화학공학소재연구정보센터
홈 로그인 로그아웃 연락처 사이트맵
Applied Chemistry for Engineering, Vol.25, No.6, 648-653, December, 2014
Export Citation
크롬(VI)-헤테로고리 착물(2,4’-비피리디늄 클로로크로메이트)에 의한 치환 벤질 알코올류의 산화반응에서 속도론과 메카니즘
Kinetics and Mechanism of the Oxidation of Substituted Benzyl Alcohols by Cr(VI)-Heterocyclic Complex (2,4’-Bipyridinium Chlorochromate)
박영조, 김영식†
  • 강원대학교 화학공학과
Young Cho Park, and Young Sik Kim†
  • Department of Chemical Engineering, Kangwon National University, Gangwon-do 245-711, Karea, Korea
E-mail:
초록
크롬(VI)-헤테로고리 착물(2,4’-비피리디늄 클로로크로메이트)을 합성하여, 적외선 분광광도법(IR), 유도결합 플라즈마 (ICP) 등으로 구조를 확인하였고, 여러 가지 용매 하에서, 2,4’-비피리디늄 클로로크로메이트를 이용하여 벤질알코올의 산화반응을 측정한 결과, 유전상수값의 증가에 따라 반응도 증가했다는 것을 보였다. 그 순서는 : N,N-디메 틸포름아미드(DMF) > 아세톤 > 클로로포름 > 시클로헥센산 촉매(HCl)를 이용한 DMF 용매 하에서, 2,4’-비피리디늄 클로로크로메이트은 벤질 알코올(H)과 그의 유도체들(p-CH3, m-Br, m-NO2)을 효과적으로 산화시켰다. 전자받개 그룹들은 반응 속도가 감소한 반면에 전자주개 치환체들은 반응속도를 증가시켰고, Hammett 반응상수(ρ) 값은 -0.67 (303 K)이었다. 속도결정단계에서 크로메이트 에스테르의 형성과정을 거친 후, 양성자 전이가 일어났다.
Cr(VI)-heterocyclic complex (2,4’-bipyridinium chlorochromate) was synthesized by the reaction between heterocyclic compound(2,4’-bipyridine) and chromium trioxide, and characterized by IR and ICP analysis. The oxidation of benzyl alcohol using 2,4’-bipyridinium chlorochromate in various solvents showed that the reactivity increased with the increase of the dielectric constant (ε), in the order : N,N-dimet-hylformamide (DMF) > acetone > chloroform > cyclohexene. In the presence of DMF solvent with acidic catalyst such as hydrochloric acid (HCl solution), 2,4’-bipyridinium chlorochromate oxidized benzyl alcohol (H) and its derivatives (p-CH3, m-Br, m-NO2). Electron-donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. The Hammett reaction constant (ρ) was -0.67 (303 K). The observed experimental data have been rationalize the proton transfer occurred followed the formation of a chromate ester in the rate-determining step.
Keywords:chromate ester;hydride ion transfer;Hammett reaction constant(ρ);rate-determining step. substituted benzyl alcohol.
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