1
00:00:00,000 --> 00:00:00,000


2
00:00:00,000 --> 00:00:03,270
I think we're ready now to
tackle some more or even more

3
00:00:03,270 --> 00:00:04,550
complicated examples.

4
00:00:04,550 --> 00:00:06,650
So let's draw something
crazy here.

5
00:00:06,650 --> 00:00:10,200
So let's see, let
me draw a chain.

6
00:00:10,200 --> 00:00:14,990
Let me draw it like that.

7
00:00:14,990 --> 00:00:17,680
And so like we've done in all
of the examples, you want to

8
00:00:17,680 --> 00:00:18,890
find the longest chain.

9
00:00:18,890 --> 00:00:19,730
We could count from here.

10
00:00:19,730 --> 00:00:23,390
One, two, three, four, five,
six, seven, eight, or maybe

11
00:00:23,390 --> 00:00:26,350
it's one, two, three, four,
five, six, seven.

12
00:00:26,350 --> 00:00:26,690
No.

13
00:00:26,690 --> 00:00:30,220
Or maybe it's one, two, three,
four, five, six, seven,

14
00:00:30,220 --> 00:00:32,150
eight, nine, ten.

15
00:00:32,150 --> 00:00:34,840
That is our longest chain.

16
00:00:34,840 --> 00:00:36,940
Let me make that in green.

17
00:00:36,940 --> 00:00:41,480
So our longest chain
here is in green.

18
00:00:41,480 --> 00:00:44,910
So this decane-- sorry,
this backbone has

19
00:00:44,910 --> 00:00:46,380
ten carbons in it.

20
00:00:46,380 --> 00:00:48,590
The prefix for ten is dec-.

21
00:00:48,590 --> 00:00:52,750
It is an alkane since it has
all single bonds, so we can

22
00:00:52,750 --> 00:00:55,240
write decane for the backbone.

23
00:00:55,240 --> 00:01:02,210
And then it has a group right
here and this group consists

24
00:01:02,210 --> 00:01:06,540
of one, two carbons attached
to the backbone.

25
00:01:06,540 --> 00:01:09,640
The prefix for two carbons
is eth-, so

26
00:01:09,640 --> 00:01:11,420
this is an ethyl group.

27
00:01:11,420 --> 00:01:14,820
The -yl is because it's a group
attached to the main

28
00:01:14,820 --> 00:01:17,510
alkane chain, so we call
this ethyldecane.

29
00:01:17,510 --> 00:01:20,160


30
00:01:20,160 --> 00:01:22,640
But we have to specify where the
ethyl group is attached.

31
00:01:22,640 --> 00:01:25,090
And we want to give it as low of
a number as possible, so we

32
00:01:25,090 --> 00:01:28,160
start counting on the
side closest to it.

33
00:01:28,160 --> 00:01:33,530
So it's one, two, three,
four, five, so this is

34
00:01:33,530 --> 00:01:36,130
5-ethyldecane.

35
00:01:36,130 --> 00:01:39,210
Now let's complicate this
a little bit more.

36
00:01:39,210 --> 00:01:41,410
So let me just to copy
and paste this.

37
00:01:41,410 --> 00:01:46,410


38
00:01:46,410 --> 00:01:48,260
So I have pasted it there.

39
00:01:48,260 --> 00:01:50,810
And let me complicate this
molecule a little bit more.

40
00:01:50,810 --> 00:01:52,635
Let me add another ethyl
group to it.

41
00:01:52,635 --> 00:01:55,440


42
00:01:55,440 --> 00:02:00,200
So let's say we have another
ethyl group over there.

43
00:02:00,200 --> 00:02:01,560
Now, what is this going to be?

44
00:02:01,560 --> 00:02:04,370
Well, the longest chain is still
going to be that thing

45
00:02:04,370 --> 00:02:06,840
in green, so it's still
going to be a decane.

46
00:02:06,840 --> 00:02:10,009


47
00:02:10,009 --> 00:02:12,350
But now we have two ethyl
groups, one on the five

48
00:02:12,350 --> 00:02:14,990
carbon, one, two, three,
four, five, and then

49
00:02:14,990 --> 00:02:16,335
one on the six carbon.

50
00:02:16,335 --> 00:02:18,950


51
00:02:18,950 --> 00:02:21,510
So we write here-- you might
be tempted to write

52
00:02:21,510 --> 00:02:25,460
5-ethyl-6-ethyldecane, which
really wouldn't be wrong, but

53
00:02:25,460 --> 00:02:27,220
it would just be maybe
more letters

54
00:02:27,220 --> 00:02:28,180
than you want to write.

55
00:02:28,180 --> 00:02:30,820
Instead you write
5,6-diethyldecane.

56
00:02:30,820 --> 00:02:41,380


57
00:02:41,380 --> 00:02:44,950
The 5,6- tells us the two
carbons on the main backbone

58
00:02:44,950 --> 00:02:47,960
that the ethyl groups are
attached to, and the di- says

59
00:02:47,960 --> 00:02:49,670
that we have two ethanes.

60
00:02:49,670 --> 00:02:51,950
Or two ethyl groups, I should
say, not ethane groups.

61
00:02:51,950 --> 00:02:56,250
Two ethyl groups, one over here
and one right over here.

62
00:02:56,250 --> 00:03:01,010
Now, let's make it even
more complex.

63
00:03:01,010 --> 00:03:04,380
Let's take our thing and let's
make it even more complex.

64
00:03:04,380 --> 00:03:12,280
So let's copy it and let
us paste it, edit,

65
00:03:12,280 --> 00:03:17,376
paste, just like that.

66
00:03:17,376 --> 00:03:18,280
Let's paste it.

67
00:03:18,280 --> 00:03:20,880
Let me make it a little
bit lower over here.

68
00:03:20,880 --> 00:03:23,170
So the exact same thing we just
dealt with, but let's add

69
00:03:23,170 --> 00:03:26,810
one more group to it.

70
00:03:26,810 --> 00:03:30,080
Let's say it looks something
like this.

71
00:03:30,080 --> 00:03:32,610
Let's say on that five carbon--
let's say on that six

72
00:03:32,610 --> 00:03:36,620
carbon right there, I have
a group that looks

73
00:03:36,620 --> 00:03:37,560
something like this.

74
00:03:37,560 --> 00:03:39,300
What is this is going
to be called?

75
00:03:39,300 --> 00:03:41,040
And here we probably want to
break it down a little bit.

76
00:03:41,040 --> 00:03:43,080
We still have the backbone,
so it's still

77
00:03:43,080 --> 00:03:44,330
going to be a decane.

78
00:03:44,330 --> 00:03:48,790


79
00:03:48,790 --> 00:03:50,530
But let's just do
it step by step.

80
00:03:50,530 --> 00:03:53,500
So we know that this right here,
this is an ethyl group.

81
00:03:53,500 --> 00:03:57,410
It's on the five carbon,
so that is a 5-ethyl.

82
00:03:57,410 --> 00:03:59,340
This is another ethyl group
on the six carbon,

83
00:03:59,340 --> 00:04:02,440
so that is a 6-ethyl.

84
00:04:02,440 --> 00:04:03,980
Now, we have this
group over here.

85
00:04:03,980 --> 00:04:06,030
So how many carbons
are on this group?

86
00:04:06,030 --> 00:04:09,470
Well, we have one, two,
three carbons on it.

87
00:04:09,470 --> 00:04:12,400
We have three carbons on it, so
we might want to just call

88
00:04:12,400 --> 00:04:14,840
it a propyl group, but
notice something.

89
00:04:14,840 --> 00:04:16,959
We are attached to the carbon,
and then it later

90
00:04:16,959 --> 00:04:17,930
branches off into two.

91
00:04:17,930 --> 00:04:19,940
It actually immediately
branches off into two.

92
00:04:19,940 --> 00:04:24,330
So we could actually call this
either sec-propyl, so this

93
00:04:24,330 --> 00:04:31,730
right here, we can either call
it sec-propyl, or because it

94
00:04:31,730 --> 00:04:34,270
is connected away from the-- I
guess it's connected directly

95
00:04:34,270 --> 00:04:37,060
to the branch the way a
propyl group works.

96
00:04:37,060 --> 00:04:38,910
You could connect it and it
immediately branches, because

97
00:04:38,910 --> 00:04:40,180
you only have three carbons.

98
00:04:40,180 --> 00:04:44,490
So just to clarify things,
it's sec- because we're

99
00:04:44,490 --> 00:04:46,670
attached to two carbons
right there.

100
00:04:46,670 --> 00:04:48,880
But sec-propyl isn't what
people normally call it.

101
00:04:48,880 --> 00:04:50,130
They normally call
it isopropyl.

102
00:04:50,130 --> 00:04:53,760


103
00:04:53,760 --> 00:04:56,820
And the iso- root comes from
anything of the form.

104
00:04:56,820 --> 00:05:01,110
So if I have a group that looks
like this, this would be

105
00:05:01,110 --> 00:05:06,360
isobutyl, because we have one,
two, three, four carbons, and

106
00:05:06,360 --> 00:05:09,130
we are attached right here, so
this is where we would attach

107
00:05:09,130 --> 00:05:10,030
to the main backbone.

108
00:05:10,030 --> 00:05:16,670
If I have a group that
looks like this,

109
00:05:16,670 --> 00:05:18,990
this would be isopentyl.

110
00:05:18,990 --> 00:05:21,700
I have one, two, three,
four, five carbons.

111
00:05:21,700 --> 00:05:23,590
I'm attached away
from the branch.

112
00:05:23,590 --> 00:05:27,190
But if we go one step closer,
so we're attached just like

113
00:05:27,190 --> 00:05:28,550
this, we're attached
to the original

114
00:05:28,550 --> 00:05:31,720
group, this is isopropyl.

115
00:05:31,720 --> 00:05:33,170
One, two, three carbons.

116
00:05:33,170 --> 00:05:37,570
Let me write-- isopropyl,
isobutyl, isopentyl.

117
00:05:37,570 --> 00:05:40,900
Notice what the isos-- the isos
are like Y's, I guess is

118
00:05:40,900 --> 00:05:42,330
the best way of thinking of it,
and you're attached to the

119
00:05:42,330 --> 00:05:43,150
base of the Y.

120
00:05:43,150 --> 00:05:45,220
In this case, you're almost
attached to the base of a V,

121
00:05:45,220 --> 00:05:46,630
but, hopefully, you
get the idea.

122
00:05:46,630 --> 00:05:50,710
So the common name for this
group would be isopropyl, or

123
00:05:50,710 --> 00:05:53,500
if we wanted to use the
systematic naming, we could

124
00:05:53,500 --> 00:05:57,720
just start at one as being-- let
me do this in a good color

125
00:05:57,720 --> 00:06:00,490
--as the carbon we are attached
to, and then we only

126
00:06:00,490 --> 00:06:02,670
have two carbons right
over there.

127
00:06:02,670 --> 00:06:04,260
So if we have two carbons,
we're dealing

128
00:06:04,260 --> 00:06:05,510
with an ethyl group.

129
00:06:05,510 --> 00:06:08,130


130
00:06:08,130 --> 00:06:11,430
And then you could say that
you have a methyl group

131
00:06:11,430 --> 00:06:14,165
attached to the first carbon, so
it would be 1-methylethyl.

132
00:06:14,165 --> 00:06:19,850


133
00:06:19,850 --> 00:06:23,210
So this could either be called
an isopropyl group, or a

134
00:06:23,210 --> 00:06:25,520
1-methylethyl group.

135
00:06:25,520 --> 00:06:28,300
And in either case-- let me
put that in parentheses.

136
00:06:28,300 --> 00:06:30,503
In either case, it's attached
to the six carbon.

137
00:06:30,503 --> 00:06:34,360


138
00:06:34,360 --> 00:06:36,750
So the prefixes are going to
be on the six carbon on our

139
00:06:36,750 --> 00:06:44,970
main-- we have a 1-methylethyl,
where the

140
00:06:44,970 --> 00:06:47,430
methyl is attached to the first
carbon on the ethyl

141
00:06:47,430 --> 00:06:53,710
chain, or we could call this a
6-isopropyl group attached to

142
00:06:53,710 --> 00:06:55,370
the six carbon.

143
00:06:55,370 --> 00:06:58,500
Now, when we decide how to write
it, how do we know--

144
00:06:58,500 --> 00:06:59,720
we're going to have to
write essentially the

145
00:06:59,720 --> 00:07:02,200
ethyl and the isopropyl.

146
00:07:02,200 --> 00:07:04,100
We're going to have to
write all of that in

147
00:07:04,100 --> 00:07:05,830
front of the decane.

148
00:07:05,830 --> 00:07:07,920
How do we decide whether
to write the eth-

149
00:07:07,920 --> 00:07:09,030
or the propyl- first?

150
00:07:09,030 --> 00:07:11,010
Well, here you just do it
in alphabetical order.

151
00:07:11,010 --> 00:07:12,220
And actually these
little prefixes

152
00:07:12,220 --> 00:07:13,960
in front don't matter.

153
00:07:13,960 --> 00:07:15,800
So you compare the P to the E.

154
00:07:15,800 --> 00:07:19,130
Eth-, E comes first in
alphabetical order, so this

155
00:07:19,130 --> 00:07:22,155
would be 5,6-diethyl.

156
00:07:22,155 --> 00:07:26,790


157
00:07:26,790 --> 00:07:30,640
So even though D-- well, D comes
even before E, but you

158
00:07:30,640 --> 00:07:31,970
don't even count that prefix.

159
00:07:31,970 --> 00:07:33,730
The E is what matters.

160
00:07:33,730 --> 00:07:38,610
Diethyl, and then
we could say,

161
00:07:38,610 --> 00:07:39,860
diethyl-6-isopropyldecane.

162
00:07:39,860 --> 00:07:48,290


163
00:07:48,290 --> 00:07:50,140
This is the common name:
6-isopropyldecane.

164
00:07:50,140 --> 00:07:57,340


165
00:07:57,340 --> 00:07:59,150
This would be the common
name for it.

166
00:07:59,150 --> 00:08:01,000
If we want to use the systematic
name, we would

167
00:08:01,000 --> 00:08:04,970
replace the 6-isopropyl
with 6,1-methylethyl.

168
00:08:04,970 --> 00:08:06,170
So let me write that down.

169
00:08:06,170 --> 00:08:09,250
So let me just copy this part.

170
00:08:09,250 --> 00:08:13,870
So copy and paste right there.

171
00:08:13,870 --> 00:08:17,500
And then I can copy and
paste this right here.

172
00:08:17,500 --> 00:08:20,340
Copy and paste.

173
00:08:20,340 --> 00:08:21,590
So it becomes
5,6-diethyl-6-1-methylethyl.

174
00:08:21,590 --> 00:08:24,430


175
00:08:24,430 --> 00:08:26,120
I know it's very confusing when
you see it, but when you

176
00:08:26,120 --> 00:08:27,780
break it down, you really
could-- you would be able to

177
00:08:27,780 --> 00:08:29,220
draw this from the structure.

178
00:08:29,220 --> 00:08:38,320
And then finally you finish
with a decane.

179
00:08:38,320 --> 00:08:40,940
So hopefully, these examples
don't confuse you too much.

180
00:08:40,940 --> 00:08:43,400
In the next few videos, we'll
do more and more examples.

181
00:08:43,400 --> 00:08:46,050
Because I think with the
nomenclature on the organic

182
00:08:46,050 --> 00:08:47,960
chemistry, the more examples
you see, the better.

183
00:08:47,960 --> 00:08:50,260
This is really core, so in the
future you don't get confused

184
00:08:50,260 --> 00:08:52,130
when people throw out
something like,

185
00:08:52,130 --> 00:08:53,380
5,6-diethyl-6-(1
-methylethyl)decane.

186
00:08:53,380 --> 00:08:58,333