全乙酰吡喃溴代葡萄糖一步法合成及结构表征

乙将未保护的D-葡萄糖与醋酸酐在高氯酸催化下制得全乙酰吡喃糖,不经分离直接与液溴和红磷反应合成了全乙酰吡喃溴代葡萄糖,分离收率达95%,其结构经核磁共振鉴定.     

溴乙酰溴中二溴乙酰溴杂质分析方法的研究

建立了间接测定溴乙酰溴中二溴乙酰溴含量的HPLC方法。将溴乙酰溴水解生成溴乙酸,辅以LC-MS技术,对其主要杂质进行定性研究。采用十八烷基硅烷键合硅胶柱,流动相为V(10 mmol/L三乙胺溶液)∶V(乙腈)=95∶5,检测波长为205 nm。溴乙酸与二溴乙酸在0.001~1.0 mg/mL浓度范围内线性关系良好,平均回收率为99.3%,RSD为0.87%,二溴乙酸相对校正因子为0.37。高效液相色谱法与离子色谱法测定结果一致,方法准确可靠,适于对溴乙酰溴原料中二溴乙酰溴杂质的控制。     

溴代正丁烷的绿色合成

以溴化钾、正丁醇为反应原料,水为溶剂,滴加浓硫酸合成溴代正丁烷。考察了反应条件对产率的影响,结果表明在溴化钾0.1 mol、正丁醇0.07 mol、浓硫酸5 mL、水2.5 mL,回流反应3 h条件下,产率为96.3%。该方法废液后处理简单,排放无污染。粗产品经气相色谱分析证明几乎不含副产物,对产品进行了密度及折光率测定、红外表征。     

氢溴酸-浓硫酸法合成1-溴代丁烷

以工业废氢溴酸与正丁醇为原料，在浓硫酸存在的条件下合成1-溴代丁烷。考察了反应条件对产率的影响，比较合适的反应条件为：正丁醇、氢溴酸和浓硫酸物质的量比为1：1．13：1．37，反应时间5h。分离产率达到93．8％。粗产品经气相色谱分析证明无副产物，产品经IR和折光率进行表征。     

无机碱催化合成α-溴代异丁酸叔丁酯

利用α-溴代异丁酰溴和叔丁醇反应,分别以三聚磷酸钠、无水硼砂、无水碳酸钠、无水碳酸钾、CaO、泡花碱、原硅酸钠、醋酸钠作缚酸剂催化合成α-溴代异丁酸叔丁酯,收率为40.2%-96.5%。其中,以化学计量的三聚磷酸钠作缚酸剂时,α-溴代异丁酸叔丁酯的收率最高(96.5%)。     

5-溴乙酰水杨酰胺合成新路线

本文介绍了以水杨酰胺为原料,先以乙酰氯酰化得5-乙酰水杨酰胺,再经溴化制得5-溴乙酰水杨酰胺的合成新路线。总收率在75%以上。     

精确合成多溴代二苯醚类化合物

用间氯过氧苯甲酸和三氟甲磺酸作为酸性氧化体系,以多种溴代碘苯及溴代苯合成了溴代二苯基碘盐.再以其与溴代苯酚在碱性条件下反应,精确合成各种多溴代二苯醚.该方法简便、反应条件温和、后处理简单、产品纯度好、收率高.     

溴代丙二酸的合成及热稳定性分析

以丙二酸为原料,研究了无机和有机体系中溴代丙二酸的合成方法及影响因素。结果表明:有机体系中的合成要优于无机体系。在有机反应体系中,冰浴,乙醚和四氯化碳为反应溶剂,反应时间60 min,减压蒸馏,结晶得到产品,其收率为56.32%,熔点为114~116℃。用FTIR和MS对产品进行了表征,并用MS对产品的热稳定性进行了分析,发现溴代丙二酸的热稳定性较差,在加热过程中易发生进一步的溴化和脱羧反应。     

5-溴代胡椒环的合成方法研究

以胡椒环为原料,采用氧化溴化体系合成5-溴代胡椒环,确定了溴化工艺条件,考察了溶剂种类、反应温度、物料配比及反应时间对反应的影响。优化工艺为:三氯甲烷为反应溶剂,反应温度为10℃,反应时间为6 h,物料配比n(胡椒环)∶n(氢溴酸)=1∶1.2。产品收率81%,产品纯度99.5%(GC)。产物的结构经1H NMR、IR、MS表征。     

4-溴代百里香酚的合成

以百里香酚为原料,通过溴取代反应合成4-溴代百里香酚。采用FTIR、¹H NMR等手段对产物进行了表征,确定了产物结构。探讨了溶剂种类、溴代剂种类和用量、反应时间、反应温度和微波加热功率对产物得率的影响,得到适宜的工艺条件为:以N-溴代丁二酰亚胺为溴代剂,n(百里香酚):n(N-溴代丁二酰亚胺)=1:1.5,溶剂为乙酸,反应温度为20℃,反应时间15min,微波反应功率500W。在上述条件下,4-溴代百里香酚的得率为65.1%。     

Dissolution of Wood with Acetyl Bromide Solutions-Reactions of Lignin Model Compounds

A Pinus radiata refiner mechanical pulp (RMP) sample and a range of lignin model compounds were treated with a solution of 25% w/w acetyl bromide (AcBr) in acetic acid to assess the reactions which take place during the dissolution of wood with the AcBr solution. The lignin model reactions were also carried out in solutions to which 4% w/w perchloric acid was added. The RMP sample gave a product which contained 9.2% bromine, and was severely degraded to low molecular weight products, the polysaccharides more so than the lignin fraction. The reactions of the lignin model compounds with AcBr included O-acetylation of phenolic and aliphatic hydroxyl groups, cleavage of β-ether bonds, C-acetylation of aromatic rings, particularly in positions para to methoxyl groups, demethylation of aromatic methoxyl groups and probable replacement of benzyl alcohol groups by bromine functions. The reactions were accelerated by perchloric acid, and the rates appeared to decrease in the order O-acetylation π bromine substitution >> β-ether cleavage π C-acetylation > demethylation. It is concluded that dissolution of wood in the AcBr solution is a consequence of depolymerisation of the polysaccharides and lignin, and acetylation to give products which would be soluble in the reaction medium.     

Comparison between extraction of lipids and fatty acids from microalgal biomass

Seven solvent mixtures have been used to extract the lipid fraction of lyophilized biomass ofIsochrysis galbana. Six of them were composed of biocompatible solvents. Each method was carried out under relaxed operating conditions (i.e., one hour at room temperature) with extraction in a nitrogen atmosphere to prevent autooxidation and degradation of polyunsaturated fatty acids (PUFAs). Apart from the well-established Bligh and Dyer method [Can. J. Biochem. Physiol. 37:911 (1959)] (Cl₃CH/MeOH/H₂O, 1∶2∶0.8, vol/vol/vol), which rendered the highest yield of lipids (93.8%), ethanol (96%) and hexane/ethanol (96%), 1∶2.5 vol/vol produced the best results (84.4 and 79.6%, respectively). To obtain free fatty acids, KOH was added to the solvent mixtures used to extract the total lipids, except for Cl₃CH/MeOH/H₂O, and direct saponification was carried out at 60°C for 1 h or at room temperature for 8 h. The highest yields obtained by direct saponicification were 81% with hexane/ethanol (96%), 1∶2.5, vol/vol and 79.8% with ethanol (96%). Partial yields of the mainn-3 PUFAs found inI. galbana, stearidonic acid (SA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were calculated for both extraction methods. For lipid extraction with ethanol (96%), yields of 91, 82 and 83% were obtained for SA, EPA and DHA, respectively. When direct saponification was used, hexane/ethanol (96%; 1∶2.5, vol/vol) produced the best yields of (91, 79 and 69% for SA, EPA and DHA, respectively).     

尼泊金辛酯和异丙酯合成方法的研究

研究了各种因素对制备尼泊金辛酯，异丙酯产率的影响，筛选出最佳反应条件可使辛酯的收率达９６％，异丙酯的收率达８２％，用ＧＣ－ＭＳ计确定了异丙酯酯化应的副产物的结构，并提出了生成该副产物的反应机理。     

Use of aqueous HCI/MeOH as esterification reagent for analysis of fatty acids derived from soybean lipids

A quick, reliable and very inexpensive method is described for the analysis of fatty acids derived from soybean lipids. The method involves extraction of soybean lipids with petroleum ether, followed by hydrolysis of lipids with KOH/MeOH (0.5 M) for 5 min at 100 C followed by esterification with aq. HC1 (36%)/MeOH (4:1, v/v) for 15 min at 100 C. No problems were encountered with the esterifica-tion procedure in the presence of water and the procedure gave results comparable to die more conventional BF₃/MeOH reagent. The aq. HCI/MeOH reagent is several hundred times cheaper than BF₃/MeOH, and does not compromise the efficiency of the reagent.     

氧气氧化对硝基甲苯合成对硝基苯甲酸的研究 Ⅰ.溶剂对对硝基苯甲酸收率的影响

研究了几种溶剂对氧气液相氧化对硝基甲苯合成对硝基苯甲酸收率的影响。发现用苯／甲醇混合溶剂（Ｖ／Ｖ＝５／１）在５０℃、２．０ＭＰａ氧压下反应１２ｈ可获得６６．４％收率和９９．６％纯度的对硝基苯甲酸粗品。     

磷酸氢钙制备磷酸二氢钾的工艺研究Ⅰ

以明胶生产中副产的磷酸氢钙和工业级硫酸钾为原料,采用复分解法制取了磷酸二氢钾。通过单因素实验考察了反应时间、反应温度、液固体积质量比及钾磷物质的量比等因素对制备磷酸二氢钾过程中的磷收率和钾收率的影响。实验结果表明较佳的工艺条件：反应时间为120 min,反应温度为60 ℃,液固体积质量比为4 mL/g,钾磷物质的量比为1.3。通过正交试验优化了工艺条件,实验结果表明最优的条件：反应时间为130 min,反应温度为50 ℃,液固体积质量比为4.5 mL/g,钾磷物质的量比为1.3,在此条件下磷的收率可达到81.15%,钾的收率可达到97.89%。     

聚丙烯酸-聚乙烯醇共混膜分离甲醇-碳酸二甲酯共沸体系

采用涂敷法制备了聚丙烯酸(PAA)-聚乙烯醇(PVA)共混膜,将其用于渗透汽化法分离甲醇(MeOH)-碳酸二甲酯(DMC)共沸物,考察了共混比例、热处理条件对甲醇分离性能的影响. 渗透汽化实验结果表明,随着热处理时间延长或热处理温度提高,分离因子先升高后降低,而渗透通量则逐渐减小;随着共混膜中PAA/PVA比例增加,分离因子先升高后降低,而渗透通量先减小后增大;当PAA/PVA质量比为7/3、热处理时间为60 min、热处理温度为150℃时,选择性最佳,在料液组成为70%(w) MeOH-30%(w) DMC及70℃的操作温度下,甲醇的分离因子为9.5(透过侧MeOH浓度为95.5%, w),渗透通量为360 g/(m2×h).     

三甲基硅酯化／GC/MS法分析荞麦籽中的脂肪酸

以无水乙醚为溶剂,采用索氏抽提法提取养麦耔中的粗脂肪,先分别采用三甲基硅酯化法和氢氧化钾/甲醇碱催化甲酯化法对粗脂肪进行衍生化处理,再通过气相色谱/质谱联用技术分析脂肪酸的组成.结果表明,通过三甲基硅酯化法处理,粗脂肪提取率达4.96％,共鉴定出18种脂肪酸成分,主要为亚油酸(34.69％)、油酸(31.08％)、棕櫊...     

A Chemoselective Hydrogenation of the Olefinic Bond of α,β‐Unsaturated Carbonyl Compounds in Aqueous Medium under Microwave Irradiation

A microwave‐assisted mild and ecofriendly catalytic transfer hydrogenation process was developed to reduce various α,β‐unsaturated carbonyl compounds into the corresponding saturated carbonyl compounds in the presence of silica‐supported palladium chloride as catalyst and a combination of MeOH/HCOOH/H₂O (1 : 2 : 3) as hydrogen source within 22–55 minutes in moderate to excellent yields with 100% chemoselectivity.     

Production of FAME from acid oil model using immobilized <Emphasis Type="Italic">Candida antarctica</Emphasis> lipase

Acid oil is a by-product in the neutralization step of vegetable oil refining and is an alternative source of biodiesel fuel. A model substrate of acid oil, which is composed of TAG and FFA, was used in experiments on the conversion to FAME by immobilized Candida antarctica lipase. FFA in the mixture of TAG/FFA were efficiently esterified with methanol (MeOH), but the water generated by the esterification significantly inhibited methanolysis of TAG. We thus attempted to convert a mixture of TAG/FFA to FAME by a two-step process comprising methyl esterification of FFA and methanolysis of TAG by immobilized C. antarctica lipase. The first reaction was conducted at 30°C in a mixture of TAG/FFA (1∶1, wt/wt) and 10 wt% MeOH using 0.5 wt% immobilized lipase, resulting in efficient esterification of FFA. The reaction mixture after 24 h was composed of 49.1 wt% TAG, 1.3 wt% FFA, 49.1 wt% FAME, and negligible amounts of DAG and MAG (<0.5 wt%). The reaction mixture was then dehydrated and used as a substrate for the second reaction, which was conducted at 30°C in a solution of the dehydrated mixture and 5.5 wt% MeOH using 6 wt% immobilized lipase. The activity of the lipase increased gradually when the reaction was repeated by transferring the enzyme to a fresh substrate mixture. The activity reached a maximum after 6 cycles, and the content of FAME achieved was >98.5 wt% after a 24-h reaction. The immobilized lipase was very stable in the first-and second-step reactions and could be used for >100 d without significant loss of activity.