CS255399B1 - Process for preparing monomeric beuzoquinanes by oxidation of mono- and dimethyl-substituted phenols - Google Patents

Abstract

The solution relates to a method for preparing monomeric benzoquinones by oxidation of mono· and dimethylsubstituted phenols. The essence of the solution lies in the fact that a solution of Cu(l)-Cl ” — substituted phenol — acetonitrile with concentrations of Cu(I) 1 : 10 -2 to 1 . TO -1 mol . . dm -3 , phenol 1 : 10 _1 to 2 . 10' 1 mol . . dm' 3 and a molar ratio (Cu(I)j : (Cl - ] equal to 1 : 6 to 1 : 10 is oxidized with dioxide at atmospheric pressure in a glass reactor at a temperature of 15 to 40 °C during irradiation with polychromatic light with a wavelength of more than 320 nm for a period of over 60 minutes.

Description

3 4 255399

The present invention relates to a process for the preparation of mono-benzoquinones by oxidation of mono-adimethyl-substituted phenols under the catalytic action of complexes, allowing under moderate conditions a high quinone yield and a high selectivity.

Benzoquinones are industrially used as oxidizing agents, they are intermediates for the synthesis of many organic substances, and are used for the preparation of polymeric substances as reducing agents, antioxidants, etc.

The essence of most of the proposed benzoquinone processes is the oxidation of alkyl-substituted phenols with a suitable oxidizing agent in the condensed phase with or without the presence of a catalyst. Peroxidation systems have hitherto been utilized with peroxyacetic acid (Jap. Pat. 55-95231), manganese dioxide (DOS 502 332), and dioxygen in the presence of a cobalt-malcomium complex (Jap.Pat. 54-28895), respectively. salcomin (DE 2 460 665C2; Rec. Trav. Chim. Pays-Bas, 36 [1967] 520) and metal oxides, peroxides, peroxygen (AO CSSR 207 934). The disadvantages of the aforementioned processes are in particular low quinone yields and byproducts. An increase in conversion and selectivity can be achieved, for example, by increasing the temperature; taknapr. while 2,6-dimethyl-β-benzoquinone in 25.0% yield (AO CSSR 207,934) was obtained in 4 hours at 20 ° C in the dimethylphenol-salcomine-oz system, at 65 ° C 2,5-dimethyl-p-benzoquinoline with 87% conversion and 90% selectivity (DE 2 460 665 C2). The use of Cu (II) tertiary amine catalyst complexes resulted in the presence of O2 to form a polyphenylene ether (or diphenoquinone) mixture (U.S. Pat. No. 3,306,874; U.S. Pat. No. 3,306,875; U.S. Pat. No. 3,110,384); dimeric quinones are also formed in the alkyl substituted phenol-Cu ion-halide-O 2 system (Fr. 1 325 480; DE-OS 2 221624). Other media complex systems require autoclaving at elevated temperature and pressure; for example, in the case of oxidation of substituted phenols with O 2 in the presence of Cu (I), Cu (II) salts, carboxylates and phenoxide, it was worked up in an autoclave at 60 ° C (Eur.Pat. Appl. 15, 22103), respectively. at a temperature of up to 150 ° C and a pressure of up to 103 bar in the presence of Cu (I) or Cu (II) ions, CN-, SCN-, NCO- and metal (DE 2 444 234 C2). In the analogous Cu (I) - Cu (II) system (GB Pat. 1511813), a dioxygen was used at a pressure of 7 to 200 atmospheres at a temperature of up to 100 ° C (at least 14 atm for mono- and dialkylphenols). Cu (I) - Gu (II) - Cu ° and Cl ", Br", I ', CN -, SCN ", NCO" ions worked at 30 to 150 ° C (US Patent 3,870,731); however, the conversion of phenol was low even after a longer reaction time. Some mono- and dimethyl-substituted phenols have been oxidized with O 2 in the presence of Cu (I) and / or Cu (II) ions [Cu (II) ions preferably], Cl ",

Br ", I-ions in solution at a pressure of up to 100 bar and a temperature of 50-70 ° C (DE-OS 2 221 624). The yields of the respective monomeric quinones obtained in this way (for 3 hours) were in the range of 40.8% (pre-cresol) to 85% (for 3,5-dimethylphenol).

The knowledge of the use of light radiation for the preparation of methyl substituted quinones has not been published.

The above drawbacks are avoided in the preparation of monomeric benzoquinones by the oxidation of mono- and dimethyl-substituted phenols by oxidation in the presence of complex media in an acetonitrile solution, the essence of which is that the Cu (I) -Cl- substituted phenol-acetonitrile solution is concentrated by Cu [I] 1. 10 and 1. 10 [mu] mol-dm-3, phenol 1. 10'1 to 2. 10-1 mol-dm-3 and the molar ratio (Cu (I)): [Cl-] equal to 1: 6 to 1: 10 is oxidized with dicyclic at atmospheric pressure in a glass reactor at 15 to 40 ° C during polychromatic light with a wavelength of more than 320 nm for more than 60 minutes The advantages of the above-mentioned process for the preparation of monomeric substituted benzoquinones are, in comparison with published processes, mainly in lower energy intensity, under mild reaction conditions (room temperature and atmosphere) the use of inexpensive and available chemicals, high phenol conversions (up to 100%), high yields of quinones (up to 98%) with high selectivity (up to 98%) and simple conversion in the glass reactor. There is a 1 ný arbitrary source of radiation emitting light with a wavelength of more than 320 nm, which makes it possible to use solar radiation, making the process more energy-efficient. For extended.

The subject matter of the invention is described by way of example only without being tied to it. Example 1 0.3362 g of CuCl 2 and 1.4837 g of LiCl were dissolved in 100 cm 3 of acetonitrile with stirring. The brown solution of chloro-diclide complexes with the addition of an excess of powdered medium (~ 1g) was reduced with stirring to a colorless solution of chloroacetate complexes. Thereafter, the solution was passed through a filter (to remove residual powder medium) with an oxygen-filled reaction vessel (150 cm 3 thermostatic glass reactor with flare lamp and magnetic stirring). After the lamp was activated (medium pressure mercury lamp, NARVA 125W ) with a sabbatical dosing arm, 0.5041 g of 1-hydroxy-2-methylbenzene (crystals) was added and the reaction started. The next sidewall was connected to a source of di-oxygen. The reaction was carried out at 293 ° C and

Claims (1)

SUBJECT A process for preparing benzoquinones by oxidation of the monomeric mono- and dimetylsubstituovaných the phenols condensed] phase copper-catalyzed komplexemi characterized in that the solution of Cu (I) - C ^- - Phenol-substituted acetonitrile of the concentration of Cu (I) 1. 10 “ ³ to 1. 10 ^_1 mol. dm ^-3 , phenol 1. vynalezu. 10 “ ¹ to 2. 10 “ ¹ mol. dm ^-3 and the molar ratio [Cu (I) j: [Cl ^- ] = 1: 6 to 1: 10 is oxidized by oxygen at atmospheric pressure in a glass reactor at 15 to 40 degrees Celsius while irradiating with polychromatic light of wavelength more at 320 nm for over 60 minutes.