硝化剂及预处理条件对软木NC氮量及其分布影响

以加拿大针叶木为原料、采用硝硫混酸和HNO3/CH2Cl2两种硝化剂分别制备了A、B、C、D级硝化纤维素(NC)样品,通过偏光显微镜分析测试了其含氮量及氮量分布(硝化均匀性)。同时采用不同的高压闪爆预处理条件,对针叶木进行预处理,比较了闪爆对高氮量B、低氮量D级NC的含氮量及氮量分布,系统研究了硝化剂体系组成及原料预处理条件对NC的含氮量及其分布影响规律。结果表明,在同样氮量级别,HNO3/CH2Cl2硝化体系比HNO3/H2SO4/H2O得到的NC氮量分布更均匀,A、B、C与D级NC的均匀性分别提高17.46%、16.98%、16.77%和25.79%;同一硝化剂体系,闪爆有利于硝化剂向软木纤维素纤维束内部扩散,能提高NC含氮量及氮量分布均匀性,B级NC,其均匀性提高6.06%,D级NC则提高7.56%。     

Nitrosation and Nitration of Tetraacetyldibenzylhexaazaisowurtzitane

Tetraacetyldibenzylhitane (TADBIW) was subjected to debenzylation by nitrosating with inorganic materials available commercially to synthesize tetraacetyldinitrosohexaazaisowurtzitane (TADNSIW). TADNSIW was purified, and its structure was determined by FTIR, 1H NMR, MS and element analysis. The debenzylation reaction of TADBIW gave quantitative benzaldehyde as a by-product. This indicates that the reaction produces an imine cation as an intermediate. Hexanitrohexaazaisowurtzitane (HNIW) was prepared from unpurified TADNSIW with the yield over 96.0 % and the purity more than 98.0 %. And the mechanism of the reaction from TADNSIW to HNIW is proposed to be oxidation of nitroso and nitration of acetyl on the molecule of TADNSIW, This reaction system involved is simple, and the reaction can complete within a short time and under mild conditions. The product can be easily to separate and the waste disposed readily.     

铌酸及其改性催化剂上甲苯的区域选择性硝化

研究了铌酸催化剂上甲苯硝化反应的区域选择性。结果表明,当反应温度为40℃,反应时间为60 min时,以CCl4为溶剂,以质量分数为95%的硝酸为硝化剂,在醋酐存在条件下,经300℃焙烧3 h后的铌酸催化剂,对甲苯硝化表现出了强的区域选择性;催化剂用量为0.8 g,甲苯硝化产物邻对位摩尔比达1.20,较硝硫混酸的1.67显著降低,产物得率达99.7%。且该催化剂循环使用5次,催化活性变化很小。制备了4种改性铌酸催化剂,结果分析表明,改性铌酸催化剂对甲苯硝化均表现出了比铌酸催化剂强的区域选择性,分别以硫酸铈改性的固体铌酸、硫酸铈和磷酸改性的铌酸、硝酸改性的铌酸、硝酸和磷酸改性的铌酸为催化剂,甲苯硝化产物的邻对位摩尔比可分别达1.15,1.11,1.09,1.04。     

Nitro derivatives of PEEK‐WC

Nitrated poly(oxa‐p‐phenylene‐3,3‐phthalido‐p‐phenylene‐oxa‐p‐phenylene‐ oxy‐phenylene) (PEEK‐WC) with various average degrees of substitution was obtained by reaction with several nitrating agents. By working under controlled reaction conditions, little degradation of the parent polymer is observed. The nitro derivatives of PEEK‐WC show a high thermal stability, and are able to form membranes by means of phase inversion technique. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1037–1045, 2001     

Temperature and storage effects on antioxidant activity of juice from red and white grapes

The effect of temperature and storage time on the phenolic composition and on the antioxidant activity of grape (Vitis vinifera L.) juices made using a red (Sangiovese, SG) and a white (Muscat of Alexandria, MA) variety was studied. Total phenolics, flavonoids, flavan‐3‐ols and hydroxycinnamoyl‐tartrates (HCT) were determined on grape extracts (GE) and juices. Total anthocyanins and anthocyanins composition were measured on GE. The antioxidant activity was assessed by means of two different in vitro tests: scavenging of the stable 2,2‐diphenyl‐1‐picrylhydrazyl radical and the inhibition of tyrosine nitration mediated by authentic peroxynitrite (ONOO^?). All the juices were analysed after 24 h and 2 weeks of storage by means of two‐way anova (factors being cultivar and temperature). Anthocyanins were not detected in MA extract, whereas in SG their content was 534 mg malvidin‐equivalent per 100 g of dry matter (d.m.) and malvidin derivatives (glycosylated and coumaroylated) were the most represented (respectively 169 and 41 malvidin‐equivalent per 100 g of d.m.). HCT content of the extracts was higher in SG (overall +33%). Also in grape juices, HCT were lower in MA and in this variety, the trans‐fertaric and cis‐coutaric acids were also undetectable. Cultivar effect proved to be highly significant, while no significant differences in the phenolic composition were observed for storage temperatures (4 and ?20 °C) and cultivar × temperature interaction. However, when statistical analysis was focused on each cultivar, MA was found to be more sensible to storage conditions and a significant reduction in total phenolics (?20%) and flavonoids (?53%) content and in the ONOO^? scavenging potential (?32%) was evident after 2 weeks at 4 °C (when compared with the same storage temperature after 24 h). On the contrary, SG juices did not show significant differences among the four storage treatments investigated. These results could be explained suggesting that anthocyanins presence in red grape plays a key role in juice stability.     

5-硝基水杨酸的合成新工艺研究

以邻氯苯甲酸为原料,采用混酸硝化生成中间体2-氯-5-硝基苯甲酸,再水解生成目标产物5-硝基水杨酸.重点对硝化反应的混酸配比、反应温度及水解反应的反应温度、反应时间进行了考察,得到了硝化反应混酸配比为浓硫酸∶浓硝酸(摩尔比)＝9∶1,反应温度0 ℃,反应时间为8 h的较优工艺条件,收率为95.7%.水解反应温度为140℃,反应时间为16 h,收率为98.3%.反应后产品用适量乙醇水溶液重结晶得到5-硝基水杨酸,含量≥99.8%(HPLC).     

甲苯的定向催化硝化

文章报导了甲苯定向催化硝化合成对一硝基甲苯的方法。在温和条件下,采用复合型催化剂,以硝酸为硝化剂,取得对位体与邻位体比值(P/O)为2.39的实验结果。与经典的混酸硝化法所得产物的 P/O 值0.63相比较,提高了1.76。     

几种芳香酸的硝化及其铅盐的合成研究

研究了对甲基苯甲酸和对氨基苯甲酸等芳香酸的硝化，合成了两种未见报道的含硝基的芳香酸铅盐，由于母体化合物的羧基邻或对位有强供电子的－ＮＨ２３等基团，故在较高温度下用过量的硝酸可使之发生脱羧基的自位硝化反应，生成三硝基衍生物。     

苯酚两相硝化反应及其机理研究

研究了利用乙醚和硝酸钠－硫酸水溶液对苯酚进行两相硝化反应，并确定了反应最佳工艺条件。利用ＨＰＬＣ技术等研究了苯酚两相硝化反应机理，结果认为：反应产物的异构体比例不随反应条件而变，实验测得值与半经验分子轨道的计算结果相符较好，有机相溶剂的性质对产物异构体比例无明显影响，并证实反应所经历的是自由基历程。     

HZSM-5催化下N2O5对氯苯的选择性硝化研究

工业传统混酸硝化法严重腐蚀设备和污染环境,同时对硝基氯苯选择性较低,针对这个问题,研究了在HZSM-5分子筛催化下,五氧化二氮对氯苯的硝化反应。由于HZSM-5优异的择形性,对硝基氯苯在硝化产物中的比例从原先的42%提高到81%。实验考察了反应温度、反应时间、催化剂用量及Si/Al等因素对反应结果的影响。研究表明,在温度为50℃,时间为1h,5gSi/Al质量比为260的催化剂HZSM-5作用下,反应条件最佳,此时氯苯硝化反应得率达到50%,对位选择性为85%。