雷酚萜醇的结构研究

雷酚萜醇属雷公藤二萜类化合物。雷公藤(Tripterygium wilfordii Hook f)系卫矛科(Celastraceae)雷公藤属植物。民间用于治疗风湿病、抗炎、抗肿瘤及抑制免疫系统等。     

反相高效液相色谱法测定大白鼠血浆中雷酚内酯浓度

雷酚内酯(Triptophenolide)是从中药雷公藤(Tripterygium wilfordii Hook.f.)根的有效部位醋酸乙酯提取物中分离得到的一种二萜内酯化合物,经药理和临床研究证明,它具有抗炎、免疫抑制作用,是雷公藤治疗类风湿关节炎的有效成分。配合临床研究,我们对雷酚内酯进行了药物动力学研究,采用液-固净化富集技术进行血样预处理,反相高效液相色谱法测定大白鼠血浆雷酚内酯的血药浓度,方法简便、灵敏、准确,取得了较好结果。     

12-钼磷酸的BrÖnsted酸位和Lewis酸位

研究了加热、抽空等预处理对固态12-钼磷酸(PMA)酸位的影响。发现了PMA上除存在B-酸位外,还可生成L-酸位。研究了PMA上L-酸位的成因,水在两类酸位形成过程中的作用,L-酸位与B-酸位的相对强度,以及PMA上酸强度的分布。据此,对Miscno等认为PMA中只存在质子酸和酸强度分布均匀的观点提出了不同的看法。     

高效液相色谱法测定啤酒花及其制品中的α-酸、β-酸和异α-酸

1引言a-酸、B-酸及异a-酸是啤酒苦味酸的主要成分，它们的分析是啤酒花及其制品质量评价及控制的主要内容，国内主要使用光度法和电导滴定法分析，这两种方法因存在许多问题而影响测定结果，因此，国外近年已逐渐用高效液相色谱法（HPIn）分析啤酒、啤酒花及各种啤酒花制品的a一酸、卢一酸及异o一酸。我们在研究啤酒花制品时需要同时分析a一酸、卢·酸及异a一酸，但是已有的HPIn法仅可以同时测定a·酸和公酸，而异a一酸是单独分析的，只有在梯度洗脱和较高的柱温时可以同时测定三者，这就限制了它的推广应用。本文建立了室温下同时测定它…     

氨荒酸膦酸树脂的合成及应用.Ⅱ.树脂的应用

本文以原子吸收光谱为检测手段,将氨荒酸膦酸树脂应用于地下水中Zn,Cd,Co,Cr,Cu,Mn,Ni,Pb等八种痕量元素的同时分析,取得了满意的结果。用美国环保局标准水样评价此分析方法的可靠性,结果表明分析结果的方差小,回收率高。文中还探讨了氨荒酸膦酸树脂对Hg~(2+)的吸附性能和吸附机理,表明树脂吸附Hg~(2+)的过程是受内扩散控制的。     

氯雷他定的合成

以N-甲基-4-哌啶酮和8-氯-10,11-二氢-4-氮杂-5H-二苯并[a,d]-5-环庚酮为原料,经McMurry反应得到8-氯-6,11-二氢-11-(1-甲基-4-哌啶烯基)-5H-苯并[5,6]庚环[1,2-b]吡啶,收率为83.9%,最后与氯甲酸乙酯反应得到氯雷他定,总收率为35.7%。对McMurry反应过程中产生的副产物3、4进行了分离、表征。     

Some Comments on Fulminic Acid (Knallsäure) and a Praise to Heinrich Wieland and his Work on Organic Derivatives of Nitrogen

The structure, vibrational spectrum, the polymerization and [3+2] cycoaddition reactions of fulminic acid are discussed. In the mass spectra of the solid deposit from gaseous fulminic acid (prepared from sodium fulminate and sulfuric acid) the mass of the adduct of HCNO with hydrogen cyanide was detected, which may be formed by Huisgen 1,3‐dipolar cycloaddition. As examples for Heinrich Wieland's experimental mastership the polymerization and his syntheses of fulminic acid and of explosive dinitrosomethanide [HC(NO)₂]^– are emphasized; the structure of the latter has recently been disclosed by X‐ray structure determination.     

The CNO free radical and its isomerization in inert-gas matrices

The CNO free radical is generated in solid Ne by in situ photolysis of fulminic acid, HCNO. Its electronic spectra and photoisomerization to NCO are examined.     

Electronic structure calculations of 1,3-dipolar cycloadditions using density functional and Hartree–Fock methods

Local spin density (LSD ) methods were used to study the concerted 1,3-dipolar cycloadditions for fulminic acid plus acetylene, fulminic acid plus ethylene, and nitrone plus ethylene. Cartesian Gaussian double-zeta split-valence basis sets augmented with one set of polarization functions (DZVP ) were used for the LSD calculations. The LSD calculations were performed with the LSD exchange functional (Dirac) and with the Vosko, Wilk, and Nusair correlation energy functional (VWN ). Nonlocal spin-density corrections (NLSD ) were estimated with the exchange functional of Becke and the correlation energy functional of Perdew (VWN + BP ) and Becke, and the correlation energy functional of Lee, Yang, and Parr (B-LYP ). Vibrational frequencies were computed at the VWN and B-LYP levels by numerical differentiation of the analytical first derivatives of the energy. Each of these reactions was examined using Hartree–Fock and Møller–Plesset perturbation theory for comparison. Geometry optimizations were carried out at the Hartree–Fock level with the 6-311G (d,p) basis set, and correlation energies were computed up to the MP 4SDTQ /6-311G (d,p) level of theory. For the reactions of fulminic acid plus acetylene, fulminic acid plus ethylene, and nitrone plus ethylene, our best estimated density functional barrier heights are 7.8 ± 1.5, 8.9 ± 0.3, and 11.05 ± 1.9 kcal/mol, respectively. These results are in reasonable agreement with the correlated wave-function calculations and experimental estimates. © 1994 John Wiley & Sons, Inc.     

An MNDO study of the reaction of methanol with fulminic acid and acetonitrile oxide

The reaction pathway of fulminic acid (HCNO) and acetonitrile oxide (CH₃CNO) with methanol as a nucleophile (RCNO + CH₃OH → RC(OCH₃)?NOH) and the formation of H-bonded complex with methanol have been studied using the MNDO method. MNDO-SCF calculations were performed with complete geometry optimization using the Davidon–Fletcher–Powell method. The reaction pathways were studied by varying all the bond lengths, the bond angles and the twist angles, using the distance C₃? O₂(R) between the carbon of the 1,3-dipoles and the oxygen of the methanol molecule as the reaction coordinate. The reaction is exothermic and proceeds in two steps. The first step is the formation of a five-centered hydrogen-bonded complex (INT ) and is the rate-determining step of the reaction. The second step involves the rearrangement of the H-bonded complex to the product, and this step requires a very small amount of activation energy. Thus, there is an intermediate on the reaction pathway, and therefore, the reaction is stepwise. Acetonitrile oxide is less reactive (activation energy 34.59 kcal/mol) relative to fulminic acid (activation energy 28.91 kcal/mol).     

Pmo analysis of cycloadditions- II. The transition state of the addition of formonitrile oxide to acetylene

Perturbation calculations on the transition state of the reaction of formonitrile oxide (fulminic acid) with acetylene are reported. The energy partitioning in covalent and non-covalent contributions reveals that the type II behavior of formonitrile oxide which is expected according to the classification scheme of cycloadditions is observed only if distortions of the molecules as in the ab-initio calculated transition state structure are taken into account. The results support unequal bond formation with a preference for the CC bond.     

Electrostatic potential topography for exploring electronic reorganizations in 1,3 dipolar cycloadditions

Topographical analysis of the molecular electrostatic potential (MESP) along a reaction path is employed for bringing out sequential electronic reorganizations for 1,3-dipolar cycloadditions of ethyne to fulminic acid as well as diazomethane. A simple and consistent set of rules for portraying electronic mechanisms of chemical reactions using the MESP topography is applied for this purpose. The MESP topography at each point on the concerted reaction path is associated with a classical electronic structure yielding a clear picture of the electronic reorganization along the reaction path.     

Cycloaddition Reactions of Butadiene and 1,3‐Dipoles to Curved Arenes,Fullerenes, and Nanotubes: Theoretical Evaluation of the Role of Distortion Energies on Activation Barriers

Diels–Alder cycloadditions of butadiene and 1,3‐dipolar cycloadditions of azomethine ylide, fulminic acid, and the parent nitrone to polyacenes, fullerenes, and nanotubes have been investigated with density functional theory and ONIOM methods. Activation barriers obtained for cycloaddition reactions on planar and curved systems have been shown to be highly correlated to the energy needed to distort the reactants to the geometry of the transition state (TS).     

The chemistry of fulminic acid revised

The availability of a new synthesis of fulminic acid by hydrolysis of trimcthylsilanecarbonitrile oxide allowed a reinvestigation of the chemistry of the title compound. Thus, cycloadditions to olefinic and acetylenic dipolarophiles are improved with respect to previous results and the oligomerisation is proved to occur via the reactive species hydroxyiminoacetonitrile oxide 7 and hydroxyiminomethyl-hydroxyiminoacetonitrile oxide 8. The Z-configuration, found for the oxime groups in these intermediates, is maintained in their derivatives, under kinetic controls.     

5-vinylisoxazole

Cycloaddition of fulminic acid to 1-butyn-3-ol gave a mixture of 5-α-hydroxyethylisoxazole (I) and 4-α-hydroxyethylisoxazole (II) in the ratio 9:1. By the dehydration of 1, 5-vinylisoxazole (III) was obtained. Compound III has also been prepared by cyclization of 4-penten-2-ynal as well as its diethylacetal with hydroxylamine hydrochloride; in both instances no isomers have been obtained. Compound III spontaneously polymerizes even at room temperature yielding a polymer still containing isoxazole rings.     

Theoretical study of hydrogen bonded clusters of water and fulminic acid

Ab initio and density functional calculations are used to analyze the interaction between a molecule of fulminic acid with 1, 2, 3, and 4 molecules of water along with a 2:2 complex at B3LYP/6-31+G(d,p) and MP2/6-311++G(d,p) computational levels. Cooperative effect (CE) in terms of stabilization energy of clusters are calculated and discussed as well. CE is increased with increasing cluster size of studied clusters. Red shifts of H–C stretching frequency for complexes involving HCNO as H-donor are predicted.