Question

For the formation of your photchromic imine you use ammonium bromide. Why? 2 reasons.

Answer 1

1. Aziridines are relatively reactive systems (like cyclopropane) and undergo nucleophilic ring opening with the accompanying ring strain in the presence of strong acids like HBr.

2. Since Photochromisim depends on the ability to inter-convert between cis and trans through the lone pair lobe of nitrogen, once it is protonated, then the molecule becomes non-Photochromic substance. A tetra substituted nitrogen becomes chiral.

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