Solubility Study of Nimodipine Inclusion Complexation with α- and β-Cyclodextrin and some Substituted Cyclodextrins

The solubility of nimodipine was measured in aqueous solutions of the following cyclodextrins: -cyclodextrin (-CD), hydroxypropyl--CD (HP--CD), -cyclodextrin (-CD), random substituted methyl--CD (M--CD), three hydroxypropyl--CDs (HP--CD) with mutually different average degree of substitution, and hydroxypropyl--cyclodextrin (HP--CD). From the determined linear solubility diagrams the values of the binding constant K₁₁ of the inclusion complexes of nimodipine with the respective CDs were evaluated. The -CDs efficiently solubilized sparingly soluble nimodipine, the highest value of K₁₁ was found for M--CD (1680 M^-1), followed by -CD (550 M^-1) and HP--CDs, where the higher degree of substitution lowered K₁₁. Only slight solubilization of nimodipine was observed in the solutions of the -CDs and HP--CD.     

Novel Host Compounds, 1,1′-Binaphthyl-2,2′-Dihydroxy-5,5′- and 6,6′-Dicarboxylic Acid, which Trap Guest Molecules Tightly in their Inclusion Crystals

The host compounds 1,1’-binaphthyl-2,2′-dihydroxy-5,5′-dicarboxylic acid (1) and 1,1′-binaphthyl-2,2′-dihydroxy-6,6′-dicarboxylic acid (2) have been synthesized, and their inclusion properties have been studied. Inclusion complexes formed by 1 and 2 with volatile guests such as acetone and methanol release the guests only at much higher temperatures than their boiling points. The crystal structures of the inclusion complexes have been determined from single crystal X-ray diffraction data and show different host lattices.     

The Reaction of Maleic and Phthalic Anhydrides with 2-Methylimidazole

The reaction of maleic anhydride with 2-methylimidazole in acetonitrile and DMF is accompanied by the appearance of strong absorption bands in the visible part of the spectrum due to the formation of molecular complexes. In acetonitrile the reaction proceeds by two routes via the formation of an amide and the molecular complex. Phthalic anhydride reacts with 2-methylimidazole to give amide but not to form molecular complexes.     

偏氟乙烯／三氟乙烯共聚物介电松弛的结晶度效应

用改进的介电松弛谱仪（精度２‰）测定了ＶＤＦ／ＴｒＦＥ（７／２７、６５／３５、５２／４８ｍｏｌ％）共聚物溶液成膜、液氮淬火、熔融慢冷和热处理试样在－１２０—１３０℃、１０－２一１０４Ｈｚ范围的复数介电常数．介电松弛研究结果显示低结晶度的淬火试样较高结晶度的熔融慢冷和热处理试样的Ｔｃ高．结晶度上升，居里点处的介电常数增大．室温以下的介电频率谱分别由代表非晶区分子运动的β松弛（低频部）和局域运动的γ松弛（高频部）叠合而成．随结晶度提高，β松弛峰减小，γ松弛峰增大；非晶松弛强度减弱．晶区松弛强度增强．     

微机在“醋酸,磷酸电位滴定”实验中的应用

微机在“醋酸、磷酸电位滴定”实验中的应用王苏文（南京师范大学化学系南京２１００２４）袁立新（南京师范大学物理系南京２１００２４）关键词计算机，Ａ／Ｄ模数转换器，电位滴定许多化学实验使用传统的方法对实验数据进行人工读数、记录、处理等。在这一过程中就必定...     

Ethyl 3,3-diamino-2-(2-p-tolylpyrimidin-4-yl)acrylate,a new representative of hetarylketene aminals

A new representative of hetarylketene aminals, ethyl 3,3-diamino-2-(2-p-tolylpyrimidin-4-yl)acrylate, was synthesized by the reaction ofp-toluamidine with the condensation product of dimethylformamide dimethyl acetal and the difluoroboron chelate of acetyl(ethoxycarbonyl)ketene (N-benzoyl)aminal. This synthesis is an example of pyrimidine ring assembly using the methodology based on transformations of chelate complexes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1638–1640, September, 1994.This research was partially supported by the International Science Foundation (Grant No. M5QOOO).     

Thermal decomposition of rare earth element enanthates

The conditions of formation of Y, La and lanthanide (from Ce(III) to Lu) enanthates were worked out, their composition and their solubilities in water at 291 K were determined, and the conditions of their thermal decomposition were studied. They were prepared as crystalline solids with general formula Ln(C₇H₁₃O₂)₃·nH₂O, wheren=2–10. On heating, they decompose in two or three steps. They first lose some water molecules and then decompose to the oxides directly (salts of Y and heavy lanthanides) or via the intermediate formation of Ln₂O₂CO₃ (salts of La, Pr, Nd, Sm and Eu). Only yttrium enanthate dihydrate loses 2 water molecules on heating to form an anhydrous complex, which decomposes directly to Y₂O₃. The temperatures of dehydration are similar for all complexes (323–343 K), while the temperatures of oxide formation vary irregularly from 823 K for CeO₂ to 1078 K for La₂O₃.     

Oxidations by a H2O2-VO3 −-pyrazine-2-carboxylic acid reagent

Alkanes (cyclohexane, hexane, heptane isomers) are effectively oxidized in CH₃CN at 20–70°C by hydrogen peroxide when catalyzed by a Bu₄NVO₃-pyrazine-2-carboxylic acid system. Alkyl hydroperoxide is the main product; an alcohol and a ketone or an aldehyde are also formed. Under these conditions benzene is oxidized to give phenol, while alkyl benzenes yield oxygenation products both of the ring and the side chain. It has been assumed that the interaction of H₂O₂ with VO₃ ^– gives rise to generation of HO radicals and other radical-like vanadium containing species that abstract a hydrogen atom from an alkane, RH. The radical R^. formed reacts with O₂ to produce ROO^. which is then transformed to alkyl hydroperoxide.Presented at the VIII International Symposium on Homogeneous Catalysis (Amsterdam, 1992).Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 64–68, January, 1993.     

Aerobic alcohol oxidation catalyzed by a new, oxygen-bridged heterometallic compound [PPh4][Ru(N)Me2(μ2-O)2Pd((−)-sparteine)]

The reaction between the new hydroxy compound [PPh₄][Ru(N)(OH)₂Me₂] and Pd(OSiMe₃)₂((−)-sparteine) produces (Me₃Si)₂O, H₂O and a new heterobimetallic compound [PPh₄][Ru(N)Me₂(μ₂-O)₂Pd((−)-sparteine)] in good yield. The Ru/Pd bimetallic compound catalyzes the oxidation of aryl and allyl alcohols to the corresponding carbonyl compound in air and the rearrangement of allylic alcohols unsaturated aldehydes. It also oxidizes PPh₃ to O-PPh₃ under O₂.     

Quantification of Valerenic Acid in Valeriana jatamansi and Valeriana officinalis by HPTLC

A simple, rapid, cost-effective and accurate high performance thin layer chromatographic method has been developed for quantification of valerenic acid in Valeriana jatamansi and Valeriana officinalis which is one of the stable compounds of Valeriana officinalis and designated as a key marker compound. Valerenic acid makes substantial contribution to the sedative and spasmolytic activity of the essential oil and extract of Valeriana officinalis. Separation and quantification was achieved by HPTLC using ternary mobile phase of hexane: ethyl acetate: acetic acid (80:20:0.5 v/v) on precoated silica gel 60F₂₅₄ aluminium plates and densitometric determination was carried out after derivatization with anisaldehyde-sulphuric acid reagent at 700 nm, in absorption-reflectance mode. The calibration curves were linear in the range of (500 ng–2.5 μg). This is the first HPTLC report for the identification and quantification of valerenic acid in Valeriana jatamansi and Valeriana officinalis.