Phthalic Acid & Phthalic Anhydride Video Lecture | Chemical Technology - Chemical Engineering

PVC plastic is typically quite rigid and
brittle when it doesn't contain a
plasticizer when it contains a
plasticizer it becomes soft and
malleable and it can be used for things
such as gloves in this video we'll be
extracting phthalates based plasticizers
from vinyl gloves and then reacting it
to form phthalic acid the phthalic acid
will then be converted into nearly pure
phthalic anhydride by sublimation
phthalic anhydride is an extremely
useful organic molecule and in a future
video I'll use it to make
phenolphthalein also over the course of
several videos all converted to
phthalimide then to enteric acid and
finally to methyl on throttle a methyl
and throttle eight is an imitation grape
flavor that's used in lots of different
candies and foods and it's used as the
main flavor additive in grape kool-aid
for this experiment I use 50 grams of
vinyl gloves 10 grams of sodium
hydroxide and 25 milliliters of
concentrated hydrochloric acid
not all gloves contain phthalates based
plasticizers and you might have to shop
around or try this experiment on several
different brands of gloves before you
find one that contains the right
plasticizer 250 milliliters of
isopropanol was added to a round bottom
flask a soxhlet extractor is then loaded
with some cotton followed by 50 grams of
cut-up vinyl gloves the gloves were cut
up into small pieces using a pair of
scissors a condenser was added to the
top of the sock suit extractor and the
water lines were attached the extraction
was allowed to run for two hours the
molecule were interested in extracting
is the plasticizer in the gloves and
it's called de HP for this step you
really don't need to use a salted
extractor but it is a much more
efficient method as an alternative you
can simply add the gloves to a beaker
containing isopropanol
boil it and filter off the gloves
afterwards the soxhlet extractor allows
for efficient and continuous extraction
of plasticizer using fresh solvent to
the right is a little cartoon of a sock
said extractor and action that I got
from Wikipedia if you want to better
explain
on how one works you can watch my video
on how to extract capsaicinoids where I
use this oxide extractor and I explain
it in more detail in short though hot
solvent travels up the sidearm and
collects in the soxhlet extractor and
once the solvent reaches a certain
height it all drains back down into the
round bottom after two hours the Sox the
extractor is removed and ten grams of
sodium hydroxide dissolved in 250
milliliters of water was added this step
is a base ester hydrolysis where the
ester bonds in the red box are
hydrolyzed this forms the salt form of
our desired phthalic acid product as
well as alcohols to complete the ester
hydrolysis reaction we're going to need
to add some heat and to do this we bring
our solution to a reflux
I only reflux it for about an hour but
it's probably better to reflux it for
around 2 to 3 hours after the reflux the
reaction flask was allowed to cool and
it separated into two layers the lower
aqueous layer contains our desired
product
disodium phthalate we don't need the
upper layer so try to decant as much of
it as possible without losing any of the
aqueous layer the remainder of the
mixture was then transferred to a
separatory funnel and then it was
allowed to stand to let the layers
separate after pouring it in the aqueous
layer might be cloudy like it is here
but you should wait until it clears up
as much as possible the equator might
however remain slightly cloudy but
that's okay once the lower layer had
cleared up as much as possible it was
drained into a beaker - this was added
25 milliliters of concentrated
hydrochloric acid to generate the
phthalic acid from its salt the solution
was stirred thoroughly and then it was
placed into a freezer to allow crystals
to form once a solution reached about
zero degrees Celsius it was removed from
the freezer at the bottom some crude
Dalek acid crystals have formed the
water was then decant it off
on a hotplate the crude phthalic acid
was dried and the remaining water was
boiled off by heating the phthalic acid
we can convert it to phthalic anhydride
which will then sublimate when it was
noticed that phthalic anhydride was
starting to sublimate off a round bottom
flask containing water was placed on top
of the beaker as a phthalic acid is
heated it melts decomposes as phthalic
anhydride which then itself is
sublimated off the sublimated phthalic
anhydride collects at the bottom of the
round bottom flask and the side of the
beaker only 30 seconds to a minute is
required on high heat and then the
beaker and the round bottom flask are
removed from heat it is very important
to allow for the beaker to cool and the
phthalic acid to re solidify if you do
not wait for to cool when the round
bottom flask is removed phthalic
anhydride dust will fly out of the
beaker once ethylic acid resolidify the
round bottom flask is removed in the
beaker we can see some nice clean white
Dalek anhydride crystals have formed
using a scoop EULA the crystals are
removed and effort is made not to touch
any of the phthalic acid at the bottom
of the beaker the nice and nearly pure
phthalic anhydride crystals are then
placed inside a DRAM vial this process
is then repeated several times until no
more phthalic anhydride is sublimated
off the final yield was nearly 4 grams
of pure phthalic anhydride shown here is
only about one gram of the total the
crystals are very fluffy and it looks
like a lot more than it really is this
is just to show you how brittle the
gloves are after the plasticizer is
being removed stretching and tearing
forces caused the pieces to break apart
quite easily
you