i'm trying to work my way through this problem but i dont understand it. HCN is a weak acid and bromine is a good leaving group. so what i have here is a sn1 reaction. right? or is it an e1? the HCN is too weak to substitute the bromine so the bromine has to dissassociate in the first step before the CN^- can attack. but what do i do then?

Ignore my last post, my mistake.

 

You need to look at the reacting carbon centre - do you think a carbocation would be stable there? As for you second question, try and draw the products for both an elimination and a substitution. The answer should become fairly obvious.

I'm confused, is the starting material equivalent to 1-bromo-2,2-dimethyl-1-phenylpropane? Or is the bromine on the aromatic ring- the 'benzene root' is confusing me.

 

Anyway, when ever I got these questions, Once I hd drawn the molecule I'ld formulate some questions in my head, for example:

 

Are there any groups that can leave in an elimination reaction? Under what conditions would they leave?

Are there any groups that can leave in a substitution reaction? What conditions?(If applicable, hard or soft nucleophiles).

Are there any groups subject to electrophilic substitution reactions? Under what conditions?

Label carbons 1⁰, 2⁰ , 3⁰ if it helps you.

 

Then look at the conditions in the question and try to match them up.