α-乙酰基-γ-丁内酯合成新工艺研究

以γ-丁内酯,乙酸乙酯为原料,金属钠和乙醇钠为催化剂,甲苯为溶剂合成α-乙酰基-γ-丁内酯。在金属钠与乙醇钠的钠摩尔比为7:3,甲苯/γ-丁内酯(w/w)=2.51,反应温度85~90℃,反应时间5h,n(乙酸乙酯):n(GBL):金属钠为2.27:0.9:1的条件下;GBL转化率≥98%,ABL收率≥95%。     

α-乙酰基-γ-丁内酯的合成优化

α-乙酰基-γ-丁内酯是医药和农药中重要的合成中间体,由于其用途被不断的开发,从而使其市场需求也不断扩大,因此,对其进行研究具有重要的意义。主要研究了α-乙酰基-γ丁内酯的合成优化。     

α-乙酰基-γ-丁内酯的合成及进展

简要介绍了α乙酰基γ丁内酯的合成方法, 指出了以乙酰乙酸乙酯和环氧乙烷为原料的生产方法的不足, 简述了以γ丁内酯和乙酸乙酯为原料的工艺路线的应用前景。     

α-氯代-α-乙酰基-γ-丁内酯的合成新工艺

介绍了α-氯代-α-乙酰基-γ-丁内酯的合成新工艺。以α-乙酰基-γ-丁内酯为原料、硅胶为催化剂、二氯海因为氯代试剂、二氯甲烷为溶剂,合成了α-氯代-α-乙酰基-γ-丁内酯。该工艺避免了传统氯代工艺存在的毒性高、腐蚀性强、污染大等缺点,符合绿色化学发展的趋势,有较好的工业应用前景。     

γ-丁内酯制备α-乙酰-γ-丁内酯的探讨

探讨了在醇钠的催化作用下,以γ-丁内酯(GBL)和醋酸乙酯缩合制取α-乙酰-γ-丁内酯(ABL)的可行性。在带搅拌的间隙式反应釜中,用正交试验设计和单因素试验研究了反应温度、进料摩尔比和反应时间以及醇钠用量对ABL收率的影响,获得了主要工艺参数。结果表明:在相同条件下,影响收率的主要因素是反应温度和反应时间。     

α-乙酰基-γ-丁内酯合成工艺研究

α-乙酰基-γ-丁内酯（简称：ABL）是现在销售紧俏的一种化工原料,本文主要探讨了ABL的现行工业合成方法,并对合成工艺进行了优化,进而提高了收率,降低了生产成本,使该产品更具有市场竞争力。     

α-甲氧甲酰基-γ-丁内酯和α-乙氧甲酰基-γ-丁内酯的合成及表征

以γ-丁内酯为原料,分别与碳酸二甲酯、碳酸二乙酯,在氢化钠的催化下,利用α氢的活泼性制得α-甲氧甲酰基-γ-丁内酯和α-乙氧甲酰基-γ-丁内酯。探索了反应温度、反应时间、反应物配比、催化剂用量对产率的影响。结果表明,适宜的反应条件为:①合成α-甲氧甲酰基-γ-丁内酯反应温度25℃,催化剂0.3 mol,反应时间3 h,反应物料物质的量比1∶1.5,产率可达85%;②合成α-乙氧甲酰基-γ-丁内酯反应温度30℃,催化剂0.3 mol,反应时间4 h,反应物物质的量比1∶2,产率可达76%。对产品进行了核磁共振氢谱、红外光谱表征。     

生产α-乙酰-γ-丁内酯废水的资源化利用

以生产α-乙酰-γ-丁内酯的磷酸盐废水为原料,通过对磷酸盐废水的成分分析,调节pH、脱水、聚合将其转化成磷酸二氢钠、磷酸氢二钠、磷酸三钠、酸式焦磷酸钠、焦磷酸钠、三偏磷酸钠、六偏磷酸钠和三聚磷酸钠,并对制得的磷酸盐的指标进行了分析。结果表明,上述产物均达到了相应的工业磷酸盐标准要求。该方法不仅提高了工业生产效益,而且达到了保护环境、节能减排的目的,实现了废物资源化利用。     

紫外分光光度法测定海产品中微量元素硒

建立了用紫外分光光度法测定海产品中Se含量的方法,结果表明,在选定的实验条件下,Se的浓度和吸光度呈良好的线性关系,标准曲线的相关系数为0.9990,对海带所做的试验,平均回收率为96.3%,稳定性RSD为0.96%,对海带、对虾、海藻等海产品中Se含量测定结果分别为0.105、0.436、0.0786μg-1.此法准确、重现性好、操作简单.     

Induced crystallization of EVA having various VA contents by compressed CO2

The crystallization induced by compressed CO₂ was investigated for rubbery ethylene‐vinyl acetate copolymer (EVA) containing various amounts of vinyl acetate (VA). The induction of crystallization was demonstrated by appearance of shoulder‐like differential scanning calorimetry (DSC) endotherms at temperatures lower than T_m of polyethylene segments of EVA after CO₂ treatments. The intensity of the endothermic shoulders and the degree of crystallinity increased with increasing VA content, suggesting that the interaction of CO₂‐carbonyl groups governed the induction of crystallization of EVA upon CO₂ treatment. The interaction of CO₂‐carbonyl group was found to decrease with increasing temperature as demonstrated by the decreased crystallization enhancement for 37°C as compared with that for 32°C. The enhancement of crystallization did not monotonically increase with increasing CO₂ pressure, resulting from the interplay of thermodynamic and kinetic driving forces, both being associated with the CO₂ pressure and thus the sorption concentration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1144–1151, 2003     

Determination of the mineral-matter contents of coals by low-temperature ashing

A new method is described for determining the mineral-matter content of coals, based on low-temperature ashing in an oxygen plasma. Unwanted side-reactions can occur during ashing, particularly oxidation of pyrite to haematite and fixation of organic sulphur as sulphate. These effects cannot be totally eliminated, but procedures are offered that minimize them, and are presented as accurate and rapid means of determining the mineral-matter content of bituminous coals. Data are presented to illustrate the magnitude of the effects under the recommended conditions of ashing. Duplicate determinations of the mineral-matter contents of 13 coals by acid demineralization and low-temperature ashing are reported in support of the new procedures. Statistical analysis of the data shows that the precision (± 2 standard deviations) of the LTA procedure under the defined conditions is 0.20. Acceptance of the procedure is suggested for routine use with most coals of bituminous or anthracite rank. The procedure as proposed is unsuitable for use with HVC coals from Western provinces of the USA or with lignites and subbituminous coals.     

HPLC法测定磷酸西格列汀原料药的含量

目的:采用HPLC法测定磷酸西格列汀的含量。方法:采用C18(4.6 mm×250 mm,5μm)为色谱柱,以0.01 mol/L磷酸氢二钾溶液(用磷酸调节p H至6.5)∶乙腈=8∶2为流动相A,乙腈为流动相B,以流动相A∶流动相B(70∶30)等度洗脱,流速为1.0 m L/min。稀释液为p H=2.0磷酸水溶液∶乙腈=70∶30,检测波长为205 nm,柱温为35℃。结果:磷酸西格列汀的线性范围为0.2300~0.3942 mg/m L;3批样品中磷酸西格列汀含量分别为99.76%、99.09%、99.48%。结论:本法简便、准确、适合于磷酸西格列汀含量测定。     

Rheological behavior of the CaO-Al2O3-based mold fluxes with different Na2O contents

The CaO-Al₂O₃-based mold flux is expected during the casting of aluminum containing advanced high strength steels. In this study, the rheological behavior of the CaO-Al₂O₃-based mold fluxes with different Na₂O contents was investigated. The results show that the viscosity in the range of 1423–1573 K reduced sharply when the Na₂O content increased from 0 wt % to 10 wt %, but the tendency slowed down with further increasing Na₂O from 10 wt % to 15 wt %. The activation energy for viscous flow also decreased from 237.76 ± 4.88 kJ/mol to 180.37 ± 7.10 kJ/mol with increasing Na₂O. The structure analyses show that the melt networks were mainly constructed by [SiO₄]^4--tetrahedral, [AlO₄]⁵-tetrahedral and Si-O-Al structural units. These networks were depolymerized with the addition of Na₂O since the charge compensation effect from Na⁺ was relativity weaker comparing with the network breaking effect from O²⁻. In addition, the break temperature of the mold fluxes also decreased from 1406 K to 1198 K due to the more precipitation of low melting point Ca₂Al₂SiO₇, rather than MgAl₂O₄ in the mold flux, during the cooling cycle.     

X射线荧光光谱法用于催化剂中贵金属含量分析

通过对X射线荧光光谱法测定催化剂中贵金属含量的研究,模拟样品组分含量和制备条件自制一系列标样,绘制工作曲线。对催化剂中Pt和Pd含量进行测定,结果与国标法分析值相符,精密度良好。     

CeO2含量对柴油机商用稀土SCR催化剂脱硝性能的影响

考察了不同CeO₂含量对柴油机商用稀土选择性催化还原（SCR）催化剂NH₃-SCR性能的影响。通过X射线衍射、N₂吸附-脱附、X射线光电子能谱、H₂-程序升温还原和NH₃-程序升温脱附等表征手段对催化剂的结构及性能进行了研究。研究发现,CeO₂含量对催化剂的晶体结构没有影响,添加后促进了稀土催化剂表面SiO₂的分散,从而对催化剂的脱硝性能及水热老化性能产生影响;CeO₂含量影响催化剂的织构性质,较大的孔体积和适当的比表面有利于催化剂水热老化后催化剂的脱硝性能的提高;随着CeO₂含量从14%增加到20%,其表面Ce含量呈先降低后升高的趋势,其中Ce⁴⁺含量与催化剂的水热老化后催化剂的脱硝性能成正相关;CeO₂含量的增加会阻碍稀土催化剂中其他组分的还原或增加其热稳定性,从而影响催化剂的还原能力和酸性位数量;通过脱硝性能测试,稀土催化剂中CeO₂的最佳含量为16%。     

裂解气中各种气体含量的气相色谱法分析

介绍了一种将色谱工作站与气相色谱仪相结合分析煤裂解气中的乙炔、乙烯、甲烷等气体含量的方法,指出该方法具有准确度及精密度高、分析速度快、所需试样量少等特点。