00:01
In this problem, we're given these four structures, and we want to know which is consistent with our carbon -13 nmr spectrum that we're given.
00:09
So notice that in your spectrum you have four signals.
00:15
So this tells us you have four unique carbons.
00:22
And remember that when carbons are in identical chemical environments, they can show up in the same signal.
00:28
So take, for example, this one.
00:30
These three ch3 groups are in the same environment, so they show up in the same environment.
00:34
The same peak.
00:35
So they have one, two, three unique carbons.
00:40
So we know that's not going to be our structure.
00:44
Here we have a symmetry.
00:47
So these two carbons show up in the same signal.
00:50
So that's one.
00:52
These two show up in the same signal.
00:54
So that's two.
00:55
And that carbon makes three...