微波辐射合成葡萄糖五乙酸酯

在微波辐射下,对甲苯磺酸催化葡萄糖和乙酸酐反应合成了葡萄糖五乙酸酯。考察了微波辐射功率、微波辐射时间、原料配比和对甲苯磺酸用量对产率的影响。通过正交实验确定了最佳条件为:辐射功率462 W,反应时间7 min,葡萄糖与乙酸酐的摩尔比1∶9,对甲苯磺酸质量分数1.5%,产率可达71.8%。     

微波辐射无溶剂催化合成季戊四醇双缩苯甲醛

微波辐射下采用硫酸氢钾作催化剂,无溶剂合成季戊四醇双缩苯甲醛.考察了微波辐射时间、辐射功率、原料配比、催化剂用量对产率的影响.实验表明,当微波辐射功率为465 W、辐射时间为5 min、苯甲醛用量为30 mmol、季戊四醇用量为15 mmol、硫酸氢钾用量为0.3 mmol时,产率可达84.5%.     

微波辐射下单质碘催化合成苯甲醛乙二醇缩醛

微波辐射下以单质碘为催化剂无溶剂合成了苯甲醛乙二醇缩醛,试验了微波辐射功率、微波辐射时间、原料配比、催化剂用量对产率的影响,最佳条件为:辐射功率为259W,反应时间为6.0min,苯甲醛与乙二醇的物质的量比为1∶1.8,单质碘用量为2.5%,产率可达86.7%。     

微波辐射下硫酸盐催化合成季戊四醇双缩苯甲醛

在微波辐射下用硫酸盐催化合成了标题化合物.考察了微波辐射时间、微波辐射功率、原料配比、催化剂用量及不同硫酸盐对产率的影响.当微波辐射功率为462 W,辐射时间为5 min,苯甲醛用量为0.03 mol,季戊四醇用量为0.015mol,硫酸铝用量为0.2 g时,产率可达90.1%.     

微波辐射下无溶剂合成葡萄糖五乙酯

在微波辐射下以硫酸铝钾为催化剂无溶剂合成了葡萄糖五乙酯,考察了微波辐射功率、微波辐射时间、原料配比、催化剂用量对产率的影响.最佳条件为:辐射功率为462W,反应时间为8.0min,葡萄糖与乙酸酐的物质的量比为1:8,硫酸铝钾用量为2.0%,产率可达88.4%.     

微波辐射下季戊四醇双缩对甲氧基苯甲醛的催化合成

首次在微波辐射下以硫酸铝为催化剂无溶剂合成了季戊四醇双缩对甲氧基苯甲醛,考察了微波辐射功率、辐射时间、原料配比、催化剂用量对产率的影响。实验表明:当微波辐射功率为462 W,辐射时间为5.0 min,季戊四醇用量为15 mmol,4-甲氧基苯甲醛用量为30 mmol,硫酸铝用量为0.3mmol时,产率可达89.2%。     

微波辐射下无溶剂合成季戊四醇双缩苯甲醛

在微波辐射下用硫酸铝钾催化无溶剂合成了季戊四醇双缩苯甲醛.考察了微波辐射时间、微波辐射功率、原料配比、催化剂用量对产率的影响.实验表明:当微波辐射功率为462 W,辐射时间为5 min,苯甲醛用量为30mmol,季戊四醇用量为15mmol,硫酸铝钾用量为0.3mmol时,产率可达83.3%.     

微波辐射下无溶剂催化合成葡萄糖五乙酸酯

首次在微波辐射下以硫酸氢钾为催化剂无溶剂合成了标题化合物,考察了微波辐射功率、微波辐射时间、原料配比、催化剂用量对产率的影响.最佳条件为:辐射功率为462W,反应时间为8.0min,葡萄糖与乙酸酐物质的量比为1:7,硫酸氢钾用量为2.0%,产率可达89.5%.     

微波辐射正硅酸乙酯负载磷钨酸催化合成柠檬酸三丁酯

以柠檬酸与正丁醇为原料,以自制固体酸为催化剂,采用微波辐射法合成了柠檬酸三丁酯(TBC)。考察了微波辐射功率、辐射时间、催化剂的用量及酸醇的物质的量之比等对TBC产率的影响,确定了最佳反应条件。当酸醇的物质的量之比为1∶4、催化剂用量为柠檬酸质量的3.0%、微波辐射功率500 W、辐射时间50 min时,TBC产率可达96.5%。     

微波辐射下合成庚酸乙酯

以对甲苯磺酸(PTSA)为催化剂运用微波辐射技术合成庚酸乙酯。其适宜的工艺条件为:酸醇物质的量比为1∶2.0,辐射时间5 min,辐射功率240 W,催化剂用量为2%(质量分数),产率可达89.6%以上。该条件下的反应速率是常规加热条件的30倍。     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.