An alkene ‘A’ (Mol. formula C 5 H 10 ) on ozonolysis gives a mixture of two compounds ‘B’ and ‘C’. Compound ‘B’ gives positive Fehling’s test and also forms iodoform on treatment with I 2 and NaOH. Compound ‘C’ does not give Fehling’s test but forms iodoform. Identify the compounds A, B and C. Write the reaction for ozonolysis and formation of iodoform from B and C.

Question

Philoid · Accepted Answer

The compounds A, B , C are

,

2 Methyl but-2-ene, Acetaldehyde and acetone respectively.

• Among B and C former is an aldehyde(responds to Felling’s test) and latter is obviously a ketone as both forms iodoforms on treatment with I₂ and NaOH. And from this clue, we can identify the alkene ‘A’ (Mol. formula C₅H₁₀) which is 2 Methyl but-2-ene also as ozonolysis does not disrupt the symmetry of the molecule.

• The equation for ozonolysis of alkene
A :

•

‘A’ ‘ C’ ‘B’

• Now, for compound ‘B’ (acetaldehyde) the iodoform reaction is as follows :

• It also gives Felling’s test which is the way to identify it as an aldehyde :

• Compound ‘C’ which is a ketone (acetone) the iodoform reaction is as follows:

But it is unable to give Fehling’s test.