We report a study on the energetics and structural properties of naphthalene-based proton sponges and their corresponding protonated cations. In particular, we have determined the experimental standard enthalpies of formation in the gas phase at T = 298.15 K for the neutral and protonated DMAN [1,8-bis (dimethylamino)-naphthalene], (221.0 +- 7.3) and (729.0 +- 11.1) kJ mol-1, respectively. A reliable experimental estimation of enthalpy associated with "strain" effect and hydrogen bond intramolecular (included within "enhanced basicity", EB) contributions to the basicity of DMAN, were deduced from isodesmic reactions, -(29.1 +- 4.6) and (87.1 +- 11.9) kJ mol-1, respectively. The gas-phase basicities (GB) of naphthalene-based proton sponges are compared with the corresponding aqueous basicities (pKa), covering a range of 149 kJ mol-1 in GB and 11.5 in pKa. Density functional calculations at the M05-2X/ 6-311++G(d,p) level of theory were used to check the consistency of the experimental results and also to estimate the unavailable GB values of the considered species.
Compounds
#
Formula
Name
1
CO2
carbon dioxide
2
N2
nitrogen
3
H2O
water
4
O2
oxygen
5
C14H18N2
1,8-bis(dimethylamino)naphthalene
Datasets
The table above is generated from the ThermoML associated json file (link above).
POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied;
the numbers refer to the table of compounds on the left.
Type
Compound-#
Property
Variable
Constraint
Phase
Method
#Points
POMD
5
Molar enthalpy of transition or fusion, kJ/mol ; Crystal
Crystal
Liquid
Gas
DSC
1
POMD
5
Triple point temperature, K ; Crystal
Crystal
Liquid
Gas
DTA
1
POMD
5
Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal
Temperature, K; Crystal
Crystal
Gas
Static calorimetry
1
POMD
5
Vapor or sublimation pressure, kPa ; Liquid
Temperature, K; Liquid
Liquid
Gas
Closed cell (Static) method
13
RXND
5
1
2
3
4
Specific internal energy of reaction at constant volume, J/g