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More Organic Chemistry Naming Examples 1

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    I think we're ready now to
    tackle some more or even more
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    complicated examples.
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    So let's draw something
    crazy here.
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    So let's see, let
    me draw a chain.
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    Let me draw it like that.
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    And so like we've done in all
    of the examples, you want to
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    find the longest chain.
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    We could count from here.
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    One, two, three, four, five,
    six, seven, eight, or maybe
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    it's one, two, three, four,
    five, six, seven.
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    No.
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    Or maybe it's one, two, three,
    four, five, six, seven,
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    eight, nine, ten.
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    That is our longest chain.
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    Let me make that in green.
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    So our longest chain
    here is in green.
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    So this decane-- sorry,
    this backbone has
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    ten carbons in it.
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    The prefix for ten is dec-.
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    It is an alkane since it has
    all single bonds, so we can
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    write decane for the backbone.
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    And then it has a group right
    here and this group consists
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    of one, two carbons attached
    to the backbone.
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    The prefix for two carbons
    is eth-, so
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    this is an ethyl group.
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    The -yl is because it's a group
    attached to the main
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    alkane chain, so we call
    this ethyldecane.
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    But we have to specify where the
    ethyl group is attached.
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    And we want to give it as low of
    a number as possible, so we
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    start counting on the
    side closest to it.
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    So it's one, two, three,
    four, five, so this is
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    5-ethyldecane.
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    Now let's complicate this
    a little bit more.
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    So let me just to copy
    and paste this.
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    So I have pasted it there.
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    And let me complicate this
    molecule a little bit more.
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    Let me add another ethyl
    group to it.
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    So let's say we have another
    ethyl group over there.
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    Now, what is this going to be?
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    Well, the longest chain is still
    going to be that thing
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    in green, so it's still
    going to be a decane.
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    But now we have two ethyl
    groups, one on the five
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    carbon, one, two, three,
    four, five, and then
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    one on the six carbon.
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    So we write here-- you might
    be tempted to write
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    5-ethyl-6-ethyldecane, which
    really wouldn't be wrong, but
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    it would just be maybe
    more letters
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    than you want to write.
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    Instead you write
    5,6-diethyldecane.
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    The 5,6- tells us the two
    carbons on the main backbone
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    that the ethyl groups are
    attached to, and the di- says
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    that we have two ethanes.
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    Or two ethyl groups, I should
    say, not ethane groups.
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    Two ethyl groups, one over here
    and one right over here.
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    Now, let's make it even
    more complex.
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    Let's take our thing and let's
    make it even more complex.
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    So let's copy it and let
    us paste it, edit,
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    paste, just like that.
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    Let's paste it.
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    Let me make it a little
    bit lower over here.
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    So the exact same thing we just
    dealt with, but let's add
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    one more group to it.
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    Let's say it looks something
    like this.
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    Let's say on that five carbon--
    let's say on that six
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    carbon right there, I have
    a group that looks
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    something like this.
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    What is this is going
    to be called?
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    And here we probably want to
    break it down a little bit.
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    We still have the backbone,
    so it's still
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    going to be a decane.
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    But let's just do
    it step by step.
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    So we know that this right here,
    this is an ethyl group.
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    It's on the five carbon,
    so that is a 5-ethyl.
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    This is another ethyl group
    on the six carbon,
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    so that is a 6-ethyl.
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    Now, we have this
    group over here.
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    So how many carbons
    are on this group?
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    Well, we have one, two,
    three carbons on it.
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    We have three carbons on it, so
    we might want to just call
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    it a propyl group, but
    notice something.
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    We are attached to the carbon,
    and then it later
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    branches off into two.
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    It actually immediately
    branches off into two.
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    So we could actually call this
    either sec-propyl, so this
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    right here, we can either call
    it sec-propyl, or because it
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    is connected away from the-- I
    guess it's connected directly
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    to the branch the way a
    propyl group works.
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    You could connect it and it
    immediately branches, because
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    you only have three carbons.
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    So just to clarify things,
    it's sec- because we're
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    attached to two carbons
    right there.
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    But sec-propyl isn't what
    people normally call it.
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    They normally call
    it isopropyl.
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    And the iso- root comes from
    anything of the form.
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    So if I have a group that looks
    like this, this would be
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    isobutyl, because we have one,
    two, three, four carbons, and
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    we are attached right here, so
    this is where we would attach
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    to the main backbone.
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    If I have a group that
    looks like this,
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    this would be isopentyl.
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    I have one, two, three,
    four, five carbons.
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    I'm attached away
    from the branch.
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    But if we go one step closer,
    so we're attached just like
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    this, we're attached
    to the original
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    group, this is isopropyl.
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    One, two, three carbons.
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    Let me write-- isopropyl,
    isobutyl, isopentyl.
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    Notice what the isos-- the isos
    are like Y's, I guess is
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    the best way of thinking of it,
    and you're attached to the
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    base of the Y.
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    In this case, you're almost
    attached to the base of a V,
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    but, hopefully, you
    get the idea.
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    So the common name for this
    group would be isopropyl, or
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    if we wanted to use the
    systematic naming, we could
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    just start at one as being-- let
    me do this in a good color
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    --as the carbon we are attached
    to, and then we only
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    have two carbons right
    over there.
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    So if we have two carbons,
    we're dealing
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    with an ethyl group.
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    And then you could say that
    you have a methyl group
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    attached to the first carbon, so
    it would be 1-methylethyl.
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    So this could either be called
    an isopropyl group, or a
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    1-methylethyl group.
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    And in either case-- let me
    put that in parentheses.
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    In either case, it's attached
    to the six carbon.
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    So the prefixes are going to
    be on the six carbon on our
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    main-- we have a 1-methylethyl,
    where the
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    methyl is attached to the first
    carbon on the ethyl
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    chain, or we could call this a
    6-isopropyl group attached to
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    the six carbon.
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    Now, when we decide how to write
    it, how do we know--
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    we're going to have to
    write essentially the
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    ethyl and the isopropyl.
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    We're going to have to
    write all of that in
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    front of the decane.
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    How do we decide whether
    to write the eth-
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    or the propyl- first?
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    Well, here you just do it
    in alphabetical order.
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    And actually these
    little prefixes
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    in front don't matter.
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    So you compare the P to the E.
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    Eth-, E comes first in
    alphabetical order, so this
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    would be 5,6-diethyl.
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    So even though D-- well, D comes
    even before E, but you
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    don't even count that prefix.
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    The E is what matters.
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    Diethyl, and then
    we could say,
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    diethyl-6-isopropyldecane.
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    This is the common name:
    6-isopropyldecane.
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    This would be the common
    name for it.
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    If we want to use the systematic
    name, we would
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    replace the 6-isopropyl
    with 6,1-methylethyl.
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    So let me write that down.
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    So let me just copy this part.
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    So copy and paste right there.
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    And then I can copy and
    paste this right here.
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    Copy and paste.
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    So it becomes
    5,6-diethyl-6-1-methylethyl.
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    I know it's very confusing when
    you see it, but when you
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    break it down, you really
    could-- you would be able to
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    draw this from the structure.
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    And then finally you finish
    with a decane.
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    So hopefully, these examples
    don't confuse you too much.
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    In the next few videos, we'll
    do more and more examples.
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    Because I think with the
    nomenclature on the organic
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    chemistry, the more examples
    you see, the better.
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    This is really core, so in the
    future you don't get confused
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    when people throw out
    something like,
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    5,6-diethyl-6-(1
    -methylethyl)decane.
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Title:
More Organic Chemistry Naming Examples 1
Description:

More Organic Chemistry Naming Examples 1

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Video Language:
English
Duration:
08:59

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