00:03
This is the answer to chapter four, problem number 43 from the smith organic chemistry textbook.
00:10
And this problem gives us, i believe, eight iupac names.
00:18
And each one of these is incorrect.
00:21
And we need to determine why it's incorrect and then give the correct name.
00:26
So for seven of these, we're actually going to have to go ahead and draw them out to figure out what the problem is.
00:33
But a is nice because a we can look at and say exactly what's wrong.
00:40
So a, the given name is 2 -2 -di -methal -4 -ethyl -heptane.
00:44
So remember, die does not count as a prefix.
00:48
The only prefix that we need to consider when alphabetizing is iso.
00:53
And so this is alphabetized incorrectly.
00:57
So we ignore the dye, and we need to compare methyl and ethyl.
01:01
And obviously e comes before m in the alphabet.
01:05
So rather than 2 -2 -dymethyl -4 -ethyl -heptane, this should be 4 -ethyl -ethyl -2 -dhythane.
01:23
So this one was just a simple alphabetizing error.
01:28
So the other ones, unfortunately, are not this straightforward and simple.
01:33
And the other ones are going to require drawing out.
01:35
So for b, we have 5 -ethyl -2 -methyl hexane.
01:39
And so we should draw that out and see what it looks like.
01:45
So hexane tells us this is going to be a hexane derivative.
01:50
1, 2, 4, 5, 5, 6.
01:52
So there's a hexane 5 -ethyl -2 methyl.
01:56
So 1 -2, we can put a methyl here and an ethyl on 5.
02:03
So 3, 4, 5.
02:05
Okay, and so i can see what the problem here is right off the bat.
02:10
Hopefully you can too.
02:12
So right here we have, we named this as an ethyl on carbon 5, but if instead we make that part of the base chain and then name this as a methyl substituent instead will make for a longer base chain, which is what we always want to do.
02:38
And so i think, yeah, so, okay, so the numbering is not going to change, right? so we'll still call this two methyl for this substituent.
02:53
But instead of five ethylhexane, this will be five methyl heptane.
02:59
So this is actually going to be 2 .5 dimethyl heptane because we always want to go with the longest base chain possible.
03:14
And so heptane is the way to name this.
03:17
Okay.
03:19
And so next we have two methyl, two isoprubal heptane.
03:23
So again, this will be a heptane derivative.
03:26
One, two, three, four, five, six, seven.
03:29
Hepate 2, methyl, 2 isopropyl.
03:33
So there's a methyl, there's an isopropyl.
03:38
And so again, this is just like part b of this problem.
03:44
So this is a longer base chain than the way that it was originally named.
03:53
So we need to just count carbons here and renumber.
03:57
So we can go one, two, three, 4, 5, 6, 7, 8.
04:05
So it would be better to name this as an octane derivative.
04:10
And so this is going to be 2 -33 -trimethyl octane.
04:16
Yep.
04:18
So 2 -3 -3 -trimethyl octane.
04:28
Okay.
04:29
And so hopefully everybody's following along.
04:32
So the problem here, again, was that we didn't, or well, not we, but whoever originally named this, did not select the longest possible base chain.
04:44
And so you have to do that, or the name's not right.
04:48
So then for d, we have 1 -5 -dymethyl cyclohexane.
04:53
So let's draw ourselves a cyclohexane.
04:58
Okay.
04:58
And so 1 -5 -dymethyl, so we'll arbitrarily make this one.
05:03
Two, three, four, five.
05:05
Oops, about to draw five.
05:09
Okay.
05:09
And so i see what the problem is here right away.
05:13
So this was numbered like this, one, two, three, four, five.
05:20
But if instead we number this as one, two, three, this becomes one three dimethylhexane.
05:29
And so, again, we always want to keep our numbers as low as, possible.
05:34
So 1 -3 dimethylhexane is the correct name for this.
05:39
Or sorry, dimethyl cyclohexane.
05:43
Right.
05:45
So we want to keep the numbering scheme as low as possible.
05:49
1 -3 is preferable to 1 -5.
05:52
You know, 1 -5 is incorrect.
05:54
1 -3 is correct.
05:56
Okay, so that's d.
05:59
So moving on to e.
06:02
For e, we have 1 -ethyl -2 -6 dimethyl cyclo -heptane...