新型可降解丁二酸-1,4-丁二醇-1,3-丙二醇-尿素共聚物的合成与表征

以丁二酸、1,4-丁二醇、1,3-丙二醇和尿素为原料,采用熔融缩聚法制备低分子量的聚酯酰胺预聚体,以甲苯二异氰酸酯(TDI)作为扩链剂对聚酯酰胺预聚体进行扩链,得到了一系列Mw为1.0×105~1.7×105的新型可降解丁二酸-1,4-丁二醇-1,3丙二醇-尿素共聚物(聚酯酰胺),并采用流延法制备了聚酯酰胺薄膜。考察了尿素含量对聚酯酰胺热性能、结晶性能、力学性能和降解性能的影响。采用FT-IR、1H NMR、GPC、TG、DSC和XRD等对聚酯酰胺进行了表征。结果表明,随着尿素含量的增加,聚酯酰胺的熔点和热稳定性下降。尿素的加入未改变聚酯酰胺中聚酯相的晶型,但破坏了聚酯链段的规整性,使其结晶度降低。随着尿素的加入,聚酯酰胺薄膜的力学性能和降解性能不断提高。     

Synthesis,characterization and conformational transitions in copolymers of 2‐(o‐chlorophenyl)‐4‐methylene‐1,3‐dioxolane with vinyl monomers

Copolymers of 2‐(o‐chlorophenyl)‐4‐methylene‐1,3‐dioxolane with methyl methacrylate and styrene were synthesized in benzene at 85 °C in the presence of 2,2′‐azobisisobutyronitrile as initiator. The structure of the resulting copolymers was investigated and a polymerization mechanism was proposed. The intrinsic viscosity of the copolymers in dilute solutions of carbon tetrachloride was determined as a function of temperature and conformational transitions were investigated. Copyright © 2004 Society of Chemical Industry     

Synthesis and crystalline structure of polyethylene containing 1,3-cylopentane units in the main chain by ring-opening metathesis copolymerization of cycloolefins following hydrogenation reaction

Polyethylene containing 1,3-cyclopentane units in the main chain was synthesized by ring-opening metathesis copolymerization of cyclopentene (CPE) or cyclooctene with norbornene (NB) following hydrogenation reaction. The copolymer with cis-1,3-cyclopentane units was obtained in good yield. The resulting copolymers showed multiple melting points. Temperature-rising elution fractionation of the copolymers elucidated a broad distribution of the copolymer composition. WAXD and FT-IR analyses of the copolymers showed existence of hexagonal crystal in hydrogenated poly(CPE-co-NB).     

Peculiar properties of lipase fromCandida parapsilosis (Ashford) langeron and talice

A newCandida parapsilosis lipase was isolated and studied. This enzyme was purified by hydrophobic chromatography on a phenyl-sepharose CL4B column followed by gel permeation on a Sephacryl S300 HR column. It was a 160 kg·mol⁻¹ molecular-weight oligomeric enzyme. Optimal activity was obtained at 45°C and pH 6.5. The lipase activity toward various acylglycerols and esters was studied. The hydrolysis rate was greater for secondary acylesters than for primary acylesters. This lipase showed a high specificity for long-chain fatty acids and particularly for polyunsaturated fatty acids. This enzyme was able to catalyze the synthesis of various oleoylesters in aqueous medium.     

The Use of Surface Renewal and Eddy Diffusivity Theories in the Ozonation of a THM Precursor: 1,3-Cyclohexanedione

Kinetic equations derived from surface renewal and eddy diffusivity theories for fast and instantaneous kinetic regimes of absorption have been applied to the results of the ozonation of 1,3-cyclohexanedione (CYC) in water. This has allowed the determination of the rate constant of the direct reaction of ozone with CYC and the liquid phase volumetric mass transfer coefficient of the system. The results obtained are close to those reported in the preceding paper (SOTELO et al., 1991) when using the film theory. However, the ozone partial pressure necessary to reach the instantaneous kinetic regime is higher for the case of the theories applied in this work.     

1,3-二取代环己烷衍生物的结构和旋光方向

按照螺旋理论,1,3-二取代环己烷衍生物的结构中存在的二面角螺旋旋光度代数和为零,不应具有旋光性,但是它们却是光学活性的.这是由于两个取代基的吸或供电子引起了相邻化学键的电子云密度发生变化,使旋光度相应变化,从而导致旋光性.但是,一般而言,这类化合物的旋光度都比较小.     

微波辐射下一锅法合成3,4-乙撑二氧噻吩类化合物

首次从2,3-二甲氧基-1,3-丁二烯衍生物出发,微波辐射下采用一锅法成功合成了一系列3,4-乙撑二氧噻吩类化合物.实验表明,该法具有反应条件温和、收率高和操作简单的优点.3,4-乙撑二氧噻吩类化合物的结构经 ~1HNMR 、~13CNMR、IR和元素分析进行了表征.也讨论了原料的量、催化剂和溶剂对3,4-乙撑二氧噻吩(EDOT)收率的影响.     

Study of Some Experimental Parameters in the Synthesis of Triacylglycerols with CLA Isomers and Structural Analysis

The present research deals with the synthesis of structured triacylglycerols (TAG) by enzymatic treatment of sn-1,3-diacylglycerol (sn-1,3-DAG) with conjugated linoleic acid (CLA) isomers using the immobilized lipase from Rhizomucor miehei (Lipozyme^® IM) under different experimental conditions. In particular, the influence of reaction parameters, such as temperature, enzymatic load, reaction time and DAG/CLA ratio has been evaluated using an experimental design software with a screening objective. Two responses have been selected, they are the percentage of CLA isomers in total TAG and in the sn-2- position and a three-level-4-factor fractional factorial experimental design was used to screen the variables. The results showed that the selected experimental variables have an influence on the enzymatic reaction, in particular, the DAG/CLA substrate ratio and the temperature, both of which inversely correlated with CLA incorporation, but also the enzymatic load and the reaction time, both directly correlated with CLA incorporation. The best results for CLA isomer % content both in total TAG (46.3%) and in the sn-2- position (52.2%) were obtained at 40 °C for 96 h, with 20% enzymatic load and a 0.5 reactive ratio.     

发酵液中1,3-丙二醇的分离精制工艺

对微生物发酵法制得的含1,3-丙二醇的发酵液进行了分离精制,分离工艺包含脱水、脱醇、除渣、精制等过程,并得到纯度大于99.2%的1,3-丙二醇产品。研究的重点是稀释剂的选取,在分别使用乙醇、正丁醇和正戊醇为稀释剂的情况下,通过对比实验结果表明正丁醇作稀释剂的效果最好。该研究的优点是分离工艺简单、技术成熟,额外引入的试剂少且易回收,发酵液中的结晶沉渣能被有效地分离,克服了精馏时釜液起泡、结块,堵塞管线的问题,可实现连续化操作。     

Photocatalytical degradation of 1,3-dichloro-2-propanol aqueous solutions by using an immobilized TiO2 photoreactor

The photocatalytic oxidation of 1,3-dichloro-2-propanol (1,3-DCP) was studied by following the target compound degradation, the total organic carbon removal rate and by identifying the oxidation products. The reaction was performed in a batch recycle reactor, at room temperature, using UV radiation, H2O2 as oxidant, and immobilized TiO2 as catalyst. 1,3-Dichloro-2-propanone, chloroacetyl-chloride, chloroacetic acid, formic and acetic acid were detected as reaction intermediates and a possible pathway for the oxidation of 1,3-dichloro-2-propanol is proposed. The effect of the oxidative agent's initial concentration was investigated and it was established that higher concentrations of H2O2 slow down the reaction rate. The investigation of the effect of the 1,3-DCP initial concentration showed no influence on the degradation process. The carbon and chloride ion mass balance calculations confirmed the fact that chlorinated intermediates are formed and that they degrade with a lower rate than 1,3-DCP.