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81.
Parisa Faibunchan Skulrat Pichaiyut Wannarat Chueangchayaphan Claudia Kummerlwe Norbert Venneman Charoen Nakason 《先进技术聚合物》2019,30(4):1010-1026
Green biodegradable thermoplastic natural rubber (GB‐TPNR) based on simple blend of natural rubber (NR) and poly(butylene succinate) (PBS) was prepared using three NR alternatives: unmodified NR and epoxidized NR with 25‐ or 50‐mol% epoxide (ie, ENR‐25 or ENR‐50). It was found that ENR‐50/PBS blend showed the best compatibility, which resulted in superior mechanical and thermal properties with the highest crystallinity of the PBS phase, on comparing with the ENR‐25/PBS and NR/PBS blends. This might be attributed to stronger chemical interactions between the epoxide groups in ENR‐50 and the polar functional groups in PBS, which were confirmed by Fourier transform infrared (FTIR). Furthermore, scanning electron microscopy (SEM), atomic force microscopy (AFM), and polarizing optical microscopy (POM) micrographs of ENR‐50/PBS blend revealed phase separation with finer‐grained cocontinuous structure than in ENR‐25/PBS and NR/PBS simple blends. Furthermore, the chemical interactions in ENR‐50/PBS blend enhanced the resistance to accelerated weathering. 相似文献
82.
83.
Bin Zhou Faridoon Xiaobo Tian Jian Li Dongliang Guan Xing Zheng Yu Guo Wei Huang 《中国化学快报》2018,29(7):1123-1126
Here, we reported a new approach of on-resin peptide ligation using C-terminal benzyl ester as the stabilized precursor of thioester, which enables both N-terminal elongation and C-terminal peptide ligation on a Rink Amide resin. 相似文献
84.
[60]Fullerene-fused pyrazolines 1 were prepared by the reaction of C60 with alky diazoacetates under the solid-state high-speed vibration milling conditions as well as in toluene solution. Pyrazolines 1 were stable in refluxing toluene and its thermolysis process in 1,2-dichlorobenzene was investigated, the decomposition rates and activation energies of pyrazolines 1 were obtained. The current work demonstrated that the liquid-phase reaction of C60 with alkyl diazoacetates undergoes via 1,3-dipolar cycloaddition pathway at room temperature, or proceeds via carbene mechanism at a temperature of refluxing toluene, thus clarifies the previous ambiguity of its reaction mechanism. 相似文献
85.
Svitlana V. Shishkina Irina S. Konovalova Sergiy M. Kovalenko Dmitriy V. Kravchenko Natalya D. Bunyatyan 《Acta Crystallographica. Section C, Structural Chemistry》2021,77(1):40-48
Being a close analogue of amflutizole, methyl 4‐amino‐3‐phenylisothiazole‐5‐carboxylate (C11H10N2O2S) was assumed to be capable of forming polymorphic structures. Noncentrosymmetric and centrosymmetric polymorphs have been obtained by crystallization from a series of more volatile solvents and from denser tetrachloromethane, respectively. Identical conformations of the molecule are found in both structures. The two polymorphs differ mainly in the intermolecular interactions formed by the amino group and in the type of stacking interactions between the π‐systems. The most effective method for revealing packing motifs in structures with intermolecular interactions of different types (hydrogen bonding, stacking, dispersion, etc.) is to study the pairwise interaction energies using quantum chemical calculations. Molecules form a column as the primary basic structural motif due to stacking interactions in both polymorphic structures under study. The character of a column (straight or zigzag) is determined by the orientations of the stacked molecules (in a `head‐to‐head' or `head‐to‐tail' manner). Columns bound by intermolecular N—H…O and N—H…N hydrogen bonds form a double column as the main structural motif in the noncentrosymmetric structure. Double columns in the noncentrosymmetric structure and columns in the centrosymmetric structure interact strongly within the ab crystallographic plane, forming a layer as a secondary basic structural motif. The noncentrosymmetric structure has a lower density and a lower (by 0.59 kJ mol?1) lattice energy, calculated using periodic calculations, compared to the centrosymmetric structure. 相似文献
86.
Electrolysis of dimethyl malonate or methyl cyanoacetate in methanol in the presence of LiCl in an undivided cell leads to formation of 1,1,2,2-cyclopropanetetracarboxylic derivatives.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1835–1836, October, 1994.This work was supported by the International Science Foundation (Grant No MHY 000). 相似文献
87.
Monodisperse, reactive hydrogel microspheres were prepared by precipitation polymerization ofp-nitrophenyl acrylate (NPA) with acrylamide, methacrylic acid, and methylenebisacrylamide in ethanol. The size of microspheres was controlled by the monomer ratio. Some fraction of reactive ester decomposed during the polymerization. The reactive hydrogel microspheres were converted to amphoteric ones by the reaction of NPA units with diamine. The isoelectric point of the amphoteric microspheres was around 4.0, but it was different from the pH at which the microspheres have the minimum size or the most shrunken state. This was attributed to the uneven distribution of induced amine groups. 相似文献
88.
Calorimetric measurements were carried out on ester-solvent systems where the esters were H(CH2)xCOO(CH2)yH, with x and y varying from 1 to 5, and the solvents were n-hexane and 1,2-dichloroethane. Calculation of the enthalpies of cavity formation enabled the enthalpies of interaction to be determined. Both enthalpies correlated with number of carbon atoms N, equal to x+y in the esters, giving for 1,2-dichloroethane
相似文献
89.
磷酰氨基酸的酯交换反应研究 总被引:1,自引:0,他引:1
本文利用^3^1P NMR , 对比研究了磷酰化组氨酸与其它磷酰化氨基酸和一级醇的磷上酯交换的反应速度,实验表明磷酰化组氨酸的反应速度最快. 由此提出了以下机理:由于咪唑环的参与,磷可以形成六配位过渡态,从而加快了反应速度. 相似文献
90.
室温下SmI2-THF-HMPA-t-BuOH体系可顺利地将二硫代氨基甲酸酯还原断裂得到二硫醚和硫代甲酰胺; 同样条件下, 硫代氨基甲酸酯还原断裂得到二硫醚篅34The reductive cleavage of dithiocarbamic esters are promoted by the SmI2-HMPA-THF-t-BuOH System successfully to give disulfides and thiocarboxamides at room temperature in good yields; The reduction of thiocarbamic esters are also promoted by the same system to give disulfides and carboxamides. 相似文献
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