Unprecedented chemo-enzymatic synthesis of stereochemically pure 3-acetoxy-2-methyl-2-vinylcycloalkanones

A new approach to 3-acetoxy-2-methyl-2-vinylcyclohexanone and 3-acetoxy-2-methyl-2-vinylcyclopentanone in stereochemically pure state, by means of a combination of yeast-catalyzed reduction and subsequent radical β-fragmentation is described.     

Novel and Efficient Synthesis of 4-Indazolyl-1,3,4-trisubstituted Pyrazole Derivatives

In the present study, 1-(4,5-dihydro-3,6-dimethyl-4-(1,3-diphenyl-1H-pyrazol-4-yl)-3aH-indazol-5-yl)methanone derivatives (9–12) and isoxazoleyl (13–16) have been synthesized by the condensation of 1,3-diphenyl-1H-pyrazole-4-carbaldehyde (1–4) with acetyl acetone via Knoevenagel/Michael/aldol reactions in a sequential manner to yield intermediate cyclohexanone (5–8). The intermediates (5–8) treated with NH₂NH₂ · H₂O/NH₂OH · HCl afforded 4-indazolyl-1,3,4-trisubstituted pyrazole and isoxazoleyl derivatives. All of these compounds are reported for the first time, and the structures of these compounds were confirmed by means of infrared, ¹H NMR, ¹³C NMR, and mass spectroscopy.     

双功能Pd/ZrHP催化剂的制备及其在苯酚选择性加氢反应中的应用

苯酚加氢制备环己酮是合成纤维（尼龙）生产过程中的重要环节。采用微波法快速合成了具有层状结构的固体酸（磷酸氢锆,ZrHP）和ZrHP负载的Pd催化剂,利用X射线衍射（XRD）、扫描电子显微镜（SEM）、高倍透射电子显微镜（HRTEM）、氮气吸附-脱附、X射线光电子能谱（XPS）和程序升温脱附（TPD）技术对催化剂的结构、形貌和表面特性进行了详细的表征,并将其应用于苯酚选择性加氢制环己酮的反应中。研究发现：在温和条件（100℃,1.0 MPa H₂）下,Pd/ZrHP比传统的氧化物（Al₂O₃、SiO₂、MgO）、分子筛（H-Beta）、活性炭（XC-72）负载的Pd催化剂具有更高的活性和稳定性,催化剂表面Pd原子的比活性最高可达612.2 h^-1,并且经过5次循环使用后催化剂无明显失活。结合表征结果推断,金属中心Pd与ZrHP表面的酸性位点之间的协同作用可能是影响苯酚加氢产物停留在环己酮阶段的关键因素。     

L‐Lysine/imidazole‐catalyzed Multicomponent Cascade Reaction: Facile Synthesis of C5‐substituted 3‐Methylcyclohex‐2‐enones

A facile and simple route for the direct preparation of substituted 3‐methylcyclohex‐2‐enone via Aldol‐Robinson cascade reaction of aldehydes and acetones catalyzed by the new catalytic system of L‐lysine/imidazole in n‐heptane with 0.5% water was reported. A variety of substrates can participate in the process efficiently. The merits of this method included inexpensive and easily available starting materials and catalyst, the good yield of products and the straightforward work‐up.     

Catalytic aerobic radical polymerization in typical redox-non-innocent solvents as potential low-efficiency initiators

Abstract

Certain complexes of some transition metal cations in the high oxidation state could oxidize some organic substrates with labile C-H moieties, leading to the corresponding cations in the lower" oxidation state and some carbon-centered radicals. The former would form oxidative complexes with molecular dioxygen to continuously oxidize organic substrates, while the latter would initiate polymerization of vinylic monomers. Such catalytic oxidation is adopted to initiate radical polymerization of methyl methacrylate (MMA) and styrene (St) with cyclohexanone (CyHO) and benzylic hydrocarbons as both the solvent and the substrate. Although, a large array of complexes could trigger the polymerization, Cu^II/2,2′-bipyridine complexes display a maximum turnover frequency above 200?h^–1 during the catalytic aerobic radical polymerization of MMA in CyHO at 70–80?°C, but only less than 0.4% of CyHO is involved in chain formatting. Cu^II/ligand-catalyzed aerobic radical polymerization of St in CyHO exhibit comparable behaviors. Only Co^II complexes could catalyze the aerobic radical polymerization of MMA in para-xylene and cumene at 90?°C, but only 0.1% of PX and 0.3% of cumene are involved in chain forming.     

离子液体热合成磷仲钨酸铯杂多酸盐催化环己醇制备环己酮

采用离子液体热合成法合成新型磷仲钨酸铯杂多酸盐Cs_3PW_(12)0_(40)’系列催化剂并对其物化性能进行了表征.同时以Cs_3PW_(12)0_(40)’-80(简称CsPW’-80)为催化剂, 30%H_2O_2为氧化剂,乙腈为溶剂,以氧化环己醇合成环己酮为催化剂性能测试反应进行催化性能评估.考察了合成催化剂溶剂离子液体占比、催化剂用量、氧化剂用量、反应温度以及反应时间对催化性能的影响.实验结果表明:在合成催化剂离子液体占比为80%、乙腈溶剂5 mL、氧化剂与反应物n(30%H_2O_2)/n(cyclohexanol)=4、反应温度70℃、反应时间8 h的最优条件下,环己醇转化率为100%,环己酮的选择性为98.46%,环己酮总收率达到98.46%.     

钛硅分子筛催化环己酮液相氨肟化固定床工艺

采用固定床模式,研究了钛硅分子筛催化环己酮制环己酮肟液相氨肟化反应.结果表明,该工艺模式具有可行性与普适性.优化的反应条件为:温度333K,体系氨浓度>2%,酮/H₂O₂摩尔比=5,H₂O₂空速0.083h^-1.此时环己酮转化率、环己酮肟选择性、H₂O₂转化率及其有效利用率分别达18.7%,99.5%,94.7%和98.7%.进一步研究了H₂O₂在该过程中的反应行为,发现固定床工艺模式能有效提高H₂O₂的有效利用率,其主要原因是该模式有利于羟胺的生成及其进一步与酮反应生成肟.适当的空速与氨和酮的浓度是实现H₂O₂高效利用的关键因素.     

Liquid Crystal and Rheological Behavior of 2,6-Bis(benzylidene)cyclohexanone

The liquid crystalline compound, 2,6-bis(benzylidene)cyclohexanone was synthesized using benzaldehyde and cyclohexanone as raw material, and tetrabutyl ammonium bromide as phase-transfer catalyst in the solution of sodium hydroxide. The effect of several factors, such as reaction time, reaction temperature, and concentration of sodium hydroxide, has been investigated. The product was characterized by infrared spectra, ¹H NMR and elemental analysis. The physicochemical behavior of the crystalline compound was studied by differential scanning calorimetry, polarizing microscope, and rheometer. The experimental results show that the synthesized compound exhibits typical semectic thermot liquid crystal. Meanwhile, the crystal of the compound was determined by x-ray single crystal diffraction analysis. The crystal of the compound belongs to monoclinic system with space group P2(1)/c, a = 9.586(1) Å, b = 18.391(2) Å, c = 9.433(1)Å, α = 90°, β = 115.816(2)°, γ = 90°, Dc = 1.217 g · cm^?3, V = 1496.9(3) Å^?3, and Z = 4.     

基于2,6-二(4-羧基苯亚甲基)环己酮的金属-有机框架化合物的合成与表征

以2,6-二(4-羧基苯亚甲基)环己酮(H₂L)为配体得到一例锰金属-有机框架化合物[MnL]_n,并运用红外、热重、循环伏安、固体紫外、X射线光电子能谱和X射线单晶衍射对其进行表征。单晶衍射分析表明该配合物属于三斜晶系,空间群P1^-,不对称单元由Mn(Ⅱ)离子和一个L^2-配体组成。配体两端的羧基均为单齿配位,配体中间羰基上的氧参与配位,每个配体L^2-和3个Mn.离子配位,形成相对稳定的三角形配位构型。配合物中的Mn.与氧原子形成六配位构型,其中赤道面中的4个氧原子来自4个配体L^2-中单齿配位的羧基,上下顶点的2个氧原子分别来自配体L^2-中的羰基,从而形成八面体构型[MnO₆]。拓扑分析表明该金属-有机框架化合物具有二维kgd结构特征。循环伏安测试表明在扫速为30 mV·s^-1时,半波电位为171 mV,固体紫外光谱表明该化合物的带隙为1.76 eV。该化合物在染料分子如亚甲基蓝、甲基橙的降解过程中,具有一定的光催化活性。     

气相色谱法定量分析2,4戊二酮、2-庚酮和环己酮混合物

采用气相色谱技术,建立了可同时测量含有2,4戊二酮、2-庚酮和环己酮混合物质的定量分析方法.选用毛细管柱Rtx-5(30 m×0.25 mm×0.25μm),利用纯物质标准品对照法进行定性分析,优化了色谱条件.运用标准曲线法实现了3种物质的定量测定,2,4戊二酮、2-庚酮和环己酮的线性范围分别为:0.1~0.4、0.7~3.5和0.9~4.4 mg/m L,r大于0.999,线性良好.方法相对标准偏差RSD均低于5%,精密度良好.3种组分的加标回收率分别为92.93%、103.17%和102.96%,均在80%~120%之间,符合质量控制要求.方法实现了同时测定2,4戊二酮、2-庚酮和环己酮,也为相关酮类物质的检测提供了参考.