SU757539A1 - Method of preparing para-carboxyphenylphosphonic acid - Google Patents

Description

The invention relates to the field of 3 chemistry of organophosphorus compounds, and in particular to methods for producing p-carbroxyphenylphosphonic acid and c can be widely used in the chemical industry for the production of plasticizers and monomers used for the synthesis of non-combustible phosphorus-containing polymers and copoly. Merov.

A method of obtaining m-and p-dioxyphosphonyl benzoic acids by the interaction of phenyldiazonium borfluorides and phosphorus trichloride in ethyl acetate in the presence of 15

copper monobromide at room temperature [1 ^.

The disadvantage of this method is the low yield of the target product - 39%.

The closest to the described 20 of the invention to the technical essence and the achieved result is a method of obtaining p-carboxyphenylphosphonic acid by way of-__ actions of methyl benzoate with dialkylphos -. Fitom in a 1: 1 molar ratio of reagents at a temperature of 120-125 ° C in the presence of di-tertiary butyl peroxide in the presence of an initiator, followed by hydrolysis of the obtained phosphonate ®

2

The disadvantage of this method is not a high yield of the target product (65%), associated with the decomposition of low-boiling peroxide, as well as the long duration of the process.

The aim of the invention is to reduce the duration of the process and the yield of the target product.

This is achieved by the described method of obtaining p-carboxyphenylphosphonic acid, which consists in the interaction of methylbenzoate and dialkylphosphite in a molar ratio of reactants 1: 1.2-1.5 at a temperature of 135-145 ° C in an inert gas atmosphere in the presence of an initiator - alkyl peroxide or perefira, temperature boiling which is higher than the temperature of the process, followed by hydrolysis of the obtained phosphonate.

 Distinctive features of the process are to conduct the process at a temperature of 135-145 ° C in an inert gas atmosphere and use as an organic peroxide, an alkyl peroxide or perefir, whose boiling point is higher than 3

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The procedures for carrying out the processes at a molar ratio of methyl benzoate:

: dialkylphosphite as V 1,2-1,5.

Peroxide is introduced into the reaction in a mixture with dialkylphosphite within 2-3 hours, keeping the temperature of the reaction mixture within the specified limits. The peroxide compounds used are: peroxyacetic acid tert-butyl ester, 1,1-di-t-butyl peroxyethane. The amount of peroxide introduced into the reaction is 0.5 mol per 1 mole of methyl benzoate. In the described method, it is also possible to use peroxide in the amount of 0.25 mol per 1 mol of methyl benzoate, which makes it possible to reduce the consumption of the peroxide compound.

The unreacted starting reagents are distilled off under vacuum, and the residue is hydrolyzed to p-carboxyphenylphosphonic acid and isolated by known methods.

The use of high-boiling pertstsnyh compounds allows the process at a temperature of 135-145 ° C, which is the most optimal for the reaction of homolytic substitution in the aromatic compound to the phosphoryl radical. At lower temperatures, the reaction rate decreases, which leads to an increase in the duration of the process, and an increase in temperature above 145 ° C leads to a significant resinification of the initial reagents and final products.

The use of high-boiling peroxide compounds with _{bales of} 180-185 ° makes it possible to carry out the process only in the liquid phase, which ensures the decomposition of the peroxide in methylbenzoate and dialkylphosphite. The use of an excess of dialkylphosphite (20-50 mol.%) Creates a higher concentration of phosphoryl radicals, while a more significant excess does not affect the duration of the process and the yield of the target product, that is, it is not a productive consumption of dimethylphosphite.

Slow dosage of peroxide mixed with dialkyl phosphite causes a constant concentration of free radicals throughout the process.

As a result, it is possible to fully and purposefully use all of the loaded peroxide and reduce its consumption for the flow of adverse free-radical reactions of recombination and decomposition.

This leads to a reduction in the duration of the process and an increase in the yield of carboxyphenylphosphonic acid.

PRI me R 1. A mixture of 14.6 g (0.1 mol) of methyl benzoate and 11.0 g (0.1 mol) of dimethyl phosphite is blown up with dry nitrogen while purging with dry nitrogen.

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145 ° C in a reactor with a stirrer with a thermometer, a dropping funnel, a reflux condenser and a gas supply tube, through which 6.1 g (0.5 mol) of tert-butyl percetate are continuously dosed over 3 hours

5.5 g (0.5 mole) of dimethyl phosphite,. maintaining the temperature of the reaction mixture 145 ° C. The ratio of methylbenzoate: dimethylphosphite is 1: 1-1.5. Next, the reaction mixture is stirred at the same temperature for 3 hours. Unreacted methylbenzoate and dimethylphosphite are returned by distillation in vacuum, the isobutylphosphonic acid dimethyl ester is distilled off at 65-75 ° C, and the residue is yellow-brown in color, hydrolyzed with concentrated hydrochloric acid at boiling for 4 hours.

The resulting bright solution is evaporated in vacuo to a syrup, which crystallizes upon cooling. The precipitated crystals (5.34 g) were extracted with boiling cyclohexane and recrystallized-allylated twice with water, yielding 3.65 g of p-carboxyphenylphosphonic acid with a _melting point of 375-377 ° (yield: 7–9% for methyl benzoate which entered the reaction).

Found,%: C-41.37; H-3.42; Р-15, .26-15,41. "

Calculated,%: C-41.58; H-3.46 ", P-115.34.

Example 2. To a mixture of 13.6 g (0.1 mol) of methyl benzoate and 11.0 g (0.1 mol) of dimethylphosphite heated to 135 ° C in the reactor as described in Example 1, 5 are metered in with a dry nitrogen purge 5, 3 g (0.025 mol)

1,1-di-tertbutylperoxyethane mixed with 2.2 g (0.02 mol) of dimethyl phosphite for 2 hours, maintaining the temperature of the reaction mixture at 135 ° C.

The ratio of methylbenzoate: dimethylphosphite is 1: 1.2.

Then the process is carried out analogously to example 1 and receive 3.55 g of p-carboxyphenylphosphonic acid with a _melting point of 375-376 ⁱⁿ C (yield: 77% for methyl benzoate).

Example 3. The process is carried out similarly to example 2. using as peroxide 1,1-di-tertbutylperoxyethane in the amount of 10.6 g (0.05 mole).

3.53 g of the desired product are obtained with Τη _Λ 375-376 ° C (yield — 77% for the methylbenzoate which has reacted).

Example 4. To heated to 140 ° C a mixture of 12.05 g (0.09 mol) of methyl benzoate and 9.75 g (0.09 mol) of dimethyl phosphite in the reactor, as described in example 1, during purging. . 9.4 g (0, 045 mol) of 1,1-di-t-butyl peroxyethane are dosed with dry nitrogen mixed with 3.5 g (0.032 mol) of dimethyl phosphite for 2 hours, under 5

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keeping the temperature of the reaction mixture 140 ° C.

The ratio of methyl benzoate: dimethyl phosphite is 1: 1.35.

The process is then carried out analogously to example 1 and 3.72 g of p-carboxyl are injected.

yephenylphosphonic acid with a _melting point of 3,75377 ° C (yield: 80% for the methylbenzoate reacted).

The proposed method has in comparison with the known number of advantages, which are reflected in the table.

Comparative indicators of the known and proposed spbsobov obtaining p-carboxyphenylphosphonic acid

Way Peroxide amount peroxide in supposedly on mole methyl benzoate The ratio (mol) of methylbenzoate: dimethylphosphite Temperature process, ° С Time reactions, (hour) Output target product, % Proposed Peroxyacetic acid tert-butyl ester 1,1-di-tertbu 0.5 1: 1.5 145 6 79 tilperoxyethane 0.25 1: 1,2 135 ’ five 77 and _ 0.5 1: 1,2 135 five 77 n 0, 5 1: 1.35 140 five 80 Known- Peroxide di-tertiary butyl 0.5 1: 1 120-125 24 65

As can be seen from the table, the use of 55 high-boiling alkyl peroxides and perefirov and the use of excess dimethyl phosphite (20-50 mol.%) Under certain conditions allows to increase the yield of the target product by 12-15% and reduce the duration of the process by 4-5 times compared with the known .

Claims (1)

Claim The method of obtaining p-carboxyphenylphosphonic acid by the interaction of methyl benzoate with dialkyl phosphite at elevated temperature in the presence of an initiator, organic peroxide 50, followed by hydrolysis of the obtained phosphonate, characterized in that, in order to reduce the duration of the process and increase the yield of the target product, the process is carried out at a temperature of 135145 ° C an inert gas atmosphere; an alkyl peroxide or pereter is used as an organic peroxide, the boiling point of which is higher than the temperature of the process And methyl benzoate and dialkilfosfit take in a molar ratio of 1: 1.2-1.5.