Different techniques are being developed for fabricating microcapsules; it is still a challenge to fabricate them in an efficient and environment‐friendly process. Here, a one‐step green route to synthesize silk protein sericin‐based microcapsules without any assistance of organic solvents is reported. By carefully changing the concentration of calcium ions accompanied with stirring, the morphology of the microcapsules can easily be regulated to form either discoidal, biconcave, cocoon‐like, or tubular structures. The chelation of Ca2+ and shearing force from agitation may induce the conformational transformation of sericin, which possibly results in the formation of microcapsules through the self‐assembly of the protein subsequently. The as‐prepared cocoon‐like microcapsules exhibit pH‐dependent stability. A potential application of microcapsules being fabricated from natural water‐soluble silk protein sericin for controlled bioactive molecules loading and release system by a pH‐triggered manner is quite feasible.
A simple sol‐gel method with and without surfactant was applied to prepare TiO2‐ZrO2 mixed oxides containing Ti and Zr at a molar ratio of 1:1. Several catalysts containing w=15% –35% H3PO4 were set up using these mixed oxides. The physical and chemical properties of catalysts were investigated by BET, SEM and pyridine adsorption‐desorption. The catalytic performance of each material was determined for the vapor‐phase acylation of veratrole (1,2‐dimethoxybenzene) to 3,4‐dimethoxyacetophenone (3,4‐DMAP), which was found to be the major product of the reaction of veratrole with ethyl acetate, with alkylated products being the minor products. 2,3‐Dimethoxyacetophenone (2,3‐DMAP) was not detected in the product stream. In the best experimental conditions, the alkylated products were less than 0.7%. This reaction may represent an environmentally friendly alternative to use the ethyl acetate as the acylating reagent. The feed molar ratios of veratrole/ethyl acetate were varied over a wide range of 0.1 to 1, and the optimum feed ratio of veratrole/ethyl acetate was 1:3. Space velocity employed in the veratrole acylation reported as WHSV (veratrole) was 1.2 h?1. The acylation reactions were carried out in the temperature range of 423 to 673 K and the optimum H3PO4 content for acylation was w=15%. 相似文献
The rising interest in advances of sustainable and greener synthetic approaches has encouraged chemists to investigate novel methods to stimulate organic compounds. The benzyl alcohol and its derivatives are industrially significant chemicals owing to their huge applications in petrochemical industries. In this context a green and sustainable approach for synthesis of Chloro substituted benzyl alcohols has been established. In present research paper cyclic voltammetry study followed by constant current electrolysis and characterization of synthesized 2-Chlorobenzyl alcohol, 3-Chlorobenzyl alcohol, 4-Chlorobenzyl alcohol and 2,4-Dichlorobenzyl alcohol has been reported. Cyclic voltammetry measurements have been employed to setup optimum conditions for electrolysis and to find out electrochemical nature of various Chloro substituted benzaldehydes. Then these results have been judiciary used to carry out electrochemical reduction of various Chloro substituted benzaldehydes using constant current electrolysis. Influence of scan rate and pH on reduction peaks has also been investigated referring irreversible electron transfer phenomenon in basic medium. The kinetic parameters for reduction reactions have been estimated showing the process under the influence of diffusion control. The characterization of electrochemically synthesized 2-Chlorobenzyl alcohol, 3-Chlorobenzyl alcohol, 4-Chlorobenzyl alcohol and 2,4-Dichlorobenzyl alcohol has been done by using spectroscopic techniques such as IR, 1HNMR and Mass spectral analysis. This has a scientific achievement in terms of the obtained products (2-Chlorobenzyl alcohol, 3-Chlorobenzyl alcohol, 4-Chlorobenzyl alcohol and 2,4-Dichlorobenzyl alcohol) and their derivatives which are industrially and pharmaceutically significant chemicals owing to their huge applications in petrochemical industries and medical sectors. Throat lozenges containing dichlorobenzyl alcohol (DCBA) are used for treatment of respiratory tract infections. 相似文献
An environmentally benign and efficient approach for the synthesis of 4-arylcoumarins from ortho-hydroxy cinnamate ester derivatives with aryl iodides was developed in water under aerobic conditions. This transformation proceeds through a palladium catalyzed Heck-arylation/cyclization cascade reaction. The present protocol features a wide substrate scope and readily available starting materials to afford the desired products in high to excellent yields. 相似文献
One‐pot multicomponent reactions are very demanding in synthetic organic chemistry. Here we report a new polystyrene‐supported cerium catalyst (PS‐Ce‐amtp) obtained via an easy two‐step procedure, which was thoroughly characterized using various techniques. PS‐Ce‐amtp catalyses the environmentally benign one‐pot multicomponent synthesis of spiro‐piperidine derivatives through the reaction of substituted aniline, cyclic active methylene compound and formaldehyde at room temperature. The catalyst also exhibits excellent catalytic activity in one‐pot synthesis of 1,4‐disubstituted 1,2,3‐triazoles via click reaction between in situ generated azides (derived from anilines and amines) and terminal alkynes. The catalyst can be recovered easily after reaction and reused five times without significant loss in its catalytic activity. The advantageous features of this catalyst are atom economy, operational simplicity, short reaction times, easy handling and high recycling efficiency. 相似文献
It is proved that the Hausdorff measure on the limit set of a finite conformal iterated function system is strongly extremal, meaning that almost all points with respect to this measure are not multiplicatively very well approximable. This proves Conjecture 10.6 from (on fractal measures and Diophantine approximation, preprint, 2003). The strong extremality of all (S,P)-invariant measures is established, where S is a finite conformal iterated function system and P is a probability vector. Both above results are consequences of the much more general Theorem 1.5 concerning Gibbs states of Hölder families of functions. 相似文献