Structure and PMR spectra of isoquercitrin and hirsutrin

Chemistry of Natural Compounds - 1. Two isomers of quercetin 3-glucoside are present in the flowers and leaves of the cotton plant of variety 108-F: hirsutrin, quercetin 3-β-D-glucopyranoside;...     

Separation and determination of podophyllum lignans by micellar electrokinetic chromatography

A micellar electrokinetic chromatography method was established for the quantitative analysis of seven podophyllum lignans in Podophyllum emodi Wall. var. chinesis sprague. The optimum buffer system was 10 mM NaH2PO4-5 mM borate-100 mM sodium dodecylsulfate-30% isopropanol (pH 7.20). Voltage was 18 kV and detection at 214 nm. The second derivative chromatogram was used to determine a low-content component and those not fully separated from adjacent ones. The RSD values of migration times and peak areas were <2.2 and <5.5%, respectively. The effects of several CE parameters on the resolutions were studied systematically.     

Oxidative dehydrogenation of C5 hydrocarbons in the presence of hydrochloric acid

Conclusions The oxidative dehydrogenation of C₅ paraffin hydrocarbons on Fe catalysts in the presence of HCl leads mainly to the formation of unsaturated hydrocarbons, which have the same structure of the carbon skeleton as the starting hydrocarbon, in which connection the yield of olefinic hydrocarbons proved to be substantially higher (25% from isopentane and 32% from n-pentane) than the yield of dienes (respectively 15% of isoprene and 11% of piperylene).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2599–2601, November, 1972.     

2-(8-quinolylazo)-7-phenylazochromotropic acid as an analytical reagent

2-(8-Quinolylazo)-7-phenylazochromotropic acid (QAPAC) has been synthesized by coupling diazotized 8-aminoquinoline with 2-phenylazochromotropic acid as well as by coupling diazotized aniline with 2-(8-quinolylazo)chromotropic acid. The properties of QAPAC and the spectrophotometric characteristics of some metal-QAPAC complexes are reported.     

Interaction between 18-crown-6-tetracarboxylic acid and positional substituents of enantiomers and simultaneous separation of positional enantiomers of methyl-DL-tryptophans by capillary electrophoresis

18-Crown-6-tetracarboxylic acid (18C6H4) is a chiral selector with high selectivity for the enantioseparation of solutes bearing the primary amine function. This work presents the simultaneous separation of positional enantiomers of methyl-DL-tryptophans by using 18C6H4 as an additive to the background electrolyte. Separation conditions such as pH, the concentration of 18C6H4, and the applied voltages have critical inference on the simultaneous separation. The addition of cyclodextrins as anionic surfactants to the background electrolyte did not improve the separation. The selector-selectand interactions between 18C6H4 and the positional enantiomers have been investigated. It was observed that both the position and type of substituents contribute to the enantioselectivity. The migration order and resolution depended on the distance from the substituents to the asymmetric carbon of the enantiomers.