Which one of the following species/compounds will be formed on heating CHCl₃ with alc.KOH?

CONCEPT:

Reaction of CHCl₃ with alcoholic KOH

• When chloroform (CHCl₃) is heated with alcoholic potassium hydroxide (alc. KOH), a base-induced dehydrohalogenation reaction occurs.
• This reaction leads to the formation of a highly reactive intermediate known as dichlorocarbene (:CCl₂).
• Dichlorocarbene is an example of a carbenic intermediate, which is neutral and contains a divalent carbon atom with two non-bonding electrons.

EXPLANATION:

• The reaction mechanism involves the following steps:
  • Alcoholic KOH first abstracts a proton (H⁺) from CHCl₃, forming the trichloromethyl anion (CCl₃^-).
  • The trichloromethyl anion then loses a chloride ion (Cl^-) to form the dichlorocarbene intermediate (:CCl₂).

The overall reaction is:

CHCl₃ + alc. KOH → :CCl₂ + KCl + H₂O

• When chloroform (CHCl₃) is heated with alcoholic KOH:
  • The product formed is dichlorocarbene (:CCl₂).
  • Dichlorocarbene is highly reactive and can participate in further reactions, such as cyclopropanation of alkenes.

Therefore, the correct answer is option 1.