环已基苯基甲基酮的合成

用无水乙醚作溶剂,以溴代环已烷和金属镁反应合成的Grignard试剂-溴代环已基镁为原料与苯甲酰氯反应,经水解合成环已基苯基甲基酮。产物结构经红外光谱确认。     

环己甲醇合成方法和应用

本文介绍了羧酸或其酯还原成醇类的一些还原剂，主要介绍了环己甲醇的一些合成方法和其主要应用考虑到经济性问题，提出了由硼氢化钾或钠作为还原剂的合成路线。     

Comparative study of poly(2,3 and 4 methyl cyclohexyl methacrylate)s. Dielectric relaxation spectroscopy (DRS)

The relaxation properties of poly(methyl cyclohexyl methacrylate)s (P2MCHMA), (P3MCHMA), (P4MCHMA) were analyzed. Dielectric spectroscopy (DS) techniques were used for this purpose. These polymers exhibit prominent α peaks, associated to the dynamic glass transitions, and then poorly defined β-relaxations and two other relaxation zones labelled as γ- and δ-relaxation in order of decreasing temperatures. The α relaxation processes were analyzed by means of the free volume theory, using the Vogel-Fulcher-Tammann-Hesse (VFTH) equation and in terms of the Havriliak-Negami (HN) empirical equation. Previously to these analyses, conductive contributions to the loss permittivity were subtracted. The apparent activation energies for the secondary processes under study have been calculated by means of Arrhenius. Comparison with previous relaxation results of poly(cyclohexyl methacrylate) (PCHMA), i.e. the polymer without substituents in the cyclohexyl ring, has been also carried out. In this way, changes in the glass transition absorptions as well as in the secondary processes have been discussed.     

Effects of hydrophobicity on the epoxidation of cyclohexene by tert-butyl hydroperoxide on TiO2–SiO2 mixed oxides

The effects of the addition of water to the reaction medium have been investigated for the epoxidation of cyclohexene by tert-butyl hydroperoxide catalysed by a series of TiO₂–SiO₂ mixed oxides prepared by a sol–gel procedure in which a fraction F of tetraethoxysilane is substituted by phenyltriethoxysilane. Infrared spectrometry gives a direct evidence of the retention of Si–C bonds by the solid. The substitution of OH groups by phenyls modifies the catalytic properties: for F=0, the solid is hydrophilic, inhibited by water and catalyses the hydrolysis of TBHP as competitive side reaction, whereas the solid obtained for F=0.2 is hydrophobic and not sensitive to a water/TBHP ratio as large as 1. This revised version was published online in July 2006 with corrections to the Cover Date.     

Soybean lipoxygenase-promoted oxidation of free and esterified linoleic acid in the presence of deoxycholate

Lipoxygenase (EC 1.13.11.12) catalyzes the reaction between oxygen and polyunsaturated fatty acids to give fatty acid hydroperoxides. Recent work showed that soybean lipoxygenase 1 can oxidize diacylglycerols when deoxycholate is present in the reaction medium. Conditions were sought to maximize 1,3-dilinolein oxidation with a commercial soybean lipoxygenase preparation. It was found that dilinolein was oxidized most rapidly in a multicomponent buffer medium that contained 10 mM deoxycholate between pH 8 and 9. When dilinolein oxidation was conducted in the individual components of the multicomponent buffer, the oxidation rate decreased two- to threefold. Addition of 0.2 M NaCl to one of the components, Tricine buffer, caused a twofold increase in the oxidation rate, demonstrating that high ionic strength is a major factor promoting rapid oxidation in the multicomponent buffer. In the deoxycholate multicomponent buffer, the order of reactivity toward oxidation was monolinolein>methyl linoleate≈ linoleic acid>dilinolein. Competition experiments in which mixtures of the substrates were presented simultaneously to lipoxygenase in the presence of deoxycholate showed that linoleic acid was the most reactive substrate. When no surfactant was present or when the surfactant was Tween 20, linoleic acid was the most rapidly oxidized substrate. Overall, the results demonstrate that monolinolein and methyl linoleate are just as reactive, or more so, as linoleic acid to oxidation by lipoxygenase under specified reaction conditions. In competition experiments, linoleic acid oxidation predominates, probably because its free carboxyl functionality allows it to be preferentially bound to the active site of lipoxygenase.     

硫酸铜催化合成醋酸环己酯的研究

分别以浓硫酸、氯化铁、硫酸铜为催化剂催化合成醋酸环己酯,考察了有无结晶水的硫酸铜对酯化反应的影响。在较优催化剂CuSO4.5H2O催化下,考察了反应时间、催化剂用量、醇酸比等因素对酯化率的影响。研究表明,当醇酸摩尔比为1.6∶1,硫酸铜用量对反应物摩尔比为1∶50时,环己烷作带水剂,反应2h,酯化率可达96.7%,且催化剂可重复使用。     

Thermal degradation of single methyl oleate hydroperoxides obtained by Photosensitized oxidation

A peroxidation mixture containing methyl 9- and 10-hydroperoxy-trans-octadecenoates (MOHP) was obtained by singlet oxygen oxidation of methyl oleate. The two hydroperoxides were collected by solid phase extraction and purified separately by high-performance liquid chromatography. Identification and single-isomer purity evaluations were carried out by comparing the chromatographic and gas chromatography-mass spectrometry parameters of the corresponding reduced hydroxy derivatives. Each purified MOHP was thermally degraded and new reaction mechanisms were proposed from the identification of the degradation products. Thermal rearrangement of each hydroperoxide isomer involved an allylic 3-carbon intermediate before further degradation steps. The two MOHP isomers obtained from singlet oxygen oxidation produced all eight hydroperoxide isomers by thermal degradation in the condensed phase at high temperature (200°C). This result supports the assumption of singlet oxygen as a promoter of the first steps of oxidation of food lipids and also reconsiders the Khan mechanism.     

Laboratory‐Scale Studies of the Impact of Oxygen on Mashing

An assessment of the impact of oxygen and hydrogen peroxide on mashing and wort parameters has been made on a laboratory scale. Oxygen has been stridently eliminated by using an anaerobic chamber during mash analysis. Additionally the relative importance of proanthocyanidin species has been assessed by comparing the behaviour of “conventional” malt and a malt produced from a low proanthocyanidin variety. It seems that oxygen and peroxide act independently in causing the oxidation of thiol‐containing materials and polyphenols in mashes and that oxygen is not primarily exerting its impacts through the intermediacy of peroxide. The removal of thiols (presumably at least in part through the production of disulphide bridges between proteins) and of polyphenols (presumably via polymerisation) both contribute to increased wort turbidity and decreased rates of wort separation after mashing. Three inhibitors (nordihydroguaiaretic acid, ethylenediamenetetraacetate and potassium cyanide) have been employed in an attempt to differentiate between enzymic and non‐enzymic events and also to identify whether lipoxygenase and peroxidase are catalysing key events. Whilst it seems that peroxidase has a key role in catalysing the oxidation of polyphenols by H₂O₂, it does not appear that either peroxidase or lipoxygenase is involved in the removal of measurable thiol. Nonetheless a significant proportion of the thiol elimination is likely enzyme‐catalysed. We have been unable to demonstrate the production of hydroperoxides in mashes, but added hydroperoxide is undetectable, which suggests that these materials are either lost by onward conversion or by adsorption onto spent grains.     

Ti-MSU分子筛催化1-丁烯氧化制环氧丁烷的研究

通过液相浸渍法制备Ti质量分数为5.5%的Ti-MSU分子筛催化剂,并采用X射线衍射、N2吸附-脱附对催化剂样品进行表征。考察了Ti-MSU催化剂对以过氧化氢异丙苯(CHP)、1-丁烯为原料制备环氧丁烷的反应工艺条件的影响。结果表明,当催化剂床层温度为100℃、反应压力为3.0 MPa、1-丁烯/CHP摩尔比为10∶1、CHP空速为2 h-1时,CHP的转化率达到81.2%,1,2-环氧丁烷(BO)选择性为60.2%,苄醇(DMBA)选择性为87.2%。     

高熔体流动性聚芳酯的合成及性能

通过相转移界面缩聚的方法,将4,4’-二乙基-1,1’-二苯基苯酚(BHPP)和2,2-双(4-羟基苯基)丙烷(BP A)、对苯二甲酰氯(TPC)以及间苯二甲酰氯(IPC)进行共聚,合成了一系列不同酰氯比例的含乙基侧基的聚芳酯(PABAs)。利用核磁共振和傅里叶变换红外光谱对BHPP单体及PABA系列聚芳酯的结构进行了表征。差示扫描量热法和热重分析结果表明,聚合物具有良好的热性能,其玻璃化转变温度(T_g)为183.7～209.9℃,初始分解温度高于436℃。拉伸测试结果表明聚合物薄膜的拉伸强度大于60 MPa,力学性能优异。同时通过流变测试表明所得聚芳酯具有优良的熔体流动性,乙基侧基的引入使其熔融加工性能得到较大提升。