催化动力学紫外光谱法测定农药合成废水中的微量甲醛

正甲醛是有特殊气味的气体,易溶于水,环境水中甲醛的含量较低,但其对人体危害较大。因此,完全有必要实时监测废水中微量甲醛的含量。测定微量甲醛的方法较多,其中催化动力学分光光度法由于其仪器要求简单,在近年得到了较快的发展。这类测定方法通常采用微量甲醛作为催化剂,催化氧化剂氧化有色染料褪色的方法,按被氧化物的种类分为甲基橙法[1-6]、甲基红法[7-10]、亚甲基蓝法[11]、溴甲酚绿法[12-14]、络黑T法[15]、溴酚蓝法[16]、二甲酚橙     

库仑滴定法间接测定泡椒风爪中甲醛

正甲醛,俗称"福尔马林",主要用于合成树脂、塑料与橡胶[1-2]。由于甲醛具有防腐、漂白作用[3-4],部分不良商家将其作为食品添加剂来凝固食品蛋白,从而达到改善食品外观、口感和延长保质期目的,但甲醛作为公认的一类致癌物,长期接触可引发呼吸功能障碍、肝中毒、骨髓病变等症状[5-6]。《食品添加剂使用卫生标准》规定严禁将甲醛用作食品添加剂。因此,建立一种简便、快速、准确的方法对食品中甲醛含量的质量监测意义重大。     

高效液相色谱法测定尿中的甲酸钠

甲醛广泛存在于环境中,许多化工产品、机动车尾气、烹调油烟、香烟烟雾、生活用品(如香水、喷发水、空气清新剂等)、建筑、装饰材料(如夹合板、粒子板、泡沫绝缘材料、油漆、新家具等)均可产生甲醛[1,2]。甲醛对皮肤、眼睛和粘膜等具有急性刺激作用和致敏作用,是潜在的致癌物。空气中的甲醛经呼吸道进入人体后,在体内经生物转化,最终以甲酸盐的形式从尿液中排出。因此尿中甲酸盐含量可以反映甲醛的体内剂量[3]。目前对尿中有机酸的测定常采用离子色谱法、毛细管气相色谱法和顶空色谱法,但由于尿样较复杂,上述方法存在柱污染问题。笔者基于溴…     

K_2O对合成DMC用Cu- Ni/V_2O_5- SiO_2催化剂性能的影响

K_2O是多种固体催化剂的有效助剂 .大多数金属表面对 CO_2的吸附非常弱,在过渡金属中加入碱金属助剂可以促进 CO_2的吸附活化 [1, 2].近期对这方面的研究主要集中在 Pt[3]、 Cu[4]、 Ru[5]和 Fe[6]等单晶金属面上 .我们已报导过 Cu- Ni/V2O5- SiO_2(VSiO)催化剂表面 CO_2和 CH_3OH吸附及其反应性能 [7, 8].本研究将 K_2O助剂引入到 Cu- Ni/VSiO催化剂中,进一步考察了 K_2O助剂对 CO_2和 CH_3OH吸附和反应性能的影响 .1实验部分 　　采用 Cu、 Ni氨络合物混合硝酸盐水溶液 (含 KNO3, K占 Cu、 Ni总原子数 5～ 15…     

3-甲醛肟-N，N-二氧喹喔啉-2-甲酸乙酯的合成、表征及抑菌活性研究

1,4-二氧喹喔啉衍生物是一类重要的苯并吡嗪类杂环化合物,这一类化合物的主要特点是毒副作用小且具有抗菌[1]、抗病毒[2]、抗肿瘤[3]、促进动物生长[4,5]等生物活性,已在医药、饲料、除草剂[6]等领域中广泛应用。近年来人们主要集中在1,4-二氧喹喔啉(图1)2号位的甲酸和甲醛的衍     

气相色谱-质谱法测定食品接触材料油墨中的苯并[a]芘

正苯并[a]芘是毒性最强的多环芳烃类化合物,该化合物在环境中持久性强、难降解、具有致癌、致畸、致突变等危害[1]。苯并[a]芘主要由煤炭、石油、汽油、木材、烟草、有机高分子化合物等不完全燃烧产生,广泛存在于大气、水和土壤中,通过大气、土壤、水等经过生物富集,最终向人体转移,对人体健康造成危害。印刷油墨广泛应用于卷烟工业,但其含有有机挥发物、多环芳烃以及颜料和助剂中的重金属     

衍生化处理-气相色谱-质谱法测定生活饮用水中的甲醛

<正>甲醛已经被世界卫生组织确定为致癌和致畸性物质[1],是一种无色,易溶于水、醇、醚的具有强烈刺激性气味的气体[2-3],具有较高毒性,主要用于酚类、三聚氰胺等有机物的生产。在我国有毒化学品优先控制名单上甲醛高居第二位[4]。甲醛对皮肤和黏膜具有刺激作用,进入人体后易对人体的中枢神经系统和视网膜造成损害[5]。长期吸入甲醛可引发鼻咽癌、喉头癌等严重疾病,是公认的变态反应源。生活饮用水及水源水中的甲醛主要来源于二氧化氯、臭氧消毒处理时有机物发生氧化产生的副产物,还有     

吸收液采样-高效液相色谱法测定室内空气中甲醛的含量

<正>甲醛是一种无色有刺激性气味的气体，被世界卫生组织(WHO)定为致畸和致癌的物质之一^[1]。我国规定室内空气甲醛的限值为0.10 mg·m-3^[2]。目前监测环境中甲醛的国家标准测定方法很多^[3],常用的有4-氨基-3-联氨-5-巯基-1,2,4-三氮杂茂(Ⅰ)(AHMT)分光光度法^[4]、3-甲基-2-苯并噻唑啉酮腙盐酸盐水合物(MBTH)酚试剂分光光度法^[5]、乙酰丙酮分光光度法^[6]、气相色谱法(GC)^[7]、     

高效液相色谱法测定汽车内饰件中的甲醛、乙醛和丙酮

正1995年甲醛被国际癌症研究机构(IARC)确定为可疑致癌物[1-4],甲醛对人体具有刺激、致敏、致突变作用,表现为嗅觉异常、刺激、过敏、肺功能和免疫功能异常等[5]。乙醛为无色易挥发液体,吸入后对人的神经、肝脏等器官造成危害[6-8]。丙酮为无色透明液体,易挥发,对人体中枢系统有麻痹作用。但是在汽车原材料和内饰件的生产过程中会不可避免地用到甲醛、乙醛和丙酮。因此,内饰件使用的橡胶、     

用于过氧化氢分解的锰铅复合氧化物催化剂

高浓度过氧化氢以其高密度、无毒性和环境友好等特点,在航天及其他领域有着广泛的应用前景,是近年来推进剂研究的热点之一[1]. 用于分解高浓度过氧化氢推进剂的催化剂主要有三类: 银网催化剂,贵金属催化剂和过渡金属氧化物催化剂[2]. 过渡金属氧化物催化剂,尤其是氧化锰催化剂,由于其价格便宜,且具有较好的抗氧化性,因而受到人们的关注[3]. 通过添加助剂来提高催化剂的性能是催化剂研究的常用方法. 文献已报道了通过添加氧化银[4]、氧化钴[5]、氧化锌[6]、氧化铁[7]和氧化铜[8]等氧化物,以提高氧化锰催化剂对H2O2分解的活性,但鲜见以氧化铅作为添加助剂. 本文主要研究了氧化铅对担载型氧化锰催化剂性能的促进作用.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.