Phenolic Compounds of Plants of the Scutellaria L. Genus. Distribution, Structure, and Properties

Information on flavones, flavanones, flavanonols, flavonols, chalcones, isoflavones, biflavonoids, lignoflavonoids, and lignane glycosides and stilbenes isolated from plants of the Scutellaria L. genus was systematized and reviewed. A list of 208 phenolic compounds was given according to flavonoid type with an indication of the plant sources, structures, and physicochemical properties and citations of the original articles.     

DFT法研究分子筛催化trans-2-丁烯的双键异构

利用一个3T簇模型模拟分子筛催化剂的酸性位, 采用密度泛函理论(DFT)的 B3LYP/6-31G(d, p)方法, 研究了分子筛催化1-丁烯双键异构为trans-2-丁烯的反应机理. 对反应各驻点进行了全优化, 经过零点能校正后, 得到了反应的活化能. 研究表明, 反应分三步进行：物理吸附→化学反应→物理脱附. 分子筛的酸性位OH基团首先吸附1-丁烯的双键形成了π配位复合物, 然后按协同反应机理发生双键异构反应, 生成吸附态的trans-2-丁烯, 最后脱附成产物. 计算得到的表观活化能为57.1 kJ•mol^-1, 与实验结果接近.     

Macrocycle opening in formyl derivatives of benzocrown ethers under the action of methylamine

A new method for synthesizing nitrogen-containing podands by nucleophilic regioselective cleavage of the macrocycle in formyl derivatives of benzocrown ethers by heating with methylamine and methylammonium chloride has been developed. This reaction is the first example of crown ether opening by a nitrogen-containing nucleophile.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 950–953, May, 1995.     

Simultaneous quantitative analysis of ketanserin and ketanserinol in plasma by RP-HPLC with fluorescence detection

A sensitive and selective high-performance liquid chromatographic assay for the quantification of ketanserin and ketanserinol in human plasma was developed and validated. The procedure involves extraction of ketanserin and ketanserinol from plasma using an Extrelut NT-1 solid-phase extraction column. The chromatograph was equipped with a Hypersil BDS column (100 x 4.5 mm, 3 micro m particle size). Separation was performed with a mixture of acetate buffer 0.01 M, pH 4.9-methanol-acetonitrile (52:40:8, v/v/v). Detection was performed with fluorescence detection (lambda(ex) = 332 nm and lambda(em) = 410 nm). Calibration curves were linear (r(2) = 0.999) in the range 0-400 ng/mL for both ketanserin and ketanserinol. The repeatability coefficient for ketanserin and ketanserinol was 3.1 and 3.0%, respectively. The reproducibility coefficient for ketanserin and ketanserinol was 10.5 and 9.1%, respectively. The limit of quantification for both ketanserin and ketanserinol was 2.0 ng/mL. The mean recovery yield for both ketanserin and ketanserinol was 60%. In an 8 h work day approximately 60 samples, including calibration and reference standards, could be processed.     

Theoretical studies on the reaction path and dynamics of the reaction CH_3+H_2O→CH_4+OH

The reaction path, the dynamical properties along the reaction path and CVT rate constants are computed by the ab initio MO method, the reaction path Hamiltonian theory and the variational transition state theory. The results show that the effect of the electron correlation energy on activation barrier is large, the recrossing and tunneling effects exist in the reaction.     

Synthese und Geruch von Tricyclo[6.2.2.02, 7]dodecan-Derivaten

Summary The acetale-ketone9 was synthesized as precursor for the preparation of -santalol derivatives posessing a bicyclo[2.2.2]octane nucleus. After methylenation of the keto-group the subsequent acidic hydrolysis of the acetal leads via a Prins reaction of the liberated aldehyde with the methylene group to tricyclo[6.2.2.0^{2, 7}]dodecane derivatives. Their olfactory properties are described.

     

Theoretical Study on the Structures and Stability of Isomers and Complex of[Si,C,O,O] Sytem

A detailed singlet potential energy surface(PES) of [Si,C,O,O] system including a van der Waals (vdW) comples SiO……CO2,eight isomers,and twelve transiton states is investigated by MP2 and QCISD(T) (single-point)methods.At the final QCISD(T)/6-311 G(2df)//MP2/6-311G(d) level with zero-point energy included,the complex SiO……CO is found to be thermodynamically and kinetically the most stable species.Although eight ismoers are located as local energy minima,they are rather unstable toward isomerization to the dissociation fragments or comples.For the reaction of silocon atoms with carbon dioxide,two competitive reaction channels are found,and the primary pathway,which leads to the products of SiO and CO fragments,is the direct oxygen-abstraction process from carbon dioxide by silicon atom with a41.16 kJ/mol reaction barrier height.Our predications are in good agreement with previous experimental and theoretical studies.     

The convergence of spline collocation for strongly elliptic equations on curves

Summary Most boundary element methods for two-dimensional boundary value problems are based on point collocation on the boundary and the use of splines as trial functions. Here we present a unified asymptotic error analysis for even as well as for odd degree splines subordinate to uniform or smoothly graded meshes and prove asymptotic convergence of optimal order. The equations are collocated at the breakpoints for odd degree and the internodal midpoints for even degree splines. The crucial assumption for the generalized boundary integral and integro-differential operators is strong ellipticity. Our analysis is based on simple Fourier expansions. In particular, we extend results by J. Saranen and W.L. Wendland from constant to variable coefficient equations. Our results include the first convergence proof of midpoint collocation with piecewise constant functions, i.e., the panel method for solving systems of Cauchy singular integral equations.Dedicated to Prof. Dr. Dr. h.c. mult. Lothar Collatz on the occasion of his 75th birthdayThis work was begun at the Technische Hochschule Darmstadt where Professor Arnold was supported by a North Atlantic Treaty Organization Postdoctoral Fellowship. The work of Professor Arnold is supported by NSF grant BMS-8313247. The work of Professor Wendland was supported by the Stiftung Volkswagenwerk