How to Build a Clean Box

In a word, tradition. Chemstry nomenclature is a mess of tradition and grandfather clauses. I'm not a chemistry historian, so this should be taken with suitable amounts of suitable salts. But I think propan-2-ol is the systematic IUPAC name for the compound. First, there is the name "propane", which is itself grandfathered (the first four hydrocarbons are methane, ethane, propane, and butane, rather than unane, diane, triane, and tetrane, which if I've got my roots right would be the systematic names for them). From "propane" the "propan-" combining form is formed by stripping the trailing vowel (and the "propyl" form, which is visible in "isopropyl alcohol"). Then there is the "-ol" suffix, indicating a hydroxy group attached to a hydrocarbon chain; this too is a historical artifact, being an abbreviated form of "alcohol", the traditional name for such compounds. "Propan-2-ol" is then formed in the systematic way from these, with the "-2-" indicating that the hydroxy group corresponding to the "-ol" is attached at carbon #2. (There is a well-defined way of numbering the carbon atoms; for the moment, we don't need to care about the details, except to know that for propane, it gives the number 2 to the middle carbon.) The other two names are formed based on the "iso" prefix attached to forms of "propane". "iso" is a pre-systematic prefix indicating "variant" (more precisely, "isomer"). In the case of isopropyl, it was allowed to survive; I think this is partly because of tradition and partly because it introduces no ambiguity - there is only one way to make a hydrocarbon out of three carbons and eight hydrogens, and only two ways to turn that into a radical, and with the straight-chain one being "propyl" and "propan-", "isopropyl" and "isopropan-" unambiguously refer to the other. (There's also "butyl", "isobutyl", and "tert-butyl", but that's another can of worms. The way this kind of nomenclature breaks down rapidly with increasing carbon-chain length is part of why the IUPAC system was developed.) One of those names is the combining form ("isopropan-") plus the same "-ol" suffix we saw earlier. The other name is basically the same thing, but with the "alcohol" detached into a separate word; the first word then becomes the group name "isopropyl" rather than the combining form "isopropan-". 1-methyl-2-ethanol actually doesn't look right to me; it's describing the compound in question as ethanol with a methyl group replacing one of the hydrogens, but as I read it, it puts the extra methyl group and the hydroxyl group on different carbons, which leads to propanol, not isopropanol. 2-hydroxypropane is just propan-2-ol rephrased, with the "hydroxy" group name instead of the "-ol" suffix. /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse at rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B