치환된 피리딘과 메틸토실레이트 반응에 대한 양성자친화력과 친핵도와의 상관관계 = Correlation of Proton Affinity with Nucleophilicity for the Reaction of Substituted Pyridines with Methl tosylate

다국어 초록 (Multilingual Abstract)

A correlation between the gas phase intrinsic nucleophilicity which is excluded the environmental trends surrounded the reactants and the solution phase observed nucleophilicity which is varied by the substituents has been studied by means of kinetic method to quantitate the reactivity variation based on a relative magnitude of nucleophilicity from the nucleophilic substitution reaction in solution.
1. The second rate constants were observed as the order of magnitude as α-picoline < pyridine < β-picoline < γ-picoline in any solvent system from the reaction of 2, 3, and 4 methyl substituted pyridines with methyl tosylate in pure protic and dipolar aprotic solvent systems. The rate constants of α-picoline were observed very low and it was explicated that the nucleophilic ability of nitrogen atom in α-picoline was decreased by means of steric effect of methyl radical substituted to α-position of pyridine.
2. The correlations between gas phase basicity(GB), proton affinity(PA) and the nucleophilicity of solution phase to interrelate for the intrinsic nucleophilicity with reactivity of solution phase was discussed. The result showed that a good correlation exhibited GB and PA were increased with Swain-Scott's nucleophilicity and Edwards' nucleophilicity without α-picoline.
3. The steric retardation factors(SRF) which were calculated from a difference of the theoretical nucleophilicity to exclude the steric retardation effect and the observed nucleophilicity were showed as 0.42∼0.79 and 0.28∼0.51 and those values were shown lover than other nucleophilic substitution reaction of solution.
4. The negative(-) charge of nitrogen atom in the nucleophile was shown to move highly to the oxygen atom of methyl tosylate, the substrate in the reaction of γ-picoline with methyl tosylate and the transition state was shown to stabilize at the early state.
While the methyl radical was removed from the substrate in the reaction of α-picoline with methyl tosylate at the early state.
5. The order of magnitude of rate constants was shown as methanol> ethanol > acetonitrile> acetone from the results of solvent effect on the reactivity .
An early transition state which was formed the hydrogen bond between methanol molecular and tosylate, the leaving group of methyl tosylate was stabilized in the reaction of methyl tosylate with substituted pyridines in methanol.
While the self ionization ability of the reactants deactivated in the reaction path to move from the ground state to transition state in dipolar aprotric solvent, such as acetone.

목차 (Table of Contents)

• 목차
• Ⅰ. 서론 = 1
• Ⅱ. 실험 = 4
• 1. 시약 및 기구 = 4
• 2. 반응속도상수의 결정 = 5
• Ⅲ. 결과 및 고찰 = 8
• 1. 치환 위치 변화에 따른 친핵도와 반응성의 상관관계 = 8
• 2. 친핵성치환반응에 미치는 용매효과 = 25
• Ⅳ. 결론 = 29
• References = 31
• Summary = 33