Prediction of retention indexes. I. Structure-retention index relationship on apolar columns

A simple method is reported for predicting the retention index (RI) of a chemical compound from the number of carbon and carbon equivalent atoms in the molecule, the RI increment for atom addition and the group retention factors (GRFs) for substituents and functional groups. Atoms other than carbon such as oxygen, nitrogen, sulfur, chlorine, bromine and iodine are assigned carbon atom equivalency of approximately 1, 1, 2, 2, 3 and 4, respectively and are counted for their contribution towards RI prediction. The GRFs of substituents and functional groups are derived from the RIs of reference compounds and series of homologues. Ring structures, ring fusion, ring connection, iso- and neo-carbons, chain branching and unsaturation are also assigned GRFs. The predicted RIs of a number of alicyclic, aliphatic and aromatic hydrocarbons, primary, secondary and tertiary alcohols, phenols, aliphatic amines, aromatic amines, heterocyclics, carboxylic acids, acid esters, aldehydes, ketones, and halogenated compounds, are found to be within +/- 3% of the observed values. The structure-retention index relationship thus developed is extremely useful in the tentative identification of radioactive side products formed in tritium labeling by radiation-induced methods.     

SYNTHESIS AND CATALYTIC PROPERTY OF POLYSTYRENE SUPPORTED PHENYLALANINE SCHIFF BASE COMPLEX OF Mn（Ⅱ） IN AEROBIC OXIDATION OF CYCLOHEXENE

The polystyrene supported phenylalanine Schiff base complex of Mn(Ⅱ)(PS-Sal-Phe-Mn)was prepared with chloromethylated styrene polymer beads, 2,4-dihydroxybenzaldehyde,L-phenylalanine and manganese(Ⅱ)acetate tetrahyrate., The polymeric ligand and the complex were characterized by FT-IR,, small area X-ray photoelectron spectroscopy(XPS), and ICP-AES. In the presence of the manganese complex, cyclohexene(1)was effectively oxidized by molecular oxygen without reductant. The major products of the reaction were 2-cyclohexen-1-ol(2),2-cyclohexen-1-one(3)and 2-cyclohexen-1- hydroperoxide(4), which was different with typical oxidation of cyclohexene. The influence of reaction temperature and additive for oxidation had been studied. The selectivity of 2-cyclohexen-l-hydroperoxide varied with reaction time and different additives. The mechanism of cyclohexene oxidation had also been discussed.     

Cycloaddition reactions of β-trifluoroacetylvinyl ethers

β-Trifluoroacetyl vinyl ethers ROCHCHCOCF₃ react smoothly as dienophiles with α,β-unsaturated carbonyl compounds to give the unexpected 2-alkoxyl-5-trifluoroacetyl-3,4-dihydro-2H pyrans. These products are formed by elimination and addition of the alcohol to the products of the normal hetero Diels-Alder reaction (2-alkoxyl-3-trifluoroacetyl-2,3-dihydro-2H pyrans). In contrast, 1,3-dipolar cycloaddition of ROCHCHCOCF₃ with ArCHN(O)Me proceeds via a Z-endo transition state to give regio- and stereospecific 4-trifluoroacetyl substituted isoxazolidines and their derivatives.     

橡胶增韧环氧树脂机理的研究

本文研究了固化剂种类、环氧基体平均网链长度和分散相与基体间键合情况对体系韧性等的影响.结果说明,基体平均网链长度是一个更为重要的影响因素.分散相与基体间的化学键合也是重要的.文中对橡胶增韧环氧树脂的机理提出了见解.在交联密度较低的材料中,在橡胶颗粒附近叠加的应力场诱发下发生纵深度较大的断裂过程.分散相与基体间的化学键合增大该应力场强度有利于加大断裂过程区.     

On the interaction of UV screens with the lignocellulosic matrix

In this report, we describe our attempt to understand the photochemical interactions that occur between dihydroxybenzophenone (DHB)-based UV screens and lignin when high-yield pulps are treated with such materials. Milled wood lignin (MWL) and filter paper were used as models, and various irradiation protocols were carried out in the presence and absence of UV screens. After irradiation, the lignin and the UV screen were extracted and the products analyzed. These experiments showed that upon irradiation, fragments of MWL-containing chromophores were linked to cellulose via an acid-labile linkage. In the presence of UV screens, these reactions were minimized. Molecular weight measurements of the extracted lignin showed that the MWL is degraded upon solid-state irradiation. The samples that contained UV screens showed a reduced tendency to degrade. Using quantitative 31P NMR, it was possible to probe further the detailed structural changes that occurred in MWL during irradiation. In general, DHB-based UV screens and derivatives were found to interact actively with MWL when irradiated.     

高活性的茂基钛配合物／正丁基锂加氢催化体系的研究

考察了茂环上不同取代基及钛上阴离子配体对茂基钛配合物／正丁基锂催化体系加氢活性和稳定性的影响。在充分发挥该体系催化活性的条件下，由配合物Ｃｐ２ＴｉＣｌ２、Ｃｐ２ＴｉＦ２和Ｃｐ２Ｔｉ［ＯＣ６Ｈ３（ＣＨ３－２）Ｃｌ－４］２组成的催化体系对辛烯－１加氢的最高活性（或初活性）达到４６￣５８ｓ＾－１。     

Synthesis and characterization of Mn2P2S6 single-crystal nanorods and nanotubes

Mn2P2S6 single-crystal nanorods with diameters 20-40 nm and lengths up to 1 microm and nanotubes with diameters 40-50 nm and lengths ranging between 110 and 170 nm have been prepared through a low-temperature solvothermal method. They have been characterized by X-ray diffraction, transmission electron microscopy (TEM), high-resolution (HR) TEM, electron diffraction, energy-dispersive spectrometry analysis, X-ray photoelectron spectroscopy, and Raman spectroscopy.     

A new isoprenyl phenyl ether compound from mangrove fungus

A new isoprenyl phenyl ether, 3-hydroxy-4-(3-methylbut-2-enyloxy)benzoic acid methyl ester (1), together with 4-hydroxybenzoic acid (2), 2-hydroxy-6-methylbenzoic acid (3), and 4-hydroxy-3-methoxybenzoic acid (4) were isolated from Mangrove fungus (No. B60) from the South China Sea. The structures of the compounds were established on the basis of NMR spectroscopic and mass spectrometric data. In the preliminary bioassay, compound 1 exhibited antibacterial and antifungal activities. Compound 1 also inhibited cytotoxicity to the hepG2 cell line with an IC₅₀ value of 10.0 μg/mL. Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 313–314, July–August, 2007.     

Orthogonal PbS nanowire arrays and networks and their Raman scattering behavior

Three-dimensional, orthogonal lead sulfide (PbS) nanowire arrays and networks have been prepared by using a simple, atmospheric pressure chemical vapor deposition (APCVD) method. These uniform nanowires (average diameter 30 nm) grow epitaxially from the surface of the initial PbS crystal seeds and form orthogonal arrays and networks in space. The growth mechanism has been explored, and the process was classified as homogeneous, epitaxial growth in the 200 directions. Furthermore, Raman spectra of PbS nanowires are reported here, and their characteristic Raman peak (190 cm(-1), no shoulder) could be used as a unique probe for the study of PbS nanomaterials.     

（H2O）^＋n（n=1,2）的几何结构优化和振动光谱分析

采用Ｈａｒｔｒｅｅ－Ｆｏｃｋ和ＭＰ２方法在多种水平下优化了（Ｈ２Ｏ）＾＋ｎ（ｎ ＝１，２）的几何结构，并进行了振动光谱分析。结果表明：对（Ｈ２Ｏ）＾＋采用ＭＰ２／６－３１１＋＋Ｇ（ｄ，ｐ）可得出最满意的结论。