Study Effect of Reaction Condition on o-Phenylenediamine and Benzaldehyde by VESI/MS

• Main Authors: Ming-Ju Wu, 吳銘儒
• Other Authors: Yeung-Haw Ho
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/39968891871777057177

碩士 === 國立高雄大學 === 應用化學系碩士班 === 104 === Benzimidazole compound synthesis reactions have been many studies, however, these studies have focused on offline in order to explore the selective product. In this study, the use of Venturi Electrospray Ionization Mass Spectrometry ( VESI-MS) for online real-time analysis, change trend generate major component observation o-phenylenediamine and benzaldehyde under different synthesis conditions benzimidazole, discussion reaction conditions included changing the solvent, the substituents o-phenylenediamine and benzaldehyde on acid catalysis conditions. Methanol as solvent, displayed within 60 minutes of the observation time is gradually reduced after the intermediate product quickly generate, along with the mono-substituted product is increased, di-substituted product will not change significantly. When changed to ethanol and water as a solvent, change trend of the various components will be different, but the intermediate change in water no too much. When the BA of number 4 carbon positions at different substituents replacement, -CN and -Cl electron-withdrawing substituents can inhibit the synthesis reaction, and the inhibitory effect -CN group is stronger than the -Cl group. Instead, electron-donating substituents -CH3 can accelerate the reaction. If o-PD of –H on the 4th carbon position replace with –CH3, it will slow down the rate of reaction. When o-PD and CH3-BA reaction, the carbon on the 4th replace on the 3rd -CH3 change on carbon, can also cause changes in the rate of formation of the intermediate product. Adding an acid to o-PD and CN-BA reaction solution can significantly increase the rate of reaction, trifluoroacetic acid (TFA) to accelerate the reaction rate is better than the effect of acetic acid, but TFA and CN-BA will be side effects. This study successfully demonstrated VESI-MS can be used as real-time changes in the components of online instant detection of benzimidazole synthesis, results show that solvent, substituent, acid will affect the reaction rate. A compound of changes observed in this study was based on intensity change in a particular ion mass spectrum, it does not represent the actual yield of the compound, and therefore can not directly affect the results of the comparison with the known synthetic conditions on the product selectivity to do