Study on The Tautomerization of 1-Aryldiazo-2-naphthalenol Derivatives by Using The Spectroscopic Technique

• Main Authors: LIN, YI-CANG, 林怡蒼
• Other Authors: LIN, SHAW-TAO
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/85644351672906327063

博士 === 靜宜大學 === 應用化學系 === 104 === The substituent effect on azo-hydrazone tautomerization of 1-aryldiazo-2-naphthalenol is studied by means of NMR and MS analysis. Among the 13C chemical shifts, the C(2) of this series compound is the most sensitive to the variation in the nature of substituent on the phenyl ring. Therefore, the variation in the chemical shifts of C(2) is used to probe the substituent effect by using the substituent chemical shifts and free energy vs. Hammett’s constant (σ+). Both methods give a negative correlation slope, which are ρ=-8.74 and ρ=-1.38 , indicating the electron-withdrawing groups favor the hydrazone tautomer form. The effect on the chemical shifts of C(2) of 1-phenyldiazo-2-naphthalenol in ten solvents can be classified as the solvent with a proton-donor, proton-acceptor and arenes system. The substituent with electron-donating character is more sensitive to the nature of solvent and it favors the azo form. Free energy obtained from the dynamic NMR technique indicates the tautomerization favors the hydrazone-form for the substituent with electron-withdrawing character. The relaxation time of carbon are slight affected by the size of substituents. In the viscosity study, an inverse-law relationship between relaxation times and viscosity was observed. An electron-ionization (EI) mass spectra of a series of 1-aryldiazo-2-naphthalenol was obtained for studying the substituent effect on the fragmentation. The correlation between the ratio, molecular ion and fragment ion, and Hammett’s constants is applied to examine the effect of the substituent on the fragmentation. The negative correction between the ratio, Imolecular ion/(I171amu + I143amu + I115amu), and Hammett’s constants, which is ρ=-0.778, indicates an electron-withdrawing group destabilized the molecular ion. An unusual long-range hydrogen transfer demonstrates an important role in the fragmentation process.