COMEDK202510 May 2025Morning ShiftChemistryHaloalkanes and HaloarenesActual
Which of the following haloalkanes will give more than one isomeric product, on being heated with alc. KOH ?
Options
- A1- Chloro-2-methylbutane
- B2- Chlorobutane.
- C2-Chloro-3, 3-dimethylpentane
- D1- Chloropentane.
Correct answer
B. 2- Chlorobutane.
Step-by-step solution
Dehydrohalogenation of haloalkanes with alcoholic KOH follows Saytzeff rule, where the major product is the more substituted alkene. If multiple distinct -hydrogens are available such that different alkenes can be formed, isomeric products are obtained. For 1-chloro-2-methylbutane ( CH₃CH₂CH(CH₃)CH₂Cl ), the only -hydrogen is on the carbon at position 2, leading to 2-methyl-1-butene. Only one product is formed. For 2-chlorobutane ( CH₃CH₂CHClCH₃ ), -hydrogens are present on C1 and C3. Elimination from C1 gives but-