The Reaction of Ninhydrin with Trimethylbenzenes under Friedel-Crafts Reaction Conditions

The reaction of ninhydrin with 1,2,3- and 1,2,4-trimethylbenzene in the presence of H₂SO₄ or AlCl₃ afforded 2-monoaryl and 2,2-diaryl-1,3-indanedione derivatives as the major products. With 1,3,5-trimethylbenzene as the arene nucleophile, either a reduction product or an indenoindanone derivative was obtained depending upon the catalyst employed in the reaction.     

Aerobic oxidation of trimethylbenzenes catalyzed by N,N′,N″-trihydroxyisocyanuric acid (THICA) as a key catalyst

The oxidation of trimethylbenzenes was examined with air or O₂ using N,N′,N″-trihydroxyisocyanuric acid (THICA) as a key catalyst. Thus, 1,2,3-, 1,2,4-, and 1,3,5-trimethylbenzenes under air (20 atm) in the presence of THICA (5 mol %), Co(OAc)₂ (0.5 mol %), Mn(OAc)₂, and ZrO(OAc)₂ at 150 °C were oxidized to the corresponding benzenetricarboxylic acids in good yields (81-97%). In the aerobic oxidation of 1,2,4-trimethylbenzene by the THICA/Co(II)/Mn(II) system, remarkable acceleration was observed by adding a very small amount of ZrO(OAc)₂ to the reaction system to form 1,2,4-benzenetricarboxylic acid in excellent yield (97%). In contrast, no considerable addition effect was observed in the oxidation of 1,3,5-trimethylbenzene. This aerobic oxidation by the present catalytic system provides an economical and environmentally benign direct method to benzenetricarboxylic acids, which are very important polymer materials.     

The transformation of 1,2,4-trimethylbenzene A probe reaction to monitor external surface modifications of HZSM-5?

The transformation of 1,2,4-trimethylbenzene is proposed as a new probe reaction to monitor the catalytic effects of inertisation of the external surface of HZSM-5. The external surface has been modified by coating ZSM-5 crystallites with an inert silicalite shell. At 723 K and a WHSV of 0.6 h⁻¹ it has been shown that the isomerisation products 1,2,3-trimethylbenzene and 1,3,5-trimethylbenzene reflect changes in external activity. The disproportionation products, 1,2,4,5-tetramethylbenzene and 1,2,3,5-tetramethylbenzene together are shown to indicate changes in overall activity and shape selective properties of the catalyst sample. The results correlate with those observed for the reaction of 1,3,5-triisopropylbenzene and n-hexane cracking.     

Rapid screening of commercial pseudocumene purity by gas chromatography

Summary A rapid gas-liquid chromatographic method for the analysis of the C₉ aromatic fraction rich in 1,2,4-trimethylbenzene, has been reported. The method utilises a short packed column of tetrakis(\-cyanoethoxy) pentaerythritol, and has been used for testing the purity of pseudocumene in commercial samples. It is rapid and admits good precision.     

The Photochemistry of Diazomethane the Reactions of Methylene with Toluene and P-Xylene in Liquid Phase (I)

The photochemistry of diazomethane in toluene and p-xylene solutions was investigated. The reactions of methylene with toluene gave eight products. In the diazomethane p-xylene solution, p-ethyltoluene, 1,2,4-trimethylbenzene, 1,4-dimethylcyclohepatriene-1,3,5 and three unidentified compounds were found as products of the reaction of methylene with p-xylene. The relative rates of addition and insertion reaction of methylene with toluene and p-xylene have been calculated.     

Transfer hydrogenation of ketones catalyzed by ruthenium complexes

Oxidation of 1,3,5- and 1,2,4-trimethylbenzenes using heteropoly vanadomolybdate as catalyst in the presence of hydrogen peroxide under homogeneous conditions has been investigated. Phenol formation in the case of 1,2,4-trimethylbenzene and only side chain oxidation in the case 1,3,5-trimethylbenzene were observed. This behavior is explained in terms of the charge densities on different centers of both substrate molecules calculated by the MNDO method.     

Synthesis of 5-<Emphasis Type="Italic">tert</Emphasis>-butyl-1,2,3-trimethylbenzene catalyzed by [Et<Subscript>3</Subscript>NH]Cl–AlCl<Subscript>3</Subscript>

Common Lewis acids and Lewis acidic ionic liquid catalysts were applied in the synthesis of 5-tert-butyl-1,2,3-trimethylbenzene from 1,2,3-trimethylbenzene and 2-chloro-2-methylpropane, where [Et₃NH]Cl–AlCl₃ demonstrated the most promising catalytic potential. The effects of reaction time, temperature, catalyst composition and dosage have been systematically studied in the presence of [Et3NH]Cl–AlCl3. The maximum selectivity of 90.32% was achieved upon heating at 10°C for 5 h with a mass fraction of [Et₃NH]Cl–AlCl₃ to 1,2,3-trimethylbenzene of 10%. Activity of the ionic liquid catalyst remained high after several cycles.     

The Photochemistry of Ketene the Reactions of Methylene with Toluene and P-Xylene in Vapor Phase (II)

In the photolysis of ketene with toluene in the vapor phase, ethylbenzene, xylenes, 2-methylcycloheptatriene-1, 3, 5, and three unidentified compounds are found as the products of the reactions of methylene with toluene. In the ketene-p-xylene system, p-ethyltoluene, 1,2,4-trimethylbenzene, 1,4-dimethylcyclohepatriene-1,3,5, and three unidentified compounds are obtained as the products of the reactions of methylene with p-xylene. The reaction mechanism is discussed.     

Rate constants for the gas-phase reactions of the OH radical with a series of aromatic hydrocarbons at 296 ± 2 K

Using a relative rate method, rate constants have been determined at 296 ± 2 K for the gas-phase reactions of the OH radical with toluene, the xylenes, and the trimethylbenzenes. Using the recommended literature rate constant for the reaction of OH radicals with propene of (2.66 ± 0.40) × 10^?11 cm³ molecule^?1 s^?1, the following rate constants (in units of 10^?12 cm³ molecule^?1 s^?1) were obtained: toluene, 5.48 ± 0.84; o-xylene, 12.2 ± 1.9; m-xylene, 23.0 ± 3.5; p-xylene, 13.0 ± 2.0; 1,2,3-trimethylbenzene, 32.7 ± 5.3; 1,2,4-trimethylbenzene, 32.5 ± 5.0; and 1,3,5-trimethylbenzene, 57.5 ± 9.2. These data are compared with the literature values.     

溶剂对柔性配体1,3,5-三(三氮唑-1-甲基)-2,4,6-三甲苯的银配合物的影响

通过在不同溶剂中硝酸银与1,3,5-三（1,2,4-三氮唑-1-甲基）-2,4,6-三甲苯（ttmb）的反应,合成了2种新型的银配合物：{[Ag（ttmb）（H₂O）]NO₃}_n（1）、{[Ag（ttmb）]NO₃·H₂O）}_n（2）。研究了室温条件下,2个配合物与相关ttmb配体的固态荧光性质。通过元素分析、粉末和单晶X射线衍射分析、红外光谱分析等对其结构进行表征,结果表明化合物1包含一个高度起伏的二维网状结构,化合物2具有一个二维的（6,3）网状结构。     

溶剂对柔性配体1,3,5-三(三氮唑-1-甲基)-2,4,6-三甲苯的银配合物的影响

通过在不同溶剂中硝酸银与1,3,5-三（1,2,4-三氮唑-1-甲基）-2,4,6-三甲苯（ttmb）的反应,合成了2种新型的银配合物：{[Ag（ttmb）（H₂O）]NO₃}_n（1）、{[Ag（ttmb）]NO₃·H₂O）}_n（2）。研究了室温条件下,2个配合物与相关ttmb配体的固态荧光性质。通过元素分析、粉末和单晶X射线衍射分析、红外光谱分析等对其结构进行表征,结果表明化合物1包含一个高度起伏的二维网状结构,化合物2具有一个二维的（6,3）网状结构。     

2,3,5-三甲基氢醌的绿色合成工艺研究

以偏三甲苯(TMB)为原料,冰醋酸为溶剂,过氧化氢(50%)为氧化剂,通过直接氧化合成了2,3,5-三甲基氢醌(TMHQ);考察了反应温度、反应时间以及氧化剂和溶剂用量等对TMHQ收率的影响,确定了优化的氧化反应条件.结果表明,最优的氧化反应条件为:反应温度85℃,反应时间3h,TMB与冰醋酸的物质的量之比1∶12,TMB与过氧化氢的物质的量之比1∶11.     

Confirmed assignments of isomeric dimethylbenzyl radicals generated by corona discharge

The controversial vibronic assignments of isomeric dimethylbenzyl radicals were clearly resolved by using different precursors. By employing corresponding dimethylbenzyl chlorides as precursors, we identified the origins of the vibronic bands of the dimethylbenzyl radicals generated by corona discharge of 1,2,4-trimethylbenzene. From the analysis of the spectra observed from the dimethylbenzyl chlorides in a corona excited supersonic expansion, we revised previous assignments of the 3,4-, 2,4-, and 2,5-dimethylbenzyl radicals. Spectroscopic data of electronic transition and vibrational mode frequencies in the ground electronic state of each isomer were accurately determined by comparing them with those obtained by an ab initio calculation and with the known vibrational data of 1,2,4-trimethylbenzene.     

Mesoporous materials with zeolite framework: remarkable effect of the hierarchical structure for retardation of catalyst deactivation

Hierarchical MFI zeolite was synthesized following a synthesis route using organic-inorganic hybrid surfactants; the resultant zeolite with mesoporous/microporous hierarchical structure exhibited remarkably high resistance to deactivation in catalytic activity of various reactions such as isomerization of 1,2,4-trimethylbenzene, cumene cracking, and esterification of benzyl alcohol with hexanoic acid, as compared with conventional MFI and mesoporous aluminosilicate MCM-41.     

The 1,2,4-triazolyl cation: thermolytic and photolytic studies

The generation of the 1,2,4-triazolyl cation (1) has been attempted by the thermolysis and photolysis of 1-(1,2,4-triazol-4-yl)-2,4,6-trimethylpyridinium tetrafluoroborate (2) and the thermolysis of 1- and 4-diazonium-1,2,4-triazoles, using mainly mesitylene as the trapping agent. Thermolysis of 2 gave mostly 1,2,4-triazole, together with 3-(1,2,4-triazol-4-yl)-2,4,6-trimethylpyridine, 4-(1,2,4-triazol-4-ylmethyl)-2,6-dimethylpyridine, and 4-(2,4,6-trimethylbenzyl)-2,6-dimethylpyridine. Thermolysis of each of the diazonium salts in the presence of mesitylene again gave mainly triazole together with very low yields of 1-(1,2,4-triazol-1-yl)-2,4,6-trimethylbenzene and the corresponding -4-yl isomer in about the same ratio. On the other hand, photolysis of 2 in mesitylene gave mainly 1-(1,2,4-triazol-1-yl)-2,4,6-trimethylbenzene. A photoinduced electron transfer from mesitylene to 2 has been observed and preliminary laser flash photolyses of 2 and the corresponding 2,4,6-triphenylpyridinium salt have been carried out. The observed transients are explained as arising from the first excited states of the pyridinium salts rather than from 1. Ab initio MO calculations are reported and indicate that the predicted electronic ground-state of the triazolyl cation is a triplet state of B1 symmetry with five pi electrons, which corresponds to a diradical cation (1c). Possible mechanisms for the formation of the various products are proposed.     

Solubilities of 1,2,3-trimethylbenzene and 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene in t-butyl alcohol+water mixtures and hydrophobic interaction

The solubilities of 1,2,3- trimethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene in mixed solvents of t-butyl alcohol (TBA) and water at 283.15, 288.15, 293.15 and 298.15 K have been determined by spectrophotometry. The mole fractions of TBA [x(TBA)] in the mixed solvent are 0.000, 0.010, 0.020, 0.030, 0.040, 0.045, 0.050, 0.060, 0.080 and 0. 1000. The Gibbs energies of hydrophobie interaction (HI) for the aggregating process of three methane molecules with one benene molecule in the mixed solvent are studied, and the effect of solvent structure and solute aggregating state on the strength of HI is discussed.     

Kinetics of the gas-phase reactions of NO3 radicals with a series of aromatics at 296 ± 2 K

Rate constants have been determined at 296 ± 2 K for the gas phase reaction of NO₃ radicals with a series of aromatics using a relative rate technique. The rate constants obtained (in cm³ molecule^?1 s^?1 units) were: benzene, <2.3 × 10^?17; toluene, (1.8 ± 1.0) × 10^?17; o? xylene, (1.1 ± 0.5) × 10^?16; m? xylene, (7.1 ± 3.4) × 10^?17; p? xylene, (1.4 ± 0.6) × 10^?16; 1,2,3-trimethylbenzene, (5,6 ± 2.6) × 10^?16; 1,2,4-trimethylbenzene (5.4 - 2.5) × 10^?16; 1,3,5-trimethylbenzene, (2.4 ± 1.1) × 10^?16; phenol, (2.1 ± 0.5) × 10^?12; methoxybenzene, (5.0 ± 2.8) × 10^?17; o-cresol, (1.20 ± 0.34) × 10^?11; m-cresol, (9.2 ± 2.4) × 10^?12; p-cresol, (1.27 ± 0.36) × 10^?11; and benzaldehyde, (1.13 ± 0.25) × 10^?15. These kinetic data, together with, in the case of phenol, product data, suggest that these reactions proceed via H-atom abstraction from the substituent groups. The magnitude of the rate constants for the hydroxy-substituted aromatics indicates that the nighttime reaction of NO₃ radicals with these aromatics can be an important loss process for both NO₃ radicals and these organics, as well as being a possible source of nitric acid, a key component of acid deposition.     

Catalytic Conversion of 1,2,3-Trimethylbenzene Over HY Zeolite

The reaction of 1,2,3-trimethylbenzene (1,2,3-TMB) over HY zeolite was investigated in a fixed-bed flow reactor at 200-300 °C under atmospheric pressure. The reaction products include toluene, pentamethylbenzene and isomers of xylene, 1,2,3-TMB and tetramethylbenzene. Based on the time-on-stream theory, the types and initial selectivities of these products were determined from plots of product selectivity. 1,2,4-TMB is initially produced from 1,2,3-TMB via isomerization whereas o-xylene, m-xylene, 1,2,3,4- and 1,2,3,5-tetramethylbenzene were primarily formed by disproportionation of 1,2,3-TMB. Isomerization and disproportionation obeyed first- and second-order kinetics, respectively; both reactions proceeded via a carbonium ion mechanism with the former occurring by methyl transfer on the benzene ring whereas the latter proceeded through the diphenylmethane transition state. The activation energies are 31.6 and 37.2 kJ mol^?1 for isomerizaion and disproportionation, respectively.     

Catalytic properties of polyvanadomolybdic acids in oxidation of 1,2,4-trimethylbenzene by peracetic acid

Polyvanadomolybdic acids catalyze the process of peracid oxidation of 1,2,4-trimethylbenzene. The selectivity with respect to 2,3,5-trimethyl-1,4-benzoquinone increases with increasing degree of replacement of vanadium atoms in the PVMA by molybdenum; this is related to increased stability of the intermediate peroxides of the heteropolyvanadates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1967–1969, September, 1989.     

合成皂石及其交联物在偏三甲苯歧化反应中的催化行为

以羟基铝低聚物与其交联制得柱撑皂石,并在偏三甲苯歧化反应中考察了它们的催化性能.结果表明,催化活性随柱撑皂石表面酸量增加而增加;四甲苯中均四甲苯和二甲苯中邻二甲苯的百分含量皆高于热力学平衡值.催化特性与柱撑皂石的柱密度相关.