cas 95-87-4, 2,5-Dimethylphenol | Articles data

Articles about 95-87-4Total 99 be found

Article title
Article abstract
Author
Journal number and time
Download

Mediated electron transfer with monooxygenases - Insight in interactions between reduced mediators and the co-substrate oxygen
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.
Tosstorff, Andreas,Dennig, Alexander,Ruff, Anna Jo?lle,Schwaneberg, Ulrich,Sieber, Volker,Mangold, Klaus-Michael,Schrader, Jens,Holtmann, Dirk
p. 51 - 58
(2014)
Read Online

Reaction of hydroxyl radical with arenes in solution—On the importance of benzylic hydrogen abstraction
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.
Waggoner, Abygail R.,Abdulrahman, Yahya,Iverson, Alexis J.,Gibson, Ethan P.,Buckles, Mark A.,Poole, James S.
(2021/08/27)

Method for synthesizing 2-5 -dimethylphenol
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.
-
Paragraph 0021; 0024-0025; 0028-0087

(2021/02/24)

Method for preparing alcohol and phenol through aerobic hydroxylation reaction of boric acid derivative in absence of photocatalyst
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.
-
Paragraph 0025-0028; 0030-0032

(2020/01/25)

Environmentally friendly preparation method for 2,5-dimethylphenol
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.
-
Paragraph 0051-0061

(2019/02/13)

Method for synthesizing high added value xylenol through isomerization of 2,6-dimethylphenol
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.
-
Paragraph 0038-0140

(2019/02/08)

Photoinduced hydroxylation of arylboronic acids with molecular oxygen under photocatalyst-free conditions
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.
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)

Regioselectivity of Hydroxyl Radical Reactions with Arenes in Nonaqueous Solutions
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.
Moores, Lee C.,Kaur, Devinder,Smith, Mathew D.,Poole, James S.
p. 3260 - 3269
(2019/03/11)

Method for preparing 2,5-xylenol by catalyzing paraxylene hydroxylation through Bi-MWW
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.
-
Paragraph 0015-0019

(2019/05/02)

A convenient synthesis of phenols
Anilines are rapidly, often within 60 minutes, converted into the corresponding phenols in up to 87% isolated yield. The presented experimentally simple protocol display broad compatibility with a variety of functional groups, and in particular, well suited for the preparation of methyl-substituted phenols. Such phenols are not easily available by other synthetic approaches. The formation of phenolic radical coupling products was not observed even for activated anilines using this open flask method.
Kristianslund, Renate,Vik, Anders,Hansen, Trond V.
supporting information
p. 2809 - 2814
(2018/12/04)

Continuous synthesis method of 2,5-dimethylphenol
The invention discloses a continuous synthesis method of 2,5-dimethylphenol. The method comprises steps as follows: two solutions are prepared from raw materials such as 2,5-dimethylaniline, sulfuricacid and sodium nitrite respectively; the two solutions are pumped into a pipeline reactor by two metering pumps respectively in a certain mass-velocity ratio and at certain flow velocity; the reaction solution is subjected to diazotization and hydrolysis reactions continuously in the pipeline reactor at the temperature of 80-120 DEG C for 200-300 s; cooling, extraction, drying and desolvation areperformed; the product is obtained, wherein the diazotization reaction and the hydrolysis reaction are conducted in the same pipeline reactor. The method has the characteristics that the raw materials have sufficient sources and low price, the synthesis process has high safety, the product yield is high, few three waste pollution is caused and the like and has higher industrial value.
-
Paragraph 0015; 0016; 0017; 0018

(2018/07/15)

Synthesis of substituted phenols via hydroxylation of arenes using hydrogen peroxide in the presence of hexaphenyloxodiphosphonium triflate
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.
Khodaei, Mohammad Mehdi,Alizadeh, Abdolhamid,Hezarkhani, Hadis Afshar
p. 878 - 882
(2018/11/06)

Tuning the Reactivity of Peroxo Anhydrides for Aromatic C-H Bond Oxidation
Phenol moieties are key structural motifs in many areas of chemical research from polymers to pharmaceuticals. Herein, we report on the design and use of a structurally demanding cyclic peroxide (spiro[bicyclo[2.2.1]heptane-2,4′-[1,2]dioxolane]-3′,5′-dione, P4) for the direct hydroxylation of aromatic substrates. The new peroxide benefits from high thermal stability and can be synthesized from readily available starting materials. The aromatic C-H oxidation using P4 exhibits generally good yields (up to 96%) and appreciable regioselectivities.
Pilevar, Afsaneh,Hosseini, Abolfazl,?ekutor, Marina,Hausmann, Heike,Becker, Jonathan,Turke, Kevin,Schreiner, Peter R.
p. 10070 - 10079
(2018/09/06)

Highly Selective and Efficient Ring Hydroxylation of Alkylbenzenes with Hydrogen Peroxide and an Osmium(VI) Nitrido Catalyst
The OsVI nitrido complex, OsVI(N)(quin)2(OTs) (1, quin=2-quinaldinate, OTs=tosylate), is a highly selective and efficient catalyst for the ring hydroxylation of alkylbenzenes with H2O2 at room temperature. Oxidation of various alkylbenzenes occurs with ring/chain oxidation ratios ranging from 96.7/3.3 to 99.9/0.1, and total product yields from 93 % to 98 %. Moreover, turnover numbers up to 6360, 5670, and 3880 can be achieved for the oxidation of p-xylene, ethylbenzene, and mesitylene, respectively. Density functional theory calculations suggest that the active intermediate is an OsVIII nitrido oxo species.
Kwong, Hoi-Ki,Lo, Po-Kam,Yiu, Shek-Man,Hirao, Hajime,Lau, Kai-Chung,Lau, Tai-Chu
supporting information
p. 12260 - 12263
(2017/09/06)

Aqueous Oxidations Started by TiO2 Photoinduced Holes Can Be a Rate-Determining Step
In aqueous TiO2 photocatalytic hydroxylation of weakly polar aromatics, a series of inverse H/D KIEs of 0.7–0.8 were observed, which is different than the normal H/D kinetic isotope effects (KIEs) usually observed for polar aromatics. This result indicated that the oxidation started by photo-induced hvb + can be the rate-determining step.
Gong, Yuanzheng,Yang, Chun,Ji, Hongwei,Chen, Chuncheng,Ma, Wanhong,Zhao, Jincai
supporting information
p. 2048 - 2051
(2017/08/23)

Vapor phase methylation of m-Cresol over Ce-impregnated Cd1-xCrxFe2O4 (x = 0, 0.25, 0.50, 0.75 and 1.0) ferrospinels
Cd-Cr ferrospinels prepared by co-precipitation method were impregnated with cerium as promoter. Ce-impregnated ferrospinels were tested for the vapor phase alkylation of m-cresol with methanol. It has been observed that with increase in value of 'x' in C
Kadian, Malvika,Gupta
p. 905 - 907
(2017/02/10)

A Ni-Mg-Al layered triple hydroxide-supported Pd catalyst for heterogeneous acceptorless dehydrogenative aromatization
In the presence of a Ni-Mg-Al layered triple hydroxide-supported Pd catalyst, the acceptorless dehydrogenative aromatization of a wide range of cyclohexanols/cyclohexanones and cyclohexylamines efficiently proceeded to give the corresponding phenols and anilines, respectively, in moderate to high yields with the liberation of molecular hydrogen.
Jin, Xiongjie,Taniguchi, Kento,Yamaguchi, Kazuya,Nozaki, Kyoko,Mizuno, Noritaka
supporting information
p. 5267 - 5270
(2017/07/10)

PROCESS OF PRODUCTION OF 2,5-DIMETHYLPHENOL
The present invention relates to a new method to produce 2,5-dimethylphenol (2,5-DMP).
-
Paragraph 0067

(2017/01/23)

Direct hydroxylation of benzene and aromatics with H2O2 catalyzed by a self-assembled iron complex: Evidence for a metal-based mechanism
An iminopyridine Fe(ii) complex, easily prepared in situ by self-assembly of cheap and commercially available starting materials (2-picolylaldehyde, 2-picolylamine, and Fe(OTf)2 in a 2 : 2 : 1 ratio), is shown to be an effective catalyst for the direct hydroxylation of aromatic rings with H2O2 under mild conditions. This catalyst shows a marked preference for aromatic ring hydroxylation over lateral chain oxidation, both in intramolecular and intermolecular competitions, as long as the arene is not too electron poor. The selectivity pattern of the reaction closely matches that of electrophilic aromatic substitutions, with phenol yields and positions dictated by the nature of the ring substituent (electron-donating or electron-withdrawing, ortho-para or meta-orienting). The oxidation mechanism has been investigated in detail, and the sum of the accumulated pieces of evidence, ranging from KIE to the use of radical scavengers, from substituent effects on intermolecular and intramolecular selectivity to rearrangement experiments, points to the predominance of a metal-based SEAr pathway, without a significant involvement of free diffusing radical pathways.
Capocasa, Giorgio,Olivo, Giorgio,Barbieri, Alessia,Lanzalunga, Osvaldo,Di Stefano, Stefano
p. 5677 - 5686
(2017/12/07)

Catalytic oxidation of aromatic hydrocarbons by a molecular iron-NHC complex
An iron-NHC complex bearing a tetradentate bis(N-heterocyclic carbene) ligand is applied as catalyst for the oxidation of methyl substituted arene substrates. Using hydrogen peroxide as the oxidant p-xylene and pseudocumene are converted to the corresponding phenols and benzoquinones. The influence of various reaction parameters like temperature, catalyst loading, and oxidant concentration is investigated and kinetic experiments reveal that a temperature reduction leads to an increased catalyst lifetime. Furthermore, an interesting selectivity towards unexpected phenolic products resulting from a methyl shift reaction is observed.
Lindhorst, Anja C.,Schütz, Jan,Netscher, Thomas,Bonrath, Werner,Kühn, Fritz E.
p. 1902 - 1911
(2017/07/15)

Au-Pd alloy nanoparticles supported on layered double hydroxide for heterogeneously catalyzed aerobic oxidative dehydrogenation of cyclohexanols and cyclohexanones to phenols
Phenol, an important industrial chemical, is widely produced using the well-developed cumene process. However, demand for the development of a novel alternative method for synthesizing phenol from benzene has been increasing. Herein, we report a novel system for the synthesis of phenols through aerobic oxidative dehydrogenation of cyclohexanols and cyclohexanones, including ketone-alcohol (KA) oil, catalyzed by Mg-Al-layered double hydroxide (LDH)-supported Au-Pd alloy nanoparticles (Au-Pd/LDH). Alloying of Au and Pd and basicity of LDH are key factors in achieving the present transformation. Although monometallic Au/LDH, Pd/LDH, and their physical mixture showed almost no catalytic activity, Au-Pd/LDH exhibited markedly high catalytic activity for the dehydrogenative phenol production. Mechanistic studies showed that β-H elimination from Pd-enolate species is accelerated by Au species, likely via electronic ligand effects. Moreover, the effect of supports was critical; despite the high catalytic performance of Au-Pd/LDH, Au-Pd bimetallic nanoparticles supported on Al2O3, TiO2, MgO, and CeO2 were ineffective. Thus, the basicity of LDH plays a deterministic role in the present dehydrogenation possibly through its assistance in the deprotonation steps. The synthetic scope of the Au-Pd/LDH-catalyzed system was very broad; various substituted cyclohexanols and cyclohexanones were efficiently converted into the corresponding phenols, and N-substituted anilines were synthesized from cyclohexanones and amines. In addition, the observed catalysis was truly heterogeneous, and Au-Pd/LDH could be reused without substantial loss of its high performance. The present transformation is scalable, utilizes O2 in air as the terminal oxidant, and generates water as the only by-product, highlighting the potential practical utility and environmentally benign nature of the present transformation. Dehydrogenative aromatization of cyclohexanols proceeds through (1) oxidation of cyclohexanols to cyclohexanones; (2) dehydrogenation of cyclohexanones to cyclohexenones; and (3) disproportionation of cyclohexenones to afford the desired phenols. In the present Au-Pd/LDH-catalyzed transformation, the oxidation of the Pd-H species is included in the rate-determining step.
Jin, Xiongjie,Taniguchi, Kento,Yamaguchi, Kazuya,Mizuno, Noritaka
p. 5371 - 5383
(2016/07/29)

Improved oxidation of aromatic and aliphatic hydrocarbons using rate enhancing variants of P450Bm3 in combination with decoy molecules
Enzyme performance can be improved using decoy molecules or engineered variants to accelerate the activity without affecting selectivity. Here we combine a rate accelerator variant of cytochrome P450Bm3 with decoy molecules to enhance the oxidation activity of a range of small organic molecules. This combined approach offers superior biocatalytic efficiency without modifying the product distribution.
Munday, Samuel D.,Shoji, Osami,Watanabe, Yoshihito,Wong, Luet-Lok,Bell, Stephen G.
supporting information
p. 1036 - 1039
(2016/01/16)

PROCESS OF PRODUCTION OF 2,5-DIMETHYLPHENOL
The present invention relates to a new method to produce 2,5-dimethylphenol (2,5-DMP).
-
Page/Page column 16-17

(2015/08/06)

Synthesis and characterization of bio-inspired diiron complexes and their catalytic activity for direct hydroxylation of aromatic compounds
Three [FeFe]-hydrogenase model complexes [(μ-dmedt){Fe(CO)3}2] [1; dmedt = SCH(CH3)CH(CH3)S], [(μ-dmedt){Fe(CO)3}{Fe (CO)2PPh3}] (1-PPh3), and [(μ-dmest){Fe(CO)3}2] [1-O; dmest = SCH(CH3)CH(CH3)S(O)], 1-O were synthesized and characterized. These model complexes, which are generally used as the functional biomimics of the hydrogen-producing dinuclear active site in [FeFe]-hydrogenase, were used as efficient catalysts for the selective hydroxylation of aromatic compounds to phenols under mild conditions. Because both the dithiolato-sulfur site and the Fe-Fe bond in the model complexes were possible active oxidation sites, DFT calculations were used to investigate the oxygenated products, that is, the S-oxygenated products or the Fe-oxygenated forms of the model complexes, which may be involved in the catalytic cycle. The experimental and computational results indicate that the thermodynamically favored Fe-oxygenated intermediates dominate the hydroxylation of the aromatic compounds. A possible mechanism for the hydroxylation is also proposed. Three FeI-FeI organometallic complexes were synthesized and used as highly selective catalysts for the direct hydroxylation of aromatic compounds to phenols, forming FeII-μ-O-FeII intermediates as the active oxygen-transfer species.
Wang, Xiao,Zhang, Tianyong,Yang, Qiusheng,Jiang, Shuang,Li, Bin
p. 817 - 825
(2015/02/19)

Triethanolamine as an inexpensive and efficient ligand for copper-catalyzed hydroxylation of aryl halides in water
The CuI/triethanolamine catalyst system efficiently promotes the direct hydroxylation of aryl iodides and bromides in water to provide the corresponding phenols in good to excellent yields. Moreover, the procedure avoids the use of toxic organic solvents and tolerates many functional groups. The CuI/triethanolamine catalyst system efficiently promotes the direct hydroxylation of aryl iodides and bromides in water to afford the corresponding phenols in good to excellent yields. Copyright
Wang, Deping,Kuang, Daizhi,Zhang, Fuxing,Tang, Siping,Jiang, Wujiu
supporting information
p. 315 - 318
(2014/01/23)

Triethanolamine as an Inexpensive and Efficient Ligand for Copper-Catalyzed Hydroxylation of Aryl Halides in Water
The CuI/triethanolamine catalyst system efficiently promotes the direct hydroxylation of aryl iodides and bromides in water to provide the corresponding phenols in good to excellent yields. Moreover, the procedure avoids the use of toxic organic solvents and tolerates many functional groups.
Wang, Deping,Kuang, Daizhi,Zhang, Fuxing,Tang, Siping,Jiang, Wujiu
supporting information
p. 315 - 318
(2015/10/05)

Study of gas phase m-cresol alkylation with methanol on solid acid catalysts
The gas-phase alkylation of m-cresol with methanol was studied at 523 K on Al-MCM-41 and zeolites ZnY, HBEA, HZSM5 and HMCM22. The acidity was determined by ammonia TPD and FTIR of adsorbed pyridine. On acid sites of moderate strength (Al-MCM-41), initially the O-alkylation rate was higher than the C-alkylation rate. In contrast, formation of dimethylphenols by C-alkylation was highly favored on ZnY and HMCM22 which have both strong acidity although different nature; Lewis (ZnY) and Bronsted and Lewis (HMCM22). High selectivity of 2,5-DMP was observed on HZSM5, probably due to diffusional constraint. All catalysts, except Al-MCM-41, showed deactivation by coke formation.
Acevedo,Bedogni,Okulik,Padr
p. 1946 - 1954
(2015/02/19)

Direct hydroxylation of p-xylene to 2,5-xylenol with hydroxylamine in ionic liquids/molybdenum catalytic system
Direct hydroxylation of p-xylene to 2,5-xylenol with hydroxylamine was carried out in an ionic liquids/molybdenum catalytic system. High 2,5-xylenol selectivity (80-98 %) can be achieved with good p-xylene conversion (5.9-9.9 %) in this catalytic system. The recycling experiments suggested the ionic liquids/molybdenum catalytic system was stable enough to be recycled for the hydroxylation reaction.
Zhang,Gao,Jin,Xue,Zhao,Wang,Wang
p. 7527 - 7531
(2015/02/02)

One step C-N bond formation from alkylbenzene and ammonia over Cu-modified TS-1 zeolite catalyst
A Cu doped TS-1 zeolite sample was applied to catalyze the formation of C-N bonds on both the ring and the side chain of toluene, as well as other alkylbenzenes. A yield of 3.4% of toluidine was obtained for the amination of toluene, with a 1.0% yield of nitrobenzene. Cyanobenzene was also obtained as the C-N bond product on the side chain with a yield of 1.0%. The selectivity for C-N bond formation was 52.4%. The catalyst promoted the formation of a hydroxylamine intermediate from ammonia and hydrogen peroxide, and then the instantaneously generated amino cation reacted with the substrate to form C-N bonds on both the ring and side chain. Cyanobenzene was produced from the dehydration of benzylamine, formed via the reaction of ammonia and toluene. The formation of C-N bonds on the ring had an ortho-orientation advantage for mono-substituted-benzenes. With the increase in the number of methyl substituents, the yield of the ring products decreased, which might be caused by steric hindrance. the Partner Organisations 2014.
Xia, Sheng,Yu, Tianhua,Liu, Huihui,Li, Guiying,Hu, Changwei
p. 3108 - 3119
(2014/08/18)

Unexpected hydrazine hydrate-mediated aerobic oxidation of aryl/ heteroaryl boronic acids to phenols in ambient air
The expedient and efficient sub-stoichimetric hydrazine hydrate-mediated aerobic hydroxylation of boronic acids that proceeds in poly(ethylene glycol) (PEG-400) has been successfully developed, providing diverse phenols in high yields. And heteroaryl boronic acids are also amenable to this protocol. the Partner Organisations 2014.
Zhong, Yanzhen,Yuan, Linxin,Huang, Zheng,Gu, Wenchao,Shao, Ye,Han, Wei
p. 33164 - 33167
(2014/08/18)

Rapid and green synthesis of phenols catalyzed by a deep eutectic mixture based on fluorinated alcohol in water
A new deep eutectic mixture based on choline chloride and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was prepared and was found to be effective for the rapid transformation of aryl/heteroaryl boronic acids to the corresponding phenols in water using hydrogen peroxide as the oxidant. Broad substrate compatibility, metal- and additive-free conditions as well as reusability of the catalyst made this procedure more environmentally benign.
Wang, Liang,Dai, Dong-Yan,Chen, Qun,He, Ming-Yang
p. 44 - 47
(2014/01/23)

CYCLIC PEROXIDE OXIDATION OF AROMATIC COMPOUND PRODUCTION AND USE THEREOF
The present invention provides a method for converting an aromatic hydrocarbon to a phenol by providing an aromatic hydrocarbon comprising one or more aromatic C-H bonds and one or more activated C-H bonds in a solvent; adding a phthaloyl peroxide to the solvent; converting the phthaloyl peroxide to a di-radical; contacting the di-radical with the one or more aromatic C-H bonds; oxidizing selectively one of the one or more aromatic C-H bonds in preference to the one or more activated C-H bonds; adding a hydroxyl group to the one of the one or more aromatic C-H bonds to form one or more phenols; and purifying the one or more phenols.
-
Page/Page column 9; 10

(2014/10/15)

Correlating lignin structural features to phase partitioning behavior in a novel aqueous fractionation of softwood Kraft black liquor
In this work, a set of softwood lignins were recovered from a Kraft black liquor using a novel pH-based fractionation process involving sequential CO 2 acidification and separation of the solvated aqueous lignin fraction. These recovered lignin fractions were characterized with respect to properties that may be responsible for their phase partitioning behavior as well as properties that may render the lignins more suitable for materials applications. Lignin fractions were recovered between a pH range of 12.8 and 9.5 with the bulk of the lignin (90%) recovered between a pH of 11.1 and 10.0. While all the fractions were found to consist primarily of lignin as validated by sample methoxyl content, the first fractions to phase separated were found to be especially enriched in aliphatic extractives and polysaccharides. From the bulk of the lignin that was recovered between a pH of 11.1 and 10.0 a number of noteworthy trends were discernible from the data. Specifically, the phenolic hydroxyl content was found to exhibit a strong negative correlation to the fractionation pH and exhibited a nearly 50% increase with recovery at decreasing pH, while the GPC-estimated molecular weights and 13C NMR-estimated β-O-4 content showed strong positive correlations to the pH at recovery. The aliphatic hydroxyl content exhibited minimal differences between recovery conditions. Overall, these results suggest that this fractionation approach can generate lignin fractions enriched in select physical or structural properties that may be important for their application as feedstocks for renewable chemicals or materials.
Stoklosa, Ryan J.,Velez, Julian,Kelkar, Shantanu,Saffron, Christopher M.,Thies, Mark C.,Hodge, David B.
supporting information
p. 2904 - 2912
(2013/10/08)

Metal-free oxidation of aromatic carbon-hydrogen bonds through a reverse-rebound mechanism
Methods for carbon-hydrogen (C-H) bond oxidation have a fundamental role in synthetic organic chemistry, providing functionality that is required in the final target molecule or facilitating subsequent chemical transformations. Several approaches to oxidizing aliphatic C-H bonds have been described, drastically simplifying the synthesis of complex molecules. However, the selective oxidation of aromatic C-H bonds under mild conditions, especially in the context of substituted arenes with diverse functional groups, remains a challenge. The direct hydroxylation of arenes was initially achieved through the use of strong Bronsted or Lewis acids to mediate electrophilic aromatic substitution reactions with super-stoichiometric equivalents of oxidants, significantly limiting the scope of the reaction. Because the products of these reactions are more reactive than the starting materials, over-oxidation is frequently a competitive process. Transition-metal-catalysed C-H oxidation of arenes with or without directing groups has been developed, improving on the acid-mediated process; however, precious metals are required. Here we demonstrate that phthaloyl peroxide functions as a selective oxidant for the transformation of arenes to phenols under mild conditions. Although the reaction proceeds through a radical mechanism, aromatic C-H bonds are selectively oxidized in preference to activated-H bonds. Notably, a wide array of functional groups are compatible with this reaction, and this method is therefore well suited for late-stage transformations of advanced synthetic intermediates. Quantum mechanical calculations indicate that this transformation proceeds through a novel addition-abstraction mechanism, a kind of 'reverse-rebound' mechanism as distinct from the common oxygen-rebound mechanism observed for metal-oxo oxidants. These calculations also identify the origins of the experimentally observed aryl selectivity.
Yuan, Changxia,Liang, Yong,Hernandez, Taylor,Berriochoa, Adrian,Houk, Kendall N.,Siegel, Dionicio
p. 192 - 196
(2013/08/23)

Efficient microwave-assisted Pd-catalyzed hydroxylation of aryl chlorides in the presence of carbonate
An efficient microwave-assisted, palladium-catalyzed hydroxylation of aryl chlorides in the presence of a weak base carbonate was developed, which rapidly converts aryl and heteroaryl chlorides to phenols, and can be used when the aryl chloride is functionalized with a ketone, aldehyde, ester, nitrile, or amide.
Yu, Chao-Wu,Chen, Grace S.,Huang, Chen-Wei,Chern, Ji-Wang
supporting information; experimental part
p. 3688 - 3691
(2012/08/28)

Chemo- and regioselective direct hydroxylation of arenes with hydrogen peroxide catalyzed by a divanadium-substituted phosphotungstate
Peroxide in, phenol out: The catalyst [-PW10O38V 2(μ-OH)2]3- showed high activity in the hydroxylation of various aromatic compounds with aqueous H2O 2. The system was regioselective, producing para-phenols from monosubstituted benzene derivatives. Furthermore, alkylarenes with reactive side-chain Ca spa 3-H bonds could be chemoselectively hydroxylated without significant formation of side-chain oxygenated products. Copyright
Kamata, Keigo,Yamaura, Taiyo,Mizuno, Noritaka
supporting information; experimental part
p. 7275 - 7278
(2012/08/28)

One-pot synthesis of phenols by hydroxylation of aromatics with hydroxylamine
In this study, a new approach for one-pot synthesis of phenols is presented, i.e., benzene, ethylbenzene, and xylene were hydroxylated with hydroxylamine to give the corresponding phenols in good yield using molybdenum as a key catalyst.
Zhang, Dongsheng,Gao, Liya,Xue, Wei,Zhao, Xinqiang,Wang, Shufang,Wang, Yanji
scheme or table
p. 369 - 371
(2012/06/01)

Process for Producing Small Molecular Weight Organic Compounds from Carbonaceous Material
The present invention discloses a process for producing small molecular weight organic compounds from carbonaceous material comprising a step of contacting the carbonaceous material with carbon monoxide (CO) and steam in presence of a shift catalyst at a predetermined temperature and pressure.
-
Page/Page column 3

(2012/01/13)

Synthesis, structural properties, and catalytic behavior of Cu-BTC and mixed-linker Cu-BTC-PyDC in the oxidation of benzene derivatives
Mixed-linker metal-organic frameworks based on the Cu-BTC structure have been synthesized in which the benzene-1,3,5-tricarboxylate (BTC) linkers have been partially replaced by pyridine-3,5-dicarboxylate (PyDC). X-ray-based techniques (powder XRD and XAS), thermal analysis, and infrared spectroscopy proved that a desired amount of PyDC (up to 50%) can be incorporated without changing significantly the crystal structure. The pyridine unit can be seen as a defect site in the local coordination environment of the dimeric copper units, which is significantly altering their electronic structure and the catalytic properties. Both Cu-BTC and the mixed Cu-BTC-PyDCs catalyze the demanding direct hydroxylation of toluene both in acetonitrile and in neat substrate. Different selectivity toward the desired ortho- and para-cresol and other oxidation products (benzaldehyde, benzyl alcohol, methylbenzoquinone) was observed for Cu-BTC and the Cu-BTC-PyDCs, respectively. Leaching tests and comparison with homogeneously dissolved Cu catalysts indicate mainly a heterogeneous reaction pathway.
Marx, Stefan,Kleist, Wolfgang,Baiker, Alfons
experimental part
p. 76 - 87
(2011/08/04)

Copper-catalyzed hydroxylation of aryl halides with tetrabutylammonium hydroxide: Synthesis of substituted phenols and alkyl aryl ethers
The selective hydroxylation of aryl iodides and aryl bromides with tetrabutylammonium hydroxide pentahydrate is described. For this, the combination of copper(I) iodide and 8-hydroxyquinaldine at 70-130C in a mixture of dimethyl sulfoxide and water (2:3) is used. The resultant phenols can be readily reacted with alkyl and allyl halides in situ to provide the corresponding alkyl or allyl aryl ethers in high yields. The reactions are simple, general, and efficient, affording substituted phenols and alkyl aryl ethers under aerobic conditions
Paul, Rajesh,Ali, Md Ashif,Punniyamurthy, Tharmalingam
supporting information; experimental part
p. 4268 - 4272
(2011/02/25)

The balance of acid, basic and redox sites in Mg/Me-mixed oxides: The effect on catalytic performance in the gas-phase alkylation of m-cresol with methanol
The reactivity of Mg/Me-mixed oxides (Me = Fe, Cr, Al) in m-cresol gas-phase methylation with methanol was studied, with the aim of finding relationships between catalytic performance and surface/bulk features. All systems exhibit similar surface properties (basically due to the presence of basic and Lewis-type acid sites), but the presence of extra cations in the MgO framework affects greatly the products obtained in the mentioned catalytic reaction, depending on the possible co-presence of redox capacity. In particular, (i) the Mg/Al/O system, characterized by no redox capacity, shows catalytic behaviour quite similar to that of conventional Bronsted-type acid catalysts, though with the advantage of exhibiting almost no deactivation during use (a rather common problem for acid catalysts activating methanol for phenol attack); (ii) the Mg/Cr/O catalyst shows a reactivity typical of a basic catalyst, with high chemo- and regio-selectivity and the favoured formation of 2,5-dimethylphenol; (iii) the Mg/Fe/O system presents a catalytic behaviour closer to that of Mg/Cr/O, if referred to the distribution of phenolic products, but it also exhibits a better activity in methanol dehydrogenation to formaldehyde (that is the true electrophilic reactant for m-cresol ring methylation), and in the decomposition of formaldehyde into light compounds. This behaviour causes a poor selectivity to dimethylphenols with respect to converted methanol, whereas the selectivity with respect to converted m-cresol is not different from that shown by Mg/Cr/O system.
Crocella,Cerrato,Magnacca,Morterra,Cavani,Cocchi,Passeri,Scagliarini,Flego,Perego
body text
p. 125 - 135
(2010/06/12)

Reaction of atomic carbon with isomeric cresols
Reaction of atomic carbon with isomeric cresols generates methyltropones and xylenols. Methyltropone to xylenol ratio was found to be highest for m-cresol and lowest for p-cresol. Stability of singlet carbenes produced after insertion of atomic carbon int
Soekmen, Ilkay,Ece, Abdulilah,Duez, Buelent,Sevin, Fatma
experimental part
p. 650 - 653
(2010/06/16)

Liquid-phase oxidation of alkyl-substituted cyclohexylbenzenes
The reactivity of alkyl-substituted cyclohexylbenzenes in liquid-phase oxidation was estimated by the k2/√k6 value which considerably decreased as the number of methyl groups in the substrate molecule increased. The observed difference in the reactivity of the title compounds was attributed to the degree of coplanarity of intermediate radical species.
Koshel',Kurganova,Smirnova,Koshel',Plakhtinskii,Belysheva
scheme or table
p. 553 - 556
(2009/04/05)

PYRAZOLE COMPOUNDS
The present invention is directed to compounds of Formula (I), and to salts and solvates thereof, their synthesis, and their use as Raf inhibitors.
-
Page/Page column 56-57

(2008/06/13)

Palladium-catalyzed C-O bond formation: direct synthesis of phenols and aryl/alkyl ethers from activated aryl halides
A simple and efficient palladium-catalyzed carbon-oxygen bond formation is reported. The palladium-tri-tert-butylphosphine complex was found to be effective in converting haloarenes to corresponding substituted phenols. This methodology offers a direct transformation of aryl halides to phenols, as well as the straightforward application to generate a wide variety of diaryl or alkyl/aryl ethers.
Chen, Guoshu,Chan, Albert S.C.,Kwong, Fuk Yee
p. 473 - 476
(2008/02/03)

The selective reaction of aryl halides with KOH: Synthesis of phenols, aromatic ethers, and benzofurans
The direct and selective synthesis of phenols from aryl/heteroaryl halides and KOH has been achieved through the use of highly active monophosphine-based catalysts derived from Pd2dba3 and ligands L1 or L2 and the biphasic solvent system 1,4-dioxane/H2O. We have also demonstrated a one-pot method of phenol formation/alkylation for the preparation of alkyl aryl ethers from aryl halides. In many instances, this protocol overcomes limitations in existing Pd-catalyzed coupling reactions of aliphatic alcohols with aryl halides. Finally, we demonstrate that substituted benzofurans can be prepared efficiently via a Pd-catalyzed phenol formation/cyclization protocol starting from 2-chloroaryl alkynes. Copyright
Anderson, Kevin W.,Ikawa, Takashi,Tundel, Rachel E.,Buchwald, Stephen L.
p. 10694 - 10695
(2007/10/03)

Orthoalkylation catalyst for phenol and process for producing orthoalkylated phenol with use thereof
The orthoalkylation catalyst for phenols of the invention is one produced by calcining a catalyst precursor comprising basic magnesium carbonate (a) and magnesium oxide (b) optionally together with manganese oxalate (c), the basic magnesium carbonate (a) and magnesium oxide (b) being mixed together at a weight ratio ((a)/(b)) of 20/80 to 80/20. The process for producing an orthoalkylated phenol according to the invention comprises performing a vapor phase reaction of a phenol with an alkyl alcohol in the presence of the above orthoalkylation catalyst so that an orthoalkylated phenol is obtained.The invention enables obtaining an orthoalkylation catalyst for phenols which has high activity and high selectivity, has long catalytic life and exhibits more stable catalytic life than those of conventional orthoalkylation catalysts for phenols. Moreover, by virtue of the use of the catalyst capable of exerting these effects, there can be obtained a process for producing an orthoalkylated phenol which ensures prolonged and constant catalyst regeneration cycle.
-
Page/Page column 7-10

(2008/06/13)

Continuous chemoselective methylation of m-cresol and phenol with supercritical methanol over solid acid and base metal oxide catalysts
The chemoselective methylation of m-cresol and phenol with supercritical methanol (scCH3OH) promoted by metal oxide catalysts (MgO, ZrO 2, Cs-P-Si and Fe-V/SiO2) was investigated in a continuous flow fixed bed reactor. The use of scCH3OH as a carrier medium led to a significant change in the product selectivity compared to that attained in the gas phase reaction, and caused a marked suppression of the degradation of CH3OH during the reaction, resulting in an improvement in the catalyst lifetime. The chemoselective outcome of the reaction was highly influenced by the acid-base character on the solid catalysts examined under supercritical conditions.
Oku, Tomoharu,Arita, Yoshitaka,Ikariya, Takao
p. 1553 - 1557
(2007/10/03)

One step hair coloring compositions using salts
A hair coloring composition comprising the following two compositions which are mixed just prior to application to the hair: (a) a composition comprising a water-soluble peroxygen oxidizing agent; and (b) a composition comprising one or more oxidative hair coloring agents selected from the group consisting of an aromatic diamine, an amino phenol, a naphthol, a polyhydric phenol, a catechol and mixtures thereof; wherein the composition comprising one or more oxidative hair coloring agents further comprises al least one water soluble carbonate releasing salts; and optionally a water soluble ammonium salt, is described.
-
(2008/06/13)

Ortho-alkylation of phenol with methanol using Pb-Cr promoted magnesium oxide catalysts
In this study, Pb-Cr promoted magnesium oxide catalysts were used to catalyze the ortho-alkylation of phenol in the presence of excess methanol. The Cr/MgO catalyst exhibited a high conversion of phenol and a relatively high selectivity for the ortho-alkylation of phenol. The catalytic activity and the stability of Cr/MgO were improved by the addition of a fairly small amount of Pb. The Pb-Cr/MgO catalyst showed specificity for the ortho-alkylation of phenol, which was proved by a series of phenol derivative reactions with methanol.
Ke, Jyh-Harng,Zena, Jyh-Myng,Wang, Fey-Long
p. 1407 - 1410
(2007/10/03)