α-蒎烯的光氧化反应研究

α-蒎烯和氧能在基态条件下形成CCT复合物,在与CCT复合物吸收相应波长的光辐照下,有利于促进蒎烯的光氧化反应。在氧化反应中,存在着明显的溶剂极性的影响,极性愈大,反应的速度愈快。这一切都说明电荷转移在反应中起着重要的作用。此外,正由于存在着基态的CCT复合物,因此α-蒎烯的氧化反应也能在暗的条件下进行。根据蒎烯光氧化和暗氧化反应产物的分析,可以肯定蒎烯在本工作实验条件下的氧化反应是通过自由基机理而进行的。     

从松节油中分离α—蒎烯,β—蒎烯工艺设计计算

介绍作者对松节油中分离α－蒎烯、β－蒎烯、β－蒎烯的精馏塔进行的应用设计计算。生产证明,设计的精馏塔分离效果完全达到预定设计要求,是进行松节油提纯加工的理想设备。     

高纯β-蒎烯的制备

为提高β-蒎烯深加工产品的质量等级,研究了一种制备高纯β-蒎烯的方法。通过用苯磺酰叠氮处理工业β-蒎烯〔m(α-蒎烯)∶m(β-蒎烯)∶m(其他组分)=4.0∶95.9∶0.1〕,制得了高纯β-蒎烯。同时考察了反应溶剂、反应温度、反应时间和后处理方法对纯化结果的影响。以乙腈为溶剂,回流8 h,反应混合物经硅胶柱分离得高纯β-蒎烯,GC检测其组分质量比为:m(α-蒎烯)∶m(β-蒎烯)∶m(其他组分)=0∶99.9∶0.1〕,β-蒎烯回收率74.0%。     

伞花烃,Ning烯,α—蒎烯的电氧化反应的对比研究

探讨了伞花烃，Ｎｉｎｇ烯，α－蒎烯的电氧化反应，分离和提纯了这些反应的主产物，并通过ＩＲ，＾１ＨＮＭＲ，ＭＳ谱证实了它们的结构。     

固体超强碱催化剂在β—蒎烯异构化反应中的应用研究

研究了团体起强碱催化的β-蒎烯异构化反应。在固体超强碱的作用下β-蒎烯异构化反应可在空温下发生,通过此反应可高收率地获得α-蒎烯。实验证明,在β-蒎烯异构化反应中β-蒎烯的转化率和α-蒎烯的选择性均能达到近100％的程度。同时也对影响异构化反应的主要因素进行了探讨。     

9,10-二氰基蒽敏化光氧化反应的溶剂效应

本文通过α-,β-蒎烯及1,4-二苯基-1,3-丁二烯的9,10-二氰基蒽(DCA)敏化光氧化反应在一系列溶剂中产物生成的相对量子效率及单线态氧(~1O_2)产物的含量,对β-蒎烯在乙腈中的反应动力学分析,讨论了反应的溶剂效应,证明了DCA敏化光氧化反应,包括~1O_2产物都是经由电子转移的反应机理。     

用分子筛催化异构化α-蒎烯和β-蒎烯及其混合体系的研究

以HY型分子筛为催化剂,开展了α-蒎烯、β-蒎烯及其混合体系的异构化反应研究,考察了α-蒎烯和β-蒎烯含量、催化剂用量、反应温度对异构化反应的影响。结果表明,催化剂在350℃下焙烧2h,当其用量为2.5g/100mL原料,反应在140℃下保持4h时,松节油有更好的异构化效果,转化率达96.13%,异构化产物中莰烯的含量为40.80%,苧烯为24.24%;并且发现了原料中的氧化物对异构化反应产生不利影响。     

α—蒎烯在β—分子筛上的三相水合反应

本文对β－分子筛催化α－蒎烯的三相水合反应进行了初步研究。主要产物为检油醇和二戊烯。实验结果表明，超声波可以加速反应和提高产率。在超声波作用与否的情况下，反应均存在一个最佳反应温度。     

α-蒎烯催化加氢合成顺式蒎烷的研究

本文研究了以镍系催化剂催化α－蒎烯加氢合成高选择性的顺式蒎烷。考察了反应压力、反应温度及催化剂用量等因素对产品的影响，在此基础上确定了适宜的工艺参数。在此条件下反应，α－蒎烯转化率＞99％，顺式蒎烷选择性＞95．7％。     

蒎烯及其衍生化合物药物活性的研究进展

α-蒎烯和β-蒎烯是松节油的主要成分,因具有多种潜在的生物活性而受到广泛的关注。关于α-蒎烯和β-蒎烯及其衍生化合物药物活性的研究已有大量新的报道,但是全面系统的介绍仍然比较缺乏。因此,综述了近年来α-蒎烯和β-蒎烯药物活性的研究,以及利用α-蒎烯和β-蒎烯合成具有药物活性衍生化合物的研究进展,展望了α-蒎烯和β-蒎烯药物活性衍生化合物未来的研究发展方向。     

α—甲氧基萘的电子转移光氧化反应

近年来芳烃和杂环化合物的电子转移光氧化反应受到日益的注意。电子转移光氧化反应不仅可应用于很多对~1O_2为惰性的烯烃和芳烃,而且对某些~1O_2活性化合物,也可给出与~1O_2反应不同的产物。因而扩展了光氧化反应的范围。在芳烃方面,迄今研究较多的是烷基芳烃的反应。产物为侧链氧化而得的芳酸与芳醛。甲氧基取代的苯和萘,虽然是好的电子给体,但由于其自由基正离子的化学惰性,因而常在电子转移反应中用做猝灭剂。它们本身的电子转移光氧化反应研究很少。由于甲氧基取代芳烃不具备可氧化的侧链,其电子转移光氧化反应的产物与历程均应与烷基芳烃不同。本文报     

氧化锌分散体光反应产生的自由基中间体

溶液中光诱导的电子转移反应已进行了大量的研究。而半导体粉末在水相或非水溶剂中的光化学研究也与自俱增。这种光化学与成像体系、太阳能转换以及光催化或污物的光降解有关。因此,越来越引起人们的重视。 Harbour和Hair用自旋捕捉技术研究了在ZnO-H_2O的分散体系中光合成过氧化氢,并检测到羟基自由基。他们认为氧化锌可能通过水的氧化将O_2还原成H_2O_2,从而使太阳能转换成化学能。人们自然会想到ZnO在其它溶剂中是否-也能观察到溶剂光氧化     

酞花菁及金属酞菁化物紫外光解的ESR研究

在较强的紫外辐射作用下,即使较为稳定的酞菁化合物也可能发生光解。水文用自旋捕捉与ESR技术相结合的方法检出了在光解中生成的氮中心自由基。     

Stabilization of photo-induced radicals in hematoporphyrin-IX-doped chitosan film

Induction and stabilization of free radicals were investigated in hematoporphyrin-IX (Hp)-doped chitosan (Hp-Ch) film by electron spin resonance (ESR) following photo-irradiation. Induced radicals were more stable in chitosan and 6-O-carboxymethyl chitin films than in carboxymethyl cellulose and sodium alginate films. Hydroxyl groups on D-glucosamine residues in chitosan are suggested as participating in accepting radicals, since spin trapping was absorbed in ESR spectra of Hp-Ch film by the use of oxygen sensitive spin trapping reagent. An induced circular dichroism spectrum was observed only for Hp-doped chitosan film over a range 360–450 nm among seven pairs of polymers and dyes; it is suggested that Hp molecules are arranged parallel along the carbohydrate backbone of chitosan, resulting in the highest acceptance of photo-induced radicals in the polymer film.     

Thermally induced homolytic scissions of interunitary bonds in a softwood lignin solution: A spin‐trapping study

Unstable chemical species, that is, radicals generated by the thermal treatment of a dimethyl sulfoxide (DMSO) solution of the lignin of a softwood, Yezo spruce (Picea jezoensis Carr.), were studied in detail with an electron spin resonance (ESR) method combined with a spin‐trapping technique. An unstable secondary carbon radical (～CH ·) in the solution was trapped as a stable nitroxide spin adduct [R? (N? O ·)? CH～ (R = tert‐butyl benzene)] when the DMSO solution was heat‐treated in the presence of a spin‐trapping reagent [2,4,6‐tri‐tert‐butylnitrosobenzene (BNB)] at about 40°C. This meant that alkyl phenyl ether bonds (～CH? O‐phenyl), known as interunitary lignin bonds, were homolytically scissioned by the thermal treatment in the lignin solution. A detailed analysis of the ESR spectrum revealed that three kinds of radicals—primary (～CH₂ ·), secondary (～CH ·), and tertiary (～C ·) carbon radicals—were trapped as stable spin adducts at about 60°C, although the phenoxy radical (Ph? O ·) was not trapped by the BNB spin trap as the counter radical of the secondary carbon radical. This suggested that a fairly large steric hindrance existed between the so‐called guaiacoxy radical with a methoxy group in the ortho position and the BNB molecule bearing two butyl groups as bulky moieties in the ortho positions. However, the phenoxy radicals in the lignin solution were stable up to about 60°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2136–2141, 2004     

Importance of surface free radicals in the reactivity of granular activated carbon under water treatment conditions

Free aqueous HOC1 reacts with phenols adsorbed on granular activated carbon (GAC) to produce a series of oxidation products, not formed in absence of carbon. When GAC is treated with a free radical quencher, BHT, however, the formation of these products is inhibited. Experimental data and measurements with ESR (electron spin resonance) show that surface free radicals are produced from the oxidation of GAC with aqueous HOC1. The radicals enter radical chain reactions and produce the observed products.Some of the free radicals on the GAC surface are associated with oxygen-containing functional groups. Outgassing of GAC at high temperatures results in reduction of surface oxygen and free radical concentration, and ability of GAC to promote the surface reactions.The ash content of the GACs studied does not correlate well with their ability to promote surface reactions. A surface reaction mechanism is postulated to explain the observed products.     

Electron spin resonance spectroscopy for determination of the oxidative stability of food lipids

Evaluation of the oxidative stability of food lipids based on the tendency of formation of radicals is shown to be possible using electron spin resonance (ESR) spectroscopy and the spin-trapping technique. Induction time can be determined for mildly accelerated conditions (50°C for lipid fraction from mayonnaise enriched with fish oil), and the length of the induction time decreases during storage and γ-tocopherol depletion. The protection by ethylenediaminetetraacetic acid against initiation of lipid oxidation is also detected in the new assay. For more oxidatively stable lipids (butter, rapeseed oil, dairy spread) the mildly accelerated conditions can be used in the assay, provided that difference in signal height for fixed times replaces determination of induction time. ESR spin trapping provides a sensitive method for evaluating the oxidative stability of food lipids. Detection of radicals in the lipid as an early event in oxidation allows mild conditions to be used, and future experiments should also include sensory evaluation in relation to determination of practical shelf life.     

THERMAL INDUCED HOMOLYTIC SCISSIONS OF LIGNIN INTERUNITARY BONDS IN THE HARDWOOD LIGNIN SOLUTION. AN ESR STUDY COMBINED WITH A SPIN TRAPPING METHOD

An electron spin resonance (ESR) method combined with a spin trapping reagent was successfully applied to trap and characterize unstable free radicals which were generated by heat-treatment of the dimethylsulfoxide (DMSO) solution of a hardwood, Japanese beech (Fagus crenata) lignin. It was found, consequently, that two unstable secondary carbon radicals, ～ CH? in the solution were created and the resulting radicals were trapped as the stable nitroxide spin adducts when the DMSO solution was heat-treated in the presence of a spin trapping reagent: 2,4,6-tri-tert-butylnitrosobenzene (BNB) at ca. 91°C. This means that so-called alkyl phenyl ether bonds, ～ CH-O- phenyl, known as important lignin interunitary bonds were homolytically scissoned by the heat-treatment of the lignin solution. Further the detailed analysis of the observed ESR spectrum revealed that two positions of alkyl phenyl ether bonds, i.e., β-O-4 and/or α-O-4 bonds as the interunitary linkages in the lignin are homolytically scissioned, although the phenoxy radical, Ph-O ? as the counter radical of the secondary carbon radicals was not trapped by the BNB spin trap. This suggests that fairly large steric hindrances operate between the syringyl with two methoxy moieties at the ortho positions and/or guaiacyl moieties with a methoxy moiety at the ortho position, and the BNB molecule bearing two bulky ortho tert-butyl groups in the phenyl ring.     

酯-二苯酮光化夺氢反应活泼自由基的ESR研究

自旋捕捉技术与ESR相结合,为检测反应过程中产生的自由基活泼中间体提供一个方便且有效的方法。近年来,国内外研究工作者利用这一方法,对固相,液相和气相中产生的活泼自由基已进行了广泛的研究。特别是对二苯酮与质子给体如:醇、胺、     

有机锡化合物光解活泼自由基的ESR研究

本文用自旋捕捉技术与ESR相结合的方法,研究了六种有机锡化合物的光解反应历程。结果表明:有机锡化合物紫外光照时,碳—锡键发生均裂,产生碳中心和锡中心自由基。其中碳中心自由基易被捕捉剂α-苯基-N-特丁基氮氧化物(PBN)或2,3,5,6-四甲基亚硝基苯(ND)所捕获;而锡中心自由基可与菲醌形成稳定的环状加合物。由于环状加合物中配体的不同,产生的空间效应也不同,从而导致加合物中的未偶电子云密度发生变化,给出相异的ESR信号。