合成香兰素新工艺的研究

介绍了以对羟基苯甲醛为原料合成甲基香兰素新路线的工艺参数，其产品达到香兰素的质量指标，产率可达８０％。     

合成香兰素新工艺的研究

本文介绍了以对羟基苯甲醛为原料合成香兰素的新工艺路线及其有关参数,其产品达到了香兰素的质量指标,收率可达80％。     

5-溴香兰素的绿色合成

以冰醋酸为溶剂,香兰素为原料,AlBr3为催化剂,HBrO3与KBrO3为溴化剂合成了5-溴香兰素.采用正交实验法考察了影响收率的因素.最佳条件为:香兰素、KBrO3与AlBr3的物质的量的摩尔比为1:0.5:0.056,反应时间6.0h,反应温度30℃.在优化条件下收率可达90.4%.产物结构通过IR、1HNMR、熔点测定和元素分析得以确认.     

香兰素新合成工艺路线的绿色化学原理解析

在系统研究之上,开发了大宗香料香兰素新合成工艺路线,以对甲酚为起始原料,经单溴化、氧化、甲氧基化三步反应制备香兰素。文中对该工艺路线进行了详细的绿色化学原理解析,分析了对甲酚氧化溴化清洁生产特性与专一区域选择性的化学原理,阐明了氧气氧化“单溴酚”生成“单溴醛”的反应机理和动力学过程,揭示了可回收精甲醇定量甲氧基化反应的工艺原理。香兰素新合成工艺案例引入制药工艺学教学,能够促进学生专业思维的培养,使学生树立绿色化学、文明生产的理念。     

乙基香兰素合成方法研究进展

综述了乙基香兰素的各种合成方法，并对这些方法的优缺点进行了比较。以对甲酚为原料制取乙基香兰素是一条极具发展潜力的绿色生产路线，而以乙基愈创木酚和乙醛酸为原料通过电解氧化合成乙基香兰素则是我国乙基香兰素生产工艺的发展方向。指出乙基香兰素在食品、饮料和酒类等行业中的应用势必取代香兰素。     

我国香兰素发展概况

香兰素按结构可分甲基香兰素和乙基香兰素2种。甲基香兰素化学名为4-羟基-3-甲氧基苯甲醛，通常也叫香兰素，乙基香兰素化学名为4-羟基-3-乙氧基苯甲醛，它们通常是白色至微黄色针状晶体，具有香荚兰豆的香气。乙基香兰素具有强烈花香味，香度为香兰素3～4倍，因此广泛用于食品工业，主要添加于冰淇淋、糖果、巧克力和饼干等，也有少量用于化妆品。     

香兰素的市场状况与趋势

香兰素的全球需求量，2006年为19000吨左右，由于黎芦醛合成方法的改变，从2007年起年需求量减少了约2000吨左右，目前香兰素国际市场的实际年需求量为17000吨左右，其中甲基香兰素约14000吨，乙基香兰素为3000吨。由于在食品添加剂方面的用量还在增加，一般认为香兰素的年需求量还会以4％～5％的速度增加。     

我国香兰素生产和专利技术进展

香兰素按结构可分为甲基香兰素和乙基香兰素2种。甲基香兰素(Vanillin)化学名为4-羟基-3-甲氧基苯甲醛，通常也叫香兰素。乙基香兰素即3-乙氧基-4-羟基苯甲醛，别名乙基香草醛，乙基凡尼林(ethylvanillin)。它们通常是白色至微黄色针状晶体，具有香荚兰豆的香气。     

香兰素制备3,4,5-三甲氧基苯甲醛的技术经济分析

对比分析了 3 ,4,5 -三甲氧基苯甲醛 ( TMB)的几种合成工艺路线 ,指出在我国随着香兰素生产技术的进步 ,成本大幅度下降 ,生产厂家增多 ,产量增加 ,使从香兰素合成 TMB成为可能 ;通过对 10 0 t/ a香兰素法 TMB生产线投资概算和经济效益分析 ,证明该项目盈利是可靠的 ,有较强的抗风险能力     

我国香兰素发展概况

香兰素按结构可分甲基香兰素和乙基香兰素２种。甲基香兰素化学名为４－羟基－３－甲氧基苯甲醛，通常也叫香兰素。乙基香兰素化学名为４－羟基－３－乙氧基苯甲醛，它们通常是白色至微黄色针状晶体，具有香荚兰豆的香气。乙基香兰素具有强烈花香味，香度为香兰素３～４倍，因此广泛用于食品工业。主要添加于冰淇淋、糖果、巧克力和饼干等，也有少量乙基香兰素用于化妆品。香兰素广泛应用于食品、饮料、烟酒、洗涤化妆品和药品的加香；应用于塑料、橡胶和其他工业品的祛臭，也是重要的医药原料和工业添加剂。国内主要用于调制食用香精，而国…     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.