5.4.2 Organic nitrogen
compounds: amines, amides,
amino acids and proteins
Benzene
Reaction
summary
http://en.labs.wikimedia.org/wiki/
A-level_Chemistry/OCR_%28
Salters%29/Reactions_of_arenes
• Burning Benzene – Smokey flame
• http://www.youtube.com/watch?v=XhRHk4
zLR8A
Methoxybenzene and
methylbenzene (toluene)
• Also undergo E+ subn. Do so more readily
than benzene.
Phenol, C6H5OH, (carbolic acid )
Phenol, C6H5OH
• Early anesthetic (but burned the skin)
• Poorly soluble (8.3 g dissolving in 100 mL )
• Does NOT behave like an aliphatic alcohol
- is acidic, pKa = 10.0 (ethanol=15.9, ethanoic
acid=4.75)
• Although acidic, unlike –COOH, phenol NOT will
react with carbonates and hydrogencarbonates
to form CO2
• Only esterifies with acid chloride (i.e. not with a
carbox. Acid, RCOOH)
…RING MUCH MORE REACTIVE
THAN BENZENE
Solubility of phenol and phenoxide anion.
Phenol in water (org solvent at bottom) >
NaOH added > acidified
http://www.sciencephoto.com/image/4210/530wm/A5000274-
Phenol_reactions-SPL.jpg
Phenol
with
Br2(aq)
c.f.
benzene!
Phenol
with
cold
dil
HNO3
c.f.
benzene!
•
http://upload.wikimedia.org/wikipedia/commons/5/5c/EAS-ortho-para-meta.png
E+ Subn in phenol
• Many (Kekule)resonance structures
http://chem-guide.blogspot.com/2010/04/electrophilic-substitution-of-phenol.html
Rxns
•
of benzene
http://clem.mscd.edu/~wiederm/oc2chp/oc2chpphenols/phenolrxnsummary.gif
Other
Reactions
(N.O.S.)
- Demonstrate
increased
reactivity of
the ring
Aspirin (synthesis #1)
• http://www.ch.ic.ac.uk/rzepa/mim/drugs/html/aspirin_text.htm
Aspirin (synthesis #2)
• http://www.ch.ic.ac.uk/rzepa/mim/drugs/html/aspirin_text.htm
Amines, amides and amino acids
• Aliphatic amines, & aromatic amines
ethylamine
phenylamine
a.
give examples of:
i.
molecules that contain amine and
amide functional groups
ii.
amino acids
• b. describe and carry out, where appropriate (using
butylamine and phenylamine), reactions to investigate
the typical behaviour of primary amines. This will be
limited to:
• i. characteristic smell
• ii. miscibility with water as a result of hydrogen bonding
and the alkaline nature of the resulting solution
• iii. formation of salts
• iv. complex ion formation with copper(II) ions
• v. treatment with ethanoyl chloride and
halogenoalkanes, eg making paracetamol
Making paracetamol
#1
•
para-acetylaminophenol
http://www.ch.ic.ac.uk/rzepa/mim/drugs/html/paracet_text.htm (good short notes on overdose problem)
Making paracetamol #2
• http://en.wikipedia.org/wiki/Paracetamol
Reduction of Nitrobenzene to
phenylamime (aniline)
Diazo formation
• 1o, 2o and 3o aromatic based amines.
Video 1o amine undergoing decomposition
T>10oC
Methyl orange via diazo coupling
http://www.science.cmu.ac.th/educate/
couresware_chem/203204/Arputtinan6.htm
The colours of Methyl Orange
< A diazo dye
• Other Azocompounds (salters chem)
Polymers
• Video of polymer – ‘bubblegum’ a.k.a.
Plastics, rubber, food colouring, sucrose
and dextrose – yum huh?
Nylons…
• Video 1 – intro to polymers
• Video 2 – nylon – brave? no glasses guy
• Video 3 – specific chemicals used nylon
• Product name : SAP-Super Absorbent
Polymer
• Chemical name : Sodium polyacrylate
• Monomer Molecular formula : C3H4O2
monomer
Many COOH (or COONa)
groups allow for widespread
large amount of interaction
with water molecules
? = addition polymer repeating unit of sodium poly(acrylate)
Super Absorbent Polymers for Diaper
http://www.made-in-china.com
Video
Other water interacting polymers
• Propeneamide
Dissolving Plastics
Poly(ethanol)
Propeneamide
•Webpage: DissolvingPolymers.mht
? = addition polymer repeating unit of poly(propeneamide)
Dun WORi, POLYURETHANES ARE NOT ON THE SYLLABUS !!!
Polyurethane formation (isocyanate with polyol)
PU video
http://ec.gc.ca/substances/nsb/images/Polyurethane_S1.gif
Condensation polymers
• Terylene is used to make
fishing nets
clothes (quick-dry, non-iron)
cassette and video tapes
Condensation polymers: There are two main types of condensation
polymer made from carboxylic acid derivatives: polyesters and polyamides.
i) Polyesters: A well-known polyester, Terylene, is made by heating
ethane-1,2-diol with dimethylbenzene-1,4-dicarboxylate (dimethyl terepthalate):
The dimethlybenzene-1,4-dicarboxylate is obtained via the following reaction
pathway:
The manufacture of ethane-1,2-diol has already been described in section 26.4.2.
Or simpler rxn (more edexcel
friendly) not using the diester as
previously, but the dicarbox acid…
Kevlar
Poly(N-substituted amide)
Kevlar again.
Synthesis of Kevlar
Should be familiar with monomers and
polymer requirements now.
Poly(N-substituted) amide – similar to Nylon
Amino acids.
• Naturally occurring ones are L acids
(laevorotatory)
• Strecker synthesis give L and R (next
slide)
T h e S tre c k e r s yn th e s is . - S yn th e s is o f a m in o a c id s
(1)
(2)
O
R
-
(1)
.
O.
..
C
H
H
(3)
(2)
(1)
R
H
C
N
H
H
O w a te r
(2)
+
N H3
H
H
.
O.
H
R
C
..
N
H
H
H
R
C
..
N
H
H
a n im in e
(1)
H
H
(2)
R
C
N
H
H
T h e n itro g e n ve rs io n o f a
c a rb o n yl. C = N c a n re p la c e C = O
(re c a ll 2 ,4 -D N P re a c tio n !!)
(2)
..
CN
CN
R
O
C
.. .
N.
H
H
CN
R
(1)
T h e im in e
C
..
N
H
H
H
( +O H
-
ions)
T he N equivalent
of the alpha-hydroxy
nitriles. A n alpha-am ine nitrile
Lik e C = O 's, C = N 's are
susceptable to nucleophilic
attack - addition - by - C N
A cid
hydrolysis
of niriles.
OH
O
C
R
*C
..
N
H
H
H
A n alpha-am ino acid
The amino acids vary
in their side chains
(indicated in blue in
the diagram).
The eight amino
acids in the orange
area are nonpolar
and hydrophobic.
The other amino
acids are polar and
hydrophilic ("water
loving").
The two amino acids
in the magenta box
are acidic ("carboxy"
group in the side
chain).
The three amino
acids in the light
blue box are basic
("amine" group in the
side chain).
Amino acids – Ninhydrin rxn and
test
Ninhydrin rxn with amino acids.
Procedure
Add about 2 mg of the sample to 1 mL of a solution of 0.2 g of ninhydrin
(1,2,3indanetrione monohydrate) in 50 mL of water. The test mixture is
heated to boiling for 15-20 sec; This reaction is important not only because it
is a qualitative test, but also because it is the source of the absorbing
material that can be measured quantitatively by an automatic amino acid
analyzer. This color reaction is also used to detect the presence and position
of amino acids after paper chromatographic separation.
Positive Test
A blue to blue-violet color is given by a-amino acids and constitutes a
positive test. Other colors (yellow, orange, red) are negative.
Complications
Proline, hydroxyproline, and 2-, 3-, and 4-aminobenzoic acids fail to give a
blue color but produce a yellow color instead.
Ammonium salts give a positive test. Some amines, such as aniline, yield
orange to red colors, which is a negative test.
Amino acids – analysis with
ninhydrin
chromatography
Protein synthesis (biological)
• Video (real time)
• Video 2
• Salters Organic Toolbox
• Salters Organic Reactions.mht