置換 Phenacylbromide와 Pyridine類와의 反應에 관한 溶媒와 置換基效果에 대한 硏究
- 置換 Phenacylbromide와 Pyridine類와의 反應에 관한 溶媒와 置換基效果에 대한 硏究
- Other Titles
- Substituent Effects of the Reaction of Phenacylbromides with Pyridines in Solvents
- Issue Date
- No. 1
- DMF와 MeOH 두 溶媒中에서 置換 Phenacylbromide와 Pyridine 類와의 反應速度를 電氣傳導度法으로 測定하였다. 反應速度는 Pyridine의 置換基에 對해서는 Electron-releasing 能力이 클수록 빨랐으며 Phenacylbromide 類에 對해서는 그 反對였다. 또 MeOH 中에서 反應速度가 빨랐으며 等速關係와 Bro¨nsted plot에서는 좋은 直線關係를 보였고 Hammett plot에서도 4-NH_2, 4-CN 基를 除外하고는 S_N-2 反應 특징인 좋은 相關性을 얻었다. 實驗結果를 分析해 보고 反應 Mechanism을 檢討해 보았다.
The rates of the reaction of substituted phenacylbromides with pyridines in MeOH and DMF were measured by electric conductivity method. The effect of substituents and solvents o the reaction were discussed. The rates of reaction were increased with the electron releasing power of substituents of pyridine and the results were more increased in DMF than MeOH. The isokinetic relationship was seen between E_a^‡ and ΔS^‡, it's temperature was 401°K in MeOH and 202°K in DMF. Br nsted linearelationship was shown as logK=0.31 PKa-2.65 in MeOH at 45℃ logK=0.36 PKa-1.79 in DMF at 45℃ The Hammett plot showed a linearity about substituents except 4-NH_2, 4-CN. This deviation of above 2 groups were considered to be attributed to the localization of π-electron on pyridine ring induced by the nitrogen atom, resonance effect, and solvent effect. From above results and the reports of Baker, Hughes, and Peason, It was considered that this reaction was S_N-2 mechanism in which nucleophile simultaneously attacks between the carbonyl group and α-carbon to form π-complex.
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