Study of reaction pathways of disubstituted benzene compound with ABTS●+

• Main Authors: CHEN, HSIN-YU, 陳心瑀
• Other Authors: HO, YEUNG-HAW
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/9uym7h

碩士 === 國立高雄大學 === 應用化學系碩士班 === 107 === The ABTS free radicals cation(ABTS●+) is a typical reagent that has been used to examinethe potency ofantioxidant.It is well knownthat antioxidantwill reduced ABTS●+ to ABTS. There are not many studies on the reaction path and products other than ABTS. We combined venturi electrospray ionization mass spectrometry (VESI-MS) developed by our laboratory, HPLC, and UV/Vis to investigate the reaction between ABTS●+ and disubstituted benzenes.Although these compounds are notpotentantioxidants, molecular structure is relatively simple.Interpretation of experimental results is easier than that of typical antioxidant.The goal of this research is to investigate substituent effect on the reaction path of disubstituted benzene compounds. VESI-MS is an on-line mass spectrometry method. It can simultaneously monitor the progress of reaction and identified the compound interested. However, VESI-MS cannot distinguished isomers. HPLC methods were used to analyze isomers generated in reaction. Moreover, compound has poor electrospray ionization (ESI) efficiency can also be detected by HPLC. Results obtained from reactions between benzenediol,aminophenol, and benzenediamine and ABTS●+ showed all ortho-, meta-, and para- compounds reduced ABTS●+ to ABTS. In addition, meta- compound formed a new condensation product [M+ABTS●+-H●] and other compounds. HPLC studies showed some compounds presented in reaction solution did not appear in VESI-MS spectrum, e.g., 1,2-benzoquinone. And, several signals showed in mass spectrum are isomers. The on-line capability of VESI-MS resulted in observations of two short-live intermediates during our studies. From the above results, we gained information of substituent position affectedthe reaction path of disubstituted benzenes. Reactions between meta-aniline derivatives and ABTS●+ showed a strong electron donating substituent,e.g., -OCH3, will formed ABTS and the condensation product [M+ABTS●+-H●]. As the electron donating capability decrease to medium and below, e.g., -NHCOCH3,-CH3,-COCH3,-Br, and -Cl, the reaction generated the condensation product but not ABTS. 3-Nitroaniline has a strong electron withdraw substituent and cannot react with ABTS●+. Results obtained from reactions of 1,8-diminonaphthalene,1,5-diaminonaphthalene, and 1,3-bis(aminomethyl)benzene suggested that compound with a meta-aniline sub-structure is necessary for formation of [M+ABTS●+-H●]. Catechin,epicatechin, and chyrsin, which are antioxidants contained meta-benzenediol sub-structure, reacted with ABTS●+ produced ABTS and condensation product as expected.