RU2084438C1 - Method of synthesis of 4-alkylpyrocatechins - Google Patents

Abstract

FIELD: organic chemistry and technology. SUBSTANCE: product: compound of the general formula

where: R - tert.-C₄H₉, tert.-C₅H₁₁, tert. -C₆H₁₃, tert.-C₈H₁₇, sec.-C₁₀H₂₁, tert.--C₁₀H₂₁-, cyclo-C₆H₁₁.. Pyrocatechin is alkylated with the corresponding alcohols in presence of catalyst. Alkylation is carried out without solvent using two-fold excess of alcohol and phosphoric acid. Method provides the synthesis of broad series of 4-alkylpyrocatechins. EFFECT: improved method of synthesis. 2 tbl

Description

где R: трет-C₄H₉-, трет-C₅H₁₁-, трет-C₆H₁₃-, трет-C₈H₁₇-, втор-C₁₀H₂₁-, трет-C₁₀H₂₁-, цикло-C₆H₁₁-.The method of producing 4-alkylpyrocatechins of the general formula

where R: t-C ₄ H ₉ -, t-C ₅ H ₁₁ -, t-C ₆ H ₁₃ -, t-C ₈ H ₁₇ -, sec-C ₁₀ H ₂₁ -, t-C ₁₀ H ₂₁ - , cyclo-C ₆ H ₁₁ -.

 The invention relates to the field of organic chemistry and can be used in the synthesis of alkyl pyrocatechols, which are used in the extraction of metals [1] and also as redoxites [2] in addition, are the starting materials in the synthesis of crown ethers [3] which are used for selective extraction and separation isotopes.

 Known methods for the synthesis of 4-tert-butylpyrocatechol by alkylation of pyrocatechol with isobutyl alcohol in the presence of phosphoric acid [4] and in the presence of KU-2 cation exchange resin [5] and also by alkylation with isobutylene [5, 6] All these methods are limited to the synthesis of one representative and have not been used for other alkyl pyrocatechins, as synthesis technology using solvents did not allow to expand a number of compounds.

 Closest to our proposed method are the methods described in sources [4] and [5] and differing from each other with the used catalysts phosphoric acid or KU-2 cation exchange resin.

 As a prototype, we have chosen the method closest to the synthesis technique [5] The disadvantage of the prototype, in relation to the proposed method, is the use of a solvent in the synthesis, which does not allow the process to be carried out at any temperatures necessary in the synthesis, and thereby obtain an extensive range of products, using different alcohols in the same way. The disadvantages of the prototype, in relation to our chosen goal, include the low thermal stability of KU-2 cation exchanger, it decomposes at the synthesis temperatures of most alkyl pyrocatechins.

 The aim of the invention is to reduce labor costs by simplifying the method, increasing the speed of the process and the yield of products, and to obtain a wide range of compounds that find extensive applications in hydrometallurgy and redox processes.

 This goal is achieved by mixing pyrocatechol with the corresponding alcohol and 85% phosphoric acid and heating at a certain temperature. The method differs from the method chosen as a prototype in that the reaction is carried out in the absence of a solvent with a double volume of the corresponding alcohol, and the initial components are loaded all at once (dropping one component to another is not required); instead of cation exchanger KU-2, phosphoric acid is used. Twice the volume of the original alcohol is necessary to increase the yield of final products. The absence of solvent is required in order to conduct the process at any temperature required by the reaction with any alcohol. In the presence of a solvent, this goal is not achieved, and it is not possible to obtain homologues other than tert-butylpyrocatechol. Obtaining an extensive range of 4-alkylpyrocatechols in the same way, only with a change in temperature, seems to be a promising preparative method that is easy to transfer to industry because of the simplicity of execution and equipment. The replacement of KU-2 cation exchanger with phosphoric acid is necessary to achieve the required reaction temperatures at which the cation exchanger decomposes.

 Example. (General methodology).

 In a round bottom flask equipped with a trap with a reflux condenser, 0.1 mol of catechol, 0.2 mol of alcohol (see Table 1) and 0.2 mol of 85% phosphoric acid are mixed. The mixture is heated in an oil bath, the temperature of the bath is shown in table 1. Synthesis ends within 1-2 hours, as indicated by the cessation of the flow of water into the receiver-trap. The mixture is cooled, 50 ml of water are added and the product is extracted with 150 ml of diethyl ether. The ether extract was washed with water until neutral and dried with anhydrous sodium sulfate. The ether is distilled off, then the starting alcohol. The product is purified by distillation in vacuo. The boiling and melting points, as well as the refractive indices of the compounds are shown in table 1. The product yields in table 1 are given for compounds purified by distillation in vacuo. The systematic names of the reaction products and analyzes of these compounds are presented in table 2 under the same numbers as in table 1.

 Sources of information.

 1. Tarnopolsky Yu.I. Kuznetsova V.S. Borbat V.F. GC. 1976, v. 21, N 8, p. 2196-2199.

 2. Abakumova R. A. Konstantinova G.V. Palchevsky V.V. Vestn. LSU Fiz. Chem. 1988. N2. from. 30-35.

 3. M. Hiraoka. Crown compound. M. Mir, 1986, p. 11-13.

 4. V.D. Tambovtseva. Proceedings of the SAGU. 1953, v. 33. p. 69.

 5. Methods for producing chemical reagents and preparations. IREA. 1964, issue 10, p. 18-19.

 6. L.N. Kirichenko, V.I. Isagulyants. Kinetics, catalysis and petrochemistry. Proceedings of the MINH and GP them. Gubkina, 1962, (2), issue. 37, p. 133.

Claims (1)

The method of producing 4-alkylpyrocatechins of the general formula

where R-tert-C ₄ H ₉ -, t-C ₅ H _{1 1} -, t-C ₆ H _{1 3} -, t-C ₈ H _{1 7} -, sec-C _{1 0} H _{2 1} ,
tert-C _{1 0} H _{2 1} -, cyclo-C ₆ H _{1 1} -,
by heating a mixture of pyrocatechol and the corresponding alcohol in the presence of a catalyst, characterized in that the mixture having a molar ratio of pyrocatechol alcohol phosphoric acid equal to 1 2 2 is heated at a temperature of 150 210 ^o C for 1 2 hours

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