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Organic chemistry
Course: Organic chemistry > Unit 13
Lesson 1: Naming aminesAmine naming 2
Amine naming 2. Created by Sal Khan.
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- What is the order according to higher priority among functional groups as substituents of the main carbon chain? Thanks.(14 votes)
- Cations > Carboxylic Acids > Sulfonic Acids > Acid Anhydrides > Esters > Acyl Halides > Amides > Imides > Nitriles > Aldehydes > Ketones > Alcohols > Thiols > Hydroperoxides > Amines > Ethers > Sulfides> Alkenes > Alkynes > Alkyl Halides > Nitroalkanes > Alkanes(52 votes)
- At @Sal says that the amino group should be given priority over the others. Is there any rule to find out which functional group should be given priority? 4:10(7 votes)
- yes there is a preference table for finding that.
go to http://en.wikipedia.org/wiki/IUPAC_nomenclature_of_organic_chemistry(18 votes)
- Why can't you count benzene as part of the backbone chain so that it has 11 carbons?(12 votes)
- So, if in the first example, If i shortened the 8-chain ring to just 5-chains, would the compound be named based on that 5 carbon chain or based on the phenyl group since the phenyl group has more carbons?(5 votes)
- why does it matter about alphabitacle order for the compund(2 votes)
- I'd hate to look in a phonebook that's not arranged alphabetically...(23 votes)
- Why does the alcohol group take priority over the amino group?(2 votes)
- The IUPAC has defined a standard order of functional groups. Several factors go into making this list, but one is atomic number, Since O > N, alcohols have priority over amines. You can see a table of priorities at http://www.chem.ucalgary.ca/courses/350/Carey5th/useful/nomen.html(12 votes)
- what are the chemical reaction of amines??(5 votes)
- 1.)Aminolysis: ammonia or amines react with an aldehyde or ketone to form an amine. The reaction needs a reducing agent like NaBH4
Ex: NH3 + H2-C=O -> CH3NH2
2.) Hoffman Rearrangement: Amides react with Br2 and NaOH to produce an amine
Ex: CH3CONH2(acetamide) + NaOH +Br2 -> CH3NH2 + CO2
3.) Curtius Rearrangement: Similar with Hoffman Rearrangement but instead of Amides, Acid Chlorides react with NaN3(sodium azide) to form amines
Ex: CH3CH2CH2COCl(butanoyl chloride) + NaN3 + heat -> CH3CH2CH2NH3 + CO2
4.) Sandmeyer Reactions: Amine reacts with HNO2 and H2SO4 to produce a Diazonium salt which reacts with a lot of reagents
-with CuBr and HBr to form Bromobenzne(from Diazotization of aniline)
-with CuCl and Hcl to form Chlorobenzene(from Diazotization of aniline)
-with HCN and KCN to form Benzonitrile(from Diazotization of aniline)
-with Cu2O and CU(NO3)2 to form Phenol(from Diazotization of aniline)
-with H3PO2 to form Benzene(from Diazotization of aniline)
5.) Diazonium Coupling Reactions: ArylDiazonium salts react with activated aromatic rings, like Phenol, to produce azo compounds
Ex: (C6H5-NN)+HSO4- reacts with Phenol to form (C6H5)-N=N-(C6H5) <- an azo compound
6.) Hoffman Elimination: An amine reacts with Ag2O and an excess of CH3I to form alkenes through an anti-zaitsev process
Ex: 2-butylamine + CH3I + Ag2O + heat -> 1-butene
7.) Reactions of an aryl or alkyl halide to form amines: Alkyl/Aryl halides react with NaN3 and the reducing agent: LiAlH4, ether to form Amines
Ex: CH3CH2CH2Br + NaN3 -> CH3CH2CH2N=N=N + LiAlH4 and ether -> CH3CH2CH2NH2
Ex: Bromobenzne + NaN3 -> (C6H5)-N=N=N + LiAlH4 and ether -> Aniline - (C6H5)-NH2(4 votes)
- if benzene is just a functional group attached to a carbon compound it's prefix is 'phenyl'.similarly what is the prefix given to a cyclohexane if it is a functional group too?(3 votes)
- why does sal start numbering the first compound from the right?
should'nt he start from the left because then only the branched chains get the lowest numbering possible?(2 votes)- The OH group takes priority over the others in the numbering.
So he has to start numbering from the end that is closest to the OH group — the right hand end.(5 votes)
- why are amines not acidic in nature? electronegativity of nitrogen and oxygen is almost same [ 3, 3.5] so the bond N - H and O - H must be almost identical ( with reference to polarity )(1 vote)
- You might be surprised at the big change in acidity a difference of 0.5 in electronegativity can make.
Here are the electronegativities of some atoms X and the pKₐ values of their X-H bonds.
C(2.55); pKₐ = 44
N(3.04); pKₐ =38
O(3.44); pKₐ =16
F(3.98); pKₐ =3
In the ionization X-H → X⁻ + H⁺, the main difference is in the stability of the X⁻ ion.
As the X atom becomes more electronegative, it is better able to stabilize the negative charge, so the position of equilibrium moves to the right.(6 votes)
- ´Hi,
I was wondering why its called 3-bromo-4-nitroaniline, and not 1-bromo-2nitroaniline?? I didnt think we could count the amine after we combined it with the benzen?(0 votes)- The carbon containing the NH₂ group is automatically number 1.
You start counting from there.(7 votes)
Video transcript
Let's see if we can handle some
slightly more difficult amine naming examples. So if we look at this blue
molecule right here, we always want to start off by finding
the longest carbon chain. It looks like it's this chain
at the bottom where we have one, two, three, four, five,
six, seven, eight carbons. So it's going to be octan. We don't want to just call it
octane because we have these functional groups up here, and
maybe one of them's going to take higher priority
than just the fact that this is an alkane. And, in fact, one
of them will. So let's look at them. So over here we an
amino group. That would make this
molecule an amine. So this is an amino
group right here. Then we have this
benzene ring. And when benzene is a functional
group, we call it a phenyl group. And that's derived from I think
it's either the Greek or the Latin word for light because
benzene was first isolated from, I guess, the
air around lanterns or something, so this is called
a phenyl group. And then finally we have this
OH, which would make this whole thing an alcohol, or we
could call that a hydroxy group, so this right here
is a hydroxy group. Now, this is just something
that you need to know. There's no way to kind
of deduce it. The people who've decided how
to name things just decided that certain groups take higher
priority over others. And out of these three groups,
the hydroxy group, the thing that's making this whole thing
an alcohol, takes the highest priority, so this is what's
going to define the suffix. So if we start numbering, we
want to start numbering this chain closest to the highest
priority group. So we'll start numbering
at this end. So it's one, two, three, four,
five, six, seven, eight. So we have a hydroxy group on
the three carbon, so this is octan-3-ol. If this was not a high priority,
we would put a hydroxy in the front, but since
this is the highest prioritiy, its defining this
as an alcohol, octanol. But we put the 3 there to say
it's on the three carbon. And then, of course, this
would be 5-phenyl. This right here is 5-phenyl. And this right here
is 8-amino. And amino comes before phenyl in
alphabetical order, so this whole molecule is going to
be-- let me write it over here-- it's going to be
8-amino-5-phenyl-octan-3-ol. And we're done. So this is an aromatic compound
because of the benzene ring. It's an amine because
of the amino group. And it's an alcohol because
of the hydroxy group. Now let's look at this molecule
here in green. And actually, I forgot
to draw part of it. This is supposed to
be a benzene ring. So let me make clear. That is a benzene ring. So let's think about
the different functional groups here. And we'll start with the one
that you've probably never seen before. This is a nitro group, and
it's highly explosive. Maybe in a future video, I'll
show you some nitroglycerin and some TNT, as you know, which
are highly explosive, but they have nitro
groups on them. So this right here
is a nitro group. It takes very low precedence in
the whole scheme of things. So this will never be the cause
of naming the suffix. We just know that this is a
nitro group right here. We, of course, have
a bromo group that we've seen many times. That is a bromo group. And then we have an amino
group right here. So this is going to be--
let me do this in a different color. This is definitely an amine. This is an amino group
right there. And out of these three groups,
the amino group is definitely of the highest priority. So you might be tempted to name
this 1-amino-2,3-brom o-4-nitrobenzene, but when a
benzene ring is attached to an amino group, this one also has
one of those special names. And let me just do it on
the side right here. So if I just have a benzene
ring attached to an amino group, so that's an NH2 right
there, we call this molecule right here, and this is just
the common name for it and it's something to put in your
toolkit, this is aniline. So that will be the base name. This whole thing right
here we call aniline. Let me write it over here. So this is aniline. And then we always want to start
numbering at the group that's really defining the
molecules, so we start numbering here. And you want to go in the order
where you're going to bump into something first. So,
one, two, three, four. So this is going to be-- if we
look at them, and bromo comes alphabetically before nitro,
so it's going to be 3-bromo-4-nitroaniline. And we are done!