Skip to content
Question of 147

Q.How can the following conversions be effected ?

(i) Ethanol ⟶ Fluoroethane (Score : 2)
(ii) But-1-ene ⟶ But-2-ene (Score : 2)
Kerala DhseKerala DHSE Plus Two Board 2019Subjective· 4mImportance★★★★★
0% · 0/147 Questions
🔒 Locked · start free trial →

You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.

Start your 14-day free trial to unlock the full solution →

(i) Convert the alcohol to a chloride, then swap Cl for F by the Swarts reaction. (ii) Add HBr to the terminal alkene, then eliminate with alcoholic KOH to give the more substituted (Zaitsev) alkene.

(i) Ethanol -> Fluoroethane (Score: 2)

Step 1: Convert ethanol to chloroethane using thionyl chloride (this avoids rearrangement and gives only gaseous, easily removed by-products):

CH3CH2OH + SOCl2 -> CH3CH2Cl + SO2 + HCl

Step 2: Alkyl fluorides cannot usually be made by direct reaction of an alcohol/halide with HF; instead, the Swarts reaction is used - heating the chloro/bromo alkane with an inorganic fluoride such as AgF (or Hg2F2, CoF2, SbF3):

CH3CH2Cl + AgF --Δ--> CH3CH2F + AgCl

(ii) But-1-ene -> But-2-ene (Score: 2)

Step 1: Markovnikov addition of HBr to but-1-ene places Br on C2 (the more substituted carbon), giving 2-bromobutane:

CH3-CH2-CH=CH2 + HBr -> CH3-CH2-CHBr-CH3

…

Unlock everything free for 14 days

  • Full step-by-step solutions
  • Concept-first explanations
  • Methods, shortcuts & mistakes
  • PYQ mapping + timed mock tests

Full access for 14 days. No credit card required.