两亲性丙烯酸酯共聚物的聚合研究

利用过氧化苯甲酰为引发剂探讨了甲基丙烯酸β－羟乙酯和丙烯酸长链烷基酯的自由基共聚合。重点讨论了合成条件如溶剂、沉淀剂、引发剂用量、单体配比、反应时间等对共聚反应的影响以及各种聚合条件对该共聚物的组成、结构和性能的影响。并用ＩＲ，ＧＰＣ，＾１３ＣＮＭＲ等手段对共聚物进行了表征。     

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.     

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.     

制备trans-Fe(CO)_3(PR_3)_2的新的取代过程

报道了用H_2Fe(CO)_4制备trans-Fe(CO)_3(PR_3)_2的新的羰基取代反应。在 过量质子存在下，H_2Fe(CO)_4中的羰基被活化，中心铁原子对膦的亲核进攻更为 敏感。在这种条件下H_2Fe(CO)_4与膦反应时，首先失去氢生成Fe(CO)_4(PR_3), Fe(CO)_4-(PR_3)再与第二个膦反应可高产率的得到trans-Fe(CO)_3(PR_3)_2。用 PPh_3与Fe(CO)_4(PPh_3)在过量质子存在下反应生成trans-Fe(CO)_3(PR_3)_2，证 实了上述过程。     

可回收(S)-脯氨醇衍生物在催化查尔酮类化合物不对称环氧化反应中的催化性能研究

将以L-脯氨酸为原料合成的光学活性脯氨醇衍生物((S)-2-吡咯烷基-α,α-二(α-萘基)甲醇1),作为有机小分子催化剂,在催化8种α,β-不饱和酮的不对称环氧化反应中表现出较好的立体选择性(58.0~84.6?)和催化活性(58.0~89.7%).反应结束后,通过简单的酸碱调整,可使催化剂回收和重复使用.循环使用5次,催化剂的回收率均在93~97%之间,催化剂的催化活性和立体选择性无明显改变.     

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.     

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.     

Synthesis, Crystal Structure and Electrochemistry Properties of a (N,N'-Ethylene-bis(salicylaldiminato)) Nickel(Ⅱ) Complex, [Ni2(salen)2]·NCS-NH4

A new Ni(Ⅱ) complex [Ni2(salen)2]·(NCS)·NH4 (salen = N,N'-bis(salicylidenea-mino)ethanato) has been prepared and structurally characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group Pbca with a = 16.8725(13), b = 19.0046(15), c = 20.0583(16) (A), Z = 8, V = 6431.8(9) (A)3, C33H32N6Ni2O4S1, Mr= 726.13, Dc = 1.500 g/cm3, F(000) = 3008, μ = 1.284 mm-1, the final R = 0.0394 and wR = 0.0767 for 4449 observed reflections with Ⅰ＞2σ(Ⅰ). The complex involves a N,N'-ethylene-bis(salicylaldiminato) Schiff base, an isothiocyanato anion and an ammonium cation. The nickle(Ⅱ) ion adopts a distorted square coordination geometry with N2O2 set of Schiff base ligand. The complexes are linked into a dimmer via intermolecular hydrogen bonds and the [Ni(salen)] moieties are connected together to form a 2-D layer structure by intermolecular N-H…O hydrogen bonds and π-π stacking. Cyclic-voltammetry method was used to characterize electrochemically the complex.