羧甲基丝素的制备工艺优化及其乳化性能

以废丝为主要原料,将不溶于水的丝素蛋白通过与一氯乙酸在乙醇溶剂中的醚化反应,合成了可溶性的羧甲基丝素。讨论了几种主要因素(如碱化时间、碱化温度、醚化时间和醚化温度等)对产物醚化度的影响,得到了制备羧甲基丝素的醚化工艺条件:碱化时间90 min、醚化时间90 min、碱化温度25℃、醚化温度70℃。所得羧甲基丝素的醚化度为0.7425。测定羧甲基丝素的表面活性后,得到羧甲基丝素的临界胶束浓度为1.25 g/L,亲水亲油平衡(HLB)值为10。丝素蛋白溶液具有一定的起泡能力,且在质量分数为1.0%～1.2%范围内的稳定性较好,但不宜作发泡剂。丝素蛋白溶液具有良好的乳化能力和乳化稳定性,可作为良好的乳化剂。     

Triflic acid catalyzed reductive coupling reactions of carbonyl compounds with O-, S-, and N-nucleophiles

Highly efficient metal-free reductive coupling reactions of aldehydes and ketones with a range of nucleophiles in the presence of triflic acid (1-5 mol%) as the catalyst are presented. The reactions can be performed at ambient temperature without exclusion of moisture or air. A range of symmetrical and unsymmetrical ethers were obtained by this method in high yields and short reaction times. For the first time, the influence of additional functionalization has been studied. Furthermore, the formation of thioethers from ketones (by addition of unmodified thiols) and of sulfonamides from either aldehydes or ketones has been achieved under catalytic conditions.     

Sulfonated carbon materials with hydrophilic and lipophilic properties

Two acidic carbon materials （H-PRC and HS-C） were used as catalysts for the condensation reaction of methanol with formaldehyde to produce dimethoxymethane （DMM） in aqueous solution （hydrophilic system） and for the etherification of isopentene with methanol to produce tert amyl methyl ether （TAME） in toluene solution （lipophilic system）. Microcalorimetric adsorptions of water and benzene showed that the HS-C was highly hydrophilic without the lipophilicity, while the H-PRC exhibited both the hydrophilicity and lipophilicity. Thus, the HS-C was well dispersed in aqueous solution and difficult to separate from it. On the other hand, the H-PRC was highly active, more active than the acidic resin （D008） and sulfuric acid, for the synthesis of DMM in aqueous solution. The H-PRC was also highly active, more active than the HS-C, for the etherification of isopentene with methanol to produce TAME in toluene solution, probably owing to its amphiphilic surface property as well as its strong surface acidity as measured by the microcalorirnetric adsorption of NH3.     

有机合成中二元醇的选择性单官能团保护

本文综述了近年来有机合成中二元醇类化合物的选择性单官能团保护的研究进展。参考文献21篇。     

Regioselective etherification of 1,2-O-isopropylidene-4,6-di-O-benzyl myo-inositol

During the etherification of 1,2-O-isopropylidene-4,6-di-O-benzyl myo-inositol, the specific regioselectivity on 3- or 5-hydroxyl group was showed to be determined by the nature of the O-alkylating agents used. As demonstrated by MM and MNDO calculation, the regioselectivity of the reaction mentioned can be rationalized by steric and/or electronic effect.     

Modeling strategy for systems with both stepwise and chainwise chemistry revisited. The directionality effect on the build-up of the network structure

A comparison of rigorous and approximate models for the build-up of epoxy-amine networks with simultaneous etherification is presented. Contrary to a recent publication, it is shown that naïve statistical models perform very well in predicting statistical parameters when the different directions of network growth are distinguished in the statement of the recursive procedure. Slightly lower values of gel conversions are predicted by the approximate model, a fact that is consistent with the wider distribution of chain lengths resulting from the random recombination procedure. © 1993 John Wiley & Sons, Inc.     

Synthesis of O-benzyl oximes by combination of phase transfer catalysis and ultrasound irradiation

The reactions of oximes with benzyl bromide catalyzed by benzyldimethyltetradecylammonium chloride are carried out at room temperature for 30–60 min in aqueous sodium hydroxide solution under ultrasound irradiation to offer O-benzyl oxime derivatives in 60–96% yields. In comparison to classical methods, the advantages of the present procedure include short reaction time, high yields and environmental friendliness. __________ Translated from Chinese Journal of Organic Chemistry, 2008, 28(4) (in Chinese)     

3,5-二(吡啶-甲氧基)苯甲酸吡啶-甲基酯的合成

具有三脚架构型的多吡啶类化合物,因其具有众多的配位原子以及较为特殊的分子构型,在与金属离子配位的过程中,一方面可以通过吡啶氮的配位键、氢键、芳香环的π-π作用等方式构筑出结构新颖的配合物[1-4];另一方面因其具有三脚架的构型,其三条侧链可自由翻转形成大小合适的空腔,能够与不同的客体分子或离子结合,有可能筛选出在分子识别、分子交换、电子传递和选择性催化等方面具有特殊性能的功能材料[5-8].因此,合成具有三脚架构型的多吡啶类配体是这些配合物在诸多领域中应用的关键.     

An efficient method for para-methoxybenzyl ether formation with lanthanum triflate

PMB ethers of alcohols are prepared in high yields and short reaction times using the trichloroacetimidate of PMB alcohol and lanthanum triflate. The mild conditions allow protection of acid-sensitive alcohols.