Brφnsted酸性离子液体中苯甲酸酯、苄酯的无溶剂微波合成

该文以1-甲基咪唑、吡啶、苄基氯、硫酸、磷酸为原料,合成了4种B r nsted酸性离子液体:1-甲基-3-苄基咪唑硫酸氢根盐(a),1-甲基-3-苄基咪唑磷酸二氢根盐(b),N-苄基吡啶硫酸氢根盐(c),N-苄基吡啶磷酸二氢根盐(d),以它们作为催化剂和反应介质,考察了苯甲酸与系列脂肪醇、苄醇与系列脂肪酸、苯甲酸在无溶剂和微波辐射反应条件下的F ischer酯化反应,结果表明,当苯甲酸或苄醇与离子液体的摩尔比为1∶0.5时,无需外加催化剂,反应即可在化学计量条件下进行,12~20 m in完成反应,苯甲酸酯与苄酯的收率分别为77%~98%和78%~98.5%,气相色谱纯度≥95%。离子液体循环使用3次,催化活性仅下降1.8%~3.4%。     

离子液体催化合成乙酸苄酯

以硫酸氢根甲基咪唑盐[Hmim]HSO_4离子液体为催化剂,乙酸和苯甲醇为原材料通过催化反应来合成乙酸苄酯,同时还讨论了以浓硫酸作为催化剂合成乙酸苄酯的方法。通过各个不同条件的实验,涉及的可变因素有酸醇物质的量比、催化剂用量、反应时间、反应温度等。实验结果表明,硫酸氢根甲基咪唑盐[Hmim]HSO_4对合成乙酸苄酯有着良好的催化活性,而且对其合成工艺进行了优化,确定最佳反应条件为:酸醇的摩尔比为1.4∶1、催化剂用量1%、反应温度110℃、加热回流1 h。在此条件下,乙酸苄酯的酯化率达96%。     

在Br(o)nsted酸性功能化离子液体中室温无溶剂合成长链脂肪酸甲酯

该文以N-甲基咪唑、苄基氯、硫酸、氯磺酸为原料,经季铵化、离子交换、磺化3步反应合成了磺酸型Br(o)nsted 酸性离子液体:1-(4-磺酸基苄基)-3-甲基-咪唑硫酸氢根盐,通过FTIR、1HNMR对其结构进行了确证.以其作为反应介质与催化剂,考察了C4～C16的直链脂肪酸与甲醇的Fischer酯化反应,确定了最佳反应条件:n(酸):n(醇):n(离子液体)=1:1:0.1,反应温度25 ℃、反应时间3～4.5 h,产率84%～98%,产物气相色谱纯度≥96%.该法无需加热、分水,产物分离简便,离子液体经真空除水后可重复使用,循环使用3次,催化活性保持不变.     

离子液体催化麻疯树籽油制备生物柴油工艺

离子液体作为绿色液体催化剂具有优良的性能而倍受关注,然而关于离子液体催化合成生物柴油的报道很少。文中以N-甲基咪唑、吡啶为原料,合成N-(4-磺酸基)苄基吡啶硫酸氢根盐离子液体,其结构经IR,1HNMR所证实;以该离子液体为催化剂,催化麻疯树籽油合成生物柴油。在单因子实验基础上,通过正交试验法对反应温度、催化剂的用量、反应时间和醇油摩尔比等影响合成生物柴油的因素进行了优化,同时也对离子液体的稳定性进行了检验。实验结果表明:在反应温度140℃、醇油摩尔比为15∶1、反应时间6 h和催化剂用量为油质量的5%工艺条件下,生物柴油产率可达89.9%,且离子液体的稳定性好,可循环使用5次。此方法制备的生物柴油的主要质量指标与国内外生物柴油生产标准接近。     

磺酸型离子液体的合成及其在酯化反应中的催化性能研究

以N-甲基咪唑、2-氯乙醇、对甲苯磺酰氯和苯为原料合成了氯化1-甲基-3-[α-甲基-(4-磺酸苄基)]咪唑盐、1-甲基-3-[α-甲基-(4-磺酸苄基)]咪唑硫酸氢根盐、1-甲基-3-[α-甲基-(4-磺酸苄基)]咪唑对甲苯磺酸盐三种离子液体,并用红外光谱和核磁共振对产物的结构做了表征.以乙腈为探针分子,采用红外光谱对合成的离子液体做了酸性类型的表征.考察了以上三种离子液体在壬二酸和甲醇的酯化反应中的催化性能,室温下n(壬二酸)∶n(甲醇)=1∶2时,反应4 h,壬二酸甲酯的产率可达到90.0%、选择性超过98.0%,且反应结束后产物易于分离.离子液体循环使用5次以上,催化活性没有明显降低.     

功能化离子液体催化合成甘油单月桂酸酯

合成了由吡啶、N-甲基咪唑、N-甲基-2-吡咯烷酮提供有机阳离子, 磷钨酸、对甲苯磺酸提供阴离子的6种离子液体。使用NMR、FT-IR和TG对离子液体表征, 并考察它们催化甘油与月桂酸酯化的催化效果。结果表明, 这些离子液体都具有较好的热稳定性, 以1-(丁基-4-磺酸基)-3-甲基咪唑磷钨酸盐离子液体的热稳定性最好。在最佳条件使用离子液体催化甘油与月桂酸反应时, 阴离子的种类对月桂酸的转化率影响较大, 以对甲苯磺酸为阴离子的离子液体催化反应时, 月桂酸转化率较以磷钨酸为阴离子的离子液体的高;1-(丁基-4-磺酸基)-3-甲基咪唑对甲苯磺酸盐离子液体做催化剂时甘油单月桂酸酯的产率最高。催化剂重复使用性方面, 离子液体重复使用5次催化活性没有明显变化。     

离子液体相转移催化氧化苯甲醛制备苯甲酸

以N-甲基咪唑、四氟硼酸铵、正丁醇、溴化钠为主要原料合成了1-正丁基-3-甲基咪唑四氟硼酸咪唑盐型离子液体。以该离子液体作相转移催化剂研究了双氧水氧化苯甲醛制备苯甲酸的反应。结果表明,该氧化反应中加入离子液体可起到溶剂及相转移催化剂的作用,当反应5 h时,苯甲醛可达最大转化率88%。反应后离子液体可回收再利用。     

酸性离子液体催化合成N，N’-亚甲基双丙烯酰胺

以N-甲基咪唑、2-氯乙基苯、硫酸氢钾合成1-甲基-3-[α-甲基-(4-磺酸苄基)]咪唑硫酸氢盐酸性离子液体.考察了酸性离子液体在甲醛和丙烯腈的反应中的催化性能,确定了最佳反应条件:n(甲醛):n(丙烯腈)=1.2:1.0,酸性离子液体用量为丙烯腈质量的8.0%,反应温度70℃,反应时间2.0h.在该条件下N,N'-亚甲基双丙烯酰胺的收率大于92%,纯度为98%以上,且反应结束后产物易于分离,酸性离子液体循环使用5次以上.     

离子液体1-丁基-3-甲基咪唑磷酸二丁酯中β-酮酸酯和环酮的选择性α-单卤代反应研究

采用微波法合成了离子液体1-丁基-3-甲基咪唑磷酸二丁酯,研究了离子液体1-丁基-3-甲基咪唑磷酸二丁酯中,β-酮酸酯类化合物及环酮的单卤化反应,与有机溶剂相比,离子液体可以加快反应的速率,缩短了反应时间并提高了产量,而且离子液体中的卤化反应更绿色环保.     

离子液体催化苯与苄氯的烷基化合成二苯甲烷

考察了离子液体催化Friedel-Crafts苄基化制备二苯甲烷,同时考察了AlCl3的摩尔分数、离子液体用量及不同离子液体等因素对苯与苄氯烷基化反应的影响。实验结果表明,离子液体的催化活性与其酸强度密切相关,酸性条件下离子液体才显示催化活性。AlCl3摩尔分数为66.7%,催化剂(离子液体)用量3.3g、反应温度80℃及常压反应条件下,1-丁基-3-甲基氯咪唑,N-丁基氯吡啶与AlCl3形成的离子液体具有较高的二苯甲烷选择性,分别为97.4%和92.1%。离子液体催化剂重复使用4次后,活性基本没有降低。     

Polyglycerol Esters

When glycerol is heated with an alkaline catalyst to over 230 C, water is evolved and polymerization occurs to form a whole family of polyglycerols ranging from diglycerol with 3 hydroxy groups, to triacontaglycerol with 32 hydroxy groups. The carboxylic acid esters of polyglycerols prepared by direct esterification or by interchange, may be solid or liquid; saturated or unsaturated; aliphatic or aromatic; mono, di- or polycarboxylic acid esters; mono-, di-, or polyesters of the polyglycerol; single or mixed acid esters; high or low molecular weight; water or oil soluble; and with an HLB from about 4 to about 13. Polyglycerol esters find utility in a wide variety of food products including beverages, desserts, topping and baked goods. They are thermally stable and find application in several industrial systems.     

Esters of N-Benzyloxyamino Acids

Methyl, t-butyl and benzyl esters of N-benzyloxyamino acids were prepared using diazomethane, t-butylacetate with perchloric acid and benzyl chloride with ethyl acetoacetate, respectively. These protected substrates may be used for the unambiguous synthesis of N-hydroxypeptides.     

Stabilization of Acrylic Esters

Acrylic acid (AA) and its esters are monomers which can easily be polymerized. In order to avoid the unintentional polymerization during the manufacture and storage, the acrylic esters are stored under air‐atmosphere to which 15 ppm (g g^–1) hydroquinone monomethylether (MeHQ) has been added. The consumption of the stabilizers, oxygen (O₂) and MeHQ, play an important role in the prognosis of the stability of the monomers. In earlier works the O₂/MeHQ‐consumption of acrylic acid during the inhibition period without radical‐starter‐addition was examined [1]. In this paper it could be shown that the examinations on acrylic acid are not transferable to different acrylic esters. The O₂‐consumption rates in the acrylic esters are approximately ten times smaller than in acrylic acid, depending on temperature and monomer. The inhibition periods of the acrylic esters are about the factor ten greater in comparison to acrylic acid. A correlation between the concentration of the C=C double bond in the esters and the O₂‐consumption is possible with the measurements of the O₂‐consumption in the different acrylic esters as a function of temperature. The O₂‐consumption of any acrylic ester can be calculated in this way on the basis of the C=C double bond concentration. The same applies to the inhibition period (the time up to the start of the polymerization). An estimation of the stability is possible with these two parameters.     

Metathesis of Unsaturated Fatty Esters

The development of a homogeneous catalyst (WCl₆Sn(CH₃)₄) for the metathesis of unsaturated fatty esters encloses new routes in fat chemistry. By these reactions an exchange of alkylidene moities takes place, thus methyl oleate is converted into 9-octadecene and 9-octadecenedioic dimethyl ester. The metathesis of poly-unsaturated esters leads to a much larger number of products, namely polyenes, mono- and dicarboxylic esters, and cyclopolyenes. Specially the formation of 1,4-cyclohexadiene is of great interest. The metathesis of unsaturated fatty oils and the cometathesis with alkenes are also possible. Reactants of technical purity with a low acid value (< 0.1) can undergo metathesis. The reaction is essentially thermoneutral; the distribution of products is statistical and no completion of the reaction occurs in one way or an other. Thus separation of reaction products and unconverted material is necessary. By the metathesis of mono-unsaturated esters this can be done by fractional crystallization. A review is given of these and other applications on account of the latest research development.     

Metathesis of Unsaturated Fatty Esters

The development of a homogeneous catalyst [WCl₆/Sn(CH₃)₄) for the metathesis of unsaturated fatty esters encloses new routes in fat chemistry. By these reactions an exchange of alkylidene moities takes place, thus methyl oleate is converted into 9-octadecene and 9-octadecenedioic dimethyl ester. The metathesis of poly-unsaturated esters leads to a much larger number of products, namely polyenes, mono- and dicarboxylic esters, and cyclopolyenes. Specially the formation of 1,4-cyclohexadiene is of great interest. The metathesis of unsaturated fatty oils and the cometathesis with alkenes are also possible. Reactants of technical purity with a low acid value (<0.1) can undergo metathesis. The reaction is essentially thermoneutral; the distribution of products is statistical and no completion of the reaction occurs in one way or an other. Thus separation of reaction products and unconverted material is necessary. By the metathesis of mono-unsaturated esters this can be done by fractional crystallization. A review is given of these and other applications on account of the latest research development.     

具有杀虫活性蔗糖酯的合成

分别以酯交换法和酰氯法合成了辛酸蔗糖酯和己酸蔗糖酯两种杀虫活性蔗糖酯,其中酯交换法产物单酯含量高,而酰氯法反应速度快。实验在n(蔗糖):n(辛酸乙酯)=2:1,DMF为溶剂,碳酸钾为催化剂,(98±2)℃条件下反应16 h制备了辛酸蔗糖酯,辛酸乙酯的转化率为68．5％(多酯按二酯计算,下同);在n(蔗糖):n(己酰氯)=2:1,DMF为溶剂、吡啶为助剂,65℃条件下反应1．5 h制备了己酸蔗糖酯,己酰氯的转化率为53．9％。产物经傅里叶红外光谱分析、薄层层析分离和分光光度分析,确定辛酸蔗糖酯和己酸蔗糖酯中n(单酯):n(多酯) 分别为1．48:1和1．37:1。以P(辛酸蔗糖酯)=4 mg／mL水溶液对舞毒蛾(Lymantria dispar)1龄幼虫进行杀虫实验,触杀方式36 h后校正死亡率达72．5％。     

酯的催化合成

本文介绍了酯的催化合成常用的催化方法，综述了合成酯的常用的催化剂和新的催化方法。     

7-苯甲酰基喜树碱酯的合成

为降低喜树碱对正常细胞的毒性,提高抗肿瘤活性和溶解性,以20(S)-喜树碱和苯甲醛为起始原料,经Minisci反应,合成了20(S)-7-苯甲酰基喜树碱(Ⅱ),再与酰化试剂如酸酐、羧酸进行酯化反应得目标化合物(Ⅲa~c)。考察了影响Minisci反应的因素,其优化条件为喜树碱0.5 g,30 mLw(H2SO4)=75%的硫酸,苯甲醛1.5mL,1.0 g FeSO4.7H2O,1.0 mLw(H2O2)=30%的双氧水,反应温度0~2℃,反应时间6 h,收率为58.2%。4个化合物的结构经IR、1HNMR和MS等手段进行了确证。     

硫辛酸N-琥珀酰亚胺基酯的合成研究

利用两种方法合成了硫辛酸N-琥珀酰亚胺基酯,并用核磁和质谱进行了结构表征。     

Formation of Furan Fatty Alkyl Esters from their Bis‐Epoxide Fatty Esters

Reactions of epoxidized alkyl soyate with four different alcohols: ethanol, isopropyl alcohol, 2‐ethylhexanol, benzyl alcohol, in the presence of Brønsted acid catalyst, were investigated. Products, not reported in prior studies of similar reactions, were found. These were furan fatty acid alkyl esters (FFE, mixture of alkyl 8‐(5‐hexyl‐2‐furyl) octanoate and alkyl 9‐(5‐pentyl‐2‐furyl)nonanoate) which were unambiguously identified by means of GC–MS and two‐dimensional NMR. Evidence suggests that the FFE are formed by an acid‐catalyzed rearrangement of the epoxidized linoleates. The FFE were formed in presence of all four alcohols tested and in the presence of either sulfuric acid or Amberlyst 15 catalyst. Yields of up to 13 %, as quantified by GC and NMR spectroscopies, were observed.