环氧氯丙烷改性稻草

环氧氯丙烷改性稻草;稻草;环氧氯丙烷;醚化;改性     

季胺型阳离子木薯淀粉制备研究

本文以3-氯-2-羟丙基三甲基氯化胺为醚化剂对木薯淀粉进行醚化制得季胺型阳离子淀粉。以互甲胺盐酸盐、环氧氯丙烷为原料,制备了醚化剂3-氯-2-羟丙基三甲基氯化胺,醚化剂制备适宜温度为20℃,二者物质的量之比1．00：1．05,反应时间3—4h．真空蒸馏3—4次提纯。采用湿法制备阳离子淀粉,反应浆液浓度30％-40%,反应温度40℃,反应体系pH值11—12,氢氧化钠与醚化剂物质的量之比2-8：1,淀粉与醚化剂物质的量之比1：0．15。取代度为0.07-0．12。67     

双氢青蒿素醚化法制备蒿甲醚的工艺优化

采用正交试验法和HPLC分析技术,对蒿甲醚的制备工艺进行优选,以蒿甲醚收率和含量为考察指标,对影响双氢青蒿素醚化的因素进行研究,其醚化的最佳条件为A2B3C4D1,即甲醇与二氯甲烷的体积比为1∶2;双氢青蒿素与三氟乙酸的量之比为10∶1;反应温度为40℃;反应时间为1.5h。该工艺稳定可行。     

固体酸催化生物柴油合成研究进展

综述了酯交换反应、酯化反应和甘油的醚化反应3类生物柴油合成方法的研究进展,评述了SO4^2-/SnO2、SO4^2-/ZrO2、B2O3/ZrO2、Mo-ZrO2、分子筛、阳离子交换树脂等固体酸在催化合成生物柴油过程中的催化特征．     

二丁胺甲基膦酸锆的苄基季胺化合物及其相转移催化作用

制得了二丁胺甲基膦酸－亚磷酸氢锆Ｚｒ（ＨＰＯ３）２－ｘ．（Ｏ３ＰＣＨ２ＮＢｕ２）．Ｈ２Ｏ（ｘ＝０．８，０．６，０．５，０．４，０．３５），用溴化苄季铵化，得部分季铵化产物，溴化苄基二丁铵甲基膦酸－二丁胺甲基膦酸－亚磷酸氢锆Ｚｒ（ＨＰＯ３）２－ｘ．（Ｏ３ＰＣＨ２ＮＢｕ２）ｘ－ｙ．（Ｏ３ＰＣＨ２Ｎ＾＋Ｂｕ２．ＣＨ２Ｐｈ．Ｂｒ＾－）．Ｈ２Ｏ（ｙ＜ｘ），用作相转移催化剂，对液／液或固／固／液相转移催化的取     

克拉霉素的合成新方法

以醚化剂1-乙氧基环己烯和硅烷化试剂1,1,1,3,3,3-六甲基二硅氨烷为保护试剂, 采用醚化-硅烷化保护法制备了克拉霉素. 以红霉素A肟为原料计算, 经肟羟基醚化、2',4"-OH硅烷化、6-OH选择性甲基化、脱保护至克拉霉素, 四步反应总收率为49.5%.     

Alkoxylation ofC-chlorovinylsilanes

The alkoxylation and isopropylideneiminoxylation ofC-chlorovinylmethylchlorosilanes with various alcohols and acetone oxime were investigated. A series of newC-chlorovinylmethylalkoxy- and -isopropylideneiminoxysilanes was characterized by IR and¹H NMR spectra. The effect of the number of chlorine atoms inC-chlorovinylmethylchlorosilanes on their reactivity in these reactions was determined.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 737–742, April, 1995.     

An unexpected product from attempted reductive etherification of a silyl alcohol with an aldehyde

Reductive etherification, using BiBr₃/Et₃SiH, between two modified amino acids, one with a silyl alcohol side chain and one with an aldehyde side chain, gave, not the desired bis-amino acid, but a tetrahydrooxazine, in good yield.     

Six-Step Continuous Flow Synthesis of Diclofenac Sodium via Cascade Etherification/Smiles Rearrangement Strategy: Tackling the Issues of Batch Processing

Diclofenac sodium is a widely used nonsteroidal anti-inflammatory drug (NSAID) as over-the-counter (OTC) medication for the treatment of inflammatory diseases. Herein, the development of an intensified six-step continuous flow synthesis of diclofenac sodium from commercially available aniline and chloroacetic acid is described. A challenging and unprecedented etherification/Smiles rearrangement cascade of 2-chloro-N-phenylacetamide and 2,6-dichlorophenol into hydroxyacetyldiphenylamine operated with the precise control of reaction conditions in continuous flow was realized as the key step in this multistep synthetic chemistry. The undesired amide hydrolysis in Smiles rearrangement was addressed and the extra installation of N-chloroacetyl group in current industrial batch mode was avoided. Diclofenac sodium was obtained in 63 % isolated yield with an average yield of above 90 % for each step in a total residence time of 205 min.     

Synthesis of the ABC and IJ ring fragments of yessotoxin

Synthesis of a 6/6/6 tricyclic ether system (3) corresponding to the ABC ring fragment of yessotoxin (1) has been achieved via coupling of a triflate and a 2-lithiofuran followed by intramolecular hetero-Michael addition. The IJ ring fragment (4) of 1 was readily synthesized via successive Sharpless epoxidation and 6-endo cyclization of the resulting vinyl epoxide.