Organic Chemistry / Leaving Group Conversions - Using HX
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Solution: Write a chemical equation for the reaction of 1-butanol with...

Question

Write a chemical equation for the reaction of 1-butanol with each of the following: 

(b) Hydrogen bromide, heat 

Video Transcript

Hey everyone in this question we're looking at our 1-butanol and we're going to be reacting it with the region. Now, that's HBR, okay? So, hydrogen, bromide and heat of course, so the first thing we need to look at is our reagent here and then we're going to look at our reactant. So, our reagent, what kind of reagent do you see here? well, this is going to be an HX, alright? Now we have an HX and we're reacting it with what kind of alcohol? a primary alcohol, so a primary alcohol with HX is going to undergo an SN2 reaction, okay? Now, for this question you see we have a primary alcohol. Now, alcohol is that a good leaving group or a bad one, right? this alcohol, alcohol guys, is a terrible leaving group, so we need to convert it into some kind of good leaving group, so that is what we're going to do here, we're going to convert it into a water and then we're going to change this alcohol into an alkyl halide, so when I first step with HBR our oxygen is going to come in grab our hydrogen and we know that hydrogen is going to be bonded to our bromine, so it's going to come in, grab the hydrogen and break this bond. Now, what we'd expect to get is while we had an alcohol before we're now going to have an extra hydrogen and there we have our water. Now, in an SN2 reaction this mechanism is going to be concerted, so what happens after this, is our bromine now is by itself, our bromide ion is going to come in and do a backside attack on this and kick off our leaving group. So, as our expected product what we're going to get, is we're going to get again a 4 carbon chain except now at the end we're going to have a bromide or bromine, okay? And as our product we're going to call thi R 1-bromo butane, so we went from r1-butanol, a primary alcohol, we know that alcohols not a good leaving group. So, with HX you know that a primary alcohol is going to an SN2 reaction, don't forget that and as our product we expect you get a one 1-bromobutane, okay? So I hope this made sense and let me know if you guys have any questions.