Something Smells fishy!

Amines have a very noticeable characteristic: odor. One example is Ammonia, but it is only unbearable in large concentrations. One smell that is almost always unbearable is the smell of rotting fish. When fish rot they produce some trimethylamine, which smells like deterioration. These types of Amines are soluble in water and are volatile. They can easily reach our noses. When an animal, such as a fish, dies the body starts decomposing and the nitrogen in the animal flesh turns into amines during the chemical reaction. Rotting fish also have another special characteristic that makes it even more unpleasant to our senses, they are diamines. Diamines are amines with two amino groups. The diamines are also present in urine, bad breath, and semen. The Diamines are also similar to a molecule that we use to make nylon, but does not exert the same intense odor.

Terms:
Amines: Organic molecules that correspond to ammonia, in which one, two, or all three of the hydrogen atoms have been replaced by R groups consisting of chains or rings of carbon atoms.
Trimethylamine: “an organic compound with the formula N(CH3)3. This colorless, hygroscopic, and flammable tertiary amine has a strong "fishy" odor in low concentrations and an ammonia-like odor at higher concentrations.”
Diamines: molecules that contain two amino nitrogen atoms.

Not only do I hate fish, but I particularly hate the smell of fish. I always wondered why the meat of fish smells so bad, but not the meat of other animals. I have always liked meat from cows and pigs and have never noticed that meat to have a particularly disgusting odor that is unbearable. Even cooked fish smells bad, though not as bad as rotten fish. I’m sure that rotten anything smells bad, but fish smell in general, even if they have only been dead for a short amount of time. It is very interesting to learn that it is because of the Nitrogen and Amines that dead meat smells bad. I wouldn’t always classify ammonia and rotten fish in the same category, but now it makes sense why they are similar, and why they are different. Ammonia does not contain diamines, while rotten fish meat does.


Colin Baird. Chemistry In Your Life. 2nd Ed. (New York: W.H. Freeman and Company, 2006) 295-296

“Trimethylamine” Wikipedia. http://en.wikipedia.org/wiki/Trimethylamine. February 16, 2009