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Construction of Multi-Substituted Benzenes via NHC-Catalyzed Reactions of Carboxylic Esters

Chinese Journal of Chemistry 2018年第4期36卷 333-337页

作者： Jichang Wu Chengli Mou Yonggui Robin Chi Laboratory Breeding Base of Green Pesticide and Agricultural Bioengi- neering Key Laboratory of Green Pesticide and Agricultural Bioengi- neering Ministry of Education Guizhou University Huaxi District Gui- yang Guizhou 550025 China School of Pharmacy Guiyang College of Traditional Chinese Medicine Huaxi District Guiyang Guizhou 550025 China

A carbene-catalyzed ester activation reaction for the synthesis of multi-substituted benzenes is developed. Tetra-substituted benzene com- pounds are efficiently synthesized through this methodology. Compared with aldehyde substrates used in previous reports, the ester substrates used here are much more readily available and inexpensive. In addition, the tempo oxidant used here is more inexpensive than the quinones commonly used in related carbene-catalyzed reactions.

关键词： N-heterocyclic carbene carboxylic ester benzene synthesis organocatalysis tempo oxidation

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The Adsorption Properties of tempo Oxidized Cellulose against the Mixture of Methylene Blue and Rhemazol Yellow FG

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Journal of Renewable Materials 2024年第8期12卷 1369-1382页

作者： I.Putu Mahendra Kartika Dinita Program Studi Kimia Fakultas SainsInsitut Teknologi SumateraJalan Terusan RyacuduWay HuwiJati AgungLampung Selatan35365Indonesia

tempo/NaOCl/NaBr treatment significantly increased the number of negative charges on the cellulose *** concentrations of NaOCl,5 and 30 mmol/g of cellulose,were used in this *** number of carboxyl groups in the two cellulosic samples oxidized using tempo/NaOCl/NaBr was 0.5160 and 1.8461 mmol/g of cellulose,*** oxidized cellulose samples treated with 5 and 30 mmol/g NaOCl exhibited higher crystallinity,at 81.15%and 80.14%,respectively,compared to untreated cellulose,which had a crystallinity of 75.95%.The pH effect indicated that the highest adsorption capacity for methylene blue was achieved under alkaline conditions(pH 9),while the highest adsorption capacity for rhemazol yellow FG was achieved under acidic *** kinetic model of tempo-oxidized cellulose for methylene blue and rhemazol yellow FG conformed to the pseudo-second-order *** initial concentration parameter revealed that the isotherm model for the adsorption of methylene blue and rhemazol yellow FG by tempo-oxidized cellulose conformed to the Langmuir *** dye removal efficiencies for methylene blue and rhemazol yellow FG using tempooxidized cellulose(30 mmol/g)were approximately 80.17%and 59.52%,*** results demonstrate that tempo/NaOCl/NaBr-oxidized samples can effectively separate cationic and anionic dye ***,the use of tempo-oxidized cellulose showed good regeneration capability,maintaining more than 95%of its adsorption capacity after 8 cycles.

关键词： Cellulose tempo oxidation cationic and anionic dyes dye separation

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Effects of chitin nanocrystals on coverage of coating layers and water retention of coating color

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Journal of Bioresources and Bioproducts 2022年第3期7卷 201-210页

作者： Ruoshi Gao Yi Jing Yeyan Ni Qiwen Jiang Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources College of Light Industry and Food EngineeringNanjing Forestry UniversityNanjing 210037China

This study assessed the applicability of chitin nanocrystals prepared by 2,2,6,6-Tetramethyl-1-Piperidine-1-oxyl radical(tempo)-mediated oxidation in traditional papermaking coating color ***𝛼-chitin nanocrystals(CTNCs)with different carboxyl content,size,and morphology were prepared from crab shells by alkali pretreatment and tempo-mediated oxidation in the water at pH 10,and then the ratio of CTNCs to latex was applied to traditional coating color system to replace part of *** results showed that when the amount of NaClO added as co-oxidant in the oxidation was 15.0 mmol/g of chitin,the carboxyl content of alkali-pretreated CTNCs was up to 0.76 mmol/*** amount of carboxyl groups presented a linear relation with the degree of individualization of nanocrystals and *** the ratio of latex to CTNCs was 90꞉10,the water retention value of the coating was 92%lower than that of the pure latex system,and the rheological property was *** relationship between the addition amount of CTNCs and the surface strength and the coverage of coating layers were also studied,and results showed that when the ratio of latex to CTNCs was 95꞉5,the surface strength was the highest of 1.45 m/s,and the coverage of coating layers rate reached the highest of 78%.

关键词： Chitin tempo oxidation Nanocrystals Coating coverage Water retention

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