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。     

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.     

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%。     

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%.     

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。     

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.     

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.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.     

Copper-catalyzed multicomponent reactions of 2-iodoanilines,benzylamines, and elemental sulfur toward 2-arylbenzothiazoles

A relatively cheap copper salt-catalyzed, three-component approach providing 2-arylbenzothiazoles in good to excellent yields from readily available 2-iodoanilines, benzylamines, and sulfur powder is reported. This methodology allows preparation of various classes of 2-arylbenzothiazoles and provides a general, reliable approach.