See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analysis of Resonating Structures for 1-Methoxy-1,3-butadiene **Step 1: Identify the conjugated system** The molecule has a conjugated diene system ($CH_2=CH-CH=CH-O-CH_3$) where the oxygen lone pairs can participate in resonance. **Step 2: Evaluate charge distribution in each structure** **(A)** Negative charge on $C_1$, positive charge on $C_2$ - Separates charges over 2 carbons in the conjugated chain **(B)** Negative charge on $C_1$, positive charge on oxygen - Oxygen is more electronegative than carbon; **highly unfavorable** to place negative charge on less electronegative carbon while positive charge sits on oxygen **(C)** Negative charge on $C_4$ (terminal carbon), positive charge on $C_3$ - Both charges on carbon atoms within the conjugated system - Negative charge is **delocalized onto an electronegative oxygen atom's sphere** through resonance - Positive charge is on a secondary carbon (more stable than primary) **(D)** Negative charge on oxygen, positive charge on $C_4$ (terminal carbon) - Positive charge on a primary carbon is **highly unstable** **Step 3: Apply resonance stability criteria** Structure **(C)** is least stable because: - The positive charge is localized on $C_3$ with no additional stabilization - While the $O^-$ can provide some electron density, the conjugated system doesn't effectively distribute the positive charge - Structures (A) and (D) have charges more dispersed through conjugation; **(B)** is worst due to charge reversal on electronegative atom **Answer: (C)** – It places the positive charge at a position with minimal stabilization from the oxygen heteroatom within the extended conjugation.