Peterson and cadaverine are nasty
smelling organic compounds that
contribute heavily to the smell of
rotting flesh both are produced during
the breakdown of amino acids which are
the chemical building blocks of proteins
future scene comes from the breakdown of
the amino acid ornithine and cadaverine
comes from lysine what might be
interesting to know is that these two
nasty smelling amines are not only
produced during putrefaction they also
contribute to other wonderful things
like the stench of bad breath or
bacterial vaginosis as well as the
characteristic smell of semen in the
past I've made both by thermal
decarboxylation but today I'll be doing
a proper chemical decarboxylation I
decided that I'd only make one of them
though because the process is pretty
much the same for both
and I chose cadaverine because I had the
precursor on hand
when we take a look at the chemicals
it's probably the most ingredients I've
ever used in a reaction I was going to
read out all of the ingredients but I
feel like I'd put you to sleep if I read
each one I adapted the procedure that
I'm using from a paper and I'll provide
a link to it in the description
the first thing that I need to do is
prepare a buffer solution and I start by
adding 3.2 grams of disodium phosphate
dodeca hydrate to a flask
I then add in about 0.6 grams of citric
acid and 90 milliliters of distilled
water
I drop in a stir bar and I mix things
until everything has fully dissolved in
chemistry a buffer solution is a
solution that resists pH change the
buffer here has a pH around 5 and if a
small amount or even a moderate amount
of acid or base is added the pH
shouldn't change very much this is
really useful for a pH sensitive
reactions and it allows us to keep a
nearly constant pH throughout the entire
process according to the paper that I
got this procedure from a pH of 5 was
extremely important when they didn't use
a buffer and the pH was allowed to
change they found that the reaction
actually took a different pathway and
led to the wrong product
anyway just for fun I used a universal
pH strip to verify that we had a pH of
about five
to the nice and freshly prepared buffer
solution I add 3.5 3 grams of l lysine
the stirring is turned on and I let
things mix until all of the lysine has
dissolved
while the lysine solution is being
stirred we can move on and make our
second solution to do this we start by
adding 20 milliliters of dimethyl
formamide also known as DMF
into the DMF we add ten point three
grams of n-bromosuccinimide or NBS for
short
the mixture is stirred until we're left
with a clear solution and all of the NBS
has dissolved the NBS solution is then
added slowly to our buffer solution you
can see that co2 is being evolved very
shortly after the solution is added
what's going on here is an NBS induced
oxidative decarboxylation of an amino
acid this is the overall reaction that
we're doing here where we're converting
the amino acid to the corresponding
nitrile according to the paper this is
the step that the pH buffer was
important for because if the pH wasn't
controlled and kept around five it would
produce an aldehyde instead of our
desired nitrile the procedure in the
paper didn't say anything about adding
it slowly and I just chose to do this
but as I was editing and I reread the
paper there was a mention in the
introduction that they added the NBS
solution drop-wise if the NBS solution
is added too quickly it might start
reacting before it can be adequately
mixed with the buffer this might cause
some areas of the solution and some
parts of the reaction to fluctuate from
a pH of five and this could possibly
lead to the wrong product and reduce our
yield this is just speculation on my
part though and I don't really have any
way to verify whether this happened or
not
anyway after all the NBS solution is
added I let things stir until there's no
more bubbling I think it took something
like five minutes for the bubbling to
stop but the paper said to stir things
for thirty minutes so that's what I did
after the 30 minutes I dumped in
twenty-two point nine grams of nickel
chloride hexahydrate this is allowed to
stir until everything dissolves you'll
notice here that I messed up a little
bit and some of the nickel chloride
didn't make it into the flask but that
really shouldn't be a problem
I weighed out 5.8 four grams of sodium
borohydride and I started to add it in
small portions it's really important
that it's slowly because the reaction is
quite vigorous also it produces a lot of
hydrogen gas so it's important to do
this in a well-ventilated area okay so
what's going on here is we're reducing
the nitrile that we made in the previous
step to the corresponding amine
in solution the sodium borohydride will
combine with the nickel chloride to make
nickel boride under normal conditions
sodium borohydride does not reduce
nitriles however in the presence of a
catalyst like nickel boride the reaction
actually proceeds quite readily
the solution is originally very dark
because we have a high concentration of
nickel chloride but as we add the sodium
borohydride we use up the nickel
chloride and the solution lightens up
however as we continue with the addition
we produce more nickel boride which is a
black solid and the solution gets dark
again
as we continue to add more sodium
borohydride each addition becomes less
and less vigorous because of this we can
start to add much larger portions and we
don't have to fear some crazy violent
reaction
once I finished adding all of the sodium
borohydride I continued to stir the
solution for about 20 minutes
what we need to do next is separate the
black nickel boride solid from the
reaction solution this can be a pretty
big pain because the nickel board that
formed is extremely finely dispersed I
tried to do a gravity filtration here
through some cotton and it clearly fails
the best way that I found a separated
was by vacuum filtration where I pulled
it through I think two or three filter
papers
the first filtration is still going to
be full of nickel boride and to clear
things up we're going to have to do a
second filtration
once everything has come through I
transfer everything in the filtration
flask back to the beaker and I pour it
through the same filter paper although
the solution looks the same a lot of the
solid was actually trapped by the filter
paper
the solid nickel board that was trapped
by the filter paper will actually itself
act as a filter
so this time when we filter things
through we have a nice clear solution
that's pretty much free of nickel boride
when I take off the filter here you can
see all of the nickel Bora that's been
trapped
I dropped a stir bar into the flask and
then I base if I'd the solution the goal
here is to get the pH of the solution
around 11 to 12 so that we can liberate
freebase cadaverine
before we be so fie things there's
actually no smell
because cadaverine is still in its salt
form cadaverine hydrochloride
by increasing the pH we're converting
the cadaverine hydrochloride to its
freebase form which is going to stink a
little some of the sodium hydroxide is
also going to react with some of the
nickel that's present and it will form
nickel hydroxide which will precipitate
out of solution
the pH was verified using Universal pH
papers so once we reached a pH of around
11 to 12
I stopped adding sodium hydroxide
everything was transferred to a
separatory funnel and it's time to
extract our cadaverine in theory I could
have filtered off all the nickels salt
that formed but there's honestly really
no point
the cadaverine solution was extracted
three times using 30 milliliters of
diethyl ether each time
the typical procedure is that we add the
extraction solvent we cap shake invent
the separatory funnel and then we place
it back on the stand for the layers to
separate
once the layers have separated the lower
aqueous layer is drained off and we
collect the upper ether layer in a
beaker this process is repeated two more
times for a total of three washings
the combined ether washings are poured
back into a clean separatory funnel and
then I pour in some saturated salt
solution
this step is somewhat optional and it's
mostly just used to dry the ether and
pull out any water that might be
dissolved in it
the aqueous layer was drained off and
our upper ether layer was poured into an
Erlenmeyer flask
just to get rid of the last water that
might remain the diethyl ether was dried
using a little bit of magnesium sulfate
the magnesium sulfate was then separated
from the diethyl ether by filtering it
through a little bit of cotton
diethyl ether is extremely volatile so I
just let it evaporate at room
temperature once all the ether was gone
I was left with a nice gooey residue at
the bottom of the beaker
cadaverine has a melting point of around
9c so it makes sense that we're left
with a goo and not a solid
with a little bit of skill the
cadaverine was transferred from the
beaker to a small vial
cadaverine didn't seem to be super
soluble in acetone so I used a very
small amount to try to get rid of any
water that might remain
I added a little bit of acetone mix
things around thoroughly and then pour
it off the liquid and then lift the vial
out for a bit for the acetone to
evaporate
this might reduce the yield a little bit
but the cadaverine should be relatively
water free and a little bit more pure
okay so I should really address the fact
that the yield of this reaction is
pretty miserable
the yield that I got was about 0.5 grams
and the theoretical is supposed to be
about 2 in the paper that I followed the
yield that they got for cadaverine was
77% which is actually more than triple
what I got
I do have an explanation for this though
and it's pretty much because I poorly
adapted the procedure from the paper the
solubility of amino acids can vary quite
a bit and the paper provided two
procedures the first procedure was for
when the amino acid was very soluble in
water and the second one was for when it
wasn't very soluble lysine hydrochloride
is pretty soluble in water and we need
to use the first method I try using the
second one and it pretty much doesn't
work at all in the first procedure after
the nickel boride was filtered off I was
supposed to pass it through a dewaxed
ion exchange column I didn't have the
supplies to set up a column so I opted
to do an extraction like they did in the
second procedure this is a problem
though because cadaverine is quite
soluble in water so it's difficult to
extract according to the solubility is
online I don't have an exact number but
it's actually more soluble in water than
it is diethyl ether and some other
extraction solvents
this means that extracting it with an
organic solvent is actually super
inefficient and we're probably leaving a
lot of cadaverine behind in the water I
honestly thought I was maybe going to be
able to get away with using the ether to
extract it but it clearly didn't work I
decided not to try to redo the prep
because I didn't really have a use for a
cadaver in any way and also I ran out of
diethyl ether if I were to redo things I
still wouldn't use a Dow X column but I
would try to other things one thing that
I could try is saturate the solution
with sodium chloride and reduce the
solubility of the cadaverine which might
make its extraction a little bit better
I'm honestly not sure how well that
would work and I'd actually think this
other idea might be better before any
base if occation is done I could simply
evaporate off all of the water
and leave behind cadaverine
hydrochloride as well as nickel salts -
the residue I could then add a small
amount of basa fide ethanol this should
freebase the cadaverine which is soluble
in ethanol but it should leave behind
the nickel salts when the ethanol is
evaporated I should be left with the
cadaverine and maybe some salts that
were able to dissolve into the ethanol
the residue could then be washed with
some ether which would pick up the
cadaverine and leave behind the salts
then when the ether is evaporated it
should contain just our cadaverine
anyway that's just an idea off the top
of my head I don't really know for sure
if it would work but I want to know what
you guys think could be a viable way to
do this so that's more or less the
question that I have for you guys in
this video do you think my suggestions
make sense and that they could be viable
or do you have any suggestions or ideas
of your own also I'm pretty much blaming
my low yield on the solubility of
cadaverine in water but do you think
this is accurate or do you think there
could be another reason why my yield is
so much lower than the papers
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