Where I live (UK), it is very hard to find n-Pentanol but n-Pentane is a lot cheaper and easier to source. I would like to do some experiments with
pentanol and possibly pentanoic acid so I'm wondering whether there is a feasible way to convert pentane to pentanol. Thanks in advance.MeshPL - 6-7-2017 at 11:54
Short answer: No
Terminal CH3 units are often less reactive than internal CH2. There are no simple reactions that would selectively oxidise terminal carbons and no
internal ones.
Radical chlorination, than substitution with OH- will produce some pentanol, but yield will be around few percent or less.
Also, I wouldn't be sure if pentane you vcan easily buy is actually pure n-pentane unless it is explicitly marketed as such and has it on a label.
Usually when alphatic alkanes are used as solvents they can be and are mixtures, with certainbstraight component being major constituent, I think at
least.
I also don't really know an easy and feasible way to produce n-pentanol. Few, bad, ideas (apart from chlorinating pentane), which are somewhat DOABLE
with basic reagents and commonly available stuff include:
-produce a bunch of bad quality moonshine in suboptimal conditions, while distilling you will obtain fusel oil, which contains n-pentanol in some
proportions. By fractional distillation you may obtain some n-pentanol.
-separate caproic acid from goat milk, by hydrolysis of fats in said milk, than perform Hundiecker reaction and substitute bromine for OH-. This
requires the use of silver salts, liquid bromine, and some really hard to oxidise solvent like CCl4 so is not good.
Better idea is to use grignard reaction or a simmilar reaction, which is doable by ammateur. If you somehow manage to obtain butyl
chloride/bromide/iodide from butyl alcohol, you may or may not be able to buy, you could react that with formaldehyde to make n-pentanol.
You could also react n-propyl halide with ethylene oxide via grignard.
You can also react n-ethyl halide derived grignard reagent with either oxetane/BF3 or acrolein/Cu(I) salt. First option gives just n-pentanol, second
gives pentanal you would need to reduce via MPV reduction to pentanol.
Grignard reagents can certainly be made by amateurs, ethylene oxide or oxetane and BF3 are a different story. Dry formaldehyde and acrolein are
possible to make in an amateur lab, but are dangerous. Not sure, how you could obtain n-propanol to make n-propyl halide either. Butanol could be
easier obtained, but may also be unavailable.
Some aldol condensation or enol alkylation could produce a compound that is reducable to n-pentanol, but neither such reaction nor such reduction is
feasible for an amateur. Although etanal with propanal could work a bit to produce pent-2-enal in about 50% yield, which could be reduced somehow to
pentanol, not sure how. And still propanal would need to be made from n-propanol, which isn't the most available reagent.
[Edited on 6-7-2017 by MeshPL]
[Edited on 6-7-2017 by MeshPL]Melgar - 6-7-2017 at 13:58
Nope. There is not. Alkanes can only react via free-radical chemistry, which isn't easy to control at all. Any process would probably involve
oxidation in gas phase over a catalyst, giving a mixture of every possible pentane oxidation product, which would then have to be separated via
distillation. There would be a lot of isomers with very similar boiling points, etc. You'd more or less need a chemical factory.
The common name for n-pentanol is "amyl alcohol" though, and "amyl" indicates it's derived from starch. Reason being, it's a product of grain
fermentation, and is part of the crap that makes cheap liquor taste bad. Better liquor brands put more effort into separating it out. I'm not sure
if that helps at all, but I figured I'd add that bit in anyway.Corrosive Joeseph - 6-7-2017 at 14:12
