Question

Which of the following tests can be used to distinguish between two isomeric ketones: 3- pentanone and 2- pentanone?

• A. $I_2/NaOH$
• B. $NaS{O}_{3}H$
• C. $NaCN/HCl$
• D. 2,4-DNP

Answer 1

The correct option is A $I_2/NaOH$

2- pentanone is a methyl ketone. It undergoes haloform reaction with iodine in presence of sodium hydroxide, to form yellow precipitate of iodoform. 3- pentanone is not a methyl ketone. It does not undergo haloform reaction. Hence, 3- pentanone and 2- pentanone can be distinguished by reaction with iodine in presence of NaOH.