高效液相色谱法同时测定染发剂中11种氨基苯酚

建立了高效液相色谱测定直接型与氧化型染发剂中11种氨基苯酚含量的分析方法。样品在亚硫酸氢钠的保护下用甲醇提取,高速冷冻离心净化;采用Agilent Zorbax SB C18色谱柱分离,流动相为5 mmol/L庚烷磺酸钠-40 mmol/L pH 2.8磷酸盐缓冲液和乙腈,梯度洗脱,11种氨基苯酚分别于230、270和400 nm下检测。11种氨基苯酚在0.05～500 mg/L线性范围内相关系数不小于0.9992,4-氨基-3-硝基苯酚、2-氨基-5-硝基苯酚、3-硝基-4-(2-羟乙基)氨基苯酚的方法定量限为5 mg/kg,其他8种氨基苯酚包括对氨基苯酚、对甲氨基苯酚、间氨基苯酚、邻氨基苯酚、5-氨基-2-甲基苯酚、4-氨基-3-甲基苯酚、2-甲基-5-(2-羟乙基)氨基苯酚和2-氨基-4-硝基苯酚定量限为20 mg/kg,方法回收率为88.5%～109.5%,相对标准偏差为2.2%～8.3%。测定了多种市售染发剂,结果表明该方法操作简单、测定结果准确,可用于直接型与氧化型染发剂中11种氨基苯酚的测定。     

离子对色谱法测定化妆品中的苯酚磺酸锌

建立了离子对色谱测定不同基质化妆品中苯酚磺酸锌的分析方法。水剂类和香波类化妆品用20%乙腈水溶液提取,膏霜类和散粉类用80%乙腈水溶液提取,唇膏类加四氢呋喃并用80%乙腈水溶液提取,提取液离心、过滤处理。以四丁基氢氧化铵为离子对试剂,考察了苯酚磺酸锌在离子对色谱中的保留行为并优化了最佳色谱条件:以Kromasil C18(4.6 mm×250 mm,5μm)色谱柱分离,流动相为5 mmol/L四丁基氢氧化铵+25 mmol/L磷酸二氢钠缓冲溶液(pH 2.5)-乙腈(80∶20),等度洗脱,流速1.0 mL/min,柱温30℃,检测波长230 nm。该方法对苯酚磺酸锌的定量下限为:水剂和香波基质中为24 mg/kg、膏霜和唇膏基质中为120 mg/kg、散粉基质中为60 mg/kg,在0.5～50 mg/L范围内,苯酚磺酸锌的线性关系良好,相关系数为0.999 8。在低、中、高3个加标水平下,苯酚磺酸锌的平均回收率为94%～99%,相对标准偏差为0.57%～3.9%。该方法快速、简便、准确,可用于化妆品中苯酚磺酸锌的测定。     

阻抑高碘酸钾氧化甲基紫褪色光度法测定苯酚

基于HAc-NaAc缓冲体系中,反应温度为25℃时,苯酚阻抑高碘酸钾氧化甲基紫的褪色反应,建立了测定苯酚的阻抑褪色光度新方法.该方法最大吸收波长为580 nm,线性范围为0.02μg/mL～2·2μg/mL,检出限为3.8×10<'-3>μg/mL,方法用于环境水中苯酚的测定,相对标准偏差为1.97%～2.25%,回收...     

高效液相色谱法测定复硝酚钠的三种组分

提出了高效液相色谱法同时测定植物激素复硝酚钠的3个组分,5-硝基愈创木酚钠、邻硝基苯酚钠、对硝基苯酚钠含量的方法。以Hypersil BDS C_(18)(200mm×4.6mm,5μm)色谱柱为分离柱,以甲醇-水(55+45)溶液为流动相,用二极管阵列检测器在235nm波长处测定。3个组分的质量浓度均在5～300 mg·L~(-1)之间与其峰面积呈线性关系。标准加入法测得回收率在99.5%～101.7%之间。加入50 mg·L~(-1)上述3个组分的混合标准溶液对方法的精密度进行试验,测得其相对标准偏差(n=6)依次为0.46%,0.37%,0.53%。     

阻抑催化光度法测定茶叶中的微量氟化物

在氨基乙酸 HCl缓冲溶液中 ,Fe3+对H2 O2 氧化 2 ,4 二氨基苯酚 (DAP)褪色具有催化作用 ,游离F- 离子与Fe3+形成的稳定络离子 [FeF6]3- 可抑制褪色 ,抑制程度与F- 量线性相关。基于此建立了测定微量F- 的阻抑催化光度分析的新方法。结果表明 ,有色溶液的最大吸收波长为 5 0 0nm ,测定的线性范围为 0～ 9.0mg/L ;摩尔吸光系数为 2 .1× 1 0 5L/mol/cm ;RSD(n =6)为 5 0 %。已应用于茶叶中微量F- 的测定     

高效液相色谱-串联质谱法测定化妆品中壬基苯酚

提出了高效液相色谱-串联质谱法测定化妆品中壬基苯酚含量的方法。化妆品试液用甲醇-二氯甲烷（8+2）混合溶液超声提取30 min[唇膏类试样用无水乙醇-二氯甲烷（8+2）混合溶液],离心分离取上清液过Oasis HLB固相萃取柱净化。从SPE净化柱所得淋出液,以WatersXBridge C₁₈色谱柱（2.1 mm×150 mm,3.5μm）为固定相分离,以不同体积比的甲醇和氨水（0.1+99.9）溶液为流动相梯度洗脱,串联质谱进行测定。采用电喷雾负离子模式多反应监测,内标法定量。壬基苯酚的线性范围为10～500μg·L^-1,测定下限（10S/N）为0.2 mg·kg。方法用于分析4种类型化妆品样品,回收率在83.1%～103.0%之间,相对标准偏差（n=6）在2.75%～9.24%之间。     

阻抑动力学光度法测定水中2,4-二甲基苯酚

在磷酸介质中,钌对过氧化氢氧化碱性品红的褪色反应具有强的催化作用,2,4-二甲基苯酚对上述指示反应具有灵敏的阻抑作用,从而提出了一种阻抑动力学光度法测定水中痕量2,4-二甲基苯酚的方法。优化的试验条件如下:①2.0×10-4mol.L-1碱性品红溶液加入量为0.5 mL;②0.1 mol.L-1磷酸溶液加入量为1.2 mL;③过氧化氢(1+99)溶液加入量为0.5 mL;④4.0 mg.L-1钌(Ⅲ)溶液加入量为1.8 mL;⑤反应温度为100℃;⑥反应时间为10 min。2,4-二甲基苯酚的质量浓度在8.0 mg.L-1范围以内与ΔA呈线性关系,检出限(3σ)为3.49×10-4mg.L-1。方法用于环境水样中2,4-二甲基苯酚的测定,测定值的相对标准偏差(n=5)小于6.0%,加标回收率在81.4%～106.3%之间。     

固相微萃取气相色谱法测定水产品中五氯苯酚及其钠盐残留量

采用自动固相微萃取(Automated SPME)超声波辅助萃取技术(UE)与气相色谱联用测定水产品中五氯苯酚及其钠盐残留量.实验优化了SPME直接萃取技术,样品调pH 2,超声波40℃萃取30 min后,用85μm聚丙烯酸酯(PA)萃取头90℃自动搅拌萃取30 min,270℃解吸5 min.最低检出量为0.01μg/kg;五氯苯酚线性范围0.001～10 μg/L,r=0.9999;对鳕鱼加标五氯苯酚1.0、5.0μg/kg回收率分别为71.0%～80.0%、77.2%～91.4%,相对标准偏差(RSD)为6.3%和8.6%(n=3).该方法简便、灵敏、稳定,无溶剂污染,是测定水产品中五氯苯酚及其钠盐残留量的理想方法.     

微波萃取-柱前衍生-气相色谱法测定水中痕量苯酚

含痕量苯酚的水样与丙酮和环己烷(1+1)的混合溶剂混合,置于控温在60℃的微波炉中加热30 s,使苯酚萃取进入有机相,分取部分萃取液在pH 8～9的条件下与衍生试剂乙酸酐反应15 min,所生成的苯酚衍生物用石油醚萃取,分取部分经脱水后的有机相进样作气相色谱分析.色谱测定中采用DB-17毛细管色谱柱(30 m×0.53 mm,1.0μm)及氢火焰离子化检测器,在优化的条件下测得方法的检出限(3S/N)为0.01 mg·L-1.按所提出方法分析了8个模拟水样,根据测得苯酚的含量值算得其相对标准偏差为4.2%,并按标准加入法求得其平均回收率为94.0%.     

三相中空纤维液相微萃取-离子色谱法测定环境水中苯酚含量

提出了离子色谱法测定环境水中苯酚含量的方法。样品采用三相中空纤维液相微萃取法萃取,以正辛醇为萃取溶剂,在600 r·min^-1转速下萃取40 min。经SH-2 Anion色谱柱分离,以12 mmol·L^-1氢氧化钠溶液为淋洗液洗脱。苯酚的质量浓度在1.00～500μg·L^-1范围内呈线性,方法的检出限（3S/N）为0.8μg·L^-1。方法用于地表水中苯酚的测定,加标回收率在90.1%～109%之间。     

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%.     

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.     

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.     

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.     

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.     

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.     

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.