isopropyl

This word has a sharp smell for me. A smell of sharpness, in fact.

Isopropyl alcohol isn’t the only isopropyl, but it’s the one I know. It’s common enough. We keep a squirt bottle of it in the kitchen for disinfecting surfaces: to disinfect blood and formica on the counter, or the same for fat and wood on the cutting board. My wife uses it more often than I do. When she’s used it, I can smell it quite a distance away.

And when I smell it, the inside of my elbow prickles. Or, well, I have a memory of sharp sensations on the inside of my elbow.

Isopropyl alcohol, for me, has its strongest association as the disinfectant used on an area of skin about to be punctured with a needle. I don’t know if it’s what is always used now, but I do believe it was when I was young.

But is isopropyl really a sharp word, memories aside?

Its crispest sounds are /p/ and /p/, which are more flat-blade consonants to my mind, not acute like /t/. It starts with /s/, which may seem cold like alcohol, or hiss like a snake with needle fangs, but is not really sharp per se. The other two consonants are liquids, /l/ and /r/. The blood flowing out to fill the syringe or sample bottle, or the isopropyl alcohol? Maybe a bit of a stretch. And the echoes of the word are more like ice (cold like alcohol) and propeller and perhaps even eyes and popular.

And the etymology? It’s the same for fat and wood.

What? Is that all Greek to you? Well, it is all Greek.

The same: iso, from ἴσος ‘equal’. Chemically it has two of the same CH3 group.

For fat: pro, from προ ‘for’, and pion, from πίων ‘fat’, but the latter trimmed down in this form to just p, just as we trim the fat off the meat. Propionic acid is the first in the fatty acid series, and gives its name to isopropyl.

Wood: yl, from ὕλη ‘wood, material’ (see ylem). In chemical names it denotes a basic chemical formed of two or three elements.

So, etymologically, this word has less to do with the sharp feeling I experienced due to needles in the arm, and more to do with the sharp sensation the meat on the cutting board probably doesn’t feel, but would if it could. And the sharp smell that comes after, if my wife decides the cutting board needs it. (I just use soap and water.)

And chemically? Isopropyl alcohol is C3H7OH, or CH3CHOHCH3 – which looks a bit like an ancient Aztec word. Or perhaps the sound I made when I was a child having a needle stuck in my arm.

2 responses to “isopropyl

  1. awesome. i had forgotten about those squeegy bottles in the lab…

  2. Stan Backs has sent me some corrections – apparently it was unwise for me to rely on dictionary sources that turn out to have been in need of some revision for details of nomenclature. He told me (a few days ago; it is my fault for neglecting to add this sooner),

    “the definition in the WTN for the suffix “–yl” is not chemically correct, especially since the word “elements” could be misunderstood in this context to mean members of the periodic table instead of chemical substituents.

    “Even if “substituents” was substituted for “elements”, the definition would still not be quite accurate.

    “A better (although longer) definition is given in the Nomenclature section at http://en.wikipedia.org/wiki/Substituent.

    “I can vouch for the accuracy of this definition.”

    He subsequently added,

    “The most important concept here is that of the substituent, which is a group of atoms that usually involves _more_ than one or two elements. The most common ones are indeed the simple ones, yes, but the complex ones are far more numerous (estimated at 3.1 million in total, according to Wikipedia) .

    “Furthermore, the behaviour of the substituent depends mostly on its molecular arrangement rather than on its basic elemental content, so using the term “elements” as Oxford does in your quote could be misleading to some people. Oxford should know better. They should be using the term “substituents” instead.

    “And the suffix –yl has been used for many years now for chemical substituents that contain silicon, germanium, tin, lead, and boron as well (and who knows what other elements in novel structures more recently). Science keeps marching on.

    “I think that you have been misled and that Oxford needs to revisit this entry.

    “By the way, be careful to say that this suffix is not used just for radicals alone (“free” radicals are an important concept in organic chemistry): it can be used for a molecule that contains the bound radical as part of its molecular structure (in which case it is called a substituent rather than a radical), as in your excellent example of isopropyl alcohol.”

    As well, he made mention of something I had left out for brevity: that the pro in priopionic may actually be from protos, which means ‘first’.

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