Elimination Reactions of Aryl Furylacetates Promoted by R2NH-R2NH2+ in 70 mol% MeCN(aq). Effects of β–Aryl on the Ketene-Forming Transition-State

Bulletin of the Korean chemical society

Bong Rae Cho¹  Sang Yong Pyun¹  Ju Chang Kim¹ 

关键词: Elimination;    E2 and E1cb Mechanism;    –Aryl Group effect;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

Ketene-forming elimination from 2-X-4-nitrophenyl furylacetates (1a-d) promoted by R2NH-R2NH2 + in 70 mol % MeCN(aq) has been studied kinetically. When X = Cl and NO2, the reactions exhibited second-order kinetics as well as Brönsted β = 0.37-0.54 and |βlg| = 0.31-0.45. The Brönsted β decreased with a poorer leaving group and |βlg| increased with a weaker base. The results are consistent with an E2 mechanism. When the leaving group was changed to a poorer one [X= H (1a) and OCH3 (1b)], the reaction mechanism changed to the competing E2 and E1cb mechanisms. A further change to the E1cb mechanism was realized for the reaction of 1a with i-Pr2NH/i-Pr2NH2 + in 70 mol % MeCN-30 mol % D2O. By comparing the kinetic results in this study with the existing data for ArCH2C(O)OC6H3-2-X-4-NO2, the effect of the β-aryl group on the ketene-forming elimination was assessed.

【 授权许可】

Unknown