5-氰基-4-氨基咪唑的合成及其热性能

咪唑基含能化合物是目前高能化合物的重要研究方向,而5-氰基-4-氨基咪唑是设计、合成新型咪唑联四唑类高能高氮化合物的关键中间体。以5-甲酰胺基-4-氨基咪唑(AICON)为原料,经其与三氯氧磷(POCl3)的脱水反应获得了5-氰基-4-氨基咪唑(AICN),通过优化反应体系、反应温度、反应时间以及物料物质的量比,使得AICN的收率>65%,纯度(HPLC)>99.5%。此外,采用NMR、IR和元素分析对其进行了结构确证,利用热重分析法研究其热性能。结果表明,AICN的最佳反应条件为以POCl3为脱水剂,n(AICON)∶n(POCl3)=1∶10,反应升温模式为先快速升温至80～85℃,维持反应30 min,然后降温至70～75℃,维持反应1.0～1.5 h;AICN在40～1000℃温度区间存在两个失重过程,对应的热分解温度区间分别为40～400℃和400～1000℃、热失重分别为19.8%和60.7%、热分解峰温分别为256.5和698.4℃,表明其具有良好的热稳定性。     

4,5-二氧代氰基咪唑盐酸盐的合成与表征

以4,5-二氰基咪唑为起始原料,通过羟胺氰基加成、重氮化取代、水解脱氯化氢等反应自主设计、合成了新型含能化合物4,5-二氧代氰基咪唑盐酸盐,总收率为58.2%;利用红外、核磁和元素分析等方法对目标化合物和中间体进行了结构表征;培养了中间体4,5-二氯肟基咪唑盐酸盐的单晶,用SHELXTL程序解析计算单晶的X射线衍射数据得到晶体的结构参数;利用DSC法分析了4,5-二氧代氰基咪唑盐酸盐的热分解性能。结果表明,4,5-二氯肟基咪唑盐酸盐晶体属于斜方晶系、Pna2(1)空间群,相对分子质量为259.47,密度为1.699g/cm3;4,5-二氧代氰基咪唑盐酸盐热分解温度始于140.23℃,经162.73℃和177.73℃两个分解放热峰,直至208.48℃分解放热结束,说明其结构比较稳定。     

3-氰基-5-氨基-1,2,4-1H-三唑的高效合成与热性能

以3-甲酰胺基-5-氨基-1, 2, 4-1H-三唑为原料,经缩合、环化、酯化、氨化和氧化等反应获得目标化合物3-氰基-5-氨基-1,2,4-1H-三唑(ATCN),通过优化制约合成工艺的氧化反应体系、反应温度以及反应时间,将收率由文献值37.0%提高至81.6%。采用核磁共振(NMR)、红外吸收(IR)和元素分析等手段表征了结构,通过差示扫描量热法(DSC)和原位红外技术研究ATCN热分解和热裂解特性,并进行热分析动力学计算。结果表明,ATCN第1个热分解峰值温度为163.01℃,对应为氨基和氰基的断裂;第2个热分解峰值温度为244.29℃,对应为三唑环结构的裂解。此外,通过热力学参数计算获得ATCN第1个热分解过程的活化能、活化焓、活化吉布斯自由能和活化熵分别为156.21、153.26、109.80 kJ·mol~(-1)和103.40 J·K~(-1)·mol~(-1)。     

印尼褐煤的热分解特性研究

采用热重分析和热解实验对印尼褐煤的热分解特性进行研究,探讨了印尼褐煤的热解机理、升温速率和热解终止温度对热解过程的影响.结果表明,印尼褐煤的热失重过程包括水分蒸发、挥发分析出和焦炭形成三个阶段;在温度低于300℃时,印尼褐煤以水分蒸发和脱除吸附小分子气体为主,300℃时开始微热解反应,400℃时热分解反应剧烈.在同一热解温度条件下,升温速率为10K/min～20K/min的慢速升温热解过程中,焦油产率维持在8.5%(质量分数)附近,升温速率对热解产物产率的影响较小;在400℃～600℃的低温热解范围内,热解终止温度对焦油产率影响较小,但热解气体产率随热解终止温度的增大而增大,而半焦产率却随之降低.     

热重-红外联用法研究液晶聚合物的热解行为及其逸出气体组成

采用热重-红外(TGA-FTIR)联用技术研究液晶聚合物(LCP)的热分解行为,研究不同升温速率(10、20、30、40、50℃/min)对LCP热稳定性的影响,同时对LCP的逸出气体组成进行分析。结果表明:LCP受热分解过程主要为一个失重阶段,LCP组分受热后,分子链断裂,降解成三聚体、二聚体、单体等化合物,有些化合物裂解成烃类物质生成CO2逸出。升温速率对LCP热分解过程的影响主要表现在最大失重速率温度(T_m)和最大失重速率(D_m)上,随着升温速率的增加,D_m增加,T_m升高。     

1-甲基-2,4-二硝基咪唑的合成及反应动力学

以4-硝基咪唑为原料,通过硝化、热重排、甲基化合成1-甲基-2,4-二硝基咪唑(2,4-MDNI),收率为87.2%,纯度不小于98%,并用红外光谱、核磁共振、元素分析等方法表征其结构。对其机理进行了假设,并通过动力学方法验证了反应机理。在动力学实验数据的基础上,计算了反应级数和反应速率常数,并计算出反应的活化能。研究了反应温度、反应时间等因素对合成及收率的影响,用正交试验得到了较优的工艺条件:2,4-二硝基咪唑、碘甲烷的摩尔比为5∶9,反应温度39~42℃,反应时间8h。用DSC研究了2,4-MDNI的热分解。     

3,6-二甲基-2,5-吡嗪二甲酸酯的合成及其卷烟加香应用

以四甲基吡嗪为原料,经氧化和酰氯化反应得到3,6-二甲基-2,5-吡嗪二甲酰氯后,与1-辛烯-3-醇经酯化反应得到潜香化合物——二(1-辛烯-3-醇)-3,6-二甲基-2,5-吡嗪二甲酸酯(DMPOE)。采用1HNMR、13CNMR、IR和HRMS表征其结构,经热重(TG-DTG-DSC)和热裂解-气相色谱/质谱(Py-GC/MS)分析测定其热性能。结果表明:合成产物为目标化合物;DMPOE的主要热失重区间为220~360℃,其失重达85.2%,从224.9℃开始降解,在312℃失重率最大,失重约65.48%;热裂解共检测到9种代表性产物,主要有2,5-二甲基吡嗪、1-辛烯-3-醇和2-异丁基-3-甲基吡嗪等香味物质;在典型中间香型烤烟烟叶中加入0.75 mg/kg的DMPOE可以改善卷烟吸食品质,增补烟香,协调香气,降低杂气和刺激性。     

TGA-FTIR联用技术研究ABS树脂热降解行为

采用热失重-傅里叶变换红外光谱(TGA-FTIR)联用技术研究了在N2气氛下ABS(丙烯腈-丁二烯-苯乙烯三元共聚物)的热稳定性及其分解失重情况.结果表明.ABS的TGA曲线只有1个失重区间.随着升温速率的增加.起始和峰值失重温度增加,热分解温度为380～480℃;ABS热分解活化能(Ea)在59.39～74.70 kJ/mil,通过Ea变化发现.分解可分为多个阶段;经FTIR测试发现.ABS的热分解过程首先是橡胶相PB(聚丁二烯)主链上接枝的SAN(苯乙烯-丙烯腈共聚物)侧链降解,随着温度升高PB主链开始分解,失重质量分数大于50%时,以连续相的高相对分子质量SAN分解为主.     

1-甲基-2，4，5-三硝基咪唑合成工艺优化

以咪唑为原料,通过两步硝化制得1,4-二硝基咪唑,然后在氯苯中热重排得2,4-二硝基咪唑,将2,4-二硝基咪唑进-步硝化并制得2,4,5-三硝基咪唑的钾盐,最后将钾盐甲基化,得到1-甲基-2,4,5-三硝基咪唑（MTNI）,收率23％。采用红外光谱、元素分析、核磁共振的方法对其结构进行表征。用DSC进行了热分解研究。优化了2,4-二硝基咪唑的合成工艺：反应温度为123±2℃,反应时间为6h,n（1,4-二硝基咪唑）：n（氯苯）=1：9。改进了前两步硝化条件和2,4,5-三硝基咪唑钾盐的合成工艺。     

膨胀型季戊四醇磷酸酯类阻燃剂合成研究

以季戊四醇和三氯氧磷为原料合成了两种膨胀型阻燃剂中间体,分别为双环笼状磷酸酯1-氧基磷杂-4-羟甲基-2,6,7-三氧杂双环[2,2,2]辛烷(化合物Ⅰ)和二(2,6,7-三氧杂-1-氧基磷杂双环[2,2,2]辛烷-4-亚甲基)磷酰氯(化合物Ⅱ)。研究了物料配比、反应温度和反应时间对化合物Ⅰ产率的影响,结论表明:化合物Ⅰ的反应溶剂二氧六环,反应的摩尔比n(POCI_3):n季戊四醇)为1:0.9,梯度升温7 h,乙醇提纯重结晶,产率86%。同时,还研究了分批加入化合物Ⅰ和原料配比对化合物Ⅱ的影响,结果表明:乙腈作溶剂,反应的摩尔比n化合物Ⅰ):n(POCI_3)为1.9:1,反应温度是75~80℃,产率78%。用红外光谱图的方法表征了产品的结构;热失重数据表明:化合物ⅠⅡ具有良好的热稳定性和成炭性,其初始热分解温度分别为270℃和340℃在600℃时残炭率分别为58.918%、56.751%。     

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.     

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.