Croatica Chemica Acta, Vol. 82 No. 1, 2009.
Izvorni znanstveni članak
Neutral Intramolecular Hydrogen-Bonded Bases
Zhixin Tian
; Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
Alireza Fattahi
; Department of Chemistry, Sharif University of Technology, Tehran, Iran
Lev Lis
; Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
Steven R. Kass
; Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
Sažetak
B3LYP/aug-cc-pVDZ computations were carried out on polyamines with up to seven amino groups. The gas-phase proton affinities of these compounds are 219.6 (1-BuNH2), 238.6 (H2NCH2CH2CH2CH2NH2), 252.8 [(H2NCH2CH2CH2)2CHNH2], 261.3 [(H2NCH2CH2CH2)2CNH2 (1)], and 288.5 kcal mol−1 [(H2NCH2CH2CH(NH2)CH2CH2)2CNH2]. These results indicate that the tetraamine is near the top of the basicity scale and the heptaamine is more basic than any neutral organic compound which has been measured to date. A gas-phase equilibrium acidity determination between 1 and DBU also was carried out, and PA(1) = 256.2 ± 2.1 kcal mol−1 was obtained. This demonstrates that multiple intramolecular hydrogen bonds can greatly increase basicities, and represents a new motif for designing super bases.
Ključne riječi
super bases; gas-phase basicity; hydrogen-bonding; computations
Hrčak ID:
37977
URI
Datum izdavanja:
30.6.2009.
Posjeta: 1.832 *