Question

Observe the following reaction and identify the correct statements about X \[ C_4H_8 \xrightarrow[(ii)\ Zn,H_2O]{(i)\ O_3} Ethanal \] I. It does not exhibit cis/trans isomerism II. It adds water in presence of dilute $H_2SO_4$ to give secondary alcohol III. It is obtained as major product in the reaction of secondary butyl chloride with alcoholic KOH

• A. II, III only
• B. I, II only
• C. I, III only
• D. III only

Hint:

Saytzeff rule: The more substituted alkene is generally the major product.

Answer 1

The Correct Option is A

Concept: Ozonolysis cleaves carbon-carbon double bonds and helps identify the structure of alkenes.

Step 1: Determine compound X.
Formation of ethanal on ozonolysis indicates \[ CH_3CH=CHCH_3 \] which is but-2-ene.

Step 2: Check Statement-I.
But-2-ene exists in both cis and trans forms. Hence Statement-I is false.

Step 3: Check Statement-II.
Hydration of but-2-ene gives \[ CH_3CH(OH)CH_2CH_3 \] which is a secondary alcohol. Therefore Statement-II is true.

Step 4: Check Statement-III.
Dehydrohalogenation of secondary butyl chloride with alcoholic KOH follows Saytzeff's rule. Major product formed is but-2-ene. Hence Statement-III is true. \[ \boxed{\text{II and III only}} \]