Study of the kaufmann method for determining iodine numbers

A study has been made of the effect of heat, light, time of reaction, and size of sample on iodine numbers obtained by the Kaufmann method. The iodine numbers of several oils have been determined by this method and compared with those found by other well-known methods. The formation of acid by the reaction between the Kaufmann reagent and a number of oils, has been investigated. Presented before meeting of American Oil Chemists’ Society, New Orleans, Louisiana, May 12–13, 1938. A cooperative organization participated in by the Bureaus of Chemistry and Soils and Plant Industry of the U. S. Department of Agriculture, and the Agricultural Experiment Stations of the North Central States of Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin.     

异氰酸酯的简单合成法

异氰酸酯是合成磺酰脲类降血糖药物的重要中间体 ,在有机合成中也有着广泛的应用。异氰酸酯有多种制备方法 :( 1 )胺与光气反应 ;( 2 )酰基叠氮物经 Cirtius重排反应制备 ;( 3 )以 CO2 为甲酰化试剂与胺作用 ,经 POCl3 或 P2 O5脱水制备 ;( 4)以 COS为酰化试剂在三乙胺存在下与胺作用 ,再与 Cl COSC2 H5反应制备 ,其中方法 ( 1 )应用较为广泛。我们改变反应溶剂 ,并采用价格相对较低的三光气 (固体光气 )代替常温下为气态的剧毒光气与胺反应。由于三光气为白色或淡黄色固体 ,易于运输、称量 ,因此简化了反应操作条件 ,而且产率较高。…     

光度法测定食盐中碘含量

为测定食盐中的碘含量,根据微量碘在水中呈现淡黄色这一特点,分光光度法测定了其浓度和吸光度的关系。结果表明,在实验范围内,碘的浓度和吸光度有良好的线性关系,食盐样品中碘含量为23.75 mg/kg,RSD=1%,F检验法说明实验结果无显著性差异,该法可以用作微量碘的测定。     

单硬脂酸甘油酯合成方法的改进

用丙酮保护的一锅合成法,即通过甘油与丙酮在对甲苯磺酸催化下反应制得异亚丙基甘油,在催化剂如吡啶、乙酸钠、乙醇钠等的催化下与相对便宜的原料三硬脂酸甘油酯反应,无机酸水解后制得单硬脂酸甘油酯。研究了酯化反应过程中物料配比、催化剂类型及用量对反应的影响,结果表明:碱性催化剂中又以吡啶的催化效果最好,n(甘油)∶n(三硬脂酸甘油酯)=1.00∶0.35,吡啶用量为甘油质量的4.0%时,可以得到质量分数为93.86%,收率为86.92%的单硬脂酸甘油酯。     

诺氟沙星合成方法的改进

1-乙基-6-氟-7-氯-1,4-二氢-4-氧代喹啉-3-羧酸与哌嗪在聚乙二醇催化下反应,以高收率得到诺氟沙星。     

2,6-二乙酰基吡啶合成方法的改进

优化了2，6—二乙酰基吡啶的合成工艺。以2，6—吡啶二羧酸为原料，经过醇化及克莱森酯缩合反应，合成了2，6—二乙酰基吡啶，2，6—吡啶二羧酸二乙醇和2，6—二乙酰基吡啶的分离收率分别为94．1％和88．9％，2，6—二乙酰基毗啶的质量分数大于99％。     

An improved method for the analysis of ruminant fats

A method is described for the separation of saturated methyl esters from mercuric acetate adducts of unsaturated esters using an ion exchange resin. The esters thus separated were analyzed by gas chromatography on a short wide-bore capillary column containing a bonded polyethyleneglycol liquid phase. Detailed analyses of sheep and beef depot fats can be produced more rapidly and with greater accuracy using this methodology than with that currently available.     

白屈氨酸合成方法的改进

改进了白屈菜酸和白屈氮酸的合成工艺。以丙酮和草酸二乙酯为原料,经过克莱森缩合,合成了白屈菜酸,再与氨水反应得白屈氨酸。在合成白屈菜酸时,简化了合成步骤,取得产品收率85．3％（文献：88％）;在合成白屈氮酸时,考察了氨水用量对产物收率的影响,比文献报道的合成方法提高反应温度80℃,缩短反应时间40h以上,产品收率90％。     

磷矿中全碘测定方法的改进

采用混合溶剂Na HCO_3-ZnO半熔融样品,以水提取分离干扰离子,用碘蓝分光光度法测定磷矿中微量的碘。在熔样过程因NaHCO_3分解放出CO_2,使矿样与空气隔绝,避免了微量碘被氧化而损失。该法测定碘的回收率99.5%,相对标准偏差(RSD)2.0%,精密度和准确度好。     

对GB/T8538-95标准中碘化物测定方法的改进

主要对国标GB／T 8538-1995:饮用天然矿泉水检测方法中碘化物的测定方法的催化还原分光光度法进行了研讨。在改进的实验条件下,标准曲线相关系数从原来的0．9提高到0．999以上,线性范围适宜,方法的准确度和精密度大为提高,改善了国标方法的适用性,能满足矿泉水中微量碘的测定要求。     

An improved method for flow network design

An improved method is presented for the design of a complex flow network system. The method employs head loss and flow rate in the iteration process for the determination of flow rates and/or pressure drop. This represents a major departure from the conventional approach which uses only the flow rate. The two-step iteration method proposed here drastically improves both the convergence rate and iteration stability. Tests on different examples have shown that, for most design applications, three iterations are sufficient to yield an accurate final solution, regardless of the initial guess.     

An improved characterization method for petroleum fractions

An improved characterization of naphtha can be obtained by assuming representative chemical components for each cut and utilizing an empirical model to predict the physical and thermodynamic properties such as critical properties, molar mass, refractive index, enthalpy of vaporization, viscosity, etc. The improved model for feed characterization utilizes a multivariable constraint optimization technique in order to arrive at the properties of the blend. It was found that this model does improve the accuracy of prediction. An application is presented for a naphtha blending system and a naphtha debutanizer. The sensitivity of the column simulation to the developed feed characterization method has been investigated by digital simulation. With the boiling point model, large deviations from the actual column performance data have been observed while a farily good match has been obtained with the improved model.     

烃基化间苯二酚杯芳烃的合成

NaH作为催化剂,以乙醇为溶剂对间苯二酚杯芳烃进行烃基化衍生反应,合成了4种化合物.该方法反应时间短、产品易处理且产率高.     

硼酸三异丙酯合成方法的改进

采用氢化钙作为脱水剂,以硼酐及异丙醇为原料合成了硼酸三异丙酯,该方法具有成本低、操作简便、条件温和、产率高的优点。     

An improved assay for the determination of phospholipase C activity

Phospholipases C (PLC, EC 3.1.4.3) are enzymes that specifically hydrolyze the C‐O‐P bond in phospholipids, yielding sn‐1,2(2,3)‐diacylglycerides and the phosphate residue bearing the corresponding headgroup. The biochemical characterization of PLC requires methods for the reliable determination of their activity. Here, an assay is described in which the phosphate residue released by the PLC is cleaved with an alkaline phosphatase. The phosphate formed is then extracted with n‐butanol and quantified as phosphomolybate complex. The applicability of this method is demonstrated for a concentration range from 10 nM to 10 mM for a range of phospholipids bearing different headgroups in an aqueous and a two‐phase system. The method has the additional advantage that the crude enzyme can be used without the need for purification.     

An improved instrument for the rapid determination of capacitance in electrochemical systems

The design and operation of an instrument for the direct, continuous monitoring of electrode capacitance under potentiostatic conditions is described. Accurate values of the capacitance can be obtained over two orders of magnitude of capacitance, even in the presence of low parallel resistances.     

原位荧光标定硝基化合物

介绍了用原位荧光标记法测定硝基化合物２，４－二氯苯基－４′－硝基苯基醚，Ｏ，Ｏ－二甲基－Ｏ－（３－甲基－４－硝基苯基）硫逐硫酸酯，Ｏ－乙基－Ｏ－异丙胺基－Ｏ－（对甲邻硝基苯基）硫逐磷酸酯，Ｏ，Ｏ－二甲基－Ｏ－（对硝基苯基）硫逐磷酸酯的方法，并报告了上述硝基化合物丹酰荧光衍生物的荧光性能。