溴酚蓝分光光度法测定盐酸西布曲明

在pH 3.70的B-R缓冲溶液中,盐酸西布曲明与溴酚蓝以摩尔比1比2反应形成具有正吸收和负吸收的离子缔合物,最大正吸收波长为436nm,最大负吸收波长为590nm,线性范围分别在3.4×10-6 mol·L-1(正吸收)、3.8×10-6 mol·L-1(负吸收)以内,表观摩尔吸光率为1.83×105L.mol-1.cm-1(正吸收)、5.51×104L.mol-1.cm-1(负吸收),据此建立了测定盐酸西布曲明含量的分光光度法。方法用于合成样品及尿样中盐酸西布曲明的测定,回收率在96.8%～102.5%,相对标准偏差(n=6)在0.9%～1.7%之间。     

孔雀石绿双波长褪色法测定药物中的卡托普利

建立了一种测定卡托普利的双波长褪色分光光度法。在pH 5.76的Tris-盐酸缓冲溶液中,卡托普利与孔雀石绿反应生成具有两个明显负吸收峰的绿色离子缔合物,最大负吸收波长位于634 nm,次大负吸收波长位于588 nm,表观摩尔吸光系数(κ)分别为1.35×10~4和1.05×10~4[L/(mol·cm)],当用双波长褪色法测定时,表观摩尔吸光系数(κ)达2.40×10~4[L/(mol·cm)],线性范围为0~3.9(mg·L~(-1)),服从朗伯-比尔定律。还优化了反应条件,探讨了吸收光谱特征和共存物质的影响。方法用于市售卡托普利药物中卡托普利的测定,结果满意。     

依文思蓝光度法测定水样中阳离子表面活性剂

在弱酸性的NaH2PO4-Na2HPO4缓冲介质中,阳离子表面活性剂(CS)溴化十六烷基吡啶(CPB)、十六烷基三甲基溴化铵(CTAB)与依文思蓝(EB)染料反应,形成离子缔合物,溶液颜色发生明显改变,最大褪色波长位于610 nm。在最大褪色波长处,CS的浓度与褪色程度呈良好线性关系,从而建立了测定阳离子表面活性剂的光度法。在最大褪色波长处,CS的浓度在5.0×10-7~2.46×10-5mol/L(EB-CPB)、9.0×10-7~3.36×10-5mol/L(EB-CTAB)范围内遵守比耳定律,表观摩尔吸光系数为1.97×104L.mol-1.cm-1(EB-CPB)、1.25×104L.mol-1.cm-1(EB-CTAB),检出限为3.6×10-7mol/L(EB-CPB)、7.4×10-7mol/L(EB-CTAB)。本法用于水样中阳离子表面活性剂的测定,结果满意。     

曙红Y分光光度法测定阳离子表面活性剂及其机理研究

在弱酸性的HCl-NaAc缓冲介质中,阳离子表面活性剂(CS)与曙红Y(EY)染料反应,形成离子缔合物,溶液颜色发生明显改变,最大褪色波长分别在514 nm(EY-CPB体系)、516 nm(EY-CTAB体系),同时在548 nm(CPB体系)、544 nm(CTAB体系)处有吸收峰,在褪色波长处阳离子表面活性剂的浓度与褪色程度呈良好线性关系,从而建立测定阳离子表面活性剂的光度法。在最大褪色波长处,CPB体系、CTAB体系中CS的浓度在0~4.79×10-5mol/L、0~2.90×10-5mol/L范围内遵守比尔定律,表观摩尔吸光系数为2.94×104、2.86×104L.mol-1.cm-1,检出限为8.97×10-7mol/L、7.87×10-7mol/L。若用双波长叠加,表观摩尔吸光系数达5.58×104、5.20×104L.mol-1.cm-1,检出限为5.87×10-7、6.25×10-7mol/L。方法适用于水样中CS的测定。本文还用密度泛函理论对反应机理进行了探讨。     

四氯四碘荧光素作显色剂测定盐酸依托必利

以四氯四碘荧光素作为显色剂,研究了测定盐酸伊托必利的适宜条件及光谱特征,建立了测定药物中盐酸伊托必利的简便、快速、准确的吸收光谱法。在弱碱性Tris-HCl缓冲溶液中,四氯四碘荧光素与盐酸伊托必利以静电作用发生显色反应生成离子缔合物,在可见光区产生2个具有较强特征的正吸收峰,最大吸收峰位于波长486 nm,次大吸收峰位于554 nm,线性范围均为0.08～7.10 mg/L,表观摩尔吸光系数分别为3.54×10~4 L/(mol·cm)和2.79×10~4 L/(mol·cm),检出限为0.042 mg/L(486 nm)和0.048 mg/L(554 nm)。采用双波长(486 nm+554 nm)叠加测定时的检出限为0.022 mg/L,表观摩尔吸光系数为6.33×10~4 L/(mol·cm),吸光度与0.08～7.10 mg/L范围内的盐酸伊托必利遵从朗伯-比尔定律。该法用于药物中盐酸伊托必利的定量检测,结果满意。     

溴甲酚紫、溴甲酚绿光度法测定阿昔洛韦

在pH 3.30的NH2CH2COOH-NaCl-HCl缓冲介质中,阿昔洛韦(Aciclovir,ACV)可与溴甲酚紫(BCP)、溴甲酚绿(BCG)反应,形成离子缔合物,溶液颜色发生明显变化,其最大褪色波长分别为428 nm(BCP-ACV)、450 nm(BCG-ACV),在此波长处,阿昔洛韦的浓度与溶液褪色程度呈良好线性关系,可用分光光度法测定。在BCP-ACV、BCG-ACV体系的最大褪色波长处,ACV的浓度分别在0~2.69×10-5mol/L、0~2.58×10-5mol/L范围内遵守比耳定律,表观摩尔吸光系数分别为2.53×104L.mol-1.cm-1、1.79×104L.mol-1.cm-1,检出限分别为5.10×10-7mol/L、7.13×10-7mol/L。方法用于药品、血浆及尿液中阿昔洛韦的测定,结果满意。     

多波长褪色分光光度法测定药物中的酒石酸美托洛尔

建立了测定药物中酒石酸美托洛尔的多波长褪色分光光度法,探讨了适宜反应条件、褪色光谱特征及共存物质的影响。在pH 5.66的Tris-盐酸缓冲介质中,酒石酸美托洛尔与固绿FCF反应生成具有3个负吸收峰(可见区)的二元离子缔合物,最大负吸收峰位于660 nm,另两吸收峰分别位于560 nm和426 nm,表观摩尔吸光系数(κ)分别为3.43×10~4(660 nm),2.53×10~4(560 nm)和2.57×10~4L/(mol·cm)(426 nm)。当用双波长或三波长叠加负吸收光谱法测定时,表观摩尔吸光系数分别可达5.96×10~4L/(mol·cm)(660 nm+560 nm)和8.53×10~4L/(mol·cm)(660 nm+560 nm+426 nm)。酒石酸美托洛尔的质量浓度在0.02~6.8 mg/L范围内服从朗伯-比尔定律。该方法用于市售酒石酸美托洛尔药物中酒石酸美托洛尔的测定,加标回收率为98.2%~102.7%,相对标准偏差RSD(n=6)为2.0%~2.3%。     

依文思蓝光度法测定阿昔洛韦及其分析应用

在pH 5.74 HAc-NaAc缓冲介质中, 阿昔洛韦(ACV)与依文思蓝(EB)反应形成离子缔合物, 溶液颜色发生明显改变, 最大褪色波长为638 nm. 在此波长处, 阿昔洛韦的浓度与褪色程度呈良好线性关系, 从而建立测定阿昔洛韦的光度法. 在最大褪色波长处, 阿昔洛韦的浓度在0～2.01×10-5 mol/L范围内遵守比尔定律, 表观摩尔吸光系数1.71×104 L·mol-1·cm-1, 检出限为7.47×10-7 mol/L. 方法具有较高的灵敏度和良好的选择性, 可用于实际药品、血浆及尿液中阿昔洛韦的测定.     

乙基紫褪色分光光度法测定药物中的美司那

建立了测定药物中美司那的褪色分光光度法。在酸性BR缓冲溶液中,美司那与乙基紫以静电引力作用生成具有2个较强负吸收峰的新物质,使溶液褪色,美司那的质量浓度在630 nm和492 nm处与生成的新物质的吸光强度的绝对值(|A|)有线性关系并服从朗伯-比尔定律,他们的线性范围为0.2～2.3 mg·L~(-1),表观摩尔吸光系数(κ)分别为1.71×10~4 L/(mol·cm)(492 nm)和2.53×10~4 L/(mol·cm)(630 nm),检出限分别为0.18 mg·L~(-1)和0.14 mg·L~(-1)。用双波长叠加法测定时,其表观摩尔吸光系数(κ)达4.24×10~4 L/(mol·cm),约是单波长法的2倍,检出限为0.080 mg·L~(-1)。该法用于市售美司那药物中美司那含量的测定,结果满意。     

柠檬酸与乙酸酐混合溶液中分光光度法测定盐酸西布曲明

柠檬酸和乙酸酐混合溶液与盐酸西布曲明在80℃的水浴中加热30 min,反应后使溶液呈紫黑色,在330 nm波长处吸收最大,据此建立测定盐酸西布曲明的分光光度法.盐酸西布曲明的质量浓度在0.17～18.5 mg·L-1范围内遵守比耳定律,相关系数为0.998 9,表观摩尔吸光率为8.16×104L·mol-1·cm-1,检出限为61.5μg·L-1.用于曲美胶囊中盐酸西布曲明的测定,测定结果与高效液相色谱法结果相符,其相对标准偏差(n=6)值均小于0.5%.     

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%.     

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.     

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.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

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%).