## 3 Results
### Amines
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Dialkylamines** & **Exp.** & **Model** & **ABS (Model – Exp.)** & **G4** & **G4 Avgd.** & **ABS (G4 Avgd. – Exp.)** \\ \hline dimethylamine & \(-18.6\) & \(-32.7\) & \(14.1\) & \(-16.0\) & \(-16.0\) & \(2.6\) \\ \hline diethylamine & \(-72.5\) & \(-74.0\) & \(1.5\) & \(-73.2\) & \(-71.0\) & \(1.5\) \\ \hline dipropylamine & \(-116.1\) & \(-115.2\) & \(0.9\) & \(-114.1\) & \(-111.5\) & \(4.6\) \\ \hline Dibutylamine & \(-156.6\) & \(-156.5\) & \(0.1\) & \(-156.2\) & \(-152.1\) & \(4.5\) \\ \hline diisopropylamine & \(-144\) & \(-129.6\) & \(14.4\) & \(-136.2\) & \(-135.6\) & \(8.4\) \\ \hline  & \(-136.3\) & \(-129.6\) & \(6.7\) & \(-136.2\) & \(-135.6\) & \(0.7\) \\ \hline diisobutylamine & \(-179.2\) & \(-170.9\) & \(8.3\) & \(-173.4\) & \(-171.3\) & \(7.9\) \\ \hline  & \(-180.8\) & \(-170.9\) & \(9.9\) & \(-173.4\) & \(-171.3\) & \(9.5\) \\ \hline diphenylamine & \(219.3\) & \(221.0\) & \(1.7\) & \(214.3\) & \(214.3\) & \(5.0\) \\ \hline averaged absolute difference & & & \(3.5\) & & & \(4.1\) \\ \hline \end{tabular}
\end{table} 
Table 3: Experimental (2014), present GC model, and G4 model values for the heat of formation for some symmetrical di-alkylamines R2 NH. All values in kJ/mol. Second entries for diisopropylamine and diisobutylamine from [PERSON] c.s. (2016). The averaged absolute differences were calculated taking into account these second entries rather than those from [PERSON] c.s. Group by itself. The other two GC values represent the experimental data within chemical accuracy. Table 5 comprises data related to a number of other secondary and tertiary alkyl amines. For the first entry, butylisobutylamine, we see a difference between the GC model and experimental values beyond chemical accuracy, but the GC value is quite close to the G4 Boltzmann averaged value. A relatively high value for the error in the experimental value has been given as 5.2 kJ/mol [34], and therefore we conclude that the GC model and G4 value can be considered within chemical accuracy of the true value. Entries 2 and 4 have a methyl Group and, in line with previous examples mentioned above, the GC value is, as expected, beyond chemical accuracy from the experimental value. However, for N-methyl-butanamine, the difference between model and experimental value is positive rather than negative as for the other (previous) examples, with a methyl Group attached to the amine nitrogen. The G4 value of \(-83.6\) kJ/mol is very much different from the experimental value, but when we consider the difference between the GC model value and the G4 value, we do find a negative difference of \(-8.8\) kJ/mol. These results strongly suggest that the experimental value is in error, and this confirms once more that only carefully verified experimental data (see also text in the Introduction) should be taken into account when developing a GC model. Entry 3, N-N-dimethyloctylamine, reveals good agreement between the GC value and the experimental value despite the presence of methyl Groups. The G4 value of \(-174.2\) kJ/mol for this species also agrees comparatively well with the experimental and GC model values. The good agreement between the values looks unexpected because of the presence of methyl Groups and contrary to other examples already presented where we see a deviation significantly beyond chemical accuracy. When we look at the last entry, N,N-dimethylbutane-1-amine, we have no sufficiently reliable experimental value, but \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**tri-N-Alkyl Amines** & **Exp.** & **Model** & **Model – Exp.** & **G4** & **G4 Avgd.** & **G4 Avgd. – Exp.** \\ \hline trimethylamine & \(-23.7\) & \(-34.6\) & \(-10.9\) & \(-25.5\) & \(-25.5\) & \(-1.8\) \\ \hline triethylamine & \(-92.8\) & \(-96.5\) & \(-3.7\) & \(-97.2\) & \(-94.1\) & \(-1.3\) \\ \hline tripropylamine & \(-161.0\) & \(-158.4\) & \(2.6\) & \(-164.2\) & \(-160.5\) & \(0.5\) \\ \hline \hline \end{tabular}
\end{table}