution and the reaction mixture to 65-70 ⁰ C is heated at this temperature is stirred for 4 hours After cooling to room temperature, the acidic components with 10% strength sodium hydroxide solution extracted is then washed with water until neutral , dried the organic phase with anhydrous sodium sulfate and stripped off the solvent on a rotary evaporator. Recrystallization from four times the amount of methanol gives 48.0 g of the pure p-nitrophenyl ester (yield 58.0% of theory, melting point: 94 ° C.).

Example 6
2,5-dichlorophenyl methacrylate

In 265 ml of cyclohexane, 34.5 g (0.21 mol) 2,5-dichlorophenol, 26.2 g (0.22 mol) thionyl chloride, 0.35 g of iron trichloride and 0.04 g of hydroquinone dissolved and heated to 45 ° C. While stirring vigorously 18.2 g (0.21 mol) of methacrylic acid within 10 minutes added dropwise. When the addition is complete, air is passed through the reaction solution and the reaction mixture is heated to 70-75 ° C. At this temperature is stirred for 2 hours. After cooling to room temperature, the acidic components are with 10% sodium hydroxide solution extracted, then washed with water until a neutral reaction, the organic phase dried with anhydrous sodium sulfate and the cyclohexane on a rotary evaporator deducted.

45.0 g of yellow-colored 2,5-dichlorophenyl methacrylate are obtained (yield 91.8% of theory).

After distillation (bp yield 74.0% d.Th, _u. 98 ⁰ C, m.p .: 44 ° C) to obtain 36.2 g of 2,5-DichIorphenylmethacrylat.

Claims (1)

Claim: Process for the production of chlorinated, brominated and / or nitrated phenyl (meth) acrylates by reacting a chloro-, bromo- and / or nitrophenol with (methacrylic acid and thionyl chloride at temperatures between 20 and 150 ⁰ C, characterized in that one or more Mixes the phenols mentioned together with thionyl chloride and an iron-containing Lewis acid with an inert diluent, in this mixture with stirring (methacrylic acid enters, the volatile products HCl and SO2 formed during the esterification during and / or after the reaction at a temperature below the boiling point the phenyester formed is blown out by means of air or with an inert gas and unreacted reactants and the diluent are separated from the crude ester formed in a manner known per se. 10