溶剂在反应控制相转移催化反应中的影响

本文主要探讨了溶剂在反应控制相转移催化反应中的影响。反应控制相转移催化体系兼具均相催化与多相催化的优点,既解决了均相催化中催化剂难以回收的问题又克服了多相催化中反应速率慢、反应时间较长、活性组分易流失以及选择性较低的缺点。催化剂在反应体系中所表现出来的反应控制相转移特性不仅和本身的阴离子、阳离子组成有关,还和体系中溶剂的种类密切相关。合适的溶剂不但可以提高底物的转化率以及产物的产率,同时还有利于催化剂的回收。本文就溶剂在多种反应控制相转移催化体系中的影响进行了综述,包括烯烃环氧化、醇氧化制备醛/酮、酯化、烯/醇氧化制备二元羧酸、缩醛反应、氧化脱硫、羟基化反应以及Se催化还原等体系。最后,对目前催化体系中存在的问题提出了可能的解决方案并对反应控制相转移催化体系在其他方面的潜在应用和发展进行了展望。     

Gemini型季铵盐阳离子表面活性剂催化双烷基联苯酮的还原

本文报道了通过黄鸣龙还原反应还原长链烷基联苯酮,合成了三种长链烷基联苯,其中的两种化合物首次报道.以联吡啶季铵盐为相转移催化剂对双烷基联苯酮的黄鸣龙还原反应进行催化,产率提高了20%～40%,反应时间从55小时缩短为23小时.作为对比,十六烷基三甲基溴化铵、溴代十六烷基吡啶、十二烷基苯磺酸钠也作为催化剂对双烷基联苯酮进行催化还原,结果表明Gemini表面活性剂在双烷基联苯酮的还原中较上述三种传统表面活性剂具有更好的催化性能.     

噁唑硼烷催化芳醛不对称炔基化反应的量化研究

对手性噁唑硼烷催化芳醛不对称炔基化还原反应的机理进行了量子化学半经验方法研究.研究表明,该反应是放热的，炔基转移是反应的控制步骤，炔基转移的过渡态具有扭曲的椅式结构，还原的主要产物是R-手性醇.     

Sm(i-PrO)3/4A分子筛催化下醛、酮的Meerwein-ponndorf-Verley型还原反应

Sm(i-Pro)3(2%)/4A分子筛能够有效地催化各类醛、酮的Meerwein-Ponndorf-Verley型还原反应, 反应转化率优良。     

BAL-树脂的合成及其在对称二醛单功能基Wittig反应上的应用

<正> 近年来,有机化学家应用不溶性聚合物试剂α-二醇、β-二醇树脂对二元醛酮单功能化反应做了大量的工作。笔者在相转移催化下,用交联的氯甲基化聚苯乙烯与2,3-二巯基丙醇(BAL)进行Williamson反应,合成了一个新的不溶性聚合物醛酮保护试剂——BAL-树酯Ⅲ(巯基容量=2.5m mol/g)。并利用鱼钓原理以Ⅲ与对称二醛(对苯二甲     

Sm(i-PrO)3/4A分子筛催化下醛、酮的Meerwein-ponndorf-Verley型还原反应

Sm(i-PrO)_3(2%)/4A分子筛能够有效地催化各类醛、酮的Meerwein-Ponndorf-Verley型还原反应,反应转化率优良     

FeCl3催化羰基化合物的还原卤代反应

在甲基二氯硅烷作用下, FeCl₃能催化羰基化合物(醛、酮)的还原氯代反应, 得到相应的氯代产物; 在甲基二氯硅烷、PBr₃或NaI作用下, FeCl₃可以催化羰基化合物(醛、酮)的还原溴代或碘代反应, 分别以良好的收率得到相应的溴代烷或碘代烷.     

HMAS-5分子筛催化合成缩醛(酮)

研究了HMAS_5分子筛催化乙二醇与环己酮、丁酮、丙酮、丙醛、丁醛、异丁醛、戊醛、异戊醛、正己醛、正辛醛、苯甲醛等醛(酮)的缩合反应。考察了反应时间、醛(酮)与醇的配比、HMAS_5分子筛用量等因素对醛(酮)与醇缩合反应的影响。结果表明,HMAS_5分子筛对醛(酮)与醇的缩合反应有较好的催化性能,选择性一般在98%以上,转化率也一般在90%以上。     

HY分子筛催化1,3-苯并二噁茂烷类化合物合成的研究

研究了HY分子筛催化邻苯二酚与环己酮、丁酮、丙酮、丙醛、丁醛、异丁醛、戊醛、异戊醛、正己醛、正辛醛、苯甲醛、二苯甲酮等十余种醛(酮)的缩合反应。考察了反应时间、酚与醛(酮)的配比、HY分子筛用量等因素对酚与醛(酮)反应的影响。实验发现,当邻苯二酚与醛(酮)摩尔比为1∶1.0、催化剂用量为每mol邻苯二酚2.5g、反应4h,选择性一般在97%以上,醛(酮)的转化率一般在57%以上,表明HY分子筛对邻苯二酚与醛(酮)的反应有较好的催化性能。     

HMCM-22分子筛催化1,3-苯并二噁茂烷类化合物合成的研究

研究了HMCM-22分子筛催化邻苯二酚与环己酮、丁酮、丙酮、丙醛、丁醛、异丁醛、戊醛、异戊醛、正己醛、正辛醛、苯甲醛、二苯甲酮等十余种醛(酮)的缩合反应.考察了反应时间、酚与醛(酮)的配比、HMCM-22分子筛用量等因素对酚与醛(酮)反应的影响.结果表明,当酚与醛(酮)摩尔比为1∶1.4,催化剂用量为3.5 g/1mol醛(酮),反应5 h,选择性一般在97%以上,转化率也一般在70%以上,表明HMCM-22分子筛对邻苯二酚与醛(酮)的反应有较好的催化性能.     

High-performance liquid chromatography of alkaloids

Literature information on the HPLC of alkaloids, including adsorption, reversed-phase, ion-exchange, ion-pair, and other variants is generalized. Results are given of the chromatographic analysis of various classes of alkaloids with an indication of the conditions of separation, and the columns used, and also of the methods of detection. The advantages and disadvantages of the HPLC variants are discussed. The review includes the literature over the last 14 years. Scientific Center for Chromatography, Institute of Chemistry and Physics of Polymers, Uzbek Academy of Sciences, Tashkent. Institute of the Chemistry of Plant Substances, Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 595–613, September–October, 1991.     

Stereospecificity of a lysophospholipase from the venom ofVespa orientalis

Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Institute of Physiology and Biophysics, Academy of Sciences of the Republic of Uzbekistan, 700095, Tashkent, ul. Niyazova, 1. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 625–627, July–August, 1995. Original article submitted November 9, 1994.     

Quantum chemistry and spectroscopy of highly excited states of coordination compounds

Institute of Inorganic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Institute of Catalysis, Siberian Branch, Academy of Sciences of the USSR. Institute of Chemistry and Chemical Technology, Siberian Branch, Academy of Sciences of the USSR. Branch of the Institute of Chemical Physics, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 29, No. 6, pp. 90–103, November–December, 1988.     

Composition of cottonseed soapstock fats

The compositions of cottonseed soapstocks from first-grade and low-grade cotton seeds have been studied by the methods of CC on polyamide and on silica gel, TLC, GLC, ESR, and UV, IR, and mass spectrometry. It has been found that saturated, and also oxygenated, fatty acids, nonpolar acylglycerols, glycolipids, sterols, arylalkanes, gossypol pigments, and ions of metals of variable valence are concentrated in the acid fat of the soapstock from low-grade seeds. The soapstock contains a very small amount of tocopherols and phospholipids, mainly phosphatidylinositols. The combined gossypol pigments of the soapstocks include stabilized gossypol radical ions.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 502–508, July–August, 1988.     

Kinetics of the β → δ solid-solid phase transition of HMX, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine

We apply differential scanning calorimetry (DSC) to measure the kinetics of the β→δ solid-solid phase transition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, HMX. Integration of the DSC signal gives a direct measurement of degree of conversion. Data is analyzed by first-order kinetics, the Ozawa method, and isoconversional analysis. The range of activation energies found in this work, centering around 500 kJ/mol, is much higher than previously reported values by Brill and co-workers [AIAA J. (1982)], 204 kJ/mol [1], and Henson et al. and Henson and co-workers [B. Henson, L. Smilowitz, B. Asay, P. Dickson, Thermodynamics of the beta to delta phase transition in PBX-9501, in: Proceedings of American Physical Society Topical Group on Shock Compression of Condensed Matter, American Institute of Physics, Atlanta, GA, 2001; L. Smilowitz, B. Henson, J. Robinson, P. Dickson, B. Asay, Kinetics of the beta to delta phase transition in PBX-9501, in: Proceedings of American Physical Society Topical Group on Shock Compression of Condensed Matter, American Institute of Physics, Atlanta, GA, 2001; P.M. Dickson, B.W. Asay, B.F. Henson, C.S. Fugard, J. Wong, Measurement of phase change and thermal decomposition kinetics during cookoff of PBX-9501, in: Proceedings of American Physical Society Topical Group on Shock Compression of Condensed Matter, American Institute of Physics, Snowbird, UT, 1999], 200 kJ/mol [4]. We discuss possible reasons for the higher activation energies measured here but do not identify the cause.     

For the 50th anniversary of the laboratory of alkaloid chemistry,Institute of the Chemistry of Plant Substances of the Uzbekistan Republic Academy of Sciences

The present review gives the main advances made in the laboratory of alkaloid chemistry of the Institute of Plant Substances of the Usbekistan Republic Academy of Sciences [IKhRV AN RUz] (Tashkent) over 50 years in the field of the chemistry of diterpene, isoquinoline, quinoline, steroid, indole, spiropiperidine, sulfur-containing, tropane, pyrrolidine, quinazoline, quinolizidine, amaryllis, and pyrrolizidine bases and possible routes for the biosynthesis of some of these groups of alkaloids.Institute of Chemistry of Plant Substances, Uzbekistan Republic Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 3–33, January–February, 1993.     

High-performance liquid chromatography of alkaloids

Literature information on the HPLC of alkaloids, including adsorption, reversed-phase, ion-exchange, ion-pair, and other variants is generalized. Results are given of the chromatographic analysis of various classes of alkaloids with an indication of the conditions of separation, and the columns used, and also of the methods of detection. The advantages and disadvantages of the HPLC variants are discussed. The review includes the literature over the last 14 years.Scientific Center for Chromatography, Institute of Chemistry and Physics of Polymers, Uzbek Academy of Sciences, Tashkent. Institute of the Chemistry of Plant Substances, Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 595–613, September–October, 1991.     

Crystal structure investigation of ternary molybdates Li3Ba2Ln3(MoO4)3 (Ln=Gd,Tm)

Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Institute of Physics, Siberian Branch, Russian Academy of Sciences. Buryat Institute of Natural Sciences, Siberian Branch, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 3, pp. 126–130, May–June, 1992.     

Electronic structure of molecules of substituted benzenes by X-ray spectroscopy. I. Nitrobenzene

Institute of Inorganic Chemistry, Academy of Sciences of the USSR, Siberian Branch. Institute of Organic Chemistry, Academy of Sciences of the USSR, Siberian Branch. Translated from Zhurnal Strukturnoi Khimii, Vol. 28, No. 5, pp. 73–80, September–October, 1987.     

Quantitative composition of the resin acids produced by the coniferous species of the USSR

Conclusions 1. The chemical composition of mixtures of resin acids isolated from the balsams of native conifer species, Scotch, Crimean, and Siberian pines andP. hamota andP. pityusa, Norway spruce, and Siberian larch, has been studied by the GLC method.2. The following resin acids are present in the balsams: pimaric, sandaracopimaric, levopimaric, palustric, isopimaric, abietic, dehydro- and dihydroabietic, neoabietic, four acids of undetermined chemical structure, and fatty acids. The balsams differ in the quantitative composition of the resin acids that they contain.Institute of Physical Organic Chemistry, Academy of Sciences of the Belorussian SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 539–541, September–October, 1970.