Question

Chemical tests to distinguish between organic compounds 2

Answer 1

1)To distinguish methanol and phenol, use ‘B’, K2Cr207 in dil. H2SO4. This reagent will oxidize methanol but not phenol and change the from an orange to a blue-green color.

2) Phenol from benzyl alcohol - the aqueous bromine test will differentiate these two. Phenol will decolorize bromine water, benzyl alcohol will not.

3)Isomeric alcohols - isopentanol and 2,2-dimethyl-propan-1-ol. This on I am uncertain about. Isopentanol will eliminate to an alkene with conc sulfuric acid but the same may occur with 2,2-dimethyl-propan-1-ol if a methyl group migrates to the terminus, via a carbonium ion to give 2-methyl-2-butene. However, isopentanol will eliminate to give mainly the same compound and also 3-methylbut-1-ene. The latter is more likely but I don’t see that you will know if you do this test in a qualitative sense. An alternative would be to react them with acetyl chloride (OK, not one of the options but…) to give isopentyl acetate (aka isoamyl acetate, essence of banana odor) and if it smells like bananas, it is isopentanol.