氢化铝锂的生产与反应

介绍了氢化铝锂的常规、高压以及NaAlH_4 3种制备方法 ,总结并且列举了氢化铝锂与卤代物、羧酸酯、醛酮、氰基、特殊情况下碳碳双键官能团的还原反应,并简述氢化铝锂的一些应用。通过对比不同实例,指出了氢化铝锂在化工领域中发挥着不同的作用,因为氢化铝锂在多方面都有很好的还原能力,因此设计合理的反应条件以便充分利用氢化铝锂最大的还原能力,在生产、科研中都是非常重要的。     

制备碱金属硼氢化物的新途径—电解法合成

<正> 碱金属硼氢化物MBH_4是制备其他硼氢化合物的基本原料,将其作为推进剂燃料或添加剂的探索一直受到广泛的重视,而作为有机合成中的选择性还原剂,则更有其独特之处。它除能将醛、酮、羧酸、酮等有效地还原成醇外,其立体选择性极强。反应可在温和的条件下进行,不需要特殊的无水无氧条件。可用醇或水作为反应介质。还可用于造纸、纺织业中漂白,橡胶、塑料工业中作发泡剂,无电电镀,金属离子的化学分离,以及燃料电池系统等。一、碱金属硼氢化物的工业制备到目前为止,真正形成工业生产能力的方法只有两种。 (一)硼酸酯法此法是先制出硼酸三甲酯,然后在较低温度下,氢化钠和硼酸三甲酯反应生成Na     

硼氢化钠在羧酸及其衍生物还原中的应用

硼氢化钠可以很容易的将醛和酮还原为相应的醇,甚至可以在水介质中等当量的反应,但在温和条件下却很难将羧酸、羧酸酯、酰胺、酰氯和氨基酸及其衍生物还原,往往需要大大过量而且长时间回流,即使这样收率也很低.通过加入甲醇、路易斯酸、碘等修饰剂可以显著的提高硼氢化钠的活性,从而将羧酸及其衍生物还原为相应的醇.介绍了硼氢化钠还原羧酸及其衍生物的机理,综述了硼氢化钠在羧酸、羧酸酯、酰胺、酰氯和氨基酸及其衍生物还原中的应用.     

N-异丁基-邻氨基苄醇的合成研究

N-异丁基-邻氨基苄醇是合成多种药物的中间体。文献报道的几种合成方法都要用氢化铝锂进行还原，因此反应条件均比较苛刻。本文改用异丁基溴与邻氨基苄醇为原料直接合成N-异丁基-邻氨基苄醇，不但避免了氢化铝锂的使用，反应条件温和，还减少了合成步骤。通过四因素三水平的正交实验考察了反应温度、反应时间、     

活化硼氢化钠在有机合成中的应用

介绍了有机合成反应中NaBH4与添加剂共同作用的反应,其中包括烯烃和炔烃的还原,羧酸的还原,氨基酸及其衍生物的还原,羧酸酯的还原,酰胺的还原,腈基的还原,酰氯的还原,硝基化合物的还原,醛酮的还原等。与LiAIH4的还原相比较,其反应条件更温和,反应过程更安全、易操控、易放大。     

一种合成苯基硼酸频哪醇酯的新方法

工业上多采用将苯基溴代物金属化后再经过硼化和酯化反应合成苯基硼酸频哪醇酯,但该方法具有反应条件苛刻、官能团兼容性差、收率较低等缺点。研究了以苯基氯代物为原料,在Pd催化体系下,以B2(pin)2为硼试剂,在室温下合成其硼酸酯的新方法。研究表明,在0.5 mol%Xphos-Pd-G2和0.25 mol%Xphos催化体系下,以B_2(pin)_2为硼试剂、K_3PO_4·7H_2O为碱、Et OH为溶剂,在室温下反应1 h,含不同取代基的苯基硼酸频哪醇酯收率均在92%以上。该方法具有原料廉价易得、官能团兼容性好、条件温和、操作简便、反应高效、适合大量制备等优点。     

烷基铝/氢化铝锂还原体系还原液体端羧基氟橡胶

采用两种还原体系二异丁基氢化铝（DIBAl-H）/氢化铝锂（LiAlH4）和三异丁基铝[Al（i-Bu）3]/LiAlH4,将液体端羧基氟橡胶（LTCFs）还原得到液体端羟基氟橡胶（LTHFs）。傅里叶转换红外光谱、核磁共振氢谱和核磁共振氟谱分析均表明,两种还原体系均能将LTCFs中的碳-碳双键和羧基分别还原成碳-碳单键和和羟基。进一步对比两种还原体系的还原能力发现,DIBAl-H/LiAlH4更适合还原LTCFs,且在反应温度为60 ℃、反应时间为8 h、羰基/LiAlH4/DIBAl-H物质的量比为1/1/2的最优条件下LTCFs的还原率可达到88%。与传统强还原剂LiAlH4相比,DIBAl-H/LiAlH4可降低反应温度,且减小还原剂用量。     

依前列醇钠的合成

以联苯甲酰基取代的Corey内酯为原料,经戴斯马丁氧化剂氧化、wittig反应、(-)二异松蒎基氯硼烷手性还原、脱联苯甲酰基保护、羟基保护、酯基还原、羧酸甲酯化、脱DHP保护、成环及脱碘化氢成盐、水解共11步反应合成依前列醇钠,产品总收率18%。产品经核磁共振氢谱﹑核磁共振碳谱以及质谱的联合确证。该工艺合成条件温和,能够满足工业化生产需要。     

动态

不用催化剂,在140℃以下,乳酸和醇反应就能制得光学纯的乳酸酯。例如,两份乳酸,三份乙基己醇和六份环己烷混合,在120℃加热3小时,得到2.2份乳酸乙基己酯。EP 287,426(190ct 1988);C.A.,110,94521在羧酸存在下,以羧酸酐通过氢化反应制备羧酸酯。例如,将5∶1的醋酸和醋酐混合,在60个大气压于250℃使氢气通过装有 Re/Al_2O_3,的还原管,就能得到乙酸乙酯。转化率为100%。     

苯并[1,2,3]噻二唑-7-醛的合成

以2-氯-3,5-二硝基苯甲酸为起始原料,经过取代、酯化、还原重氮化等反应,合成了苯并[1,2,3]噻二唑-7-羧酸乙酯。并采用二异丁基氢化铝将其一步还原制备了苯并[1,2,3]噻二唑-7-醛。     

New thermosetting coatings using blocked carboxyl groups

Characteristics of blocked carboxylic acid compounds obtained by blocking carboxyl groups with alkyl vinyl ethers were studied, and new thermosetting coatings using blocked carboxyl groups and epoxide were also studied. Polybasic carboxylic acids were esterified with alkyl vinyl ethers to obtain blocked carboxylic acids having the hemiacetal ester moieties. Most of blocked carboxylic acids obtained were liquids and showed an excellent solubility in organic solvents and a good compatibility with epoxy resins. Although the blocked carboxylic acids were stable under ambient conditions, they could regenerate the corresponding carboxylic acids accompanied by the elimination of alkyl vinyl ethers by the thermal dissociation. They could be used as noble thermal latent hardeners. Curing of the blocked carboxyl groups and epoxide in the presence of relatively weak Lewis acid proceeded through a sequence of three-step reactions consisting of deblocking of alkyl vinyl ethers, esterification of epoxide, and the addition of alkyl vinyl ether to 2-hydroxyalkyl ester. The main product of the curing system was 2-acetalalkyl ester, but not 2-hydroxylalkyl ester. The new one-package thermosetting coatings using blocked carboxyl groups have been evaluated for use in the practical automotive and coil coatings line production. VOCs reduction, low-toxicity, and cost saving are satisfactory for the application of the systems. And the cured films of the coatings offered advantages in the high durability, the acid resistance and the soil resistance.     

有机叠氮化合物的合成与应用进展 Ⅰ.有机叠氮化合物的合成方法

综述了近年有机叠氮化合物的合成方法及其应用。介绍了有机叠氮化合物合成中的安全性及9种合成方法,如卤化物与叠氮化试剂的取代反应,醛、羧、酯、醇、环氧化合物、芳香胺/杂环(芳香)胺的叠氮化反应,含叠氮基分子向目标化合物的连接反应以及醛、醇与叠氮化试剂的三组分偶联反应。阐述了有机叠氮化合物在有机合成、超分子化学、聚合物与材料科学、药物与生物技术及精细化学品等领域的应用。     

甘油法制备二氯丙醇反应副产物的鉴别与机理分析

以甘油为原料,氯化氢气体为氯化剂,分别在自制无机催化剂和有机酸的催化作用下制取了二氯丙醇. 采用气相色谱-质谱联用分析,对反应副产物进行了鉴别,分析了羧酸催化甘油氯化时副反应的反应历程,发现副产物主要包括羧酸甘油酯、羧酸自聚物、羧酸氯丙醇酯及甘油自聚物. 同时比较了有机酸与无机催化剂的优缺点,结果表明,无机催化剂催化下甘油氯化反应对一氯丙醇及二氯丙醇的总选择性可达99%以上,与有机酸催化相比,提高了4%.     

有机叠氮化合物的合成与应用进展 Ⅱ.有机叠氮化合物在有机合成中的应用(2)

综述了近年有机叠氮化合物的合成方法及其应用。介绍了有机叠氮化合物合成中的安全性及9种合成方法,如卤化物与叠氮化试剂的取代反应,醛、羧酸、酯、醇、环氧化合物、芳香胺/杂环(芳香)胺的叠氮化反应、含叠氮基分子向目标化合物的连接反应以及醛、醇与叠氮化试剂的三组分偶联反应。阐述了有机叠氮化合物在有机合成、超分子化学、聚合物与材料科学、药物与生物技术及精细化学品等领域的应用。     

有机叠氮化合物的合成与应用进展 Ⅱ.有机叠氮化合物在有机合成中的应用(1)

综述了近年有机叠氮化合物的合成方法及其应用。介绍了有机叠氮化合物合成中的安全性及9种合成方法,如卤化物与叠氮化试剂的取代反应,醛、羧、酯、醇、环氧化合物、芳香胺/杂环(芳香)胺的叠氮化反应、含叠氮基分子向目标化合物的连接反应以及醛、醇与叠氮化试剂的3组分偶联反应。阐述了有机叠氮化合物在有机合成、超分子化学、聚合物与材料科学、药物与生物技术及精细化学品等领域的应用。     

Lipase made active in hydrophobic media

Enzymes are distinguished from other catalysts by their high substrate specificity. This is a great asset when one wants to apply them for syntheses of various compounds. Their usage, however, generally is limited to hydrophilic reaction media, because they usually are not soluble and active in hydrophobic media. Recently, we have been able to make various enzymes soluble and active in highly hydrophobic organic solvents. The key to this success is the chemical modification of enzymes with an amphipathic synthetic polymer, polyethylene glycol. The activated polymers can be attached to enzymes in aqueous buffer solutions, and once enzymes are modified they become soluble and active in various organic solvents such as benzene, toluene and cholorinated hydrocarbons and exhibit high enzymic activities in these organic solvents. Modified hydrolytic enzymes catalyzed the reverse reaction of hydrolysis in organic solvents. The modified lipase catalyzed various ester synthesis reactions. Because the reactions were conducted in the pure solvent system, it also was possible to study the kinetics and the substrate specificity for ester synthesis reaction. It also catalyzed the polymerization of a hydroxy group containing carboxylic acid due to the bifunctional nature. The modified lipase catalyzed ester exchange between an ester and an alcohol, between an ester and a carboxylic acid and between two esters in organic solvents. When the two substrates for ester exchange were liquid, the reaction could take place without organic solvents. The modified lipase catalyzed an ester exchange reaction between trilaurin and triolein when dissolved in these substrates. Dilauroyl-monooleoylglycerol and monolauroyl-dioleoyl-glycerol were formed from these two substrates in the presence of the modified lipase. The modified enzyme was extremely thermostable in its substrates. In the ester synthesis and ester exchange reactions, a trace amount of water was necessary for expression of the enzymic activity. It is suggested that the amphipathic polymer molecules retained water in close proximity to the enzyme. Presented at the symposium “The Biology, Biochemistry and Technology of Lipase” at the 78th annual meeting of the American Oil Chemists’ Society held May 17–21, 1987, in New Orleans, Louisiana.     

Chemical modification of polynorbornene: transformation of ester moiety containing polynorbornene to carboxylic acid structure

Polynorbornene (PNB) having methyl ester in side chain was partially hydrolyzed under alkaline condition in mixed organic solvents containing tetramethylammonium hydroxide as a base. Through hydrolysis of methyl ester group in PNB under basic condition, PNB having carboxylic acid can be obtained and degree of hydrolysis (DH) were evaluated by ¹H NMR measurement from 0.1 to 0.8, depending upon reaction conditions such as reaction time, solvent, and amount of base. The resulting hydrolyzed PNB were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, and size exclusion chromatography. No remarkable decreasing of molecular weight was observed and chain scission does not occur during the hydrolysis of PNB in the reaction condition examined here. The glass transition temperature of hydrolyzed PNB increased with increase in DH which can be attributed to the existence of intermacromolecular association of carboxylic acid in hydrolyzed PNB. Esterification of PNB having carboxylic acid was also carried out by using alkyl halide and DBU.     

氟代苯甲醛的合成研究进展

氟代苯甲醛是制造医药、农药、香料、染料等多种精细化工产品的中间体。综述了氟代苯甲醛化学合成方法的研究进展,包括氟代甲苯氧化法、氟代甲苯的氯化水解法、氟代苯甲醇氧化法、酯或羧酸还原法、氟苯的醛基化法、氟化法等。通过对各方法优缺点的探讨,对其工业应用前景进行了展望。     

High efficiency ester condensation using hydrophobic zeolite membranes

We successfully developed zeolite membranes with hydrophilic character, by choosing appropriate zeolites in terms of hydrophilicity and high acid tolerance. We evaluated thus developed membranes by their pervaporation (PV) performance, dehydration from acidic organic solvent. The zeolite membranes we developed, based on merlinoite (MER), chabazite (CHA) or phillipsite (PHI), are shown to exhibit stable dehydration performance, respectively. We successfully applied the membranes to the selective removal of water in an ester condensation reaction starting from a stoichiometric mixture of a carboxylic acid and an alcohol. The availability of pervaporation-assisted ester condensation reaction was validated by various kinds of combinations of carboxylic acid and alcohols, which implies the general availability of pervaporation-assisted process intensification by zeolite membranes. This paper was presented at the 11th Korea-Japan Symposium on Catatysis held at Seoul, Korea, May 21–24, 2007.