顶空-气相色谱法测定水中7种苯系物

建立顶空-毛细柱气相色谱法测定水中苯、甲苯、乙苯、对二甲苯、间二甲苯、邻二甲苯和苯乙烯7种苯系物的方法。对色谱条件及顶空条件进行了优化,采用自动顶空进样方式,经70℃平衡30 min,用Rtx-Wax毛细管柱分离,使用火焰离子化检测器检测。7种苯系物的质量浓度在10～100μg/L范围内与其对应的色谱峰面积呈线性关系,相关系数在0.999 0～0.999 6之间,方法检出限为0.2～0.9μg/L,7种苯系物的回收率为96.5%～106.5%,测定结果的相对标准偏差为1.0%～2.2%(n=6)。该方法操作简单,重现性好,测定结果准确可靠,检出限满足国家标准要求,可用于水中7种苯系物的检测分析。     

自动顶空毛细管气相色谱法测定水中8种苯系物

建立自动顶空-毛细管气相色谱同时测定水中8种苯系物的方法.采用stabilwax-DA色谱柱,对平衡温度、平衡时间等顶空条件进行了优化,并对水中苯系物进行测定.8种苯系物平均加标回收率为93.3%～115.0%,检出限为1.2～2.0 μg/L,测定结果的相对标准偏差为1.8%～7.3%(n=6).该法操作简单、灵敏度高、重现性好,可以满足饮用水中苯系物的测定.     

顶空-气相色谱法同时测定饮用水中八种挥发性苯系物

利用顶空-毛细管柱气相色谱技术对饮用水中的苯、甲苯、乙苯、邻二甲笨、对二甲笨、间二甲笨、异丙苯、苯乙烯的测定方法进行了研究,并对平衡时间、气／液体积比、水中含盐量等影响测定因素进行了探讨,对色谱条件和顶空进样条件进行了优化。该方法选用HP-INNOWAX色谱柱,使一直较难分离的间、对二甲苯得到了很好的分离。对八种苯系物进行了最低检出限、线性、回收率、精密度试验,其平均回收率为97．4％～1063％（n=7）,相对标准偏差为2．55％～3．83％（n=7）,最低检出限为0．06～0．10μg／L。测定结果表明,该法操作简单,重现性好,灵敏度高,完全可以满足饮用水中挥发性苯系物的测定。     

纳米复合材料催化发光法测定空气中的苯系物

基于苯系物在纳米材料上的催化发光现象,建立了一种快速测定空气中苯系物的方法。在铜锰铁复合纳米材料上的最佳测定条件为：检测波长460nm,表面温度320℃,气体流速120mL/min。方法的检出限（3σ）为0．5mg／m^3,线性范围为1～80mg／m^3,相关系数为0．9995。对常见共存物的研究表明,方法有较好的选择性。     

气相色谱法测定修正液中11种苯系物

建立了气相色谱测定修正液中11种苯系物的方法.通过对样品前处理方法的考察及色谱条件的优化,确定采用乙酸乙酯作为溶剂对样品进行提取,提取液经离心、过滤后由气相色谱法测定,外标法定量.11种苯系物在1.0～200.0 mg/L质量浓度范围内呈良好线性,相关系数(r2)为0.999 2～0.999 9,检出限(LOD)均为1.0 mg/kg,加标回收率为90％ ～ 105％,相对标准偏差(RSD,n=6)均小于6％.该方法简便,快速,结果准确可靠.     

顶空气相色谱法同时测定饮用水中苯系物和溴代苯、对氟溴苯

建立顶空气相色谱同时测定水中8种苯系物和溴代苯、对氟溴苯的方法。水样经气液平衡后,用Sepelco Wax 10色谱柱分离,气相色谱FID检测器进行分析。在所建立的最佳实验条件下,苯系物和溴代苯、对氟溴苯得到有效分离。苯系物和溴代苯、对氟溴苯的色谱峰面积分别与其质量浓度呈良好的线性关系,线性相关系数不小于0.999 7。方法的检出限为0.94~2.36μg/L,测定结果的相对标准偏差为1.4%~5.7%(n=6),加标回收率为90.8%~99.1%。该方法灵敏度高,操作简便,干扰少,适用于生活饮用水中8种苯系物和溴代苯、对氟溴苯的同时分析。     

离子色谱法测定水样中的氯化物

建立离子色谱法测定水样中氯化物的方法,Cl^-浓度在0．40～4．00mg／L范围内与色谱峰面积呈线性关系,线性方程为A=0．0680c＋0．0011,线性相关系数r=0．9995。样品6次测定结果的相对标准偏差为1．01％,加标回收率为91．8％～97．3％。与硝酸银滴定法进行比对试验,两种方法测定结果基本一致。离子色谱法操作方便快捷,污染少,测定结果准确、可靠。     

固相微萃取-高效液相色谱联用测定水样中的痕量苯并(k)荧蒽

研究了固相微萃取(SPME)-高效液相色谱(HPLC)联用测定水样中痕量苯并(k)荧蒽的的分析方法。对SPME的条件如萃取时间、萃取温度、离子强度、解吸方式、解吸溶剂、解吸时间和HPLC条件进行了优化，建立了SPME-HPLC联用分析水样中痕量苯并(k)荧蒽的方法，并用于自来水、雨水和纯净水等实际水样的分析。SPME优化的条件为室温、搅拌速度1100r／min、萃取时间30min、甲醇解吸溶剂、解吸时间2min。HPLC的条件为C18反相色谱柱、甲醇流动相、流速1mL/min、紫外检测器、波长244nm，以峰高为测量信号。方法的线性范围为0～8．00μg／L，检出限为0．014μg／L，相对标准偏差(n=6)为6．7％，回收率为82．0％～104．2％。该方法适合于水样中痕量苯并(k)荧蒽的分析。     

顶空固相微萃取-气相色谱法测定环保水性涂料中的挥发性有机物

建立了一种固相微萃取．气相色谱同时测定环保水性涂料中的苯系物和卤代烃的方法。选择涂层厚度为70μm的聚乙二醇-二乙烯苯(CW-DVB)萃取纤维,对固相微萃取的萃取条件进行了优化。该法相对标准偏差小于10％,样品的加标回收率大于72．2％,已成功地测定了11种水性涂料中的苯系物和卤代烷。     

流动注射在线萃取荧光法测定痕量阳离子表面活性剂

1引言环境水样中痕量阳离子表面活性剂的测定已报道的有分光光度法、荧光法等。本文发现,在pH为9．5的氨水-氯化按溶液中,阳离子表面活性剂与曙红Y生成离子缔合物,此统合物可用苯萃取,其在苯相中的荧光强度与阳离子表面活性剂浓度在一定范围内呈线性关系。据此建立了测定痕量阳离子表面活性剂的流动注射在线萃取荧光分析方法。方法测定的线性范围为1.0～5．0mg/L,进样频率为11样/h。方法用于水样中阳离子表面活性剂的测定,结果令人满意。2实验部分2．1试剂与仪器溴化十六烷基三甲基按标准溶液：1．0－5．0mg／L;载流：二次去离子水…     

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.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.