Epoxidation of methallyl chloride with t-butyl hydroperoxide

By applying a statistical method of experiment planning the optimum conditions of methallyl chloride epoxidation with t-butyl hydroperoxide have been determined. The influences of the temperature, molar ratio of the methallyl chloride to t-butyl hydroperoxide, catalyst concentration and reaction time on the selectivity of the synthesis of methylglycerol epichlorohydrine in relation to reacted t-butyl hydroperoxide have been examined.     

Parameters of the epoxidation of 1-octene by t-butyl hydroperoxide

The epoxidation of 1-octene with t-butyl hydroperoxide in the presence of Mo(CO)₆ has been studied. The influence of the crucial parameters on the yield of 1,2-epoxyoctane in relation to hydroperoxide, on the hydroperoxide conversion, on the selectivity of the transformation of 1-octene to epoxy compound and on the yield of 1,2-epoxyoctane in relation to 1-octene has been described by the use of regression functions in the form of a second order polynomial. The optimal values of parameters: reaction time, temperature, olefin to hydroperoxide mol ratio, Mo(CO)₆ to hydroperoxide mol ratio, ensuring the maximum values of these functions have been determined.     

肼基甲酸叔丁酯的合成工艺

以氯甲酸苯酯为原料,经过叔丁醇酯化、水合肼肼化得到肼基甲酸叔丁酯,考察了酯化和肼化过程中影响反应的因素。结果表明：酯化反应时间为3 h、反应温度为25～30 ℃条件下,可以得到收率为77%的叔丁基苯基碳酸酯;当水合肼与叔丁基苯基碳酸酯的摩尔比为2∶1,反应温度为100 ℃时,反应产物肼基甲酸叔丁酯的收率可以达到93%,两步总收率为71.7%,其结构经质谱和红外分析确认。     

Highly Enantioselective Epoxidation of α,β‐Unsaturated Ketones Catalyzed by Primary‐Secondary Diamines

The asymmetric epoxidation of α,β‐unsaturated ketones has been achieved by using functional and readily accessible primary‐secondary diamines as the catalysts, giving the useful alkyl epoxy products with good yields and high enantioselectivities (up to 99% ee).     

A Hydrophobic Gel for Epoxidation of Olefins with Organic Peroxides

The epoxidation of cyclooctene by tert-butyl hydroperoxide (t-BuOOH) over a TiO₂–SiO₂ xerogel made from a permethylated cyclooligosiloxane, tetraethylorthosilicate, and a Ti chloroalkoxide, was carried out in acetonitrile as the reaction solvent. The organic moieties of the hybrid gel (in this case, –CH₃ groups) and the Ti content of the catalyst appear to be stable on prolonged exposure to the reaction medium. Besides very good stability, the hybrid catalyst in this study displays 100% selectivity toward cyclooctene epoxide production. Solid state ²⁹Si magic angle spinning NMR (²⁹Si MASNMR), diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), and chemical analysis were used to monitor the stability of the hybrid material. The kinetics of olefin epoxidation was studied in a batch reactor in the 313–343 K range.     

New Perspectives on Direct Heterogeneous Olefin Epoxidation

Important commercial direct oxidation processes include the epoxidation of ethylene to ethylene oxide and the newer epoxidation of butadiene to epoxybutene (EpB), both carried out with silver catalysts. However, detailed reaction mechanisms for these processes are still matters of debate. The guiding hypothesis of our research is that surface oxametallacycles are key intermediates in selective olefin epoxidation. By a combination of surface science experiments and density functional theory (DFT) calculations, we have synthesized the first stable surface oxametallacycles and have verified their identities and structures. In the case of EpB chemistry, we have been able to demonstrate direct connections between surface oxametallacycles and epoxide products. The EpB ring opens with an activation energy of 8.4 kcal/mol on Ag(110) to form a stable surface oxametallacycle. Spectroscopic results for this species are in excellent agreement with DFT calculations for an oxametallacycle bound to three silver atoms of a seven-atom cluster. This oxametallacycle undergoes 1,2 and 1,4 ring-closure reactions during temperature programmed desorption to form EpB and 2,5-dihydrofuran, respectively. This reaction represents the first demonstration of surface oxametallacycle ring closure to form an epoxide, and we suggest that surface oxametallacycles are of general importance in silver-catalyzed olefin epoxidation.     

过氧叔丁醇和二叔丁基过氧化物合成方法的改进

过氧叔丁醇(ＴＢＨＰ)和二叔丁基过氧化物(ＤＴＢＰ)是高分子合成中重要的引发剂,在有机合成中也有着广泛的应用[1]。ＴＢＨＰ和ＤＴＢＰ的合成方法很多[2,3]。ＴＢＨＰ的合成方法有[4]:氧气自氧化法;过氧化氢法;臭氧反应法等。ＤＴＢＰ的合成方法有[5]:碱催化合成法;酸催化合成法;金属离子催化法;自氧化法等。ＭｉｌａｓＮＡ等人报道了以叔丁醇、双氧水为原料,以硫酸作催化剂而合成ＴＢＨＰ和ＤＴＢＰ的方法[2,3],产率分别为51%和85%,该法属于合成ＴＢＨＰ的过氧化氢法和合成ＤＴＢＰ的酸催化合成法。本文针对此法操作较为繁琐,反应时间较…     

环己烯的环氧化研究进展

综述了以环己烯环氧化为代表的烯烃的环氧化研究进展 ,并介绍了有机过氧化物体系、分子氧体系及电化学合成等工艺的优缺点     

过氧化叔戊醇对苯并噻吩类衍生物的氧化

Homogeneous oxidation using an oil-soluble oxidant, tert-amyl hydroperoxide (TAHP), for ultra-deep desulfurization was performed under mild conditions in the presence of molybdenum oxide catalysts. Dibenzothio-phene (DBT), benzothiophene (BT) and 4, 6-dimethyl-dibenzothiophene (DMDBT), which are the refractory sulfur compounds for hydrodesulfurization (HDS), were employed as model substrates for a simulated diesel fuel. Activ-ity of molybdenum oxide supported on a macroporous weak acidic resin was investigated. The mass conversion of DBT reached near 100% at 90°C and a TAHP/DBT molar ratio of 3 with 1% of molybdenum oxide supported on Amberlite IRC-748 resin for 1 h. It was further found that the activities of the model substrates decreased in the or-der of DMDBT＞DBT＞BT. In the flow oxidation using TAHP as the oxidant, mass conversion of DBT increased remarkably from 61.3% to 98.5% when dropping the weight hourly space velocity (WHSV) from 40 h－1 to 10 h－1. A series of experiments dealt with selectivity of this oxidation using TAHP revealed that the model unsaturated compounds, i.e. 4, 6, 8-trimethyl-2-nonylene, and 2-methylnaphthalene did not affect the oxidation of DBT. Car-bazole had nearly no effect on the conversion of DBT using TAHP, but had some influence on the one using tert-butyl hydroperoxide (TBHP). The mass conversion of DBT decreased remarkably from 75.2% to 3.6% when the content of carbazole increased from 0 to 500 μg•g－1. In the flow oxidation using TAHP as the oxidant, the con-centration of DBT in model fuels was reduced from 500 µg•g－1 to 7.2 µg•g－1 at WHSV of 10 h－1, and then reduced to 3.8 µg•g－1 by adsorption of Al2O3.     

N-TS-1催化1-己烯环氧化合成1,2-环氧己烷

以H2O2为氧化剂,N-TS-1为催化剂催化1-己烯环氧化合成了1,2-环氧己烷。研究了温度、H2O2用量、催化剂用量以及反应时间对反应的影响,较优化的反应条件为:反应温度343 K,H2O2用量0.8 mol/L,催化剂用量10.7 g/L,反应时间5 h。在优化的条件下,H2O2的转化率为58.1%,H2O2的选择性为93.9%,1-己烯的转化率为52.7%,1,2-环氧己烷的选择性为94.3%。     

固体超强碱催化分解环己基过氧化氢的工艺研究

以水合三氧化二铝为载体,在340℃下加入20 g氢氧化钠及金属钠制得固体超强碱催化剂,采用该固体超强碱对环己基过氧化氢进行催化分解;考察了反应温度、反应时间及催化剂用量等因素对分解反应的影响。结果表明:在100 mL氧化液中,加入催化剂4.0～6.0 g,反应温度55～60℃,分解时间35～45min,采用4釜串联,环己基过氧化氢分解转化率大于等于99%,环己酮与环己醇的总收率大于等于95%,且无废液碱产生。     

乙烯环氧化助催化作用的研究──多晶银表面化学修饰法

根据多晶银（电解银）表面吸附态氧主要是吸附态原子氧和次表层溶解氧的特性，探索并证实了电解银表面具有乙烯环氧化反应活性，从而研究了Ｂａ和Ｃｓ化合物修饰电解银表面对乙烯氧化反应的助催化作用．Ｂａ增加了活性，Ｃｓ降低了活性，但增大了环氧乙烷的选择性．对比了负载银添加Ｂａ和Ｃｓ化合物后的助催化性能，获得了一致的结果．表明电解银表面化学修饰可作为选择和研究Ａｇ助催化剂的一种合理而简便的手段．     

SIS的环氧化反应

研究了ＳＩＳ在甲苯溶剂中的环氧化反应,得到了甲苯溶剂中ＳＩＳ环氧化反应的适宜条件：ＳＩＳ溶液浓度为１５％,甲酸／过氧化氢（摩尔比）＝１．５：１,反应温度５０℃,反应时间２小时。所得产物的环氧含量为３．３５０ｍｏｌ／Ｋｇ。     

烯烃不对称环氧化反应研究进展

综述Salen-Mn配合物,手性酮,生物酶催化剂催化的不对称环氧化反应研究进展情况,详细介绍了酮催化剂的发展趋势。     

极性化SBS的环氧化改性

以甲酸和过氧化氢为氧化剂对极性化SBS(SBSVP)进行了环氧化改性。通过环氧含量、双键减少量以及副反应程度的测定,讨论了影响SBSVP环氧化反应的主要因素:n甲酸/n过氧化氢、反应温度、反应时间、SBSVP的质量分数。得到了SBSVP环氧化的适宜条件:SBSVP质量分数10%,n甲酸∶n过氧化氢=1∶1,反应温度60℃,反应时间2.5 h,所得产物的环氧基质量分数为11.1%。     

催化分子氧环氧化环己烯的研究进展

介绍了分子氧的构型、催化烯烃环氧化机理及其催化环氧化环己烯的研究进展,提出以分子氧为氧源,催化环氧化环己烯的关键在于高效催化剂的制备及廉价易得还原剂的筛选。     

Epoxidation of propylene by air over modified silver catalyst

Epoxidation of C₃H₆ to C₃H₆O by air was studied over a silver catalyst modified with alkali or alkaline earth chloride salts. The catalyst preparation factors and the operational conditions could affect obviously the catalytic epoxidation property of the silver catalyst. It was shown that, as a promoter of the silver catalyst, NaCl or BaCl₂ is more suitable than LiCl or NH₄Cl. The loading of NaCl should be controlled at about 3.8 wt%. Using a feed gas of 10% C₃H₆/air at a space velocity of 1.75×10⁴ h⁻¹, 18.6% C₃H₆ conversion and 33.4% selectivity to C₃H₆O were obtained at 350°C. Using a feed gas of 5% C₃H₆/air at a space velocity of 2.4×10⁴ h⁻¹, 54.0% C₃H₆ conversion and 26.3% selectivity to C₃H₆O were obtained at 390°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

乙烯环氧化助催化作用的研究——多晶银表面化学修饰法

根据多晶银(电解银)表面吸附态氧主要是吸附态原子氧和次表层溶解氧的特性,探索并证实了电解银表面具有乙烯环氧化反应活性,从而研究了Ba和Cs化合物修饰电解银表面对乙烯氧化反应的助催化作用。Ba增加了活性,Cs降低了活性,但增大了环氧乙烷的选择性;对比了负载银添加Ba和Cs化合物后的助催化性能,获得了一致的结果。表明电解银表面化学修饰可作为选择和研究Ag助催化剂的一种合理而简便的手段。     

凹凸棒粘土负载WO3催化环戊烯环氧化

以钨酸钠为钨源,凹凸棒粘土(AT)为载体,采用浸渍法制备了凹凸棒粘土负载WO_3(WO_3/AT)催化剂,采用FT-IR和XRD对其进行了表征。以30%H_2O_2为氧源,叔丁醇为溶剂,研究了凹凸棒粘土负载WO_3在环戊烯环氧化反应中的催化性能。结果表明,WO_3与凹凸棒粘土载体中的金属离子(Mg~(2+)、Al~(3+)和Fe~(3+))之间有强的相互作用,形成了M~+—O—W键。反应的最佳工艺条件为:反应温度308 K,反应时间24 h,催化剂用量1.5 g,WO_3负载质量分数40%,催化剂焙烧温度823 K,焙烧时间3 h。在此条件下,环戊烯环氧化物收率为42.2%,环戊烯转化率为96.3%。     

SBS的环氧化研究

通过红外光谱对SBS的环氧化产物中环氧基团的存在进行证实。考察了SBS环氧化反应合成条件的影响因素：反应时间，反应温度，SBS的浓度，甲酸，过氧化氢。