See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

## Solution: Elimination Reaction of 1,1,2,2-Tetrafluoro-1,2-dichloroethane **Step 1: Identify the substrate** The starting material is $\ce{Cl-CF2-CF2-Cl}$ (or written as shown: two carbons each bearing Cl and F atoms). **Step 2: Recognize the reaction type** The reaction is heated ($+°$), indicating an **elimination reaction** (likely E2 mechanism). Heat promotes $\beta$-elimination of HX. **Step 3: Determine what is eliminated** For elimination to occur, we need: - A hydrogen on a $\beta$-carbon (adjacent carbon) - A leaving group on the $\alpha$-carbon The only available hydrogens are on the chlorine-bearing carbons. When heat is applied, we eliminate **HCl** (or **HF**). Since Cl is a better leaving group than F, and considering the structure, **HF elimination** occurs preferentially because: - F atoms are on both carbons (geminal arrangement) - Elimination removes HF, leaving a C=C double bond **Step 4: Write the product** Removal of HF from the structure: $$\ce{Cl-CF2-CF2-Cl ->[heat] Cl-C(F)=C(F)-Cl}$$ This gives **$\ce{Cl-CF=CF-Cl}$** with F atoms on the double bond carbons. **Step 5: Match with options** Option **(C)** shows: $\ce{Cl-C(F)=C(F)-Cl}$ This matches the elimination product perfectly. **Why others are wrong:** - **(A)**: C≡C triple bond—too much elimination - **(B)**: Two Cl on one carbon—rearrangement product, not elimination - **(D)**: C≡C with F and Cl terminal—incorrect connectivity **Answer: (C)**