Question

Compound A is formed when compound B reacts with reagent (R). When compound C reacts with the same reagent (R), the product formed will be (S). Identify reagent (R) and product (S). 

• A. Structure 1
• B. Structure 2
• C. Structure 3
• D. Structure 4

Answer 1

The Correct Option is C

Concept:
Alcohols undergo dehydration in the presence of strong acids such as concentrated \(H_2SO_4\) or \(H_3PO_4\). The dehydration reaction converts alcohols into alkenes via an elimination reaction. Vicinal diols can undergo successive eliminations to form conjugated dienes. Step 1: Reaction of compound B. Compound B is an alcohol. In the presence of strong acid (\(H^+\)), dehydration occurs: \[ ROH \xrightarrow{H^+} Alkene + H_2O \] Thus B loses water and forms alkene A. Step 2: Identify reagent (R). The reagent that promotes dehydration of alcohol to alkene is: \[ \text{conc }H_2SO_4 \text{ or } H_3PO_4 \] Hence \(R = \text{conc }H_2SO_4/H_3PO_4\). Step 3: Reaction of compound C. Compound C is a diol. In presence of strong acid, dehydration occurs twice producing a conjugated diene. \[ HO-CH_2-CH_2-CH_2-CH_2-OH \xrightarrow{H^+} CH_2=CH-CH=CH-CH_3 \] Thus the product S is a conjugated diene. Step 4: Final conclusion. \[ R = \text{conc }H_2SO_4/H_3PO_4 \] \[ S = CH_2=CH-CH=CH-CH_3 \] \[ \boxed{\text{Option (3)}} \]