磺胺二甲嘧啶中4-氨基苯酚杂质的HPLC检测方法

建立了高效液相色谱测定磺胺二甲嘧啶药物中4-氨基苯酚杂质的分析方法,严格按照美国药典USP29<1225>、人用药品注册技术国际协调会议指导文件ICH Q2A和ICH Q2B对方法进行了验证.色谱柱采用Phenomenex LunaC18(4.6×250 mm,5 μm)反相色谱柱,流动相为V(Na2HPO4(8.95 g/L)):V(NaH4PO4(3.90 g/L)):V(甲醇)=3:3:2,检测波长为235nm.当4-氨基苯酚的浓度在0.05～1.00μg/mL时,色谱峰面积与浓度呈良好的线性关系,线性相关系数R=0.9993.方法的检出限为2.0 mg/kg,定量限为5.0 mg/k.方法的准确度、精密度和专属性均满足USP29<1225>、ICH Q2A和ICH Q2B的要求.将方法用于实际磺胺二甲嘧啶原料药检测,结果未检出含有4-氨基苯酚.本方法适合于磺胺二甲嘧啶及类似药物中4-氨基苯酚杂质的检测.     

气相色谱-质谱联用法测定食品包装材料中4种苯酚类抗氧剂迁移量

建立了气相色谱-质谱联用(GC-MS)测定食品包装材料中2,6-二甲基苯酚、对叔丁基苯酚、2,6-二叔丁基对甲酚和叔丁基-4-羟基苯甲醚迁移量的方法。采用水、4%(体积分数)乙酸、50%(体积分数)乙醇和异辛烷作为食品模拟物,样品经食品模拟物浸泡:水基模拟物浸泡液经乙酸乙酯液液萃取后测定,异辛烷浸泡液则直接测定。采用DB-1701色谱柱(30 m×0.25 mm×0.25μm)进行分离,选择离子模式进行检测,外标法定量。结果表明,在优化实验条件下,4种苯酚类抗氧剂在0.1~10 mg/L质量浓度范围内线性良好,相关系数(r)均大于0.999,方法检出限(LOD)均为0.01 mg/L,定量下限(LOQ)均为0.03 mg/L。在0.1、1.0、10.0 mg/L 3个加标水平下,方法的回收率为91.5%~110%,相对标准偏差(RSD,n=5)为1.9%~9.3%。该法准确、可靠、灵敏度高,适用于食品包装材料中4种苯酚类抗氧剂迁移量的测定。     

活性炭富集光度法测定水中痕量苯酚

水中痕量苯酚用粒度≤80μm的活性炭从pH 6左右的介质中吸附富集,并用50 g.L-1氢氧化钠解吸后从pH 4的磷酸溶液中蒸馏分离。分取部分馏出液,在氨性缓冲介质中使苯酚与4-氨基安替比林和铁氰化钾反应生成橙红色络合物,在510 nm波长处对试剂空白测定其吸光度,标准曲线用苯酚标准溶液制备,其线性范围为0.5~12.5μg(52.5 mL显色液中)。方法的检出限为2.9×10-6g.L-1,应用此方法测定了4种水样中的苯酚,相对标准偏差在3.5%~4.7%之间,回收率在92%~107%之间。     

苯酚氧化羰基化反应产物的高效液相色谱分析

采用高效液相色谱法分析了苯酚氧化羰基化反应产物,确定了色谱条件:KromasilTM C18色谱柱(150 mm×4.6 mm,5μm),检测波长254 nm,流动相V(甲醇):V(水)=65:35,流速0.6 mL/min.对碳酸二苯酯(DPC)和苯酚进行了定量分析,DPC和苯酚的外标曲线相关系数分别为0.99966...     

高效液相色谱法测定聚碳酸酯副产物氯化钠中双酚A和苯酚

建立了高效液相色谱法测定聚碳酸酯副产物氯化钠溶液中双酚A和苯酚含量的方法.采用C18色谱柱(250 mm×4.6 mm,5μm),以乙腈–甲醇、水作为流动相(体积比为54:6:40),流量为1.0 mL/min,在波长为278 nm处采用紫外检测,以外标法定量.双酚A、苯酚的质量浓度在1.0～8.0 mg/L范围内与色...     

反相高效液相色谱法同时测定对苯氧基苯酚和对氯苯酚

建立了一种同时测定对苯氧基苯酚和对氯苯酚的反相高效液相色谱方法。采用Diamonsil(钻石)C18(250 mm×4.6 mm i.d.,5μm)色谱柱,以甲醇-水(V(甲醇):V(水)=8∶2)为流动相,在波长为230 nm处进行检测。对苯氧基苯酚和对氯苯酚在20~230μg/mL范围内,峰面积与质量浓度呈良好的线性关系,相对标准偏差RSD分别为0.26%、0.53%,回收率在99.0%~101%之间。方法可用于对苯氧基苯酚的合成工艺研究及成品质量控制。     

橡胶及橡胶制品中4种酚类防霉剂的高效液相色谱法测定

建立了橡胶及其制品中硝基苯酚(PNP)、2,3,5,6-四氯苯酚(TeCP)、五氯苯酚(PCP)、邻苯基苯酚(OPP)4种酚类防腐剂的高效液相色谱测定方法。样品冷冻粉碎后,经甲醇超声提取,在Venusil-XBP C18色谱柱(250 mm×4.6 mm,5μm)上以10 mmol/L醋酸铵和甲醇为流动相梯度洗脱,采用二极管阵列检测器,PCP、TeCP、OPP的检测波长为220 nm,PNP的检测波长为320 nm。4种酚类防霉剂的质量浓度在0.5~250mg/L范围内与峰面积呈良好的线性关系,相关系数大于0.999 4。丁苯橡胶、硅橡胶基体的加标回收实验结果表明:TeCP、PCP、OPP、PNP在不同基质中的平均加标回收率分别为82%~95%、68%~90%、85%~98%、87%~98%,相对标准偏差小于5%。     

离子色谱法测定硝基苯光降解产物中邻、间、对硝基苯酚及硝酸根

研究了离子色谱法同时测定硝基苯光降解的中间产物邻硝基苯酚、间硝基苯酚、对硝基苯酚及硝酸根的分析方法.采用7.5mmol/L的碳酸氢钠,1.5mmol/L的碳酸钠混合溶液为淋洗液,紫外检测波长215nm.回收率在96.8%～101.3%之间;RSD小于1.5%;检出限在8.5×10-4以下.     

胶束毛细管电泳在线推扫富集技术测定工业废水中痕量苯酚和硝基苯酚

利用胶束毛细管电泳在线推扫富集技术建立了测定工业废水中痕量苯酚、邻硝基苯酚和间硝基苯酚的方法。采用未涂层熔硅弹性石英毛细管(60cm×75μm,有效柱长52cm),选择20mmoL/L硼-砂80mmoL/L十二烷基硫酸钠(SDS)(pH9.45)为缓冲溶液,分离电压18kV,紫外检测波长214nm,在200s内可实现苯酚、邻硝基苯酚、间硝基苯酚的分离检测。在优化条件下,苯酚、邻硝基苯酚、间硝基苯酚的检出限分别为0.03、0.020、.02mg/L;相对标准偏差RSD(n=3)分别为3.42%、4.15%、3.48%;间硝基苯酚富集倍数可达1000倍。     

苯酚和氯苯酚的Pt／TiO2催化光解

在TiO_2和Pt/TiO_2催化作用下水溶液中苯酚、对氯苯酚、2,4-二氯苯酚和2,4,6-三氯苯酚均能发生光致降解(λ≥345nm)。在固定于反应器内壁的薄层Pt/TiO_2催化作用下,这些化合物的光致降解均呈现一级反应动力学;表观反应速率常数K_(ob)的相对大小为:苯酚<对氯苯酚<2,4-氯苯酚<2,4,6-三氯苯酚。少量H_2O_2(1.9×10~(-2)mol·L~(-1))能提高这些化合物的光解速率。光照1.0～5.0h后这些化合物的降解率大于97％,COD去除率大于95％。     

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.