阅读说明：本技术 一种对位取代酚的氧化方法 (Method for oxidizing para-substituted phenols ) 是由 衷晟 王继斌 于 2018-07-20 设计创作，主要内容包括：本发明提供一种以双氧水为氧化剂,钼化合物为催化剂,氧化石墨烯和溴化物为助催化剂,在水相溶液中将对位取代酚高转化率和高选择率氧化成醌醇和过氧醌醇的方法。本法的优点是合成工艺简单且安全环保,产品分离容易,能耗低,产品纯度和收率高。(The invention provides methods for oxidizing para-substituted phenol into quinol and peroxyquinol with high conversion rate and high selectivity in aqueous phase solution by using hydrogen peroxide as an oxidant, a molybdenum compound as a catalyst and graphene oxide and bromide as cocatalysts.)

The oxidation method of substituted phenols is characterized in that hydrogen peroxide is used as an oxidant, a molybdenum compound is used as a catalyst, graphene oxide/graphene and a bromine compound are used as catalytic assistants, and the oxidation reaction of para-substituted phenol is carried out in a water-phase solvent or a water-organic mixed solvent.

2. The method of claim 1, wherein the substituted phenol has the general structural formula,

wherein: r₁= H or-CH₃or-C₂H₅or-C₃H₇or-C₄H₉，R₂= H or-CH₃or-C₂H₅or-C₃H₇or-C₄H₉，R₃= -CH₃or-C₂H₅or-C₃H₇or-C₄H₉。

3. The molybdenum compound catalyst according to claim 1, which comprises molybdenum trioxide and/or an alkali metal molybdate and/or an alkaline earth metal molybdate, etc., in an amount of 0.005 to 0.5 times, preferably 0.05 to 0.3 times the amount of the raw material phenol substance.

4. The oxidant of claim 1 is hydrogen peroxide, the concentration range of the oxidant is 5-80%, preferably 30-50%, the dosage of the hydrogen peroxide is 1-10 times, preferably 1-5 times of the dosage of the raw material phenol substance, and the adding mode can be continuous adding or multiple times of batch adding.

5. The solvent according to claim 1, which is an aqueous phase of mono , or a water-organic mixed solvent, wherein the organic solvent may be a lower alcohol of C1-C6, a ketone of C3-C6, or an ether miscible with water, and the volume ratio of the organic solvent to water is 10: 1-1: 10, preferably 5: 1-1: 5, such that the concentration of the raw material is 0.2 mol/L-2 mol/L.

6. According to claim 5, the solvent is made alkaline by alkali, the alkali comprises alkali metal or alkaline earth metal hydroxide and/or alcoholate and/or hydride, wherein the amount of the substance added with alkali is 0.1-10 times, preferably 0.2-5 times of the raw material phenol.

7. The method according to claim 1, wherein the oxidation reaction requires graphene oxide/graphene as a promoter, and the addition amount of the graphene oxide/graphene is 0.1-10%, preferably 0.5-5% of the mass of the raw material phenol.

8. The method according to claim 1, wherein a bromine compound is used as a co-catalyst in the oxidation reaction, and the bromine compound comprises an alkali metal bromide and/or an alkaline earth metal bromide and/or ammonium bromide and/or an alkylammonium bromide, and the amount of the bromine compound is 0.01 to 0.5 times, preferably 0.05 to 0.3 times, the amount of the phenol material.

9. The process of claim 1, wherein the reaction temperature is usually 10 ℃ to 60 ℃.

10. The method of claim 1, wherein the product has the general structural formula

Quinonol peroxyquinol

Wherein: r₁= H or-CH₃or-C₂H₅or-C₃H₆or-C₄H₉，R₂= H or-CH₃or-C₂H₅or-C₃H₆or-C₄H₉，R₃= -CH₃or-C₂H₅or-C₃H₆or-C₄H₉。

Technical Field

The invention relates to a method for obtaining quinol and peroxyquinol by oxidizing para-alkyl substituted phenols.

Technical Field

The method for oxidizing para-substituted phenol reported at present comprises an electrolytic method, a photocatalytic oxidation method, a chemical oxidation method and the like, wherein the electrolytic method and the photocatalytic oxidation method are not industrially applied due to low oxidation efficiency and poor selectivity, and the chemical oxidation method comprises oxidation of an organic oxidant, oxidation of an inorganic salt, oxidation of oxygen and oxidation of hydrogen peroxide according to different oxidants, wherein the oxygen and the hydrogen peroxide are considered as the cleanest oxidants and are also hot spots of current research.

U.S. Pat. No. 3,489,818 reports a method for oxidizing 2, 4, 6-trimethylphenol under alkaline conditions with oxygen as an oxidizing agent, wherein the conversion rate of phenol is 70-80%, and the selectivity of quinol is about 60-70%; US patent 4164516 reports a method for oxidizing 2, 4, 6-trimethylphenol by using oxygen as an oxidant, a Salen-Co complex as a catalyst and amine and triphenylphosphine as auxiliaries, wherein the conversion rate of the phenol can reach 100 percent at most, the selectivity of the quinol can reach 95 percent, but the catalyst and the product of the system are difficult to separate and are not applied industrially; US4560801 and US4612401 disclose the process of oxidizing 2, 4, 6-trimethylphenol with chlorine as oxidant in alkali condition, phenol converting rate up to 98% and quinol selectivity up to 90%U.S. Pat. No. 4,65895 reports a method for oxidizing 2, 4, 6-trimethylphenol with manganese dioxide as an oxidizing agent under sulfuric acid conditions, the conversion of phenol can reach up to 100%, the selectivity of quinol is about 65-70%, European patent WO2012107877A1 and Chinese patent CN201280008069 both report and methods for oxidizing 2, 4, 6-trimethylphenol with singlet oxygen released from hydrogen peroxide by using a bismuth compound as a catalyst, in which the conversion of phenol can reach up to more than 90%, and the selectivity of quinol and peroxyquinol is about 75%, Jean-Marie Auby, et c, Tetrahedron Letters, 43 (2002), 8731,8734, and basic H with molybdate as a catalyst₂O₂A method for oxidizing 2, 4, 6-trimethylphenol by releasing singlet oxygen from a solution, in which the conversion of phenol can reach more than 100%, but the selectivity for quinol and peroxyquinol is not given (after repeating the experiments of the document, the researchers of the present invention have found that the selectivity for quinol and peroxyquinol is between 60% and 70%). The document M. Carmen Carreo, etc., Angew. chem. int. Ed., 2006, 45, 2737-₃CN/H₂O is used as solvent to oxidize the para-substituted phenol, so as to obtain the quinol yield of over 90 percent.

Disclosure of Invention

Aiming at the defect of existing in the existing catalytic systems, researches on the method for synthesizing the quinol and the peroxyquinol by oxidizing the para-substituted phenol by using hydrogen peroxide as an oxidant, a molybdenum compound as a catalyst and graphene oxide and bromide as cocatalysts are developed by simpler, green and economic methods for synthesizing the quinol and the peroxyquinol by oxidizing the para-substituted phenol by the oxidation.

The technical scheme adopted by the invention is as follows:

the oxidation reaction of para-substituted phenol is carried out in a water phase solvent or a water-organic mixed solvent by using hydrogen peroxide as an oxidant, a molybdenum compound as a catalyst and oxidized graphene/graphene and a bromine compound as a catalytic assistant.

Technical scheme in the method, the general structural formula of the substituted phenol is,

wherein: r₁= H or-CH₃or-C₂H₅or-C₃H₆or-C₄H₉，R₂= H or-CH₃or-C₂H₅or-C₃H₆or-C₄H₉，R₃= -CH₃or-C₂H₅or-C₃H₆or-C₄H₉。

In the method of the technical scheme, the molybdenum compound catalyst comprises molybdenum trioxide and/or alkali metal molybdate and/or alkaline earth metal molybdate, and the dosage of the molybdenum compound catalyst is 0.005-0.5 time, preferably 0.05-0.3 time of the dosage of the raw material phenol substance.

In the method of the technical scheme, the oxidant is hydrogen peroxide, the concentration range of the oxidant is 5% -80%, preferably 30% -50%, the dosage of the hydrogen peroxide is 1-10 times, preferably 1-5 times of the dosage of the raw material phenol substance, and the adding mode can be continuous adding or multiple times of batch adding.

In the method of the technical scheme, the solvent can be a water phase of mono , or can be a water-organic mixed solvent, wherein the organic solvent can be a lower alcohol of C1-C6, or a ketone of C3-C6, or an ether miscible with water, and the volume ratio of the organic solvent to the water is 10: 1-1: 10, preferably 5: 1-1: 5, and the amount of the solvent is such that the amount concentration of the raw material substance is 0.2 mol/L-2 mol/L.

In the method, a solvent needs to be adjusted to be alkaline by alkali, the alkali comprises alkali metal or alkaline earth metal hydroxide and/or alcoholate and/or hydride, and the amount of the substance added with the alkali is 0.1-10 times, preferably 0.2-5 times of that of the raw material phenol.

In the method of the technical scheme, graphene oxide/graphene is used as a cocatalyst in the oxidation reaction, and the addition amount of the graphene oxide/graphene is 0.1-10%, preferably 0.5-5% of the mass of the raw material phenol.

According to the technical scheme, in the method, a bromine compound is required to be used as a cocatalyst in the oxidation reaction, the bromine compound comprises alkali metal bromide and/or alkaline earth metal bromide and/or ammonium bromide and/or alkyl ammonium bromide and the like, and the addition amount of the bromine compound is 0.01-0.5 times, preferably 0.05-0.3 times of the amount of the raw material phenol substance. .

Technical scheme in the method, the reaction temperature is usually 10-60 ℃.

In the method of the technical proposal, the general formula of the product structure is

Quinonol peroxyquinol

Wherein: r₁= H or-CH₃or-C₂H₅or-C₃H₇or-C₄H₉，R₂= H or-CH₃or-C₂H₅or-C₃H₇or-C₄H₉，R₃= -CH₃or-C₂H₅or-C₃H₇or-C₄H₉。

The invention makes a great improvement on the method reported in the document Jean-Marie Auby, etc., Tetrahedron Letters, 43 (2002), 8731-8734, and obtains more excellent effect. Firstly, water is used as a solvent, so that a reaction product is easier to separate, and the product can be separated from a reaction system by simple extraction; secondly, graphene oxide/graphene is adopted as a cocatalyst, and the effect is as follows: the graphene oxide/graphene can be stably dispersed in a solvent system mainly containing water, so that the electron transmission capability in the oxidation-reduction process is enhanced, the reaction rate is improved, the reaction activation energy is reduced, and meanwhile, the graphene oxide/graphene can form a pi-pi effect with phenol, thereby being beneficial to the oxidation of the phenol; and thirdly, the reaction system adopts bromide as a cocatalyst, so that the oxidation reaction process is changed, and the utilization rate of hydrogen peroxide is improved.

Detailed Description