固相萃取-气相色谱法测定橄榄油中4种脂肪酸乙酯

橄榄油中脂肪酸乙酯(FAEEs)的含量是衡量其产品品质的重要指标之一，GB/T 23347-2021《橄榄油、油橄榄果渣油》中要求特级初榨橄榄油中FAEEs应≤35 mg/kg。目前橄榄油中FAEEs的国际标准检测方法是硅胶柱层析-气相色谱法(GC),该方法存在操作复杂、耗时长、试剂消耗量大等缺点。本研究建立了硅胶固相萃取(Si SPE)-气相色谱分析橄榄油中棕榈酸乙酯、亚油酸乙酯、油酸乙酯和硬脂酸乙酯4种FAEEs的检测方法。考察了载气类型，选定He气作为载气；筛选了内标化合物，确定使用十七碳烯酸乙酯(顺-10)作为内标物质；优化了SPE条件，对比了不同品牌Si SPE柱对回收率的影响，确定了称取0.05 g橄榄油，使用正己烷提取，1 g/6 mL Si SPE柱净化的前处理方法。该方法处理一个样品大约仅需2 h前处理时间和23 mL试剂。对优化后的方法进行方法学验证，结果表明，4种FAEEs在0.1～5.0 mg/L的范围内线性关系良好(决定系数(R²)>0.999),方法检出限为0.78～1.11 mg/kg,定量限为2.35～3.33 mg/kg,在...     

钒催化剂选择性氧化乳酸乙酯制丙酮酸乙酯

The structure and surface acidity of vanadium oxide supported on α-Al₂O₃、TiO₂、SiO₂ have been studied by XRD、IR、TPR and adsorption microcalorimetry. The catalytic performance of the catalysts for selective oxidation of ethyl lactate to ethyl pyruvate was determined in a continuous flow fix-bed reactor. The results showed that the dispersion of vanadium oxide on the supports weakened the V=O bond and actived the terminal oxygen, which increased the reaction activity. On the otherhand, The surface acidity is harmful to the selectivity of ethyl pyruvate. V/α-Al₂O₃ exhibited a lower conversion since its dispersion is low. The low selectivity on V/SiO₂ is due to its fairly strong surface acidity. Addition of K⁺ weakened the surface acidty and enhanced selectivity of V/SiO₂. V/TiO₂ exhibited the best activity and selectivity among the catalysts studied because of its weak surface activity. The conversion of ethyl lactate and selectivity to ethyl pyruvate are 97% and 81%, respectively, over the V/TiO₂ catalyst at 473K.     

α-溴甲基丙烯酸乙酯的合成

以丙二酸二乙酯为原料,经过碳负离子反应、卤化反应和酯化反应3步合成了α-溴甲基丙烯酸乙酯,收率73．4％。其结构经^1HNMR和IR表征。     

氨基磺酸/浓硫酸协同催化合成羧酸乙酯

以肉桂酸和无水乙醇为原料、廉价的氨基磺酸/浓硫酸为协同催化剂、环己烷为带水剂,合成了肉桂乙酯,收率90.0%。反应的优化条件为:氨基磺酸/浓硫酸/肉桂酸/无水乙醇=1.9/1/9.1/31.8(物质的量之比),时间3 h。利用该优化条件,共合成了9种羧酸乙酯,包括芳香酸、脂肪酸、二元酸、不饱和酸的乙酯。该法突出的优点有:催化剂价廉易得且可重复使用、产率高、后处理简便。     

N—乙酰基—β—（2—萘基）—D—丙二酸乙酯的合成

对Ｎ－乙酰基－β－（２－萘基）－Ｄ－丙二酸乙酯的合成方法进行了改进，在相转移催化条件下，实现了乙酰氨基丙二酸二乙酯的烷基化，产率由７５％提高到７８％。     

氰甲酸乙酯和氯甲酸乙酯的气相色谱分析

1　引　　言氰甲酸乙酯 (ＥＣＹＦ)是一种有机合成原料 ,可用于生产酯类、酰氨类以及杂环类化合物。常见的氰甲酸乙酯的合成方法是采用氯甲酸乙酯 (ＥＣＨＦ)的氰化法 ,产品中常有部分未反应的氯甲酸乙酯反应物存在。而氯甲酸乙酯和氰甲酸乙酯的气相色谱法分析还未见有文献报道。作者建立了用毛细管气相色谱法分离氯甲酸乙酯和氰甲酸乙酯的方法 ,并采用内标法对氰甲酸乙酯和氯甲酸乙酯进行了定量分析 ,结果令人满意。2　实验部分2 .1　仪器和试剂　ＧＣ 16Ａ气相色谱仪 (日本岛津公司 ) ,配有Ｃ Ｒ3Ａ数据处理机 ,氢火焰离子化检测器。氯甲…     

精馏法合成乳酸乙酯

精馏法合成乳酸乙酯封孝华余敦寿，刘序章，易吉萍（武汉大学环境科学系武昌４３Ｏ０７２）（武汉大学生命科学院）乳酸乙酯既是优质溶剂￣［２］，又是酒类、饮料等食的添加剂￣［３］，在工业上有广泛用途。我国自８０年代初开始生产乳酸乙醋以来，由于产品销路好，利润...     

凝胶渗透色谱对二次催化溶胶-凝胶法制备硅胶微球过程的监控

采用凝胶渗透色谱法(GPC),通过对二次催化溶胶-凝胶法制备硅胶微球原料硅酸乙酯 40(TES40)、中间产物聚硅酸乙酯(PES)分子量的在线测定,实现了对反应过程的监控.采用Shodex KF-802凝胶色谱柱,以四氢呋喃为流动相,流速0.5 mL/min,柱温40 ℃,采用示差折光检测器检测.校正曲线为1gMw= ...     

溴代丙酮酸乙酯的新合成法

溴代丙酮酸乙酯的新合成法黄锦霞，徐章煌，方国苏（湖北大学化学系武汉４３００６２）溴代丙酮酸乙酯是一种重要的化学物质，广泛用于医药、农药及天然产物的合成中［１］。它的合成已报道的有三条路线￣［２－４］，这些方法存在的不足之处是：（１）收率均不高（分别为...     

乙酸—1—甲基—2—乙氧基乙酯新合成法

乙酸-1-甲基-2-乙氧基乙酯(MEA)是一种用途广泛的有机溶剂,可用于医药及涂料等领域中。国外对MEA的合成研究工作始于80年代初左右,国内目前尚无工业化生产。MEA合成路线包括:1-乙氧基-2-丙醇(EP)与乙酸酐酯化法、EP与乙酸乙酯的酯交     

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。     

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.     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

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.

     

NiY分子筛表面酸性影响其选择性吸附脱硫性能的机理研究

采用原位红外光谱技术,以噻吩、环己烯和苯为模型探针分子,分别考察单一烃分子在NiY分子筛上的吸附与反应行为以及噻吩与烯烃、芳烃间的竞争吸附和催化反应行为。单一探针分子吸附研究发现,NiY分子筛中与Ni物种相关的Lewis(L)酸位是噻吩的选择性吸附活性位;噻吩和环己烯在NiY分子筛中Brnsted(B)酸位上发生的质子化和低聚反应明显弱于HY分子筛。双探针分子竞争吸附研究发现,环己烯二聚体在NiY中强B酸位上的强化学吸附与噻吩存在显著的竞争吸附行为。另外,苯和噻吩在NiY上的竞争吸附现象在373K时明显减弱。由此,在选择性吸附脱硫过程中,减少吸附剂表面B酸中心可降低烯烃对噻吩的竞争吸附,另外适当提高吸附体系的温度可以有效避免芳烃对噻吩的竞争吸附。     

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^-。     

照度对呋喃西林水溶液的表观光反应级数的影响

研究呋喃西林水溶液光解反应的表观反应级数和光照度以及浓度的关系。配制三种不同浓度的呋喃西林水溶液, 分别考查其在三种光照度下的降解反应级数。试验表明当光照度一定时，呋喃西林水溶液的光反应级数随浓度的减小而增大，当初浓度一定时，光反应级数随照度的增大而增大。呋喃西林水溶液在光作用下的表观反应级数与药物的初浓度和入射光的照度都有关。     

On the possibilities of theoretical analysis of kinetics of the thermal decomposition of solids

The main reasons for changes in the environment surrounding us are discussed on the basis of thermodynamics of irreversible processes. Subsequently, relations between thermodynamics of irreversible processes and chemical kinetics are shown, then the possibilities of theoretical determination of rate constants on the framework of the modified RRKM theory are presented. These latter considerations are supplemented by a discussion concerning the possibilities of determining the activation barriers and structural changes (necessary to account for entropy changes upon reaction) in molecules kept on the surface of crystalline phases by combination of quantum chemistry methods for isolated molecules with those reflecting the influence of the environment (i.e. interaction within the lattice). Finally, the future of theoretical methods in examining the reactivity of solid state systems is briefly discussed.