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Basicity Constants (pK<sub>BH+</sub>) of 5-Substituted 2-Furaldehydes
Basicity Constants (pKBH+) of 5-Substituted 2-Furaldehydes
Journal of the Korean Chemical Society. 2002. Aug, 46(4): 323-330
  • Published : August 20, 2002
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Lee, Jong-Pal
Im, Gwi-Taek
Lee, Yong-Hui
Gu, In-Seon
Ryu, Jun-Ha

Abstract
The protonation equilibrium of 5-substituted 2-furaldehydes is investigated spectrophotometrically in aqueous sulfuric acid at $25^{\circ}C$ and the basicity constants(p$K_{BH+}$) of the substrates is calculated by means of the excess acidity method. The basicity constant of 5-metyl-2-furaldehyde having electron donating group is larger than that of 5- nitro-2-furaldehyde having electron withdrawing group. Difference between the basicity constants(p$K_{BH+}$) of these two compounds was about 3.25 pK unit. The m value which is the degree of solvation of the protonated substrate is similar to that of acetophenone having same protonation site. The dependence of p$K_{BH+}$ on m value shows good linear cor-relation.
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