00:01
Question asked the alkene mixture obtained on dehydration of 2 comma 2 dimethyl cyclohexanol contains a significant amount of 1 -2 diomethal cyclohexene and to draw the structure of this and to show the mechanism that forms alkyne product and draw and give names of any other alkene products and explain how they can arise from dehydration.
00:27
Essentially, dehydration wants to take this alcohol and turn it into an alkene.
00:34
So to do this, we're going to need h2s -o -4 and heat.
00:41
This essentially will turn water into hydronium that can protonate the alcohol.
00:50
So the mechanism here, that h2s -4 is going to turn water into hydronium, this makes this alcohol look like a nucleophile.
01:04
It's going to take one of these hydrogens and then the water is going to pronate out therefore the next step is going to be a good leaving group which is what we wanted and then these two methyl groups now what water is going to do is that it's going to try to take a beta hydrogen so in this case the best place is to take a beta hydrogen is going to be this one right here so it'll take that form a double bond here where this acts a great leaving group.
02:01
Therefore, we can say that actually the first step before this, i forgot to state, is that this leaving group will occur first.
02:30
So that will leave and then it will leave us with a carbocadion right here.
02:38
But now since we have an extra methyl group, a methyl shift will occur.
02:42
Where the methyl group will go to the carbokaryon, which will then form this compound where the carbocon shifts here because we shifted the methyl group.
02:57
Now we can have the water attack of beta hydrogen, and it's going to want to go for the most substituted one...