3-Bromocyclohexene is a secondary halide, it undergo SN1 substitu...

Question

3-Bromocyclohexene is a secondary halide, it undergo SN1 substitution about as fast as most tertiary halides. Use resonance structures to explain this enhanced reactivity. 3-bromocyclohexene

Accepted Answer

Hey everyone, let's solve this problem. It says five chlor a 13 cycle hex a dying. A secondary alcohol. I can give sN one substitution reactions at a rate comparable to that of a tertiary alcohol. Hail I'd draw the resonance stabilized intermediates to explain the increased reactivity of the compound. Okay, well what can we recall about SN one reactions? Sn one reactions. Do they have a intermediate or a transition state? They have an intermediate and sn one intermediates. Do they like to be substituted or un substituted? They love a substituted carbo cat eye on intermediate. Okay, so that's why we're looking at the substitution here. The problem mentions tertiary alcohol. Hey lied versus a secondary alcohol. Hey lied. So since SN one reactions love a tertiary is more substituted. Right, So it's going to favor that tertiary compound. So that's why the problem is saying why is the secondary alcohol? Hey line having a similar rate to that tertiary alcohol? Hey line. So we have to draw our compound so we can draw the resonance structures. So let's do that. So we see, I'm going to start with the base of the name. Right? So cyclone means a ring. Hex A is six carbons. So let's start our six member ring. Okay, dying and outfront we see a one and a three. So the double bonds are going to be on carbons one. So let's say if we start at the top 123 And then a chlorine at carbon five. So 1, 2, 3, 4, 5. Okay, so there is our compound, our secondary alcohol. Hayley. So let's draw the resonance structures once this compound is ionized. So we know that chlorine is a good leaving group. Right? That's what happens first in an S. N. One. So goodbye chlorine. So we get our chlorine ion and then let's see what this compound looks like. So we have our double bonds and then the carbon where that chlorine atom was attached will now have a positive charge. Okay, and what do we know about residents? When I see a charge next to a pi bond that equals resonance. Right, that's what that's when resonance occurs. So here I see a pi bond right next to my car broke head ion. So this pi bond, we'll shift over there towards that carbo cat ion. And now our positive charge will be where that third carbon at the third carbon. Okay, is there another resonance form? We can have you bet there is. So let's draw another ring. So now this pi bond up here on carbon one will come down to carbon too. So it can. How about that positive charge? So now we still have our double bond at carbon four and now a double bonded carbon two and our positive charge is going to be up here at carbon one. Are there any other resonance forms? We can have no because if we drew the double bond going back towards that positive charge, it would just be the same as before. Right, so this compound or the secondary carbo can ion has three resonance forms. Ah, so that's why this S. N. One reaction is favored because it has three residents forms. So that's going to make that resonance. Or this carbo cat on intermediate, very stable. Okay, so that is why this compound has a comparable reaction rate to the tertiary alcohol. Hey lied. I hope this makes sense, and thanks for watching.

3-Bromocyclohexene is a secondary halide, it undergo SN1 substitution about as fast as most tertiary halides. Use resonance structures to explain this enhanced reactivity. 3-bromocyclohexene

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