Nonrigid group theory for 1,3,5‐trimethylbenzene

Using nonrigid group theory, the full nonrigid (f‐NRG) group of 1,3,5‐trimethylbenzene (TMB) is shown to be isomorphic to the group S₃[C₃] = C₃ S₃ of order 162, where denotes the wreath product of groups, and C₃ is the cyclic group of order three and S₃ is the symmetric group of order six on three letters. This group has 22 conjugacy classes and irreducible representations. The character table of the full nonrigid TMB is then derived for the first time. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

氯仿、硝基苯与三甲苯异构体的过量摩尔体积

在298.15 K下,用振动管密度计在全浓度范围内测量了氯仿、硝基苯分别与均三甲苯、偏三甲苯构成的二元液体混合物的过量摩尔体积VE.其中氯仿与均、偏三甲苯的VE为正值,且均三甲苯＞偏三甲苯;硝基苯与均、偏三甲苯的VE为负值,且偏三甲苯＞均三甲苯.     

铝柱联合成皂石上三甲苯转化的研究

以１，３，５－ＴＭＢ和１，２，４－ＴＭＢ转化为模型反应，探讨了铝柱联合成皂石（简称Ａｌ－ＰＳＳ）上表面酸性质的特点。结合不同脱附温度下吡啶吸附量及ＮＨ＿３－ＴＰＤ研究，实验证明，Ａｌ－ＰＳＳ表面具有数目较多，强度较大的酸性中心　和较弱的碱性中心　，与铝柱联天然膨润土（简称Ａｌ－ＣＬＢ）比较，有较高的脱烷基选择性。两种三甲苯在Ａｌ－ＰＳＳ上的转化，不论是单一反应物还是二者混合反应物，其产物分布基本相同，四甲苯在其异构体中含量均高达８０％，说明在本研究反应条件下，两种探针分子以Ａｌ－ＰＳＳ为催化剂进行转化，其产物结构由催化剂结构和性质决定。     

工业填料γ-Al_2O_3催化氧化偏三甲苯制2,3,5-三甲基苯醌

以工业填料γ-Al_2O_3为催化剂,30%H_2O_2为氧化剂,冰醋酸为溶剂,一步法催化氧化偏三甲苯(TMB)合成2,3,5-三甲基苯醌(TMBQ)。考察了催化剂用量、反应温度、反应时间、氧化剂用量对该反应的影响。条件优化的结果为:m(γ-Al_2O_3)/m(TMB)=0.005,m(30%H_2O_2)/m(TMB)=2.5,反应时间2 h,反应温度80℃,得到TMB转化率为21.3%,TMBQ收率为16.0%,选择性为75.2%。通过XRD、FTIR、SEM、BET等技术手段,证明γ-Al_2O_3结晶度是影响氧化反应催化活性的关键因素。填料γ-Al_2O_3具有较大孔隙结构、比表面积较大、颗粒分布不均匀,为不规则片状,是廉价易得的工业品,具有较好的应用前景。     

Experimental and kinetic modeling study of combustion of JP-8, its surrogates and components in laminar premixed flows

Experimental and kinetic modeling studies are carried out to characterize premixed combustion of jet fuels, their surrogates, and reference components in laminar nonuniform flows. In previous studies, it was established that the Aachen surrogate made up of 80 % n-decane and 20 % trimethylbenzene by weight, and surrogate C made up of 57 % n-dodecane, 21 % methylcyclohexane and 22 % o-xylene by weight, reproduce key aspects of combustion of jet fuels in laminar nonpremixed flows. Here, these surrogates and a jet fuel are tested in premixed, nonuniform flows. The counterflow configuration is employed, and critical conditions of extinction are measured. In addition, the reference components tested are n-heptane, n-decane, n-dodecane, methylcyclohexane, trimethylbenzene, and o-xylene. Measured critical conditions of extinction of the Aachen surrogate and surrogate C are compared with those for the jet fuel. In general the alkanes n-heptane, n-decane, and n-dodecane, and methylcyclohexane are found to be more reactive than the aromatics o-xylene and trimethylbenzene. Flame structure and critical conditions of extinction are predicted for the reference components and the surrogates using a semi-detailed kinetic model. The predicted values are compared with experimental data. Sensitivity analysis shows that the lower reactivity of the aromatic species arises from the formation of resonantly stabilized radicals. These radicals are found to have a scavenging effect. The present study on premixed flows together with previous studies on nonpremixed flows show that the Aachen surrogate and surrogate C reproduce many aspects of premixed and nonpremixed combustion of jet fuels.     

Molecular Mechanics Study of the Inclusion of Trimethylbenzene Isomers in α-Cyclodextrin

Molecular mechanics calculations were employed to study the inclusion of triethylbenzene isomers in -cyclodextrin and their solvation energy in aqueous solution. Trimethylbenzene penetrates partially into the cavity of -cyclodextrin to form 1 : 1 or 2: 1 host–'guest complexes. The interaction energy between host and guest is dominated by van der Waals energy. The inclusion complexes have higher solvationenergies than free -cyclodextrin.