95-87-4Relevant articles and documents
Mediated electron transfer with monooxygenases - Insight in interactions between reduced mediators and the co-substrate oxygen
Tosstorff, Andreas,Dennig, Alexander,Ruff, Anna Jo?lle,Schwaneberg, Ulrich,Sieber, Volker,Mangold, Klaus-Michael,Schrader, Jens,Holtmann, Dirk
, p. 51 - 58 (2014)
One of the most important obstacles to overcome in biocatalysis with monooxygenases is the enzyme's dependency on the costly redox cofactor NAD(P)H. Electrochemical regeneration systems, in which an electrode serves as electron donor, provide an alternative route to enzymatic redox reactions. Mediators are often used to accelerate electron transfer between electrode and enzyme. We investigated the mediated bioelectrochemical conversion of p-xylene to 2,5-dimethylphenol (2,5-DMP) by a P450 BM3 variant and were able to produce 2,5-DMP electrochemically. Due to the fact that mediator reduction is limited by the electrode surface a scale-up was performed. However, increasing the electrode surface area to reactor volume ratio led to a drastic increase in cathodic oxygen reduction, causing a drop in product formation. It was shown that reduced cobalt sepulchrate reacts with the co-substrate oxygen. Furthermore, the reportedly oxygen stable mediator [Cp*Rh(I)(bpy)H] + was compared to cobalt sepulchrate. While its turnover frequency is of comparable magnitude to cobalt sepulchrate when transferring the electrons between electrode and enzyme, using NADP+ as intermediary between the mediator and the enzyme significantly increased the mediator's turnover frequency. The rhodium mediator [Cp*Rh(I)(bpy)H]+ does not appear to be significantly more oxygen stable.
Reaction of hydroxyl radical with arenes in solution—On the importance of benzylic hydrogen abstraction
Waggoner, Abygail R.,Abdulrahman, Yahya,Iverson, Alexis J.,Gibson, Ethan P.,Buckles, Mark A.,Poole, James S.
, (2021/08/27)
The regioselectivity of hydroxyl radical reactions with alkylarenes was investigated using a nuclear magnetic resonance (NMR)-based methodology capable of trapping and quantifying addition and hydrogen abstraction products of the initial elementary step of the oxidation process. Abstraction products are relatively minor components of the product mixtures (15–30 mol%), depending on the magnitude of the overall rate coefficient and the number of available hydrogens. The relative reactivity of addition at a given position on the ring depends on its relation to the methyl substituents on the hydrocarbons under study. The reactivity enhancements for disubstituted and trisubstituted rings are approximately additive under the conditions of this study.
Method for synthesizing 2-5 -dimethylphenol
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Paragraph 0021; 0024-0025; 0028-0087, (2021/02/24)
The invention discloses a method for synthesizing 2,5-dimethyl phenol. The method comprises the steps: utilizing 2,5-dimehtyl-benzenesulfonic acid as a raw material, supercritical distilled water as areaction medium, sodium hydroxide as a catalyst and oxygen as an oxidant; reacting to obtain a 2,5-dimethyl phenol crude product; finally, sequentially filtering, ethanol refining and filtering and drying to obtain a 2,5-dimethyl phenol pure product. The method disclosed by the invention utilizes the supercritical water to synthesize the 2,5-dimethyl phenol, so that the method is the most appropriate method in the present; reaction steps are reduced, and a technological process is shortened; thus, the environmental pollution problem is fundamentally solved, and no three wastes (waste water, waste gas and waste solid) are generated. Therefore, according to the method disclosed by the invention, the technology utilizing the supercritical water to synthesize the 2,5-dimethyl phenol has a very obvious effect.
Method for preparing alcohol and phenol through aerobic hydroxylation reaction of boric acid derivative in absence of photocatalyst
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Paragraph 0025-0028; 0030-0032, (2020/01/25)
The invention discloses a method for preparing alcohol and phenol through aerobic hydroxylation reaction of a boric acid derivative in the absence of a photocatalyst, wherein the boric acid derivativeis aryl boronic acid or alkyl boronic acid, and the corresponding target compounds are respectively a phenol-based compound and an alcohol-based compound. According to the method, by using a boric acid derivative as a reaction substrate, an additive is added under a solvent condition, and a hydroxylation reaction is performed under aerobic and illumination conditions to obtain a corresponding target compound. According to the invention, the new strategy is provided for the synthesis of phenols through aerobic hydroxylation of aryl boronic acid without a photocatalyst; the catalyst-free aerobic hydroxylation method for photocatalysis of aryl boronic acid or alkyl boronic acid by using triethylamine as an additive is firstly disclosed; and the new method has advantages of photocatalyst-freecondition, wide substrate range and good functional group compatibility.
Regioselectivity of Hydroxyl Radical Reactions with Arenes in Nonaqueous Solutions
Moores, Lee C.,Kaur, Devinder,Smith, Mathew D.,Poole, James S.
, p. 3260 - 3269 (2019/03/11)
The regioselectivity of hydroxyl radical addition to arenes was studied using a novel analytical method capable of trapping radicals formed after the first elementary step of reaction, without alteration of the product distributions by secondary oxidation processes. Product analyses of these reactions indicate a preference for o- over p-substitution for electron donating groups, with both favored over m-addition. The observed distributions are qualitatively similar to those observed for the addition of other carbon-centered radicals, although the magnitude of the regioselectivity observed is greater for hydroxyl. The data, reproduced by high accuracy CBS-QB3 computational methods, indicate that both polar and radical stabilization effects play a role in the observed regioselectivities. The application and potential limitations of the analytical method used are discussed.
Method for preparing 2,5-xylenol by catalyzing paraxylene hydroxylation through Bi-MWW
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Paragraph 0015-0019, (2019/05/02)
The invention discloses a method for preparing 2,5-xylenol by catalyzing paraxylene hydroxylation through Bi-MWW. The method comprises the steps that a silicon source, a bismuth source, a crystal seedand boric acid are added into a ball mill successively, grinding is conducted to obtain mixed dry powder, then the dry powder is mixed with water, steaming and drying are conducted at a constant temperature, then static crystallization is conducted in template steam, then a Bi-MWW molecular sieve is obtained through acid washing, the obtained Bi-MWW is mixed with paraxylene and hydrogen peroxideunder a certain solvent system, reacting is conducted at 30-90 DEG C for 1-9 h, and the product 2,5-xylenol can be obtained. Accordingly, Bi is introduced into the MWW molecular sieve through mechanical ball milling one-step dry gel conversion, the C-H bonds of a benzene ring in paraxylene can be well activated, the activity of a paraxylene hydroxylation catalytic system is greatly improved, and the conversion rate of obtained paraxylene can reach 58.5%, and the selectivity of 2,5-dimethylphenol can reach 95.4%. The reaction condition is mild, and the catalyst material property is stable.
Environmentally friendly preparation method for 2,5-dimethylphenol
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Paragraph 0051-0061, (2019/02/13)
The invention relates to an environmentally friendly preparation method for 2,5-dimethylphenol. The preparation method uses 2,5-dimethyl isopropylbenzene as an initial raw material, and obtains 2,5-(dimethyl)phenyl isopropyl peroxide through air or oxygen oxidation under the action of a solvent and a composite catalyst; and 2,5-dimethylphenol can be obtained through direct rearrangement of the obtained peroxide under an acidic condition. The preparation method is cheap and easy in raw material obtaining, convenient in operation, good in reaction selectivity and high in product yield; and by-product acetone can be produced while the 2,5-dimethylphenol is prepared, so that the preparation method is high in reaction atomic economy, less in the three wastes (waste gas, waste water and industrial residue), and low in product cost.
Method for synthesizing high added value xylenol through isomerization of 2,6-dimethylphenol
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Paragraph 0038-0140, (2019/02/08)
The invention discloses a method for synthesizing high added value xylenol through isomerization of 2,6-dimethylphenol. The method comprises: 1, pouring a catalyst and 2,6-dimethylphenol into a reaction bottle, uniformly stirring, and carrying out a thermal insulation reaction to obtain a reaction product; 2, carrying out a hydrolysis reaction on the reaction product, carrying out standing layering, and separating to obtain a water phase and an organic phase; and 3, combining the extractant obtained by extracting the water phase and the organic phase, and sequentially carrying out washing, drying, decolorization and pressure reducing distillation treatment to obtain xylenol. According to the present invention, 2,6-dimethylphenol is subjected to methyl rearrangement isomerization under theaction of the catalyst to obtain the wide-use and high-added value xylenol including 2,5-dimethylphenol, 3,5-dimethylphenol, 2,3-dimethylphenol and 3,4-dimethylphenol, such that the low value productis converted into the high value product, the raw material and process costs are reduced, the environmental pollution is low, and the method is suitable for industrial production.
Photoinduced hydroxylation of arylboronic acids with molecular oxygen under photocatalyst-free conditions
Xu, Yu-Ting,Li, Chen-Yuan,Huang, Xiao-Bo,Gao, Wen-Xia,Zhou, Yun-Bing,Liu, Miao-Chang,Wu, Hua-Yue
supporting information, p. 4971 - 4975 (2019/09/30)
Photoinduced hydroxylation of boronic acids with molecular oxygen under photocatalyst-free conditions is reported, providing a green entry to a variety of phenols and aliphatic alcohols in a highly concise fashion. This new protocol features photocatalyst-free conditions, wide substrate scope and excellent functional group compatibility.
Synthesis of substituted phenols via hydroxylation of arenes using hydrogen peroxide in the presence of hexaphenyloxodiphosphonium triflate
Khodaei, Mohammad Mehdi,Alizadeh, Abdolhamid,Hezarkhani, Hadis Afshar
, p. 878 - 882 (2018/11/06)
A mild and efficient protocol for the synthesis of phenols from arenes has been developed using aqueous hydrogen peroxide as an oxidizing agent and hexaphenyloxodiphosphonium triflate as a promoter. The reactions were carried out with the simple procedure in EtOH-H2O at room temperature in short reaction times.
