CS232126B1 - Preparation method of p-benzoquinone - Google Patents

Description

The present invention relates to a process for the preparation of p-benzoquinone by photo-assisted phenol oxidation with homogeneously catalyzed complexamide media.

The catalytic oxidation systems of the compounds based on media have been utilized in the oxidation of phenols described above with oxygen. The most commonly used Cu catalysts (Ilj-morpholine described by Brackman (1955), Cu (II) -multi complexes described by Hay (1959), Endres (1963), Finkbeiner (1966), Hewitt (1967), Demmin (1981), CuCl in pyridine described Demmin (1981) and Nishid (1982), the salts of the medium in dimethylformamide described by Hutchings (1975) and Cu (NO3,) 2 described by Tsuruy (1977) usually provide a mixture of quinones, dimers and polymers. CHsCl led to the formation of diphenoquinone as described by Churchill (1980), p-benzoquinone was obtained only in the presence of CuCl 2 in some non-aqueous solvents, as reported by Beltrame (1979) despite claims by Ionezawa (1968) and Blanchard (1962) on catalytic] inactivation of CuCl2 in analogous systems The preparation of p-benzoquinone was accomplished by oxidation of phenol with oxygen, catalyzed by CuCl2 in dimethylformamide, dimethylsulfoxide, 1,4-dioxane and ethylene glycol, described by] Beltram (1979). The reaction was carried out in steel reactors at a temperature of 50 to 110 ° C and an O2 pressure of 3.5 MPa. Information on the effect of light radiation on the yield of p-benzoquinone resulting from the oxidation of phenol with oxygen has not been published.

The above drawbacks are eliminated in the process for the preparation of p-benzoquinone by photo-assisted phenol oxidation homogeneously catalyzed by media complexes with oxygen in acetonitrile medium, the principle being that the Cu (I) -Cl ^- phenol-acetonitrile solution with Cu (I) concentrations of 1.10 ^-3 to 1.10 ^-1 mol.

. dm ³ , phenol 2.10 ^-2 to 2.10 ^-1 mol. dm ^-3 and molar ratio (Cu (I)): [Cl ¹ ] -4-1: 1 to 1:10 is bubbled through oxygen at atmospheric pressure in a glass reactor at 20 to 50 ° C in the dark or during light irradiation o A wavelength exceeding 315 nm for more than 20 minutes.

Irradiation of the solutions resulted in an increase in the yield of p-benzoquinone by 100% relative to the systems bubbled with oxygen in the dark.

In this process, catalytic multiplication of the complexes of the media is utilized, the presence of which is essential for the formation of p-benzoquinone by a mechanism involving the formation of phenoxide radicals and activation of oxygen. Irradiation of the reaction mixture leads to an increase in the concentration of phenoxide radicals resulting from the process of deactivating photoexcited complexes by the medium, resulting in an increase in p-benzoquinone yield.

The advantages of said process for the preparation of p-benzoquinone are, in comparison with the published procedures, mainly in lower energy intensity, in mild reaction conditions such as room temperature and atmospheric pressure, and in the ease of implementation in a simple reactor glass reactor. For simultaneous irradiation experiments, a fubovof radiation source emitting light having a wavelength of more than 315 nm can be used. It is also possible to use light radiation in the form of solar radiation, which makes the process energy-efficient.

Example 1

The reaction mixture was prepared from Cu (I) -Cl ^- acetonitrile stock solutions of Cu (Ij 1 10 ^-1 mol dm ^-3 , LiCl acetonitrile solutions of 1.10 ^-2 mol .. dm ^{-3 by} pipetting a LiCl stock solution and adding solid phenol, respectively by weighing solid LiCl and phenol so that the resulting solution has a Cu (I) concentration of 1.10 ^-1 mol dm ^-3 , molar ratio (Cu (I)). [Cl] = 1: 1 and The concentration of phenol 2.10-f mol dm &^lt; ³ >. Oxygen was introduced into a 50 cm ³ reaction mixture so prepared in a glass-tempered glass reactor at 30 ° C + 1 ° C. After 120 minutes of O2 introduction at atmospheric pressure, The results of thin layer chromatography and elemental organic analysis, melting point values and spectrum spectra were in good agreement with published data or standards, and the concentration of p-benzoquinone formed was determined titration after isolation from the reaction mixture. If the reaction mixture in the reactor was irradiated with the light of a 125 W lamp under other conditions, the unchanged p-benzoquinone yields increased by 100% relative to the initial amount of phenol compared to the non-irradiated solutions.

Example 2

The procedure was as in Example 1 except that the molar ratio in the resulting solution was [Cu (Ij): [Cl ^- ] = 1: 8. The yields of p-benzoquinone were 100% higher than in Example 1, with irradiation under conditions in Example 1, the yield of p-benzoquinone was increased by an additional 100% relative to the non-irradiated solutions.

Claims (1)

SUBJECT A method of synthesis of p-benzoquinone or by thermal oxidation of the phenol fotoasistovanou dikyslíkom in the presence of a copper complex in an acetonitrile was characterized in that the solution composed of Cu (I) Cl phenol acetonitrile, prepared from a stock solution of Cu (I) Cl ^_ acetonitrile, LiCl, and phenol, so that the concentration of CuI (Ij is 1.10 ~ ³ to 1.10 ^-1 mol% dm ^-3 and the molar ratio [Cu (Ij): [Cl ^- ] = 1: 1 to 1: 10, the phenol concentration is 2.10 ^-2 and 10 to 1 mol of dm ^-3 and this is bubbled through oxygen with oxygen at 20 to 50 ° C for more than 20 minutes, or under irradiation with a wavelength greater than 315 nm.