聚氧化乙烯大单体与苯乙烯的接枝共聚物对某些有机反应的相转移催化效应

以叔丁氧基钾为引发剂合成了由甲基丙烯酰基封端的聚氧化乙烯大单体,用VPO、GPC与UV进行了表征。其数均官能度接近0.90,分子量分布较窄(Mw/Mn<1.10)。将这类大单体与苯乙烯经自由基共聚,制备了接技共聚物。初步考察了这类接技共聚物对酚类化合物与环氧氯丙烷或β-溴乙苯反应时的相转移催化作用,发现产物收率随接技共聚物中氧化乙烯含量的增加而提高。     

Synthesis of carboxymethyl potato starch and comparison of optimal reaction conditions from different sources

Carboxymethyl potato starch (CMPS) was synthesized under heterogeneous reaction conditions. The influences of etherification temperature, alkalization and etherification time, sodium hydroxide to monochloroacetic acid (MCA) molar ratio (n_NaOH/n_MCA), theoretical degree of substitution (DS_t), the ratio of isopropyl alcohol (IPA) volume to starch mass (v_IPA/m_st) on degree of substitution (DS) and reaction efficiency (RE) of CMPS were investigated. Compared with the previous literature data, the results had significant difference for the optimal carboxymethylation conditions of potato starch from different sources. CMPS prepared under optimal conditions showed the highest DS and RE, which were 1.36 and 0.88, respectively. Furthermore, the RE value in this work is considerably higher than that reported in the literature. The time of alkalization and etherification were also discussed independently. In addition, CMPS was characterized by Fourier transform infrared spectrophotometry and scanning electron microscopy (SEM). Copyright © 2008 John Wiley & Sons, Ltd.     

Light-Promoted Nickel Catalysis: Etherification of Aryl Electrophiles with Alcohols Catalyzed by a NiII-Aryl Complex

A highly effective C−O coupling reaction of (hetero)aryl electrophiles with primary and secondary alcohols is reported. Catalyzed by a Ni^II-aryl complex under long-wave UV (390–395 nm) irradiation in the presence of a soluble amine base without any additional photosensitizer, the reaction enables the etherification of aryl bromides and aryl chlorides as well as sulfonates with a wide range of primary and secondary aliphatic alcohols, affording synthetically important ethers. Intramolecular C−O coupling is also possible. The reaction appears to proceed via a Ni^I–Ni^III catalytic cycle.     

通过聚苯的磺化和碳化制备酸性树脂-碳复合材料

用浓硫酸在170℃下处理聚苯,发生了磺化和碳化过程,生成了一种酸性树脂-碳复合材料.其比表面积为14 m2/g,与磺酸基相关的强酸量为1.2 mmol/g,氨吸附量热测定的起始吸附热较高,表明表面磺酸基没有形成焦硫酸根;部分磺酸基在400℃以上才开始分解,表现出很高的热稳定性.该强酸性复合材料在异戊烯与甲醇醚化生成甲基...     

改性豌豆淀粉用于改进玻纤浸润剂的性能

以豌豆淀粉为原料, 先用异淀粉酶处理, 再将酶化的淀粉进行醚化反应, 研究淀粉成膜剂的制备条件. 考察酶解时间、 环氧丙烷用量、 醚化
时间、 反应温度和氢氧化钠用量对成膜剂的性能影响. 通过正交试验得到制备淀粉成膜剂的最优条件： 酶解时间12 h, 环氧丙烷用量4 g, 醚化时间16 h, 反应温度45 ℃, 氢氧化钠用量0.4 g. 拉丝实验结果表明, 改性淀粉作为成膜剂用于玻璃纤维浸润剂, 可保证拉丝工艺顺利完成.     

Synthesis and polymerization of oligo(oxyethylene) macromonomer bearing sodium sulfonate

Oligo(oxyethylene) macromonomers bearing sodium sulfonate group have been synthesized through four reactions: (1) ring-opening polymerization of oxirane, (2) etherification of monomethoxyl oligo(oxyethylene) and epichlorohydrin, (3) sulfonation of cycloxyl compound, and (4) end-capping of sodium oligo(oxyethylene) sulfonate by methacrylic group. A desired length of oligo(oxyethylene) in the macromonomers can easily be achieved by controlling the ratio of reactants in the ring-opening step. The structures of the products of each reaction were identified by IR, ¹H-NMR, and GPC. Polymers of the monomers were also characterized by GPC and DSC. © 1993 John Wiley & Sons, Inc.     

Selective preparation of key intermediates for the synthesis of key intermediates for the synthesis of gemini surfactants by phase-transfer catalysis

A comparison of liquid-liquid and solid-liquid PTC for the selective synthesis of diglycidyl ether from protected pentaerythritol and epichlorohydrin is presented. Solid-liquid PTC was found to be more useful than liquid-liquid PTC because the use of water or other solvents can be avoided and higher yields and selectivity are achieved. It was proved that etherification takes place in the solid phase-organic phase system even in the absence of the phase-transfer catalyst. However, the use of tetrabutylammonium bisulfate as catalyst is essential due to its crucial effect on the enhancement of the rate of etherification and on the improvement of the selectivity to diglycidyl ether, which is higher than 98%.     

对苯二酚在K2CO3—Al2O3负载型碱试剂作用下的单醚化反应

在Ｋ２ＣＯ３－Ａｌ２Ｏ３负载型碱试剂作用下，对苯二酚可发生选择性的单醚化反应，单醚产率高，操作简便，文中讨论了影响单醚产率的各种反应条件和可能的反应机理。     

Convergent synthesis of the FGHI ring system of yessotoxin: stereoselective construction of the G ring

A convergent synthetic route to the FGHI ring system of yessotoxin, a marine ladder polyether, has been developed. The synthesis features convergent coupling of the diol and the aldehyde to form α-cyano ethers via acetal formation followed by ring closing metathesis and reductive etherification to construct the oxocane ring G and tetrahydropyran ring H, respectively. The β-methyl group on the G ring was stereoselectively introduced by alkylation of the corresponding ketone.     

AlSi-ZSM-48沸石分子筛的合成及其催化性能

 考察了以廉价的1，6－己二胺为模板剂合成AlSi－ZSM－48沸石分子筛的条件及其在醚化碳四烯烃裂解生成丙烯和乙烯反应中的催化性能．结果表明，合成体系的碱度和盐类的加入对AlSi－ZSM－48沸石的合成影响极大，n（OH－）／n（Si）大于0．15时得不到AlSi－ZSM－48沸石，盐类如NaF和NaCl等的加入会抑制AlSi－ZSM－48的生成，而更利于ZSM－5等杂晶的产生．在醚化碳四烯烃的裂解反应中，AlSi－ZSM－48表现出优越的催化性能，可以得到高收率的丙烯和乙烯，两种烯烃的总收率可达40％以上