大气丙酮碳同位素组成测定方法的研究

利用气相色谱/燃烧/同位素比值质谱(GC/C/IRMS)分析技术,研究了具有不同碳同位素组成的丙酮与衍生剂2,4-二硝基苯肼(DNPH)的液相反应及其相应的气相反应实验过程中的碳同位素效应,探讨了以该方法测定大气丙酮碳同位素组成的可行性。研究结果表明,在衍生化过程中不会产生碳同位素分馏。本实验通过测定衍生剂DNPH与相应的衍生物的碳同位素值,大气中丙酮碳同位素组成通过质量平衡方程计算而求得。采用该方法对大气丙酮碳同位素组成的初步测定结果表明,具有相同排放源的大气丙酮碳同位素比值基本不变。本方法实验重现性好,测定精度高,可以用于分析大气丙酮的排放源研究。     

氨基酸-乙酰丙酮分光光度法测定水样中甲醛

试验了用氨基酸代替氨水或乙酸铵作为胺源的条件下,乙酰丙酮与甲醛反应生成有色化合物的适宜条件并提出了氨基酸-乙酰丙酮分光光度法测定水中甲醛的方法。优化的试验条件如下:①0.12mol·L-1甘氨酸衍生剂用量为2mL;②反应温度为50℃;③反应时间为15min;④反应体系的pH为4.7。甲醛的质量浓度在0.2~1.0mg·L-1范围内与吸光度呈线性关系,检出限为5μg·L-1。加标回收率均不小于98.0%,测定值的相对标准偏差(n=6)均不大于4%。方法应用于地表水样中甲醛的测定,测定值与国标法测定结果相符。     

比久农药中游离偏二甲肼的高效液相色谱快速测定

建立了用甲醛衍生测定农药比久样品中微量的偏二甲肼的方法。采用甲醛与偏二甲肼柱前衍生,在室温、中性溶液中反应10 min,生成确定量的有较强紫外吸收的偏二甲腙,不须富集可直接用HPLC法测定偏二甲肼。研究了甲醛与偏二甲肼的反应条件及产物的光谱特征,测得衍生物的最大吸收波长λmax=237 nm和表观摩尔吸光系数ε=3.6×103(L.mol-1.cm-1),选定ZorbaxODS色谱柱,V(磷酸盐缓冲溶液,pH 7)∶V(甲醇)=94∶6为流动相,检测波长为237 nm。结果表明:在0.56~960μg/mL范围内回归方程为:A=0.4677ρ-0.2790,R2=0.9998,检出限为1.3μg/g,回收率为97.5%~103.4%,相对标准偏差为0.9%~1.8%。     

Friedel-Crafts酰基化反应的改进及其在对叔丁基苯乙酮制备中的应用

大学基础有机化学实验教学中,苯乙酮的制备通常利用Friedel-Crafts酰基化反应进行,但目前该反应存在药品乙酸酐购买受限,催化剂无水三氯化铝易失效、难保存等问题。针对实验中所存在的上述困难,对Friedel-Crafts酰基化反应的条件进行了探索与改进,并将其应用于对叔丁基苯乙酮的制备中。实验采用浓硫酸为催化剂,五氧化二磷为脱水剂,冰醋酸为酰化试剂与叔丁基苯进行反应,物料的物质的量比为1∶0.75∶2∶1,反应温度为78℃,成功制得了对叔丁基苯乙酮,结构经1HNMR和13CNMR得到确证。该方法不仅反应条件温和、原料廉价易得、操作简单,而且还兼顾了学生对芳香化合物的取代基定位效应、位阻效应知识的认识,另外实验中增加的减压蒸馏操作,也有利于学生实验技能的训练和教学内容的充实。     

二甲基亚砜捕获-高效液相色谱法测定羟基自由基

本文建立了一种简便灵敏的方法用于测定Fe(Ⅲ)催化的光反应产生的·OH。通过二甲基亚砜(DMSO)捕获·OH生成甲醛,再与衍生试剂2,4-二硝基苯肼(DNPH)反应生成相应的腙(HCHO-DNPH),并用高效液相色谱法进行分析测定。研究了衍生试剂浓度、pH、不同衍生温度和衍生时间对衍生化反应的影响,确定衍生试剂浓度为270μmol/L,pH=4,温度为50℃,时间为30 min的最佳衍生化条件。同时确定了色谱条件。在优化的实验条件下,甲醛在0.10～5 mg/L范围内与衍生物HCHO-DNPH峰面积线性关系良好,相关系数为0.9962,对·OH的检出限为0.0027 mmol/L,定量限为0.0090 mmol/L,平均回收率范围为102.41%～117.61%,相对标准偏差小于8%。采用该方法对Fe(Ⅲ)参与的光反应生成的·OH进行了测定,结果满意。     

木质素对木质素-脲醛共聚树脂的影响及反应机理

通过调控甲醛与尿素摩尔比, 降低脲醛树脂胶黏剂中游离甲醛的含量, 以生物质玉米芯为原材料, 用碱液提取得到的碱木质素溶液与甲醛和尿素进行三元逐步共聚, 弥补降低醛脲比带来的胶合强度的快速下降问题. 以降低游离甲醛含量同时兼顾胶合强度为原则进行探索, 得到最佳实验条件为甲醛与尿素摩尔比(F/U)为0.91∶1, 木质素添加量为20%(质量分数), 在此条件下木质素-尿素-甲醛共聚树脂(LUF)胶合强度为0.99 MPa, 游离甲醛含量为0.26%. 对共聚树脂进行了结构表征, 表明木质素参与到反应中, 并能提高树脂的热稳定性和耐水性, 同时对反应的机理进行了讨论.     

气相色谱法测定胶粘剂中的游离甲醛

采用超声波萃取胶粘剂中游离甲醛,经2,4-二硝基苯肼衍生后用气相色谱一电子捕获检测器法测定．对提取方法、衍生化条件及色谱条件进行了研究,确定了甲醛检测的最佳条件．研究数据显示,该方法对甲醛的检出限为0．175μLg／g,在0．1～60．0μg／mL浓度范围内,线性相关系数R^2=0．9999;在1、2和8μg／mL3个添加水平下的添加回收率在98．97％-102．24％之间,5个实验室对同一样品中甲醛含量测定值的相对标准偏差为4．0％．结果表明本方法简便、快速、检测限低、回收率高、重现性好．     

含D-氨基葡萄糖分子的酰基硫脲衍生物合成

以D-氨基葡萄糖盐酸盐为原料,经酰化保护羟基后得1,3,4,6-四-O-乙酰基-2-脱氧-β-D-氨基葡萄糖,再与芳酰基异硫氰酸酯反应,合成了12种新型的糖基酰基硫脲衍生物。实验表明,优化反应条件为芳酰异硫氰酸酯∶上述氨基葡萄糖=1∶1.2(摩尔比),在二氯甲烷溶液中加热至40℃,反应6 h。产物结构经IR、~1H NMR、~(13)C NMR分析确证。     

天然丰度氘核磁共振测定一级和二级动力学氘同位素效应(Ⅱ)——外标的分子内和分子间竞争法

建立了用外标的天然丰度~2 H NMR同时测定一级和不同类型二级动力学同位素效应的方法。用此法测定了苯氯化和溴化,甲苯氯化以及苯甲醇氧化等反应的同位素效应值。     

氧化羰化法合成碳酸甲乙酯热力学及催化性能的研究

研究了在甲醇、乙醇温和溶液中,氧化羰化一步合成不对称碳酸甲乙酯(MEC)反应。通过热力学计算考察了反应的可行性及程度。计算结果表明,在298.2K下主反应平衡常数为2.39×1080,说明此反应的可行性和程度均很大。实验发现在氧化羰化合成碳酸甲乙酯的过程中,不仅存在氧化羰化过程,同时也存在酯交换过程;含氮席夫碱(Schiff)的种类,甲醇和乙醇相对用量,反应温度和压力对碳酸甲乙酯(MEC)的合成均有影响。当以氯化亚铜(CuCl) 1,10 菲罗啉(phen) N 甲基咪唑(NMI)为催化剂时,摩尔比n(CuCl)∶n(NMI)∶n(phen)=1∶1.25∶1.25,在393K,2.4MPa,VMeOH∶VEtOH=2∶8,CuCl浓度为0.20mol L的条件下,反应2h,甲醇的转化率为44.3%,乙醇的转化率为22.3%,MEC产率为10.4%。与单纯CuCl催化剂相比,甲醇和乙醇的转化率分别提高17倍和9倍,MEC产率提高74倍。对氧化羰化反应机理也进行了探讨。     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.