Ncert Exercises & Solutions

An aromatic compound ‘4’ (molecular formula $C_{8} H_{8} 0$ ) gives positive 2, 4-DNP test. It gives a yellow precipitate of compound ‘8’ on treatment with iodine and sodium hydroxide solution. Compound ‘A’ does not give Tollen's or Fehling's test. On drastic oxidation with potassium Permanganate it forms a carboxylic acid ‘C’ (molecular formula $C_{7} H_{6} 0_{2}$ ), which is also formed along with the yellow compound in the above reaction. Identify A, B, and C and write all the reactions involved.

Molecular formula =

C_{8} H_{8} O

Degree of unsaturation = $(C_{n} + 1) - \frac{H_{n}}{2}$
$= (8 + 1) - \frac{8}{2} = 9 - 4 = 5$

Degree of unsaturation > 5 ie., it may contain benzene ring having degree of unsaturation equal to 4 and one degree of unsaturation must be carbonyl group.
Thus, possible structures are

‘According to question, compound ‘A’ does not respond to Tollen's or Fehling's test, So, itis a ketone not aldehyde. Therefore, structure | is correct. Complete reaction sequence is as follows

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