Data to demonstrate that the alkyl inductive effect is not responsible for alkylamine basicity

This is in line with recent published work (J. Chem. Educ. 2026, 3156) which shows that the inductive effect and polarizability effects (which have long been conflated) behave in subtly different ways.</p><p dir="ltr">In order to set up reaction energies, including isodesmic reactions, calculations on a small range of alkanes are required to balance the equations.</p><p dir="ltr">The amine calculations above use natural bond orbital calculations.

In addition, we include a selection of calculations using canonical orbitals so that the orbital energies can be compared and contrasted. Alkyl groups raise the energy of the highest occupied molecular orbital of an amine. While this can be construed as 'making the lone pair more available' this is due in part to geometric changes and should not be attributed to an alkyl group inductive effect as the above charge calculations clearly show.</p><p dir="ltr">The impact of geometry is finally demonstrated with calculations on geometrically constrained ammonia, in which the lone pair energy is raised as the molecule is forced to become planar.

This shows clearly that the orbital energy change is not solely due to the incorporation of alkyl groups.</p><p><br></p>