2026-10-10T20:06:17Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34005588 2026-09-28T12:40:29Z category_31817 portal_1117 item_type_3 month_year_09_2026

Data to demonstrate that the alkyl inductive effect is not responsible for alkylamine basicity Mark Elliott (19077767) Chemical sciences Organic chemistry - Study and teaching (Higher) Computational chemistry Currently, many university organic chemistry textbooks and A-level exam boards teach the effect of alkyl groups on amine basicity as being due to an inductive electron-donating effect from the alkyl groups in the amine. This is at odds with the research literature from as long ago as the 1960s, where alkyl group polarizability in the ammonium ion was postulated to be responsible. The fact that these developments have not been reflected in modern teaching is a concern, and this dataset is intended to provide data that can be used to address this problem.The dataset is organised in the following way:Calculations on amines. These show that alkyl groups are electron-withdrawing, and therefore do not make amines more basic according to the mechanisms currently taught (making the lone pair more available due to inductive electron-donation). This can be seen by examination of the partial atomic charges (Hirshfeld, NPA).Calculations on ammonium ions, showing that alkyl groups are electron-donating, and this is a distinct effect (polarizability). 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.In order to set up reaction energies, including isodesmic reactions, calculations on a small range of alkanes are required to balance the equations.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.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. 2026-09-28T12:40:29Z Dataset Dataset 10.17035/cardiff.34005588.v1 https://figshare.com/articles/dataset/Data_to_demonstrate_that_the_alkyl_inductive_effect_is_not_responsible_for_alkylamine_basicity/34005588 CC BY 4.0