00:01
Calculate the number of degrees of unsaturation for each molecular formula propose two possible structures.
00:07
So we've got, well, let's do this first.
00:10
So degrees of unsaturation is going to equal the number of pi bonds in a structure.
00:18
Remember that a double bond is one pi bond, a triple bond.
00:24
That's a terrible triple bond.
00:25
A triple bond is two pi bonds.
00:28
So one pi bond, two pi bonds.
00:31
So let's just end.
00:33
We know that this is actually a mathematical formula, two times the number of carbons plus two plus nitrogens minus halogens, minus hydrogen.
00:52
All of that divided by two.
00:55
Okay, so let's take a look at our first one.
00:57
A.
00:58
So degrees of unsaturation is going to equal to, times 8 plus 2 plus 0 minus 0 minus 12 by 2 that is 16 18 18 minus 12 6 6 65 by 2 is 3 so we have 3 pie bonds there's also this also allows for cyclic like cyclical compounds but we're just going to focus on pie bonds so if we were to propose two possible structures for something with eight carbons and 12 hydrogens, i would start by just drawing an eight carbon chain.
01:39
So one, two, three, four, five, six, seven, eight, eight carbons, three pie bonds.
01:47
How about we just add three, three, double bonds? one, two, three.
01:55
And then let's fill in some hydrogens where we need.
01:58
So we've got hydrogen, hydrogen, hydrogen there.
02:03
To that carbon.
02:05
Two hydrogens here.
02:08
One hydrogen, one hydrogen, hydrogen, hydrogen, hydrogen, hydrogen, and two, hydrants.
02:17
So one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve.
02:21
So look at that.
02:22
One valid structure.
02:24
Now what we can kind of tell is that if we were to shift these double bonds, i bet it would still work.
02:30
Three, four, five, six, seven, eight let's go ahead and put them in the middle just like that and sure enough if we were to do our math here one two three one so we've got three four five six seven eight nine ten eleven twelve second valid structures that is as part a uh three we've got three degrees of insaturation two viable structures uh let's look at b all right so we've got four or b degrees of unsaturation equals two times 10.
03:18
It's a big number plus two plus zero minus zero minus 10 divided by two.
03:26
So we've got 22 minus 10 is 12 over two is six.
03:32
So we've got six pie bonds and we've got 10 carbons, 10 carbons, 10 hydrants, 10 hydrants...