COMEDK2023Evening ShiftChemistryAlcohols Phenols and EthersActual
Choose the correct order of increasing acidic strength of the following compounds.
Options
- ACH ₃ CH ₂ OH < CCl ₃ CH ₂ OH < CF ₃ CH ₂ OH
- BCCl ₃ CH ₂ OH < CF ₃ CH ₂ OH < CH ₃ CH ₂ OH
- CCH ₃ CH ₂ OH < CF ₃ CH ₂ OH < CCl ₃ CH ₂ OH
- DCF ₃ CH ₂ OH < CCl ₃ CH ₂ OH < CH ₃ CH ₂ OH
Correct answer
A. CH ₃ CH ₂ OH < CCl ₃ CH ₂ OH < CF ₃ CH ₂ OH
Step-by-step solution
The acidic strength of alcohols depends on the stability of the conjugate base (alkoxide ion) formed after the loss of a proton. The stability of the alkoxide ion is increased by the presence of electron-withdrawing groups (EWG) through the inductive effect (-I effect). The compounds are CH ₃ CH ₂ OH , CCl ₃ CH ₂ OH , and CF ₃ CH ₂ OH . In CH ₃ CH ₂ OH , the ethyl group is electron-donating (+I effect), which destabilizes the alkoxide ion, making it the least acidic. In CCl ₃ CH ₂ OH and CF ₃ CH ₂ OH , the halogen