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= ...     

氢氧化铯作用下α-烷基(或α,α-二烷基)丙二酸二乙酯的合成

以DMF为溶剂,卤代烃(RX)与丙二酸二乙酯(1)在氢氧化铯(CsOH)催化下合成了α-烷基丙二酸二乙酯(2)和α,α-二烷基丙二酸二乙酯(3). 当r[n(RX) ∶ n(CsOH) ∶ n(1)]=1.0 ∶ 1.0 ∶ 1.0时,2为主要产物;当r=2.2 ∶ 2.0 ∶ 1.0时,3为主要产物.化合物的结构经1H NMR和MS表征.     

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...     

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.     

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.

     

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。     

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.     

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.     

Study of the thermodynamics of adsorption of hydrolyzed modified polyacrylnitrile

The thermodynamics of adsorption has been studied of hydrolyzed modified polyacrylnitrile (HMP) in water solutions with a concentration ranging from 0.25 g/l to 2.00 g/l on bleached sulphate and unbleached and bleached sulphite celluloses at temperatures of 0, 20, 40, and 60 C.It has been established that with the rise in temperature, the amount of adsorbed polymer —(HMP) decreases. The values of the enthalpy change are negative and show a linear decrease with the increase in the amount of adsorbed polymer. The adsorption equilibrium is defined by the logarithmic isotherm of Tjumkin, valid for uniform heterogeneous surfaces.With the increase in the amount of adsorbed HMP the values of the entropy change become negative and linearly decrease. A compensation effect has been noticed which results from the simultaneous action of the entropy and energy factors.The values of the change of the chemical potential for the three types of cellulose are negative and linearly decrease with the increase in the amount of adsorbed HMP and with the rise in temperature.     

Investigation of Kinetics of Solid-Phase Synthesis of Lithium Orthosilicate

The kinetics of the interaction between lithium carbonate and silica with various degrees of dispersion was investigated by TG and DTA methods. It was found that the utilization of pyrogenic silica with a specific surface area of about 300 m²g^-1 instead of aerosil with one of 175 m²g^-1 leads to an increase of the reaction rate between lithium carbonate and silica, which depends on the formation and growth of lithium orthosilicate crystals in the first stage, and is conditioned by the diffusion of lithium and oxygen ions through the lithium orthosilicate layer formed at temperatures above 800 K. This supposition is supported by the kinetic analysis results obtained with the use of the different models. The optimal regime of heating is recommended. This revised version was published online in July 2006 with corrections to the Cover Date.     

Features of the mechanism of oxidative dehydrodimerization of propynol

Analysis of kinetic regularities for the propynol oxidative coupling under the action of cupric salts in pyridine and in the presence of a buffer is undertaken. The reaction mechanism, including the formation of Cu(I) acetylides, is considered.     

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^-。     

小环化合物中饱和碳质子化学位移的计算

小环化合物由于其张力、构型、构象和各向异性效应等原因,环碳上质子化学位移缺乏规律性,难以预测,对此作者曾提出一种近似算法。本文根据303种小环化合物中饱和碳质子的化学位移实验数据,将适于计算这类质子化学位移的公式表述为: