Roger Alder has made a career-long contribution to structure and reactivity in organic chemistry. He was the first to recognise and utilise the enhanced basicity of tertiary amines brought about by sterically-driven proton capture (proton sponges) and the first to develop a systematic relationship between geometry and properties in bridgehead amines.
Using bicyclic medium-ring compounds, he obtained the first structure of a compound with a three-electron bond, and made a detailed study of the effect of geometry on N−H···N bonds. He also demonstrated the important effects arising from quaternary carbon centres in polymer chains.
Roger prepared the first stable acyclic diaminocarbenes, and elucidated the mechanism of their dimerisation. He has made several challenges to the status quo through computational and experimental chemistry, for example in planar tetracoordinate carbon and radical-driven aromatic rearrangements — for example, that of azulene to naphthalene.