[rooroo]

What happens when you react 2,2-dimethyloxirane and HCl catalyst with benzene?

[Rico]

Hey rooroo

What happens is an acid catalyzed electrophilic aromatic substitution, where the protonated epoxide is the electrophile and benzene is the nucleophile. The nucleophile (benzene) opens the epoxide at the more substituted end, under the acidic conditions (can be explained in terms of a "loose S_N2 transitionstate"). The reaction can also be catalyzed by Lewis acids, e.g. aluminumtrichloride.

Hope this answers your question

Rico