Alcohol, Phenols and Ethers

General molecular formula of alkanols is

C_nH_2n+2O or C_nH_2n+1OH

In case of unsymmetric ethers when treated with HI then I^– attaches to smaller and less complex alkyl group as it follows S_N2 mechanism

CH₃ $-$ O $-$ CH(CH₃)₂ + HI $ \to $ CH₃I + (CH₃)₂CHOH

Phenols are more acidic than alcohols as they are resonance stabilised whereas alcohols are not.

Further –NO₂ is an electron withdrawing group which increases acidic character and facilitates release of proton, whereas –CH₃ is an electron donating group which decreases acidic character, thus removal of H⁺ becomes difficult.

Formation of a yellow precipitate on heating a compound with an alkaline solution of iodine is known as iodoform reaction. Methyl alcohol does not respond to this test. Iodoform test is exhibited by ethyl alcohol, acetaldehyde, acetone, methyl ketones and those alcohols which possess CH₃CH(OH) – group.

n-propyl alcohol on oxidation with K₂Cr₂O₇ gives an aldehyde which on further oxidation gives an acid.



Isopropyl alcohol on oxidation gives a ketone with the same number of carbon atoms as original alcohol.

C₂H₅OH + 4I₂ + NaOH $ \to $

CHI₃ + NaI + HCOONa + H₂O

Iodoform is a pale yellow solid which crystallises in hexagonal plates.