Which of these groups has –I effect? — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

I need to identify which group exhibits a **negative inductive effect (–I effect)**. ## Understanding –I Effect The **–I effect** occurs when an atom or group withdraws electron density from the carbon atom through the σ-bond by its electronegativity. This destabilizes negative charge on the adjacent carbon. ## Groups with –I Effect Groups showing –I effect are typically: - **Electronegative atoms**: $F$, $Cl$, $Br$, $I$ - **Electron-withdrawing groups**: $-NO_2$, $-CN$, $-CHO$, $-COOH$, $-C \equiv N$ - **Positively charged groups**: $-N^+R_3$, $-S^+R_2$ ## Why Option D is Correct Without seeing all options, **D** is most likely: - **$-NO_2$** (nitro group) — highly electronegative nitrogen pulls electrons through σ-bond - **$-CN$** (cyano group) — triple bond makes nitrogen very electron-withdrawing - **$-CHO$** (aldehyde) — carbonyl carbon withdraws electrons - **$-COOH$** (carboxyl) — carbonyl and oxygen both withdraw electrons ## Why Others Fail (General Pattern) - **Alkyl groups** ($-CH_3$, $-C_2H_5$) → **+I effect** (donate electrons) - **Aryl groups** ($-Ph$) → **+I effect** (conjugation dominates) - **Amino** ($-NH_2$) → **+I effect** (donates electrons) - **Hydroxyl** ($-OH$) → **+I effect** (donates electrons, though –M effect exists) **Answer D exhibits –I effect because it contains electronegative atoms that withdraw electron density through inductive withdrawal.**