28. Synthesis of Nylon 6,10
Polymers are large molecules made up by joining together many small
molecules. The small molecules that go into making a polymer are called
monomers.
When just two monomers join together the product is called a dimer. When
three link together, a trimer. What would a molecule be called that is made up of 4
molecules? 5 ? 6? Oligomers are medium sized molecules usually made from 8 to
about 20 molecules.
Polymers can be made up from between about 20 and 10,000 monomers or
more. Polymers make up a large bulk of the commercially important organic
chemicals.
Today each of you will make Nylon-6,10. Nylon is an alternating polymer used
in a wide variety of household product including stockings, windbreakers,
shoestrings, car parts, tents, and fishing poles.
PRE-EXPERIMENT ASSIGNMENT
Read this document. Additional information is found in the on-line notes. This
material will not be on the final exam. A notebook does not have to be prepared for
this activity.
Safety Considerations
Sebacoyl Chloride reacts with water immediately to form HCl gas. Sebacoyl
chloride caused severe burns upon contact. Keep away from skin, eyes and
clothes. Wear gloves, goggles and a lab coat while performing this experiment.
Sebacoyl Chloride is a lachrymator. This means it causes severe irritation to the
eyes and results in prolific tearing and pain. Wear goggles at all times during this
experiment. If any bodily contact is made with sebacoyl Chloride, wash with
copious amounts of water immediately.
Chlorinated hydrocarbons tend to be toxic. Keep methylene chloride away from
skin.
EXPERIMENT
As you have seen previously, a condensation reaction is a reaction where two
(or more) molecules join together to form one larger molecule and a small molecule
typically water being produced as a side product. In today’s reaction the small side
product molecule is not water but HCl. Hence, this reaction should be done in the
hood, and the product rinsed in sodium bicarbonate water to neutralize the acid
before handling.
In this reaction 1,6-hexanediamine or 1,6-diaminohexane (also commonly
called hexamethylene diamine) is reacted with sebacoyl chloride (also called
decadioyl chloride). Both amine ends of the 1,6-diaminohexane react with both
acid chloride ends of the sebacoyl chloride to form new amide linkages. The
polymer which forms is made up of alternating 1,6-diaminohexane and sebacoyl
groups. This is called an alternating copolymer. This particular Nylon is made of
alternating units of 6 carbons between two nitrogen atoms, an amide linkage, and
another unit of 10 carbons. This repeats many many times; therefore this is
Nylon-6,10.
Procedure
Work with a partner. Obtain two 50 mL beakers. Be sure these are very
clean. Wash with soap and water, then acetone if necessary. Label one beaker
“W” for water based. Label the other “M” for methylene chloride based.
Into the “M” beaker place 12 mL (two 6 mL pumps) of methylene chloride
(dichloromethane).
Carefully, while wearing gloves, fill pre-marked pipette to line (~ 0.5 mL)
with sebacoyl chloride. Dispense immediately into beaker containing methylene
chloride. Dispose of pipette in large beaker in hood marked “Used Sebacoyl
Chloride Pipettes”. Swirl “M” beaker to mix.
Into other “W” beaker place 6 mL (1 pump) of 1,6-diaminohexane
solution in water.
Bring both beakers and a copper hook and a wooden stick to any other
open hood space.
Water is less dense than methylene chloride (1.0g/mL vs 1.3 g/mL). It is
desired to layer the 1,6-diaminohexane in water on top of the sebacoyl chloride
in the methylene chloride. To do this, slowly pour the contents of the “W”
beaker down the inside of the “M” beaker with the least amount of mixing
possible. There should be two definite layers. Set the beaker down on the floor
of the hood.
The nylon forms spontaneous at the interface of the two liquids.
Work with partner on next step. One person will hook the nylon which
forms at the interface with a copper hook and pull slowly straight up as high as
possible. The second person uses a wooden stick and grabs a portion of nylon
string and pulls as high as they can go. Repeat until no more nylon forms.
Another alternative to this method is for the first person to pull the nylon
and wrap it on a 100 mL graduated cylinder. Then the cylinder is rotated and
the nylon strand is coiled around the cylinder.
Dunk formed nylon into sodium bicarbonate solution to neutralize any
hydrochloric acid. Dry on paper towel. Feel free to take home or tape in lab
notebook.
Clean-up
Dispose of residual liquid from “M” beaker into halogenated organic
liquid waste container. If you have any residual liquid from the “W” beaker,
dispose of it into the aqueous liquid waste container. Replace copper hook on
back bench. Wipe work area down with wet sponge. Wash hands.
POST-EXPERIMENT ASSIGNMENT
Prepare for your final exam.
Revised November 20, 2014 S. L. Weaver