Synthesis and properties of nitro derivatives of 2‐tert‐butyl‐ and 2,7‐di‐tert‐butylpyrene

Abstract Nitration of 2‐ tert ‐butyl‐ and 2,7‐di‐ tert ‐butylpyrene affords molecules with severely hindered nitro groups. A nitro group ortho to a tert ‐butyl group is twisted at least 82° out of the plane of the aromatic nucleus. The lack of interaction between the hindered nitro group and the aromatic system is reflected in the chemical behaviour, as well as in the spectroscopic properties, of these nitro derivatives. Upon fragmentation in the mass spectrometer, the tert ‐butyl group is always replaced by a hydrogen atom. Nitro groups are only replaced by a hydrogen atom if they are ortho to a tert ‐butyl group.