Stories that don’t belong elsewhere

Chemical celebrities
All students of biology learn about the metabolism of alcohol. Its pretty simple, just 2 steps.

1. Ethanol drunk is converted to acetyldehyde by alcohol dehydrogenase, 2. acetyldehyde is then converted to acetic acid (vinegar) by acetyldehyde dehydrogenase where it can later be turned into the empty calories that alcohol provides.

Alcohol--->acetyldehyde--->acetic acid

If you substitute methanol for ethanol it goes Methanol--->formaldehyde--->maybe formic acid (if you live).
Formaldehyde being the stuff of embalming, and it destroys your eyes (and nerves) first. Plus formic acid freely converts back to formaldehyde. Formic acid is also what black ants squirt their enemies with.

And of course some folks (usually from the Pacific rim) lack sufficient or active enough acetyldehyde dehydrogenase, so the acetyldehyde accumulates if they drink but one drink. They flush bright red, get high blood pressure, feel funny in the head and just plain get sick.

From this understanding, Antibuse (disulfuram) was created. It blocks the activity of acetyldehyde dehydrogenase, making Alcoholics (or anybody) who took this pill, deathly ill with the first drink had.

All this talk of acetyldehyde.

But today, I met acetyldehyde face to face. Its quite flammable, boils at just above room temperature, and it smells just like a bunch of grapes!

Not grape juice or grape kool-aid. When you sit with a big bowl of grapes, there is this faint but characteristic, sort of musty smell I associate with them. That smell is acetyldehyde!

I occasionally encounter the same odor when eating salads, but I can't recall precisely which salad items give me these memories.

While musing over this and sniffing away, my ears starting to ring. Time to put it back in the lab fridge.

Chemical connections, chemical memories
Today I opened the lab cupboard and shoved some bottles around while looking for a particular chemical. I pull my hand out to scratch an itch on my nose and get hit with the unmistakable odor of trimethylamine.
Smells like... Stinky Fish! Really stinky fish.
White crystals formed from the simple mixing of formaldehyde and ammonia. A squirt of lemon juice from a lemon wedge would neutralize the odor (as it does on fish) because simple amines are weakly basic and react with the stronger acid.
I washed my hands instead.

Stinky amines are a hallmark of putrefaction. The other common stinky molecules of life, the stubby, short chain organic acids like acetic, lactic and butyric come from the happy fermentations of bacteria which are not necessarily associated with death, just decay. In addition, all manner of decay (and death) seeking insects seek out these stubby acids because thats where the grub is at. Of course with these acids, a squeeze of lemon won't do. You need something alkaline like the baking soda in your fridge or the wood ashes people used to throw on the outhouse pile.

I keep stumbling across this stinky fish stuff.

As a young teenager reading all about WWII, I read of RDX (sometimes called cyclonite),an explosive developed to augment TNT in the war effort. It was made by nitrating Hexamine with nitric and sulfuric acids. Interesting.

Later, I discovered that hexamine was used as a camper's fuel in small stoves.
I picked one up in the now defunct MassArmyNavy store. It turns out that THESE little stoves were invented to heat the little C-ration cans. The hexamine came in little tubes containing 6 "pills" of hexamine fuel. The fuels tabs smell like fish. Faintly

During a somewhat impulsive and penniless trip to NYC during a frigid January kirilisa and I used the little hexamine tablets to heat a can of baked beans while we shivered under a footbridge in a park somewhere between 116th and 125th streets. Those where some good beans.

Still later I discover that the Germans had their own stove. The ESBIT The stove remains absolutely unchanged to this very day. I wonder if they still use the same machinery to produce them. The Esbit tablets smell like stinky fish. Unmistakeably so.

Even later, I discovered that the British copied the Esbit and it remains standard issue in the British Army to this day. Convenient for all that tea. The Brit version is a bit bigger and they call it a Hexi cooker

From explosives to ration cookers, the smell of stinky fish could be found throughout the duration of WWII, and in my little collection of pocket stoves.

Recently I read "Uncle Tungsten" by Oliver Sacks I learned of a mischievous young Sacks who would whip up a batch of hexamine from the formaldehyde and ammonia and "poison" the fish his mother was prepared Gefilte from. One whiff and she'd toss the lot out. Personally, I'd say trimethylamine smells more like stinky fish than any of the stinky fish I've ever actually encountered :-p


And today, Grocott's Methenamine Silver(PDF file)stain to demonstrate the presence of fungi.

Trimethylamine, Hexamine, Methenamine- Different names for the same thing, and it all stinks of fish.

Life Imitating Art?

Long ago, in sixth grade, my friend Greg asked me a question during our weekly "art" class. While gluing together scraps of colored cellophane with rubber cement, he asks
"Is it possible to stop an acid leak with a Hershey bar?"
He explained that on an episode of macgyver, the hero macgyver used chocolate to stop a sulfuric acid leak. Although obsessed with chemistry back then, I didn't know the answer to his question, nor had I seen the episode. In fact, I had never encountered the scene he was referring to, despite watching the show myself throughout the 80's. Along with the A-Team, Transformers, etc. The question has been on my mind, now and again other the years but never had anything come of it.

Fast forward to 2006. mrtee tries dealing with recent sleepless nights with some stuff off of netflix. It turns out this Hershey bar vs acid scene in question is from the pilot episode of macgyver which I had never seen. The hero tells his girlfriend of the day that is not just chocolate its ...blah,blah..lactose a dissaccharide which will react with the acid to form a sticky residue...

And that was it. It was the sugar and acid. I'm pretty sure there is much more sucrose than lactose in milk chocolate, but who cares?

One of the simplest chemical demonstrations which I fear will soon become forgotten is the "chemical snake"
Described in "After-Dinner Science" by Kenneth Swezey which I had picked up at a used book sale and in "Chemical Magic", by Leonard Ford and Winston Grundmeier.
After-Dinner science is a long out of print book filled with great pictures and Chemical magic is a Dover books reprint filled with all kinds of tricks, some of which honestly are too dated to be done anymore (and too dangerous--for instance, white phosphorus smoke)

I can't find my copy with the cool pictures, so I set off to replicate them, on a sleepless night, of course.

So Greg, if you are out there, Macgyver was counting on the high sugar content of the chocolate to react with the acid, forming the goop similar to that described below.

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