乳浊液进样—火焰原子吸收光谱法测定润滑油中锌铅

将样品的苯溶液用乳化剂OP乳化成乳浊液 ,取适量样品乳浊液配制成试液 ,喷入火焰 ,以氯化石蜡乳浊液作参比 ,用标准加入法测定。建立了测定润滑油中锌和铅的FAAS方法。对乳化剂的选择、背景吸收干扰、参比溶液的配制及检出限进行了考察。测定结果与灰化法 火焰原子吸收光谱法一致 ,相对误差小于± 3.0 %。方法简便、快速、准确。在火焰原子吸收光谱法中 ,用乳浊液进样技术取代灰化法处理样品是可行的     

测定润滑油添加剂中钙钡的乳浊液进样-火焰原子发射光谱法

将乳浊液进样技术应用于火焰原子发射光谱法 ,建立了测定润滑油添加剂中钙和钡的灵敏、快速分析方法。对乳化剂的选择、化学干扰的消除、空白溶液的选择及检出限进行了考察。将样品的苯溶液用乳化剂OP乳化成乳浊液 ,取适量样品乳浊液加入适量琼脂溶液及释放剂配制成试液 ,喷入火焰 ,用标准加入法测定。该法的测定结果与灰化 -火焰原子发射光谱法一致 ,相对误差小于±2.9 %,t检验表明两种方法之间无显著性差异。方法的相对标准偏差小于2.7%,检出限:钙0.12mg/L、钡0.99mg/L。     

非完全消化-火焰原子吸收光谱法测定人发中的钾和锌

1　引　　言用非完全消化法处理人发样 ,即在低温下用浓硝酸及过氧化氢消化人发至溶液呈透明黄棕色 ,再加乳化剂ＯＰ溶解消化化过程中所产生的油脂 ,制得一均匀的样品乳浊液。取适量乳浊液配制成试液 ,喷入空气 乙炔火焰 ,用工作曲线法测定。建立了火焰原子吸收光谱法测定人发中钾、锌的快速分析方法。测定结果与灰化法一致 ,相对误差小于± 0 .8%。方法简便、快速、准确。目前 ,人发样品的预处理方法通常是传统的灰化法及消化法 ,其缺点是耗时长 ,一般需要 3～ 6ｈ ,不能满足快速分析的要求。我们在 80～ 130℃以浓硝酸及过氧化氢处理发样…     

悬浮液进样火焰原子吸收光谱法测定豆米类粮食中镁

将样品磨细配制成悬浮液,并对悬浮剂的选择及化学干扰的消除进行了考查。为消除化学干扰，取适量悬浮液，加入La3+溶液制成试液。将试液喷入空气-乙炔火焰，以空白溶液为参比，用工作曲线法进行测定。测定结果与灰化法一致，相对误差小于±1.3％。方法简便、快速、准确。     

乳化技术-火焰原子吸收法测定石油磺酸钙中钙

用乳化剂OP乳化样品的乙酸丁酯溶液而配制成乳浊液,建立了乳化技术 火焰原子吸收光谱法快速测定石油磺酸钙中钙的新方法。以La3 作为释放剂,以水为参比用工作曲线法测定。实验表明,试液的黏度与水一致,不存在背景吸收干扰。测定结果的相对标准偏差小于0.8%。加标回收率100.4%～101.0%,线性范围0～12μg mL,检出限为0.64μg mL。本方法测定结果与灰化法一致,相对误差小于±1.4%。     

试样非完全消化-火焰原子吸收光谱法测定清漆中锰锌

将非完全消化技术应用于火焰原子吸收光谱法测定了清漆中锰、锌。用高氯酸-硝酸混合酸（1＋3）消解样品,用乳化剂吐温-80消解产物而配制成均匀、透明的样品溶液,用工作曲线法测定。对消解溶剂及乳化剂进行选择,对化学干扰、混合酸、介质、试液与空白溶液粘度一致性及背景吸收干扰进行了考察。测定结果的RSD小于3．9％,加标回收率98．2%-102．9％,方法简便。     

悬浮液技术-火焰原子吸收光谱法测定明胶中钙镁

用悬浮液技术处理明胶样品。将样品烘干、粉碎、过筛,制备成琼脂悬浮液。取适量样品悬浮液加入释放剂Sr2+配制成试剂,喷入空气-乙炔火焰进行测定,建立了悬浮液技术-火焰原子吸收光谱法快速测定明胶中钙、镁的分析方法。以空白溶液为参比,用工作曲线法测定。对琼脂溶液用量、化学干扰、试液与空白溶液粘度一致性、背景吸收干扰及检出限进行了考察。测定结果与灰化法一致,相对误差小于±0．9％,相对标准偏差小于5．2％。方法简便、准确。     

消解乳化-火焰原子光谱法测定氯丁橡胶中的钠钾镁锌

用消解乳化技术处理氯丁橡胶样品,即先用浓硝酸消解样品,再用乙醇 甲基异丁基酮混合溶剂溶解消解产物并用乳化剂TritonX 100或OP乳化成乳浊液。以原子吸收法测定镁、锌,以原子发射法测定钠、钾,建立了快速测定氯丁橡胶中钠、钾、镁、锌的火焰原子光谱法(FAS)法。分别以硝酸钾、Ba2 作为钠、钾的消电离剂。对样品处理方法、溶剂及乳化剂的选择、试液与空白溶液粘度的一致性、各种干扰及检出限进行了考察。测定结果的相对标准偏差<1.5%,加标回收率99.5%～103 0%。     

消解乳化-火焰原子发射光谱法测定丁苯橡胶中钠和钾

用消解乳化技术处理丁苯橡胶样品,先用浓硝酸消解样品,再用乙醇-甲基异丁基酮混合溶剂溶解消解产物,并用乳化剂Triton X-100乳化成乳浊液。以钡离子作为钠和钾的消电离剂,以空白溶液为参比,用工作曲线法测定,建立了快速测定丁苯橡胶中钠和钾的FAES法。对溶剂及乳化剂、试液与空白溶液粘度的一致性、干扰及检出限进行了考察。测定结果的相对标准偏差小于2．4％,加标回收率98．0％～104．7％。     

非完全消化-火焰原子吸收光谱法测定杜仲叶中的微量元素

用非完全消化法处理杜仲叶,在低温下用浓硝酸消解样品,加入乳化剂Triton X-100(OP)溶解消化过程中所产生的油脂,获得均匀的样品乳浊液,取适量的乳浊液制成试液,用火焰原子吸收光谱法快速测定了样品中的微量元素,并对检出限、加标回收率进行了测定。结果表明,相对标准偏差小于2.1%,测定结果与灰化法一致,且相对误差小于±1.8%。用非完全消化法结合火焰原子吸收光谱法对杜仲叶进行预处理取代灰化法是可行的,且方法简便、准确。     

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.