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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 39, Number 8
JKCSEZ 39(8)
April 20, 1995 

 
Title
Oxidation of Benzyl Ethers in Sodium Hypochlorite Mediated Piperidine-1-oxyl System

촉매량의 Piperidine-1-oxyl과 NaOCl계에서 벤질 에테르 유도체들의 산화 반응
Author
Nam Sook Cho*, Chan Heun Park

조남숙*, 박찬헌
Keywords
Abstract
여러가지 비대칭 벤질 에테르들과 벤질 알킬 에테르들을 CH3CO2Et-NaOCl수용액 (6.6 mol eq.)의 2상 용매계에서 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (0.03 mol eq., 4-methoxy-TEMPO)을 이용하여 산화시키면 벤조에이트로 산화가 일어난다. 4-methoxy-TEMPO는 2차 산화제인 NaOCl에 의하여 본 반응의 산화제인 N-oxo-4-methoxy-2,2,6,6-tetramethy-lpiperidium 염 (N-oxoammonium 염)으로 변환된다. N-oxoammonium 염은 에테르를 산화시키고 N-hydroxy-4-methoxy-2,2,6,6-tetramethylpiperidine(hydroxy-amine)으로 환원된다. Hydroxy-amine은 NaOCl에 의하여 N-oxoammonium 염으로 순환 재생되므로 4-methoxy-TEMPO는 촉매량 사용하였다. 이 반응은 또한 조촉매인 KBr(0.03mol eq.)가 필수적이고 반응 중 pH는 8.0 이하로 유지되어야 한다. 0~5℃의 반응 온도로 2.5시간 반응시키면 대부분 벤조에이트로 산화되었다. 벤질 알킬 에테르들의 선택성 산화는 수소의 산도와 알킬기의 입체효과에 영향을 받음이 고찰되었다.

The oxidation of various benzyl ethers and benzyl alkyl ethers to benzoates has been studied in two-phase system of CH3CO2Et and aqueous NaOCl (6.6 mol eq.). The oxidant N-oxo-4-methoxy-2,2,6,6-tetramethylpiperidium bromide (N-oxoammonium salt) was prepared in situ and recycled by addition of 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (0.03 mol eq., 4-methoxy-TEMPO), co-catalyst KBr (0.03mol eq.) and second oxidant NaOCl. Thus the catalytic amount of 4-methoxy-TEMPO was used. An adjustment of the pH value of below 8.0 was also required for this reaction with 2.5 hr of reaction time at 0∼5℃. Under these conditions benzyl ethers were oxidized to benzoates. The selectivity of oxidation of benzyl alkyl ethers is dependent on the acidity of hydrogen and steric effect of alkyl group.

Page
657 - 665
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