infrablue
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Putrescine and Cadaverine
By decarboxylation of lysine or ornithine, it is possible to synthesize these horrid smelling compounds. Lysine gives cadaverine (5 carbons), while
ornithine gives putrescine (4 carbons).
Roughly equal amounts of lysine hydrochloride and NaOH were placed in a test tube, along with a small amount of water. The mixture was heated over an
alcohol lamp flame. No discoloration was observed. No smell resulted save perhaps a very faint suggestion of a clean plasticky aroma.
After the mixture had sat approximately 24 hours, some pyridoxal-5-phosphate (activated vitamin B6) arrived in the mail, and a small amount was added
to the solution. It gave a yellow color to the mixture. This mixture was then heated over the alcohol lamp for a few minutes. A color change was
noted; the solution became greenish, but very little odor was observed.
The next day, the solution had cooled and remained greenish in color. A definite odor was now observable. I would have to describe it as mousy, like
wet mildewy animal fur mixed with raw pasta. It was not what I expected, but it also wasn't a very strong concentration at all. I had to put my nose
right up to the mouth of the test tube to smell it.
To test whether the smell could have been a breakdown product of the B6, the same amount of lye and pyridoxal were added to a fresh test tube. About
1/3 as much water was used this time, in order to encourage the release of any odorant formed rather than risk trapping it in the water solution. Upon
heating, the same color change took place (yellow to greenish), but no odor resulted.
Added ornithine hydrochloride to the second tube and heated it. This time, the water actually started to boil, since there was less volume of it. Now
an odor began to develop, very similar to the one from the lysine tube. This odor was slightly less musty and slightly less mousy than the odor from
the lysine tube, but overall very similar in character.
Isopropyl alcohol was added to both tubes after they had cooled. It formed a clear layer above the olive-chartreuse aqueous solution, and refused to
mix. Both putrescine and cadaverine are soluble in ethanol, and presumably would also be soluble in isopropanol. Lysine and ornithine are not very
soluble in alcohol; sodium hydroxide is a little bit soluble, though if it all reacted to sodium chloride it would only dissolve slightly in IPA. No
yellow color was seen in the alcohol layers, indicating the B6 did not dissolve. And the wet mousy smell transfered to the alcohol after less than a
day, even being perceptible after the alcohol layer was removed and placed in a separate container. The odor strengths of the putative PUT and CAD
were perceptually about equal to that of the IPA.
Upon sitting cold for a couple days, a white precipitate could be seen in the alcohol layers in both tubes. This precipitate clings to the side of the
tube, but can be jarred loose, after which it settles between the two liquid layers. I wonder if this may be small amounts of unreacted amino acid
and/or unreacted NaOH dissolving in the alcohol and precipitating due to evaporation.
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heksogen pl
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Try adding some copper catalyst and increasing the temperature by employing a higher boiling solvent. Anyway, it seems interesting to figure out the
components of the rotten meat smell.
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infrablue
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Good idea thank you!
Trying the copper now. Added some CuSO4 to the lysine and lye step. I gotta say copper lysinate (?) must be the deepest most beautiful blue I've ever
seen in a science experiment. After adding the B6, the solution started to smell like cadaverine before even heating it, although the dissolving lye
did heat the bottom of the tube.
It seems to be making a brown precipitate though... could something be reducing the copper to CuOH I wonder.
[Edited on 2021-10-1 by infrablue]
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thioacetone
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hi can anyone describe the smell of putrescine to me?
I tried making some by decarboxylation of ornithine (heating it like nile red did) but it doesn't smell putrid to me, it just smells really strongly
of semen.
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Raid
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thioacetone, that's what putrescine is supposed to smell like, It's naturally produced in the body in small amounts giving it that characteristic
smell.
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