果糖在酸性离子液体中脱水制备5-羟甲基糠醛

制备了多种离子液体,并将其作为催化剂和溶剂催化果糖脱水制备5-羟甲基糠醛（HMF）。 制备的酸性离子液体包括磺酸基功能化酸性离子液体、咪唑类酸性离子液体和吡啶类酸性离子液体。 利用核磁共振仪和红外光谱仪对离子液体的结构进行表征。 利用紫外可见光分光光度计结合Hammett指示剂计算Hammett酸度函数,比较了酸强度的大小对反应的影响。 结果表明,离子液体的酸强度对反应有较大影响,在无其它催化剂和溶剂的情况下,离子液体具有较高的催化活性,通过使用1-丁基-3-甲基咪唑氯盐(BmimCl)作为催化剂,当反应温度为120 ℃,反应进行到4 h时,HMF收率可以达到74.97%。     

离子液体催化制备5-羟甲基糠醛的研究进展

本文综述了离子液体催化制备5-羟甲基糠醛的研究进展。运用离子液体作为反应溶剂和催化剂,与常规合成HMF的方法相比,其反应在常压、低温下进行,更易于操作控制;副反应数量明显减少,HMF的产率稳定,可达90%;离子液体催化活性稳定,可重复利用,减少了有机溶剂的使用量;利用离子液体作为媒介,能将反应原料从单一的果糖扩展到葡萄糖和纤维素等廉价原料,降低了生产成本。由此可见,运用离子液体催化制备HMF将是今后研究的重点和发展的必然趋势。     

果糖脱水制备5-羟甲基糠醛

5-羟甲基糠醛(HMF)是一种重要的生物基材料单体,具有非常广泛的应用价值。果糖等己糖选择性脱水是制备5-羟甲基糠醛的主要方法之一。本文首先从催化剂的角度出发,介绍了近年来不同均相和多相酸性催化剂在该反应中的应用。按照反应溶剂体系进行分类,总结了近年来该领域中不同溶剂体系的研究进展,包括双相溶剂体系、亚/超临界流体溶剂体系和离子液体溶剂体系等。最后,指出了新型多相酸性催化剂以及高效溶剂体系的开发和改进是该领域将来主要的研究方向。     

离子液体中树脂催化转化果糖为5-羟甲基糠醛

开发了以离子液体1-丁基-3-甲基咪唑氯盐([BMIM]Cl)为溶剂, 固体酸离子交换树脂NKC-9为催化剂转化果糖为5-羟甲基糠醛的绿色工艺. 在此催化体系中, 100 ℃下反应10 min时5-HMF的产率达到78.0%, 其反应时间远远小于已有文献报道的长达数小时的反应时间. 在此催化体系中, 果糖起始浓度的增加对5-HMF产率影响不大, 因而此工艺同样适用于处理高浓度的果糖溶液. 离子液体[BMIM]Cl和树脂组成的催化体系可以循环使用, 经过9次重复使用后仍能保持稳定的催化活性.     

离子液体中Lewis酸催化葡萄糖和果糖脱水制备5-羟甲基呋喃甲醛

在离子液体中采用不同的Lewis酸催化葡萄糖和果糖脱水制备5-羟甲基呋喃甲醛(5-HMF).结果表明,CrCln和SnCln均可高效催化葡萄糖转化为5-HMF.另外,Lewis酸的酸性越强,其催化果糖转化为5-HMF的产率越高.镧系金属氯化物在反应中表现出较好的催化活性和产物选择性.同时还研究了离子液体结构对催化反应的...     

Br(o)nsted酸性离子液体催化异丁醛和叔丁醇缩合反应

考察了Br(o)nsted酸性离子液体同时作为溶剂和催化剂催化异丁醛和叔丁醇缩合制备 2,5-二甲基-2,4-己二烯的反应性能.结果表明,Br(o)nsted酸性离子液体具有良好的催化性能,反应后反应产物与离子液体自动分层易分离,离子液体经过真空干燥处理后可以作为溶剂和催化剂循环使用.调变离子液体中的阳离子或阴离子的结构对催化性能有较大的影响.     

离子液体中磺化无定形炭催化菊糖制备5-羟甲基糠醛

研究了以1-丁基-3-甲基咪唑氯盐([Bmim]Cl)离子液体作溶剂,磺化无定形炭为催化剂催化菊糖脱水制5-羟甲基糠醛(HMF)的反应.考察了溶剂、水量、反应温度、反应时间和催化剂用量对HMF收率的影响.实验结果表明,反应温度为100°C,反应时间60min,R=5(R为水的物质的量与菊糖中所含果糖单位的物质的量的比值),m(催化剂):m(菊糖)=1:3时,HMF的收率可达50%.     

硅胶固定功能化离子液体的制备及其在5-羟甲基糠醛合成中的应用

通过γ-氯丙基三甲氧基硅烷将磺基功能化离子液体-N-磺丙基咪唑盐化学键合到微球硅胶上,制得微球硅胶固定化离子液体(IL3). 用FTIR、TG、~(13)C NMR、SEM、BET及酸度测定等测试技术对IL3进行了表征,并考察其在果糖脱水合成5-羟甲基糠醛(HMF)过程中的催化性能. 研究结果表明,氯丙基三甲氧基硅烷可以将磺基功能化咪唑型离子液体化学键合到微球硅胶上. 微球硅胶固定化磺基咪唑离子液体能有效催化果糖脱水生成HMF. 果糖在固载率45.4%的IL3催化下、乙二醇甲醚(EGME)溶剂中、115 ℃反应5 h,HMF收率可达82.1%. 催化剂循环使用4次后,HMF的收率下降为53.0%.     

催化选择转化多羟基化合物制备高附加值化学品研究进展

对近年来催化转化多羟基化合物制备5-羟甲基糠醛、乙二醇、1,2-丙二醇、1,3-丙二醇等高附加值化学品进行了综述. 分析了果糖、葡萄糖、纤维素等不同结构的碳水化合物制5-羟甲基糠醛存在的挑战, 并对相应的解决方法进行了总结. 对于5-羟甲基糠醛的转化, 我们重点讨论了5-羟甲基糠醛选择性氧化制备2,5-二甲酰基呋喃和2,5-呋喃二甲酸以及它们作为聚合单体的潜在应用. 概述了催化氢解纤维素、糖醇、甘油等多羟基化合物制备乙二醇、1,2-丙二醇、1,3-丙二醇等二元醇的方法, 并对可能的机理进行了讨论. 依据近年来多羟基化合物催化选择性转化制备高附加值化学品的研究现状, 对今后的研究热点进行了展望.     

由果糖催化合成5-羟甲基糠醛的研究进展

5-羟甲基糠醛(HMF)是一种具有重要应用价值的原材料和中间体,以果糖脱水合成HMF具有实现生物质转化利用的重大意义。本文综述了近三年来果糖制备HMF过程的两大关键因素:催化剂和反应介质的重要进展。固体酸(特别是杂多酸及其盐)、离子液体(ILs)中添加卤化物或ILs作为催化剂是近几年来研究的热点,固体酸的优点是可多次重复使用且易于分离,而ILs中果糖的降解条件较温和,副反应较少。目前,用于果糖转化HMF的反应溶剂优、缺点并存。最后对该反应存在的问题和今后的研究进行了总结和展望。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Summary of development of the theory of stability of colloids and thin films

In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

Thermodynamics of the formation of oxosulfides of rare-earth elements

The enthalpies of solution of several oxosulfides of rare-earth elements and the high-temperature enthalpies of oxosulfides and oxosulfates of lanthanum and yttrium were measured using solution calorimetry and high-temperature microcalorimetry techniques. Standard enthalpies of formation and some thermodynamic properties of oxosulfides and oxosulfates were calculated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2 pp. 294–297, February, 1997.     

探究“铁的锈蚀条件”实验创新设计

设计了铁的锈蚀实验,说明了铁钉的处理方法,增加了温度、酸、碱的影响条件,实现了铁跟蒸馏水及空气中氧气快速反应而生锈,使实验在5 min左右就能够得到准确的结果。