(a) The compound shown in the margin, with the common name 1,3-dibromo-5,5-dimethylhydantoin, is useful as a source of electrophilic bromine (Br⁺) for addition reactions. Give a more systematic name for this heterocyclic compound. 

(b) An even more remarkable heterocyclic compound (ii) is prepared by the following reaction sequence. Using the given information, deduce structures for compounds i and ii, and name the latter. 

Heterocycle ii is a yellow, crystalline, sweet-smelling compound that decomposes upon gentle heating into two molecules of acetone, one of which is formed directly in its n→ π* excited state. This electronically excited product is chemiluminescent.

Heterocycles similar to compound ii are responsible for the chemiluminescence produced by a number of species [e.g., fireflies and several deep-sea fish]; they also serve as the energy sources in commercial chemiluminescent products.

Transcribed Image Text:

H;C CH3 1,3-Dibromo-5,5-dimethylhydantoin, 98% H,O, Ag+-OČCH, C=C → C,H13BrO2 C,H12O2 -AgBr, -CH,COOH H;C CH3 i ii