荷移分光光度法测定氨酪酸

研究了氨酪酸(ABA)与2,3-二氯-5,6-二氰-1,4-苯醌的荷移反应.确定在硼砂缓冲溶液中,于50℃水浴中恒温40 min,可获得11的络合物,其λmax=340 nm,表观摩尔吸光率ε=1.37×103L·mol-1·cm-1.用拟定方法测定片剂中氨酪酸的含量与标准方法一致,回收率为98.5%～101.9%,相对标准偏差为1.3%～1.9%.     

固相萃取净化-超高效液相色谱-三重四极杆质谱法测定土壤中草铵膦、草甘膦及其代谢物氨甲基膦酸

建立了固相萃取净化-超高效液相色谱-三重四极杆质谱法测定土壤中草铵膦、草甘膦及其代谢物氨甲基膦酸含量的方法。将土壤样品与水、二氯甲烷混合后,高速匀浆1 min后离心,取上清液3 mL过Oasis HLB固相萃取小柱,收集最后1 mL的流出液,过0.22μm滤膜。用超高效液相色谱-三重四极杆质谱测定滤液中的草铵膦、草甘膦及其代谢物氨甲基膦酸含量。在色谱分析中,以不同体积比的5 mmol·L~(-1)的乙酸铵(用氨水调节pH至12)和乙腈的混合溶液为流动相进行梯度洗脱,以Dikma Polyamino氨基色谱柱为固定相进行色谱分离。采用电喷雾离子源(ESI)负离子模式和多反应监测(MRM)模式进行质谱测定。采用基质匹配混合标准溶液系列制作工作曲线。结果表明:草铵膦、草甘膦、氨甲基膦酸工作曲线的线性范围分别为0.005～0.5 mg·L~(-1),0.01～1.0 mg·L~(-1),0.01～1.0 mg·L~(-1);检出限(3S/N)分别为0.01,0.02,0.02 mg·kg~(-1)。对土壤样品进行3个浓度水平的加标回收试验,回收率为77.5%～92.0%,测定值的相对标准偏差(n=6)为5.9%～9.0%。     

柱前衍生-固相萃取-高效液相色谱法测定饮用水中草甘膦和氨甲基膦酸

提出了柱前衍生-固相萃取-高效液相色谱法测定饮用水中草甘膦和氨甲基膦酸。水样经9-芴基甲基三氯甲烷衍生和C18固相萃取小柱净化后,洗脱液采用Waters Atlantis T3色谱柱分离,流动相为甲醇-0.02mol·L-1乙酸铵溶液(60+40),荧光检测器激发波长为266nm,发射波长为315nm。草甘膦和氨甲基膦酸的质量浓度在5.00~500μg·L-1范围内与其峰面积呈线性关系,检出限均为0.002μg·L-1。对水样进行加标回收试验,草甘膦和氨甲基膦酸的回收率分别在84.4%~92.0%和87.8%~96.8%之间,相对标准偏差(n=6)分别在1.2%~4.3%和1.1%~4.0%之间。该方法适用于水厂出水水样中草甘膦和氨甲基膦酸的同时测定。     

超高效液相色谱-串联质谱法测定饲料中氨苯胂酸和洛克沙胂

采用超高效液相色谱-串联质谱法测定饲料中氨苯胂酸和洛克沙胂的含量。粉碎过筛后的样品用乙腈(1+1)溶液超声提取30min,离心后,上清液用二氯甲烷净化,取水层(上层)过0.22μm水系滤膜。以Thermo HYPERCARB色谱柱为固定相,以不同体积比的0.05%(体积分数)甲酸溶液和乙腈混合液为流动相进行梯度洗脱,串联质谱分析中采用电喷雾负离子源和多反应监测模式。氨苯胂酸和洛克沙胂的质量浓度均在0.05～10.0mg·L~(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)为0.01～0.05mg·kg~(-1)。以空白样品为基体进行加标回收试验,所得回收率为82.0%～106%,测定值的相对标准偏差(n=6)为1.0%～7.9%。     

RP-HPLC法分离和测定荆花胃康原料药和胶丸中的对-异丙基甲苯和α-萜品烯

建立了分离和测定荆花胃康原料药和胶丸中的主要成分对-异丙基甲苯（ρ-cymene）和α-萜品烯（α-Terpinene）的反相高效液相色谱梯度洗脱的方法.采用Spherisorb ODS1分析柱;甲醇-水梯度洗脱：0～15 min（V（甲醇）：V（水）=75：25）,15～22 min（V（甲醇）：V（水）=85：15）,22～28 min（V（甲醇）：V（水）=75：25）;紫外检测波长220 nm.对-异丙基甲苯在2.0～6.0 mg/mL,α-萜品烯在4.0～12.0 mg/mL范围内,峰面积与其质量浓度呈良好的线性关系;平均加样回收率对-异丙基甲苯为99.6%（RSD=1.3%）,α-萜品烯为98.2%（RSD=1.1%）.该方法灵敏度高,重现性好,结果稳定,可用于同时测定荆花胃康原料药及胶丸中的对-异丙基甲苯和α-萜品烯.     

多元校正分光光度法同时测定兔血清内的氨甲苯酸和酚磺乙胺

氨甲苯酸和酚磺乙胺在紫外区均有吸收,但吸收光谱重叠而形成干扰,较难直接进行分析。本文采用紫外分光光度法对氨甲苯酸和酚磺乙胺两组分混合溶液进行测定,并将所得光谱数据用化学计量学多元校正方法处理。本法测定氨甲苯酸和酚磺乙胺的的线性范围均为2.0~20.0μg/mL。用拟定的方法测定了兔血清中的氨甲苯酸和酚磺乙胺,并与高效液相色谱法的结果进行了比较,两者无显著性差异。     

5-NO2-PADAT光度法同时测定钴、铑、钯的研究

提出了以 5 (5 硝基 2 吡啶偶氮 ) 2 ,4 二氨基甲苯 (5 NO2 PADAT)作为钴、铑、钯同时测定的新试剂 ,在 586nm处 ,钴、铑、钯与试剂形成的配合物的吸光度具有良好的加和性。基于该试剂与钴、铑、钯显色反应温度和酸度的差异 ,建立了钴、铑、钯同时测定的新方法。方法灵敏度为ε586Co =1 .46×1 0 5L·mol-1 ·cm-1 ;ε586Rh =1 .63× 1 0 5L·mol-1 ·cm-1 ;ε586Pd =9.5×1 0 4L·mol-1 ·cm-1 。钴质量浓度在 0～ 0 .30 μg mL、铑质量浓度在 0～ 0 .60 μg mL、钯质量浓度在 0～ 0 .95μg mL范围内服从比耳定律。已用于合成样中微量钴、铑、钯的同时测定。     

氨酪酸与邻硝基酚的荷移反应研究

采用分光光度法研究了氨酪酸与邻硝基酚的荷移反应。由实验得知,用二甲亚砜做溶剂,室温下反应10 min后,可生成稳定的1∶1型的黄色络合物,其最大吸收波长λmax=446 nm,氨酪酸的浓度在2～16μg/mL的范围内遵循比尔定律,表观摩尔吸光系数ε=3.7×103L·mol-1·cm-1,桑德尔灵敏度S=0.028μg·cm-2。用拟定的方法测定氨酪酸片的含量,回收率在97.0%～102.7%范围内,相对标准偏差不大于2.1%。     

液相色谱-串联质谱法测定稻米中的草甘膦和氨甲基膦酸残留

采用液相色谱-串联质谱建立了稻米中草甘膦及氨甲基膦酸残留量的测定方法。试样经水提取和C18固相萃取柱净化后,在硼酸缓冲液中与9-芴甲基氯甲酸酯(FMOC-Cl)进行衍生反应。以5 mmol/L乙酸铵溶液(pH 9)和乙腈为流动相,草甘膦和氨甲基膦酸的衍生产物在C18柱进行液相色谱分离;质谱检测采用电喷雾负离子化模式和多反应监测模式。结果表明,草甘膦和氨甲基膦酸在0.00050～1.0 mg/L范围内线性良好,线性相关系数(r)分别为0.9997和0.9999。通过对空白大米样品进行3个加标水平的添加回收实验(n=5),草甘膦和氨甲基膦酸的平均回收率和相对标准偏差(RSD)分别为72.5%～113.6%和3.8%～16.2%,方法的检出限分别为2.0 μg/kg和3.0 μg/kg。该方法快速、灵敏,适用于稻米中草甘膦和氨甲基膦酸的同时分析。     

柱前衍生-超高效液相色谱-电化学检测法测定牙膏中氨甲环酸

约1g牙膏样品用水50mL超声萃取30min后再离心10min,然后取上清液加入等体积的衍生试剂溶液[含有150mg·L~(-1)邻苯二甲醛(OPA)和1.3g·L~(-1)亚硫酸钠],在室温下反应5min,完成对氨甲环酸的衍生化,衍生化后的样品溶液用超高效液相色谱-电化学检测器(UPLCECD)分析。采用Waters ACQUITY UPLC BEH C18色谱柱作为固定相,以体积比为2∶8的乙腈-30mmol·L~(-1)乙酸铵缓冲溶液(pH 3.6)为流动相进行等度洗脱。结果显示:氨甲环酸的质量浓度在0.495～19.800mg·L~(-1)内与其对应的色谱峰面积呈线性关系,检出限(3S/N)为0.18μg·g~(-1)。对牙膏样品进行了加标回收试验,回收率为98.6%,测定值的相对标准偏差(n=6)为2.4%。氨甲环酸衍生产物在12h内保持稳定(衍生产物峰面积降低了不到5%)。方法用于6个牙膏样品的分析,在已知添加的牙膏样品中检出了氨甲环酸,其质量分数为0.23mg·g~(-1)。     

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.