T:Toxic;
105-67-9Relevant academic research and scientific papers
Sodium perborate: A convenient reagent for benzylic hydroperoxide rearrangement
Kabalka,Reddy,Narayana
, p. 7667 - 7668 (1993)
Sodium perborate in boron trifluoride etherate has been found to be an effective reagent for the hydroperoxide rearrangement of electron rich and highly substituted benzylic tertiary alcohols to phenols in good yields.
Catalytic oxidation of aromatic hydrocarbons by a molecular iron-NHC complex
Lindhorst, Anja C.,Schütz, Jan,Netscher, Thomas,Bonrath, Werner,Kühn, Fritz E.
, p. 1902 - 1911 (2017)
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.
Photochemical reactions of oxygen atoms with toluene, m-xylene, p-xylene, and mesitylene: An infrared matrix isolation investigation
Parker, James K.,Davis, Steven R.
, p. 4108 - 4114 (2000)
The photochemical reactions of oxygen atoms with methylated benzenes (toluene, m-xylene, p-xylene, and mesitylene) were investigated in solid argon matrices at 12 K with UV light of λ ≥ 280 nm, producing ketene functionalities. The toluene/O atom reaction
One-pot synthesis of phenols by hydroxylation of aromatics with hydroxylamine
Zhang, Dongsheng,Gao, Liya,Xue, Wei,Zhao, Xinqiang,Wang, Shufang,Wang, Yanji
, p. 369 - 371 (2012)
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.
Application of two morphologies of Mn2O3for efficient catalyticortho-methylation of 4-chlorophenol
Gui, Wenying,Liu, Xiaofei,Wang, Zhenlu,Zhang, Chunlei,Zhang, Hongqiang,Zhang, Li,Zhu, Wanchun
, p. 20836 - 20849 (2021)
Vapor phaseortho-methylation of 4-chlorophenol with methanol was studied over Mn2O3catalyst with two kinds of morphologies. Here, Mn2O3was prepared by a precipitation and hydrothermal method, and showed the morphology of nanoparticles and nanowires, respectively. XRD characterization and BET results showed that, with the increase of calcination temperature, Mn2O3had a higher crystallinity and a smaller specific surface area. N2adsorption/desorption and TPD measurements indicated that Mn2O3nanowires possessed larger external surface areas and more abundant acid and base sites. Simultaneously, in the fixed bed reactor, methanol was used as the methylation reagent for theortho-methylation reaction of 4-chlorophenol. XRD, XPS, TG-MS and other characterizations made it clear that methanol reduced 4-chlorophenol and its methide, which were the main side-reactions. And Mn3+was reduced to Mn2+under the reaction conditions. Changing the carrier gas N2to a H2/Ar mixture further verified that the hydrogen generated by the decomposition of methanol was not the reason for dechlorination of 4-chlorophenol compounds. Here we summarized the progress of 4-chlorophenol methylation based on the methylation of phenol. Also, we proposed a mechanism of the 4-chlorophenol dechlorination effect which was similar to the Meerwein-Ponndorf-Verley-type (MPV) reaction. The crystal phase and carbon deposition were investigated in different reaction periods by XRD and TG-DTA. The reaction conditions for the two kinds of morphologies of the Mn2O3catalyst such as calcination temperature, reaction temperature, phenol-methanol ratio and reaction space velocity were optimized.
The role of ion-molecule pair intermediates in acid-catalyzed solvolysis. General base-catalyzed formation of 4-methylbenzyl carbocation and its trapping by nucleophiles
Thibblin
, p. 7427 - 7433 (1993)
The specific acid-catalyzed hydrolysis of 3,6-dimethoxy-3,6-dimethyl-1,4- cyclohexadiene (1) in 25 vol % acetonitrile in water at 25 °C provides 2,4- dimethylphenol (2a), 2,5-dimethylphenol (2b), 2,4-dimethylanisole (3a), 4- methylbenzyl alcohol (4), and small amounts of 2,5-dimethylanisole (3b) and 4-methylbenzyl methyl ether (5). The formation of 3b and 5 is proposed to involve intramolecular rearrangement of carbocation-molecule pair intermediates. The formation of 4-methylbenzyl alcohol (4) is catalyzed by general bases, indicating that dehydronation of the cyclohexadienyl carbocation is rate-limiting in its reaction to benzylic products. The Bronsted parameter was measured with carboxylate anions as β = 0.28. The 4- methylbenzyl carbocation, which is postulated to be an intermediate in this reaction, discriminates between added nucleophiles and solvent water: k(SCN)/k(HOH) = 37, k(Cl)/K(HOH) = 9.8, k(EtOH)/k(HOH) = 1.9, and k(MeOH)/k(HOH) = 2.1 (ratios of second-order rate constants). The rate constant for reaction of the carbocation with solvent water is estimated as k(HOH) = 1.4 x 108 M-1s-1 (5.6 x 109 s-1), assuming a diffusion- controlled rate constant of 5 x 109 M-1s-1 for its reaction with thiocyanate anion. The nucleophilic selectivity values are considerably smaller than those exhibited by 4-methylbenzyl bromide under the same reaction conditions: k(Cl)/k(HOH) = 210, k(EtOH)/k(HOH) = 3.8, and k(MeOH)/k(HOH) = 5.3. These differences are concluded to be due to different mechanisms. The bromide reacts by a concerted bimolecular S(N)2 mechanism with chloride anion. With alcohols and water, the reactions occur either by a concerted uncoupled mechanism or via the ion pairs.
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)
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.
Evaluation of acute toxicity and genotoxicity of liquid products from pyrolysis of Eucalyptus grandis wood
Pimenta,Bayona,Garcia,Solanas
, p. 169 - 175 (2000)
Slow pyrolysis of Eucalyptus grandis wood was performed in an oven laboratory, and smoke was trapped and condensed to yield liquid products. Polycyclic aromatic hydrocarbons (PAHs) and phenolic fractions were isolated from the former liquid products using adsorption column chromatography (ACC) and identified by GC/MS. Concentrations of PAH and phenolic fractions in total pyrolysis liquids were respectively 48.9 μg/g and 8.59% (w/w). Acute toxicity of total samples of pyrolysis liquids and the phenolic fraction was evaluated by means of two bioassays, namely, 24-h immobilization bioassay with Daphnia magna and Microtox(TM) bioassays, the latter employing the luminescent bacteria Photobacterium phosphoreum. Total pyrolysis liquids and the PAH fraction were evaluated for genotoxicity by the Microtox(TM) bioassay conducted using rehydrated freeze-dried dark mutant of the luminescent bacteria Vibrio fisheri strain M169. Total pyrolysis liquids and the phenolic fraction, respectively, in concentrations of 170 and 68 mg/L were able to immobilize 50% (EC50) of the D. magna population following 24-h exposure. Concentrations of 19 and 6 mg/L, respectively, for total pyrolysis liquids and phenolic fraction were the effective concentrations that resulted in a 50% (EC50) reduction in light produced by bacteria in the Microtox(TM) bioassay. Accordingly, the Microtox(TM) bioassay was more sensitive to toxic effects of both kind of samples than the D. magna bioassay, particularly for the phenolic fraction. Regarding to the genotoxicity evaluation, the results achieved by Microtox(TM) bioassay showed that total pyrolysis liquids had no genotoxic effects with and without exogenous metabolic activation using rat liver homogenate (S9). However, the PAH fraction showed toxic effects with rat liver activation and had a dose-response number (DRN) equal to 1.6, being in this way suspected genotoxic. The lowest detected concentration (LDC) of the PAH fraction able to cause genotoxic effects was 375 μg/L.
Photoinduced Decomposition of Peracetic Acid in Xylenes. Orientation in Aromatic Substitution of Methyl and Hydroxyl Radicals
Ogata, Yoshiro,Tomizawa, Kohtaro
, p. 785 - 788 (1980)
The photolysis of peracetic acid (1) in o-,m- or p-xylenes (2) has been carried out using 2537-Angstroem or >2900-Angstroem light at 20-22 deg C.The yields of ethyltoluenes (3), trimethylbenzenes (4), and dimethylphenols (6) are higher at 2537-Angstroem than those at >2900-Angstroem photolysis, but the reverse is true with the yield of methylbenzyl alcohol (5).The isomer distribution of trimethylbenzenes (4) formed from o- (2a) or m-xylene (2b) suggests that an attack of methyl radical at the position meta to the methyl group is favored with 2537-Angstroem light, while an attack at the ortho position is preferential with >2900-Angstroem light.On the other hand, the isomer distribution of dimethylphenols (6) at 2537 Angstroem suggests that an attack of hydroxyl radical is favored at positions ortho and para to the methyl group.These orientations of radical attack are briefly discussed.
Highly Selective and Efficient Ring Hydroxylation of Alkylbenzenes with Hydrogen Peroxide and an Osmium(VI) Nitrido Catalyst
Kwong, Hoi-Ki,Lo, Po-Kam,Yiu, Shek-Man,Hirao, Hajime,Lau, Kai-Chung,Lau, Tai-Chu
, p. 12260 - 12263 (2017)
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.
