NYLON ROPE BY INTERFACIAL CONDENSATION
THEORY:
Amides are produced when an acid chloride reacts with an amine. The student should be able to
draw the mechanism for this reaction.
: O:
R
C
H
..
:
Cl
..
+
..
N
: O:
R'
R
C
H
acid chloride
..
N
+
R'
HCl
H
amine
amide
The byproduct HCl acid will consume half of the basic amine reagent, so two moles of amine
reagent must be used per mole of acid chloride. Alternately, NaOH can be added to an aqueous
amine phase to consume the byproduct HCl, while the acid chloride remains dissolved in an
organic phase. The amine migrates into the organic phase to react with the acid chloride and the
HCl produced in the organic phase, migrates to the aqueous phase where it is neutralized. NaOH
is a good nucleophile and would preferentially react with the acid chloride (producing a
carboxylate salt) if it were soluble in the organic phase but NaOH is insoluble in the organic
phase.
Nylon 6,6 [Dupont’s trade name for poly(hexamethylene adipamide)] is produced when
hexamethylenediamine (HMDA) reacts with adipoyl chloride. The reaction can be carried out in
a single phase (bulk polymerization) or as in this experiment, at the interface between two
separate phases.
adipoyl chloride
(hexanedioyl chloride)
Nylon rope pulled from the
interface.
HMDA + NaOH in water
O
Cl
C
hexamethylenediamine
(HMDA)
O
CH2
4
C
H2N
+
CH2
Cl
-
6
NH2
HCl
Nylon 6,6 at interface
O
O
Adipoyl chloride in CH2Cl2
Cl
C
CH2
4
C
HN
CH2
6
NH2
poly(hexamethylene adipamide)
(Nylon 6,6)
BB/CH605/Nylonropexp.doc
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NYLON ROPE BY INTERFACIAL CONDENSATION
PROCEDURE:
1. Prepare reagent a) and b) in separate flasks:
a) Prepare 5% adipoyl chloride in CH2Cl2. [Caution: Adipoyl chloride is corrosive. Use in
a fume hood]
b) Prepare an aqueous solution that is 5% HMDA and 2%w NaOH.
2. Pour the denser organic solution into a small beaker first.
3. Slowly and carefully pour an equal volume of the aqueous solution on top of the organic
layer. Do not allow the solutions to mix when combining them. You should obtain two
separate layers. A thin white layer will appear at the interface when the two solutions are
brought into contact. This is Nylon 6,6 formed by interfacial condensation.
4. Use a wire or tweezers to slowly pull the white solid layer up out of the solution and a long
fiber is drawn.
5. Rinse the fibers under running water and study their feel and strength.
QUESTIONS:
1. Show the mechanism of amide formation during reaction of an acid chloride and an amine.
2. Identify the polymerization type as one of the following: chain growth, step growth
(condensation or rearrangement) or ring scission.
3. Identify the polymerization technique as one of the following: bulk, solution, suspension or
emulsion.
4. Identify the polymer type as either thermoplastic or thermoset.
5. Identify the end use of the polymer as one of the following: rubber (elastomer), plastic
(resin), fiber, coating, adhesive (sealant), film, composite, cellular or biopolymer.
BB/CH605/Nylonropexp.doc
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