自动电位滴定法定量测定烷基羧基甜菜碱类表面活性剂含量

研究了酸化剂种类、酸化温度及时间等对电位滴定法测定烷基羧基甜菜碱含量的影响。结果表明,酸化剂的pH,酸化温度和时间等对测定结果有显著影响,关键是保证甜菜碱分子的完全酸化。以pH=3的醋酸-醋酸钠缓冲溶液作酸化体系,于70～80℃下酸化2～3 h后用十二烷基硫酸钠(SDS)进行电位滴定,对C12-C18单长链烷基甜菜碱以及双十二烷基甜菜碱都能得到满意的结果,回收率达到97%～102%。以硫酸作酸化剂,将pH提高到2左右,于室温下酸化1 h后滴定,亦可得到满意的结果。对工业级甜菜碱样品,其中的游离叔胺在测定条件下也定量参与滴定反应,所得结果为甜菜碱和相应叔胺的总量,由于叔胺含量能用独立的方法测出,借助于电位滴定可以测出甜菜碱含量。     

采用蒸馏-中和的电位滴定法测定水中氨氮

蒸馏-中和滴定法测定氨氮时,采用甲基红-亚甲蓝混合指示剂确定滴定终点,但由于人眼分辨颜色的能力不同,判断出的终点往往有一定差异。以电位代替指示剂确定终点,以数字滴定仪代替滴定管,降低标准酸的浓度至0.01 mol/L,提出纯粹空白的概念,并最终通过试验找出了用盐酸滴定含有氨氮的硼酸吸收液的试验终点,即终点时溶液的pH值为5.8～5.9。电位滴定法摆脱了滴定操作对试验员的苛刻要求,而以数字信号代替颜色信号也使滴定终点更易辨别,测得的试验数据更加准确。     

十二烷基二甲基氧化胺含量的化学法测定

本文提出了测定十二烷基二甲基氧化胺含量的化学分析法。在测定过程中,用烷基卤化物排除叔胺干扰,盐酸作为标准滴定溶液,百里香酚兰作为指示剂,此法与电位滴定法对照,结果一致,且具有快速,简便的特点。     

非对称性Gemini季铵盐阳离子沥青乳化剂的合成

以N,N-十二烷基二甲基叔胺、N,N-十八烷基二甲基叔胺、盐酸和环氧氯丙烷为原料,异丙醇作溶剂,合成3个碳链分别为12、3和18非对称性Gemini季铵盐阳离子沥青乳化剂。通过IR光谱测定出目的产物的结构。以溴酚蓝为指示剂、二氯乙烷为分散相两相化学滴定法测定产物的含量。结果表明,产物的含量大于96.5%,乳化剂对沥青具有良好的乳化效果，且稳定性能好。     

PET装置工艺废水醛含量的测定

通过加入一定量的亚硫酸钠,用硫酸标准滴定溶液进行滴定,以百里酚酞为指示剂,通过观察溶液颜色变化判断滴定终点,根据消耗标准滴定溶液的体积计算得出样品中醛含量.结果表明:该方法精密度高、重现性好,准确可靠.     

聚丁二酸丁二醇酯切片端羧基滴定方法优化

采用化学试剂滴定的方法测定聚丁二酸丁二醇酯切片的端羧基值,对溶剂的配比、滴定溶剂选择、指示剂的选择等影响因素进行条件试验。研究发现,用氯仿作为溶剂,以0.05 mol/L的NaOH-乙醇溶液作为滴定剂,以百里香酚蓝作指示剂,滴定终点颜色由黄色变为蓝色,颜色变化明显,平行性和准确性都很好。     

EDTA络合滴定法测定Al2O3的改进

生产水泥用的原料如粘土及矾土中铝的测定通常采用络合滴定法,以二甲酚橙作指示剂,用锌盐、铅盐为标液进行返滴定,终点由黄色变为红色,不易掌握。本法采用铜盐为标液,返滴定过量的EDTA,仍以二甲酚橙为指示剂,同时加入少量氯化十六烷基吡啶,滴定终点由黄色变为蓝色,突跃更为敏锐,从而改善了方法的准确度,且易于掌握。     

低分子量端羧基氟弹性体的端基分析

以低分子量固体氟弹性体为初始原料,研究了KOH和双氧水用量对所得低分子量端羧基氟弹性体分子量及其分布的影响.进一步以电位滴定测得的羧基含量和化学计量等当点的pH为基础,对多种酸碱指示剂进行优选.研究结果表明:以溴甲酚紫为指示剂时滴定结果与电位滴定最接近,且终点颜色变化明显,更易于判定.最后,结合产物数均分子量和端羧基含...     

水解反滴定法测定乙烯/乙酸乙烯酯中VA含量方法的优化

通过对ISO 8985:1998(E)水解反滴定法测定乙烯/乙酸乙烯酯(EVA)中乙酸乙烯酯(VA)含量(质量分数)的研究,发现该方法存在指示剂颜色不易判断、分析数据平行性差等问题。拟采用电位滴定法取代ISO8985:1998(E)回流反滴定法中颜色指示剂法测定EVA中VA含量,利用电位突跃点判断滴定终点,并对该方法的测定条件进行优化。结果表明,电位滴定法克服了指示剂不能准确判断滴定终点的问题,与颜色指示剂法相比,电位滴定法具有精密度高,操作简便、快捷等优点。     

两相滴定法测定醇醚羧酸盐羧甲基度

采用两相滴定法测定表面活性剂醇醚羧酸盐的羧甲基度。以藏红T为指示剂,氯仿和水为两相溶剂,用氯代十六烷基吡啶进行滴定,以上下两相颜色相同时为滴定终点。结果表明,方法的准确度和精密度良好,测定结果与传统的离子交换法接近,但大幅节约了分析时间,具有操作简便、快速的优点,能更好的满足工艺研究和生产需要。     

聚醚与二乙胺的临氢胺化反应研究

以聚醚PEP-600与二乙胺为主要原料,雷尼镍为催化剂,通过临氢胺化反应制备了端叔胺基聚醚。反应产物通过滴定分析,确定为伯、仲、叔胺的混合物。对轻组分的GC-MS及GC分析表明:临氢胺化制备叔胺时,二乙胺发生了自身的缩合反应,生成氨气、一乙胺、二乙胺和三乙胺。     

胺类环氧固化剂胺值测定方法的探讨

介绍了伯胺值、仲胺值和叔胺值的测定方法,以及改性胺固化剂理论用量的计算公式。     

糖苷基季铵盐表面活性剂的合成及性能

以自制的3-氯-2-羟丙基糖苷(CPG)与叔胺为原料,在正丙醇水溶液中合成了糖苷基季铵盐(CAPG)表面活性剂。优化工艺条件为:n(氯代糖苷)/n(叔胺)=1.4,m(正丙醇)/m(水)=0.5,反应时间4 h,在该条件下叔胺的转化率为88.4%。通过FTIR对产物的结构进行了分析,并对产物的表面活性、复配稳定性、泡沫性能及在硬水中的稳定性进行了测定。结果表明,其CMC为1.57×10-3mol/L,γCMC为27.3 mN/m;与十二烷基硫酸钠(K12)的混合溶液在n(CAPG)/n(K12)<0.6或n(CAPG)/n(K12)>1.0时,透光率均大于90%,具有很好的稳定性;在硬水中的平均稳定性、差示稳定性分别为5和5 5 5;在二次蒸馏水中初始泡沫体积为292 mL,在ρ(CaCO3)=300 mg/L硬水中的初始泡沫体积为255 mL。     

The determination of unreacted amines in long chain amine oxides by potentiometric titration

During the manufacture of amine oxides information on the amount of unreacted tertiary amine present is needed in order to follow the reaction. A number of analytical procedures have been devised to obtain this information. Wet methods include redox titrations of the amine oxide and differential titrations using derivatization of the amine or amine oxide. Various chromatographic procedures using GC, TLC and HPLC also have been reported. All of these procedures have some limitations. A simple, rapid, quality control procedure would be useful. A rapid, nonaqueous titration procedure has been developed in our laboratory that makes use of the “anomalous salt” behavior of amine oxides. A modified solvent and titrant is used to obtain two potential breaks in the titration. The first break corresponds to half of the amine oxide. The second break represents the second half of the amine oxide plus any unreacted amine. With this information the amine oxide and unreacted amines can be calculated. The precision and accuracy of the titration have been studied using samples spiked with known amounts of amine.     

叔胺萃取分离钴(II)、铁(II)

研究了不必预先氧化二价铁,直接用叔胺从氯化物溶液中萃取分离钴(II)、铁(II)的新方法. 考察了不同改性剂对叔胺萃取钴(II)、铁(II)的影响以及各种因素对钴(II)、铁(II)萃取、洗涤及反萃的影响. 提出了用叔胺萃取分离钴(II)、铁(II)的最佳工艺参数.     

Effect of tertiary amines on yellowing of UV‐curable epoxide resins

The work reported demonstrates that the yellowness of UV‐curable epoxide resins can be improved by adding certain tertiary amines in appropriately determined amounts. According to the results of our experiments, 2.0 wt% benzoyl peroxide added to a resin effectively enhances the crosslinking density, and phenolic free radicals are produced during UV curing, which consequently induce yellowness via the reaction of oxygen and the free radicals. Imidazole (1‐amine) and tertiary amines, including 1,2‐dimethylimidazole (2‐amine), 2,4,6‐tris(dimethylaminomethyl)phenol (3‐amine), 1‐methylimidazole (4‐amine) and 2‐methylimidazole (5‐amine), were chosen to be added to resins, and their effects on UV conversion and yellowness were investigated. According to the experimental results, tertiary amines in the resin can provide a certain degree of improvement in yellowness index (ΔYI) and color parameter (ΔE*_ab) of the resin sample. Whatever the type of tertiary amine, it is found that the optimum content of amine in resin is 1.0 wt%. Also, among the studied amines, the 3‐amine exhibits the highest UV reactivity and the best efficiency for yellowness improvement with values of Δa*, Δb*, ΔYI and ΔE*_ab as low as ? 1.4, 6.23, 11.27 and 6.48, respectively. Copyright © 2007 Society of Chemical Industry     

The effect of different ammonium structure of quaternary ammonium resin on the electrochemical properties

The quaternary ammonium resin is synthesized by the ring-opening reaction of an epoxy resin with a tertiary amine in the presence of a proton donor in the solution. This kind of resin can be dispersed in the water phase to form a conductible milky dispersion. In this study, different kinds of tertiary amines including the full-alkyl group and the ester group-containing or urethane group containing tertiary amine are reacted with DGEBA-type epoxy resin to synthesize the quaternary ammonium resins. The resin characteristics and the electrochemical properties of its emulsion are investigated. In addition, properties of the emulsion prepared from tertiary amine salt resin are also measured for comparison. It is found that if the substituted groups of the ammonium structure of the quaternary ammonium resin are all alkyl groups, rupture voltage of the emulsion is very low. But when one of the substituted group contains an ester group or an urethane group, rupture voltage increases remarkably and the resin can be used for electrodeposition. Meanwhile, the electrodeposition theory of quaternary ammonium resin and its thermal cross-linking reaction and the electrochemical properties of coemulsion prepared by mixing the quaternary ammonium resin and the tertiary amine salt resin are also discussed. © 1993 John Wiley & Sons, Inc.