阳离子香豆胶的合成及结构表征

以3-氯-2-羟丙基三甲基氯化铵(HAT)为阳离子醚化剂,天然香豆胶为原料,异丙醇为分散剂制得季铵盐型阳离子香豆胶。研究了HAT、催化剂NaOH、反应温度和反应时间对合成阳离子香豆胶(CFG)的影响,用凯氏定氮法测定了CFG的取代度。合成CFG的优化实验条件为:m(香豆胶)∶m(异丙醇)∶m(HAT)∶m(NaOH)=1∶(1.6~2)∶(0.15~0.3)(∶4~8),反应温度40~50℃,反应时间2~3 h,制得的产品能满足工业应用要求的黏度及取代度范围(500~800 mPa.s,DS=0.86~1.32)。用FTIR和13CNMR对CFG的结构进行了表征。     

蔗渣木聚糖醋酸酯的合成与表征

以蔗渣木聚糖为原料,醋酸酐为酯化剂,对甲基苯磺酸为催化剂,在冰醋酸体系中合成了蔗渣木聚糖醋酸酯。考察了诸因素对产品取代度的影响。在m(木聚糖)∶m(醋酸酐)=4∶5,m(木聚糖)∶m(催化剂)=4∶0.2,m(木聚糖)∶m(冰醋酸)=4∶10.49,酯化温度为70℃,酯化时间为4 h的条件下,合成了取代度为0.20的蔗渣木聚糖醋酸酯。采用FTIR、XRD和SEM对蔗渣木聚糖醋酸酯结构进行了表征。分别测定了蔗渣木聚糖醋酸酯的糊化性能和热黏度,表明蔗渣木聚糖醋酸酯比蔗渣木聚糖糊化温度低,热黏稳定性显著改善。     

玉米芯木聚糖硫酸酯化条件的研究

用碱提法从玉米芯中提取木聚糖,采用氯磺酸吡啶法进行硫酸酯化,通过正交试验确定最佳工艺条件为:吡啶与氯磺酸摩尔比1∶1,温度65℃,时间6h;木聚糖硫酸酯wisX-S通过DEAESepharoseFF层析柱分离得到一个相对分子量为1.3×104的组分,硫酸基取代度为2.24。对此木聚糖硫酸酯进行红外光谱分析,结果显示在波数1259、1228和813cm-1处分别有S=O和C-O-S键的特征吸收峰。     

氨基三磺酸钠水相酯化法合成蔗渣木聚糖硫酸酯

以蔗渣木聚糖为主要原料,以氨基三磺酸钠为酯化剂,在水相中合成了蔗渣木聚糖硫酸酯.用氯化钡-明胶分光光度法对蔗渣木聚糖硫酸酯的取代度进行了测定.考察了诸因素对取代度的影响,确定了反应的较佳条件.结果表明,当酯化温度为50℃,酯化时间为4.0 h,溶液pH值为9.0,亚硝酸钠和蔗渣木聚糖的配比为0.057 mol比5g,反应溶液体积和蔗渣木聚糖的质量配比为75 mL比5g时,木聚糖硫酸酯的取代度为1.22.采用紫外光谱法、红外光谱法和扫描电镜对产物结构进行了表征,结果表明所得产物为蔗渣木聚糖硫酸酯.     

紫外吸收剂阿拉伯木聚糖肉桂酸酯的合成和表征

从玉米麸皮中提取水溶性的阿拉伯木聚糖(AX),以DMF为溶剂,三乙胺为缚酸剂,醚化产物与肉桂酰氯反应,生成高分子紫外吸收剂阿拉伯木聚糖肉桂酸酯(AX-CM)。UV检测表明,AX-CM在283 nm处有较高的紫外吸收,且光稳定性良好。     

新型蔗渣木聚糖醋酸酯的合成与表征

摘要：以蔗渣木聚糖为原料,醋酸酐为酯化剂,对甲基苯磺酸为催化剂,在冰醋酸体系中合成了蔗渣木聚糖醋酸酯。考察了诸因素对产品取代度的影响。在m(木聚糖)∶m(醋酸酐)=4∶5,m(木聚糖)∶m(催化剂)=4∶0.2,m(木聚糖)∶m(冰醋酸)=4∶10.49,酯化温度为70℃,酯化时间为4h的条件下,合成了取代度为0.20的蔗渣木聚糖醋酸酯。采用FTIR、XRD和SEM对蔗渣木聚糖醋酸酯结构进行表征。分别测定蔗渣木聚糖醋酸酯的糊化性能和热黏度,表明蔗渣木聚糖醋酸酯比蔗渣木聚糖糊化温度低,热黏稳定性显著改善。     

羧甲基蔗渣木聚糖的合成与表征

以蔗渣木聚糖和一氯乙酸为主要原料,乙醇水溶液为溶剂,冠醚为催化剂,经碱活化、醚化反应两步合成了羧甲基蔗渣木聚糖。考察了物料摩尔比、反应时间、反应温度和溶剂中水含量等因素对合成工艺的影响,确定的较佳工艺条件:n(蔗渣木聚糖结构单元)∶n(氢氧化钠)∶n(一氯乙酸)=1∶3.25∶1.25,溶剂V(乙醇)∶V(水)=4∶1,45℃碱化2 h,70℃醚化3 h,所得羧甲基化产物的取代度可达0.59。用FTIR与SEM对原料和产物的结构进行了表征。热分析表明,反应后蔗渣木聚糖在234~312℃内分解量由总质量的46.27%降至30.58%。质量浓度为12 g/L的产物水溶液的表面张力为63.6 mN/m。     

羧甲基香豆胶的制备与表征

通过加入NaOH与一氯乙酸钠(SMCA)固体进行香豆胶(FG)的碱化和醚化,制备了不同取代度的羧甲基香豆胶(CMFG)。研究了不同分散介质、反应温度与时间、NaOH与SMCA用量等因素对取代度与反应效率的影响。以异丙醇/水为分散介质,产物取代度与反应效率最大,优化的反应温度为50℃、反应时间5h、醇水体积比52.5∶7.5。醇水体积比为50∶10、n(SMCA)∶n(NaOH)∶n(FG)=1∶1∶1时取代度为0.75,反应效率达75%。NaOH对取代度的影响大于SMCA。采用一步羧甲基化反应制备取代度1.05的CMFG,反应效率可达到70%。CMFG溶液黏度随取代度增大而增大,w(CMFG)=2%时,取代度为0.78,溶液黏度为116mPa.s。CMFG水溶液黏度4d降低8.6%～28.0%,黏度稳定性高于在w(NaCl)=1%的盐水溶液中的稳定性。     

双亲阳离子阿拉伯木聚糖的合成及其在香波中的应用

以玉米麸皮阿拉伯木聚糖为原料,以环氧氯丙烷和不同烷基链长的叔胺作为季铵化试剂,在碱性条件下,在水溶液体系里合成双亲阳离子阿拉伯木聚糖。通过核磁共振氢谱和碳谱对其结构进行表征。随烷基链长的增加,双亲阳离子阿拉伯木聚糖溶液粘度增加。添加了双亲阳离子阿拉伯木聚糖的洗发水有着良好的帮助硅油沉积的能力,同时有着良好的梳理性能,而且烷基链越长,取代度越高,帮助硅油沉积的能力越强,干梳和湿梳性能也越好。     

双亲阳离子阿拉伯木聚糖的合成及其在香波中的应用

以玉米麸皮阿拉伯木聚糖为原料,以环氧氯丙烷和不同烷基链长的叔胺作为季铵化试剂,在碱性条件下,在水溶液体系里合成双亲阳离子阿拉伯木聚糖。通过核磁共振氢谱和碳谱对其结构进行表征。随烷基链长的增加,双亲阳离子阿拉伯木聚糖溶液粘度增加。添加了双亲阳离子阿拉伯木聚糖的洗发水有着良好的帮助硅油沉积的能力,同时有着良好的梳理性能,而且烷基链越长,取代度越高,帮助硅油沉积的能力越强,干梳和湿梳性能也越好。     

Relationship between molecular structure and moisture‐retention ability of carboxymethyl chitin and chitosan

Carboxymethyl chitins and chitosans (CM‐chitins, CM‐chitosans) of different substitution sites were prepared under different reaction conditions, and partially depolymerized carboxymethyl chitins of various molecular weights from 24.8 × 10⁴ to 0.26 × 10⁴ were obtained by degrading with chemical reagents. Degree of substitution (DS) was estimated by potentiometric titration. Substitution site was confirmed by infrared and ¹³C‐NMR spectra. Molecular weights were determined with gel permeation chromatography and gel permeation chromatography combined with laser light scattering (GPC‐LLS). Moisture‐absorption and retention abilities of these compounds were tested in comparison with those of hyaluronic acid (HA). The results reveal that 6‐carboxymethyl group in the molecular structure of chitin and chitosan is a main active site responsible for moisture retention. Although carboxymethylation at OH‐3 and N position is not essential, they contribute to the ability. Moisture‐retention ability is also related to molecular weight; that is, higher molecular weight helps to improve moisture‐retention ability. 6‐O‐CM‐chitin (chitosan) with a DS above 0.8 and molecular weight higher than 24.8 × 10⁴ has the potential to substitute for HA for use in cosmetics and clinical medicine. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1233–1241, 2002     

Synthesis and characterization of carboxymethylated red angico (Anadenanthera macrocarpa) exudate polysaccharide

Red angico is a heteropolysaccharide (arabinogalactan) obtained from Anadenanthera macrocarpa trees. Carboxymethylation of angico gum (AG) with monochloroacetic acid (MCA) in alkaline aqueous medium resulted in samples which were characterized by ¹³C nuclear magnetic resonance spectroscopy and gel permeation chromatography. The effects of reaction parameters, such as alkali concentration, MCA/AG ratio and temperature on the reaction yield and degree of substitution (DS) were investigated. The DS and MCA total efficiency values increase up to 2 h reaction time and then decrease. The DS varied from 0.11 to 1.10 depending on NaOH/MCA/AG ratio and temperature. The highest MCA total efficiency (0.57) was obtained for NaOH/MCA/AG molar ratio equal to 3:1:1, at 70°C. (DS = 0.63, yield = 91.0%). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) analysis shows that polymer degradation was observed in all samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2985–2991, 2007     

玉米芯木聚糖硫酸酯抗凝血及抗血小板聚集的活性研究

水不溶性木聚糖(wisX)经硫酸酯化获得玉米芯木聚糖硫酸酯wisX-S2、wisX-S4和wisX-S6,硫酸取代度(DS)分别为0.58、0.81和1.62,相对分子质量分别为1.1×105、1.3×105、1.0×105kDa。采用活化部分凝血活酶时间(APTT)、凝血酶时间(TT)、凝血酶原时间(PT)和血小板聚集实验检测了三者的抗凝血和抗血小板聚集活性。结果表明,wisX-S4和wisX-S6能明显延长APTT和TT,提示wisX-S是通过内源性和(或)共同途径发挥抗凝血作用的。同时wisX-S6体外能抑制血小板聚集。DS是影响wisX-S抗凝血活性的重要因素之一。     

酶法合成右旋糖酐相对分子质量的控制

用海藻酸盐固定的肠膜状明串珠菌所产右旋糖酐蔗糖酶合成右旋糖酐,在合成过程中加入右旋糖酐酶,使超高相对分子质量的右旋糖酐裂解,以调节产物的相对分子质量;用凝胶渗透色谱(GPC)作为表征手段,对右旋糖酐相对分子质量与右旋糖酐酶的添加量及反应时间的关系等进行了研究。结果表明,右旋糖酐酶在最初的2h就能使右旋糖酐的重均相对分子质量从8.52×105降至2.00×105,随后作用减缓;右旋糖酐的重均相对分子质量随右旋糖酐酶用量的增加而减小,并且酶用量对产物相对分子质量的影响是非线性的;右旋糖酐蔗糖酶与右旋糖酐同时进入反应体系所得右旋糖酐的收率最高可达86.8%。在100 mL蔗糖质量浓度为100 g/L的底物溶液中,加入15 U右旋糖酐蔗糖酶液,同时加入0.19~0.75 U右旋糖酐酶,反应24 h,可以得到相对分子质量为1.0×105~2.0×104的右旋糖酐。     

血红蛋白类红细胞代用品理化性质的色谱分析

目的 建立血红蛋白类红细胞代用品的色谱分析方法。方法 通过高效液相系统与二极管矩阵检测器、多角度激光散射检测器和蒸发光散射检测器进行组合,检测聚乙二醇(PEG)化牛血红蛋白(PEG-bHb)的色谱纯度、相对分子质量分布和磷脂含量。结果 PEG-bHb为多位点不均一修饰的混合物,数均相对分子质量为1.211×10~5,重均相对分子质量为1.347×10~5,残余磷脂含量低于1μg/ml。结论 色谱分析方法是进行血红蛋白类红细胞代用品理化性质分析的适宜方法。     

活性炭负载硫酸氢钠催化合成乙酸丁酯动力学

在间歇反应釜中以活性炭负载硫酸氢钠为催化剂,丁醇和乙酸为原料催化合成乙酸丁酯。在消除内外扩散影响的前提下,以初始速率法回归动力学方程。结果表明:在催化剂粒径小于0.075 mm,实验转速为200 r/min条件下,反应内外扩散可以消除。在实验范围内获得了本征动力学方程,反应动力学方程表达式为:-r_A=f(w)k_0exp(-E_a/RT)(C_AC_D-C_EC_W/K)=(0.028w+0.0135)×4.31×10~5×exp(-4.39×10~4/RT)×(C_AC_D-C_EC_W/2.78)。其中,反应活化能为43.99 kJ·moL~(-1),指前因子k0=4.31×10~5 moL~(-1)·L·min~(-1)。     

TS-1分子筛催化环己酮氨肟化反应的失活动力学

采用间歇反应器,对液相环己酮氨肟化过程中TS-1分子筛的催化活性变化规律进行了考察,在失活原因分析的基础上建立失活动力学模型:rde=1.01×1014exp(-1.17R×T105)C0A.76C0B.82C0C.38a1.64,并对模型参数进行估值。     

四种乳酸聚合方法的比较

以乳酸为原料,辛酸亚锡为催化剂,采用乳酸直接聚合(一步法)、丙交酯开环聚合(两步法)、熔融-固相聚合、溶剂回流脱水等不同的实验方法分别合成出了不同相对分子质量的聚乳酸。实验结果表明:实验方法不同,所得聚合物的相对分子质量不同,其中丙交酯开环聚合(两步法)所得聚合物的相对分子质量最大,可达80万左右,溶剂回流脱水法的可达24000左右,熔融-固相聚合的为10800,乳酸的直接聚合(一步法)的只有5000。     

Fast Transmethylation of Total Lipids in Dried Blood by Microwave Irradiation and its Application to a Population Study

A methodology combining finger-pricked blood sampling, microwave accelerated fatty acid assay, fast gas chromatography data acquisition, and automated data processing was developed, evaluated and applied to a population study. Finger-pricked blood was collected on filter paper previously impregnated with 0.05 mg of the antioxidant butylated hydroxytoluene and air-dried at room temperature. Transmethylation was accelerated by microwave irradiation in an explosion-proof multimode microwave reaction system. The chemical procedure was based on a one-step direct transmethylation procedure catalyzed by acetyl chloride. The short-term stability of PUFA in blood dried on filter paper and storage at room temperature was examined using venous blood. The recoveries ranged from 97 to 101 % for the categorized fatty acids as well as the ratios of n-6 to n-3 PUFA and the n-3 % highly unsaturated fatty acid. Specifically, recoveries were 99, 98, 97, and 97 % for linoleic acid (18:2n-6), arachidonic acid (ARA), α-linolenic acid (ALA), and docosahexaenoic acid (DHA), respectively. The mol% (mean ± SD, 95 % confidence interval) of fatty acid composition in subjects from the population study was determined as 36.2 ± 3.8 (35.8, 36.7), 23.2 ± 3.0 (22.8, 23.5), 36.8 ± 3.5 (36.4, 37.2) and 3.79 ± 1.0 (3.68, 3.91) for the saturated, monounsaturated, n-6 and n-3 PUFA, respectively. Individually, the mean mol% (95 % CI) was 22.6 (22.3, 22.9) for 18:2n-6, 9.5 (9.3, 9.7) for ARA, 0.51 (0.49, 0.53) for ALA, 0.42 (0.38, 0.47) for eicosapentaenoic acid (EPA), and 1.67 (1.61, 1.73) for DHA. This methodology provides an accelerated yet high-efficiency, chemically safe, and temperature-controlled transmethylation, with diverse laboratory applications including population studies.     

Mechanical properties and water vapor permeability of thin film from corn hull arabinoxylan

Isolated corn hull arabinoxylan was dissolved in water and provided a clear solution. Plasticizer (glycerol, propylene glycol, or sorbitol) was added to the arabinoxylan solution at 0–20 wt % (film dry weight), which was cast into stable films. Film thickness ranged from 22 to 32 μm. Mechanical properties, moisture content, and water vapor permeability (WVP) were studied for the arabinoxylan‐based films as a function of plasticizer concentration. Measured data for the corn hull arabinoxylan–based films were 13–18 wt % moisture content, 10–61 MPa tensile strength, 365–1320 MPa modulus, 6–12% elongation, and 0.23–0.43 × 10^?10 g m^?1 Pa^?1 s^?1 water vapor permeability. Plasticized arabinoxylan films produced in this study had lower WVPs than those of unplasticized films, which is likely attributable to the phenomenon known as antiplasticization. Scanning electron micrographs showed a homogeneous structure on film surfaces. Films containing sorbitol had the best moisture barrier properties. When grapes were coated with arabinoxylan and arabinoxylan/sorbitol films, weight loss rates of the fruit decreased by 18 and 41%, respectively, after 7 days. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2896–2902, 2004