乙酰乙酸乙酯与乙二醇在活性炭负载磷钨酸催化剂上缩合反应

表面活性剂处理的活性炭(C)过量浸渍负载磷钨杂多酸(PW)制备活性炭负载磷钨酸催化剂(PW/C);氨气程序升温脱咐对催化剂酸性质表征,结果显示,负载质量分数为30%,催化剂30%PW/C具有最大酸量。反应测试表明,磷钨酸负载量为30%时催化剂具有最大活性,苹果酯收率为87.5%,适宜的原料配比n(乙酰乙酸乙酯)∶n(乙二醇)=1∶1.5,最佳反应温度80℃,最佳反应时间30 m in,表面活性剂处理过的催化剂连续使用9次,苹果酯的收率保持在85%以上。     

活性炭负载磷钨杂多酸催化剂上苹果酯合成研究

活性炭(C)过量浸渍负载磷钨杂多酸(PW)制备PW/C催化剂并表面活性剂处理,负载PW质量分数为30%时,30%PW/C催化剂具有最大活性,合成苹果酯收率为87.5%,适宜的原料配比n(乙酰乙酸乙酯)∶n(乙二醇)=1∶1.5,最佳反应温度80℃,最佳反应时间30min,催化剂连续使用9次,苹果酯的收率保持在85%以上。     

活性炭负载磷钨酸催化剂上萘的异丙基化

采用过量浸溃法制备了一系列活性炭(C)负载磷钨酸(PW)催化剂,并用N2吸附、XRD、NH3-TPD和BET等手段对其物化性质进行了表征。结果表明,负载磷钨酸后,样品仍然保持较大的比表面积,负载质量分数达30％时,磷钨酸仍在活性炭表面高度分散。随着负载量的增加催化剂酸量增加,负载质量分数为30％时酸量最大,负载量进一步增大,酸量下降,30％PW／C具有最大的萘的异丙基化催化活性。     

H3PW12O40／SiO2催化合成苹果酯-B

以H3PW12O40／SiO2为催化剂,对以乙酰乙酸乙酯和1,2-丙二醇为原料合成苹果酯-B的反应条件进行了研究。考察了原料物质的量比、催化剂用量（质量）、带水剂用量（质量）、反应时间对产品收率的影响。试验结果表明H3PW12O40／SiO2是合成苹果酯-B的良好催化剂,最佳反应条件为：n（乙酰乙酸乙酯）：n（1,2-丙二醇）=1：1．5,催化剂质量为反应物总质量的0．8％,带水剂环己烷6mL,反应时间90min。上述条件下,苹果酯-B的收率可达68．9％。     

负载型甲磺酸对合成乙酸异戊酯的催化性能研究

以活性炭、陶瓷球、石英砂、硅胶为载体负载甲磺酸，制得一系列负载型固体酸催化剂，用乙酸和异戊醇的酯化反应作探针反应，研究了这些固体酸的催化性能。结果表明，不同栽体的甲磺酸催化剂的活性与载体表面特性有关，CH3SO3^-／C催化剂对酯化反应显示出极高的催化活性，并可重复使用，在一定条件下，酯收率达97％。     

二氧化钛负载磷钨杂多酸催化合成苹果酯-B

以自制二氧化钛负载磷钨杂多酸H3PW2O40/TiO2为多相催化剂，以乙酰乙酸乙酯和1，2-丙二醇为原料合成苹果酯一B，研究了原料摩尔比、催化剂用量、反应时间诸因素对产品收率的影响。实验表明：适宜反应条件为n（乙酰乙酸乙酯）：n（1，2-丙二醇）=1：1．4，催化剂用量为反应物料总质量的0．8％，环己烷为带水剂，反应时间1．0h。上述条件下，苹果酯-B的收率为76．3%。     

合成磷霉素的环氧化催化剂的研究

采用原位法制备活性炭负载磷钨酸催化剂,在制备催化剂过程中加入修饰剂,获得活性炭负载修饰型PW/C催化剂,并用于顺丙烯磷酸的环氧化反应.结果表明,加入质量分数5%的修饰剂可以使该催化剂环氧化收率明显提高,重复使用稳定性也明显改善.采用BET、IR和XRD方法表征证明,在活性炭负载催化剂上主要催化活性成分为H3PW12O4...     

H3PW12O40/Y-β催化丙酸异戊酯的绿色合成

采用Y-β复合分子筛负载H3PW12O40（H3PW12O40/Y-β）为催化剂,由丙酸与异戊醇合成丙酸异戊酯,考察了催化剂用量、醇酸摩尔比、反应时间及催化剂重复使用次数等因素对酯收率的影响.结果表明,该催化剂具有催化性能高,易回收并有较好的重复使用性能等优势.最佳反应条件为：丙酸0.1 mol,醇酸摩尔比1.5,催化剂用量0.6g,反应时间30 min,收率95.4％.     

活性炭固载磷钨酸催化合成己酸异戊酯的研究

以活性炭为载体制备了PW12／C催化剂，研究了催化合成己酸异戊酯的最适宜反应条件。实验证明：活性炭同载磷钨酸催化剂具有良好的催化活性，以环己烷为带水剂，在醇酸物质的量比为n(异戊醇)：n(己酸)=1.3：1的条件下，催化剂用量2.5g／0.2mol己酸，反应时间120min，酯化率达到了99.1％：     

纳米H3PW12O40／SiO2复合杂多酸催化合成乙酸正己酯

以纳米二氧化硅为载体,采用溶胶-凝胶法负载磷钨酸,以冰乙酸、正己醇为原料,纳米H3PW12O40／SiO2复合杂多酸为催化剂,考察原料配比、催化剂用量、反应时间、反应温度等因素对酯化反应的影响,同时也考察了催化剂循环使用的情况。实验表明,纳米H3PW12O40／SiO2复合杂多酸催化剂是合成乙酸正己酯的良好催化剂,其最优合成条件为：纳米H3PW12O40／SiO2复合杂多酸催化剂用量约为反应酸醇配料总质量的2．5％,酸醇配比为1：1．4,反应时间1h,反应温度130℃,产率达89．72％。     

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.     

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.     

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.