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RISS 인기검색어
- 검색키워드
- 저자 : Hu Guoqin (검색결과 8 건)
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Hu, Guoqin,Li, Hua,Liu, Juan,Zhu, Jiang Korean Chemical Society 2011 대한화학회지 Vol.55 No.4
CTAB 혹은 CTAB-나피온 촉매를 속빈 실리콘 튜브형 MCM-41에 담지시켰다. 이들 촉매들을 XRD, SEM, BET 등으로 분석하였다. 이들을 1,7-heptanediol 의 브롬화 반응 촉매로 사용하였고 다른 촉매들과 비교하였다. 이들 촉매들은 CTAB 보다 효과가 좋았으며 CTAB-Nafion/MCM-41 이 성능이 가장 우수하였다. CTAB or CTAB-Nafion catalyst were successfully supported on siliceous hollow tubular MCM-41 which synthesized by hydrothermal method using CTAB as a single template or CTAB and Nafion-Na as mixed templates. The properties of two kinds of catalysts were characterized with XRD, SEM and adsorption and desorption isotherms of nitrogen and pore diameter distribution, respectively. Then they were applied to catalyze brominating reaction of 1,7-heptanediol, moreover the rate of brominating reaction with different catalysts was compared. The results showed that catalytic activities of CTAB/MCM-41 and CTAB-Nafion/MCM-41 are better than CTAB, and that of CTAB-Nafion/MCM-41 is the best because of its phase-transfer and strong acidity function. The two kinds of catalysts can be separated from the reactive products and recycled.
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Hua, Li,Guoqin, Hu,Dan, Li Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.11
Due to the importance of isoflavone content in soybean extracts, the microwave-assisted process (MAP) was compared to the conventional extraction methods. For comparison of the three methods, all extraction parameters (solvent, sample to solvent ratio, temperature, etc.) were kept the same; the microwave extractor was operated at 187.5 W with an emission frequency of 2450 MHz under atmospheric pressure conditions and the extractions were carried out at 75 ${^{\circ}C}$ for 3 min while the conventional reflux was at 75 ${^{\circ}C}$ for 3 h. Total yield and crude isoflavone content were determined by ultraviolet spectrophotometric and compared with the three methods. Results indicated that the MAP was comparable to the conventional method in its capability to extract target compounds without causing any degradation; in addition it dramatically reduced the extraction time from 3 h to a few minutes, suggesting that it can be an alternative technique to the time-consuming conventional reflux method.
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Hua, Li,Guoqin, Hu,Dan, Li Korean Chemical Society 2009 대한화학회지 Vol.53 No.4
대두 잔기로부터 유기용매를 사용하여 이소플라본을 추출하는 열역학적 메카니즘을 조사하였다. 대두 잔기로부터 유기용매를 사용한 이소플라본 추출과정에서의 분배 계수를 결정하기 위한 간단한 모델을 설정하고 $K,\;{\Delta}H^0,\;{\Delta}S^0\;and\;{\Delta}G^0$ 간에 열역학적 함수를 계산하였다. 그 결과 대두 이소플라본 추출은 흡열과정이며 엔트로피 증가과정임을 발견하였다. 온도가 증가할수록 ${\Delta}G^0$가 감소하였다. The thermodynamical mechanism of the extraction of soybean isoflavones from soybean residuals using organic solvent method has been studied. On the basis of experiments, a simple model for determining the distribution coefficients in organic solvent extraction was employed to calculate the thermodynamical functions between $K,\;{\Delta}H^0,\;{\Delta}S^0\;and\;{\Delta}G^0$ in the soybean isoflavones extraction process. The results show that the soybean isoflavones extraction is an endothermic and an entropy-increasing process: the ${\Delta}G^0$ decreases when the temperature arises.
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Li Hua,Hu Guoqin,Li Dan 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.11
Due to the importance of isoflavone content in soybean extracts, the microwave-assisted process (MAP) was compared to the conventional extraction methods. For comparison of the three methods, all extraction parameters (solvent, sample to solvent ratio, temperature, etc.) were kept the same; the microwave extractor was operated at 187.5 W with an emission frequency of 2450 MHz under atmospheric pressure conditions and the extractions were carried out at 75 oC for 3 min while the conventional reflux was at 75 °C for 3 h. Total yield and crude isoflavone content were determined by ultraviolet spectrophotometric and compared with the three methods. Results indicated that the MAP was comparable to the conventional method in its capability to extract target compounds without causing any degradation; in addition it dramatically reduced the extraction time from 3 h to a few minutes, suggesting that it can be an alternative technique to the time-consuming conventional reflux method.
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Dissolution Kinetics of Thiourea in Triglycol Solution
Li, Hua,Guo, Feng,Hu, Guoqin,Zhao, Lei,Zhang, Yadong Korean Chemical Society 2010 대한화학회지 Vol.54 No.1
이소프로필 멀케푸탄은 중요한 약품 중간체이며 싸이오우레아와 트리글리콜은 이소프로필 멀케푸탄을 합성을 하는데 중요한 화합물이다. 그러므로 트리글리콜 용액에서의 싸이오우레아의 용해는 이소프로필 멀케푸탄의 생산에 중요하다. 트리글리콜용액에서 싸이오우레아의 용해 반응속도론을 조사하고 이소프로필 멀케푸탄을 생산하는 대체 공정을 제시하는것이 본 연구의 목적이다. 트리글리콜용액에서 싸이오우레아의 용해 반응속도론을 조사하기 위하여 용액 농도와 반응 온도를 중점적으로 관찰하였다. 싸이오우레아의 용해속도는 용액농도와 온도가 증가할수록 증가하였다. Isopropyl mercaptan is an important pharmaceutical intermediate and chemical material. And thiourea and triglycol are the main materials for the synthesis of isopropyl mercaptan. Therefore the dissolution of thiourea in triglycol solution is very important for the production of isopropyl mercaptan. The aims of this study are to examine the dissolution kinetics of thiourea in triglycol solution, and to present an alternative process for producing isopropyl mercaptan. In order to investigate the dissolution kinetics of thiourea in triglycol solution, the concentrations of solution and reaction temperature were selected as experimental parameters. It was determined that the dissolution rate of thiourea increased with the increase in solution concentration and temperature. An empirical equation was used in fitting the data. Statistical analysis indicated small errors and the results should be reliable.
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Preparation of 2,3,4,5-Tetrafluorobenzoic Acid
Li, Hua,Wang, Hongkai,Zhao, Ruiju,Liu, Juan,Zhao, Zhengui,Hu, Guoqin,Liang, Zhengyong Korean Chemical Society 2010 대한화학회지 Vol.54 No.6
Fluoroquinolone 항생제의 중요한 중간체인 2,3,4,5-tetrafluorobenzoic acid를 tetrachloride phthalic anhydride에서 출발 하여 imidation, fluorination, hydrolysis과 decarboxylation단계를 거쳐서 합성하였다. Imdation 단계에서는 상전이 촉매를 이용하여 98.2%의 수율로 합성하였으며, fluorination 단계에서는 81.3%, 가수분해 단계에서는 88.6%, 마지막으로 decarboxylation단계에서는 81.6%의 수율로 합성하였다. 2,3,4,5-Tetrafluorobenzoic acid, an important intermediates of fluoroquinolone antibiotics, was synthesized from tetrachloride phthalic anhydride through imidation, fluorination, hydrolysis and decarboxylation. The effects of phase transfer catalyst on imidation and fluorination reaction and the effects of surfactants on the hydrolysis reaction were studied, respectively. Experimental results showed that the imidation reaction time was greatly reduced in the presence of a phase transfer catalyst, hexadecyltrimethyl, resulting in imidation yield as high as 98.2%. The fluorination yield reached 81.3% when tetrabutylammonium bromide was chosen as a phase transfer catalyst. The hydrolysis reaction time was also decreased by adding hexadecyltrimethyl while increasing the yield to 88.6%. In the post-processing, the sublimation method was used to purify the product, and ideal effect was obtained. In the decarboxylation reaction, tetrafluoride phthalic acid was obtained by decarboxylation in the solvent of tri-n-butyl amine and decarboxylation yield reached 81.6%. Compared with the literature method, the overall reaction time of the improved method decreased from 53 h to 20.5 h and the total yield increased from 47.3% to 57.4%.
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