Determination of the acid dissociation constants of the p-sulphonato-calix[4]arene

محورهای موضوعی : Journal of Nanoanalysis

Monireh Hajmalek ¹ (Department of Chemistry, Islamic Azad University, Science and Research Branch, Tehran, Iran)
Mohammad Sajjad Khalili ² (Department of Chemistry, Faculty of Science and Engineering, Islamic Azad University, Saveh Branch, Saveh, Iran)
Karim Zare ³ (Department of Chemistry, Islamic Azad University, Science and Research Branch, Tehran, Iran)
Omid Zabihi ⁴ (Department of Chemistry, Islamic Azad University, Science and Research Branch, Tehran, Iran)

تاریخ دریافت : 1396/03/10 تاریخ پذیرش : 1396/03/10 تاریخ انتشار : 1393/01/12

کلید واژه: p-sulfonatocalix[4]arene, acid–base properties, acid dissociation constant,

چکیده مقاله :

The acid dissociation constants of the hydroxyl groups in 25, 26, 27, 28-tetrahydroxy-5, 11, 17, 23-tetrasulphonic-calix[4]arene (SC4) were determined at 25οC by a combination of potentiometric and spectrophotometric titration method. The first and second acid dissociation constants (pKa1, pKa2) were found to be 3.19 and 12.1, which demonstrated pKa shift due to intramolecular hydrogen bonding interactions among hydroxyl groups in SC4.