크로세酸의 아조커플링 反應에 關한 硏究 = A Study on the Azocoupling Reaction of Croceic Acid

다국어 초록 (Multilingual Abstract)

The azocoupling reactions of Croceic acid with several monosubstituted benzenediazonium salts have been studied kinetically in an aqueous solution buffered at pH 7.10 and in some other medium conditions.
The fact that the rate of coupling reaction depends on the ionic strength and pH of the medium shows that the reaction is followed by Bartlett's ionic mechanism explaining the reaction between naphtholate ion and diazonium ion.
Base catalysis of pyridine on the azocoupling of Croceic acid with p-nitro and p-methylbenzenediazonium salts indicates the dependence of this reaction on two step processes.
We also observed that the effect of steric hindrance in the molecule of Croceic acid as well as G-acid decreases the reaction rate of the coupling of Croceic acid as compared with Cassella's acid and N.W. acid.
In the aqueous solution mixed with 20~80% of DMSO and THF respectively, the rate of the coupling of Croceic acid increases according to the increased concentration of the aprotic solvent, and the solvent effect of DMSO has been more effective than that of THF.
The rate for the coupling is more favorable in the presence of an eletron-withdrawing group in active components than of an eletron-donating group, and the coupling reaction with diazotized m-nitroaniline proceeds 90 times more rapidly than that with the benzenediazonium salt, which is coupled 110 times faster than the diazotized p-anisidine.
The activation energies measured in the coupling reaction of Croceic acid with diazotized sulfaniilic acid, m-nitroaniline, p-chloroaniline, p=bromoaniline, p-iodoaniline, m-toluidine, p-toluidine, p-anisidine, aniline are 8.45, 6.95, 7.46, 9.69, 10.19, 9.20, 12.67, 13.92, 15.15, and 11.68 Kcal/mol, respectively.
A linear free energy relationship has been essentially observed and also YukawaTsuno modified Hammett plot permits a good log k/k??=ρ(σ+r·△σ??) linear relationship when considering the mesomeric effect.
The calculated raction constant of thses azocoupling reactions is ρ=2.63, and the reaction constant of resonance contribution is calculated as r=0.39 at 20℃.

목차 (Table of Contents)

• 1. 緖論
• 2. 實驗方法
• 3. 實驗結果 및 考察
• 4. 結論