The products A and B in the following reactions, respectively are

Step 1: Reaction with AgNO₂

1-Bromopropane + $\ce{AgNO2}$ → ?

$\ce{AgNO2}$ is a covalent silver salt where the metal is covalently bonded to nitrogen.

In nucleophilic substitution:

• $\ce{NO2-}$ (nitrite ion) is ambidentate - can attack through N or O
• With AgNO₂ (covalent), the nucleophile attacks through nitrogen (N-bonded)
• Product: nitroalkane ($\ce{R-NO2}$)

$\ce{CH3CH2CH2Br + AgNO2 -> CH3CH2CH2-NO2 + AgBr}$

Product A = 1-nitropropane ($\ce{CH3CH2CH2NO2}$)

Step 2: Reaction with AgCN

1-Bromopropane + AgCN → ?

$\ce{AgCN}$ is also a covalent silver salt.

$\ce{CN-}$ (cyanide ion) is ambidentate - can attack through C or N:

• With AgCN (covalent), the nucleophile attacks through nitrogen (N-bonded)
• Product: isocyanide ($\ce{R-NC}$)

$\ce{CH3CH2CH2Br + AgCN -> CH3CH2CH2-NC + AgBr}$

Product B = 1-isocyanopropane ($\ce{CH3CH2CH2NC}$)

Step 3: Summary

• A = $\ce{CH3CH2CH2NO2}$ (nitropropane)
• B = $\ce{CH3CH2CH2NC}$ (isocyanopropane)

Answer: (d)

Key Distinctions:

| Reagent | Type | Product | Structure | |---------|------|---------|------------| | NaNO₂ | Ionic | Alkyl nitrite | $\ce{R-O-N=O}$ | | AgNO₂ | Covalent | Nitroalkane | $\ce{R-NO2}$ | | NaCN or KCN | Ionic | Nitrile | $\ce{R-C≡N}$ | | AgCN | Covalent | Isocyanide | $\ce{R-N≡C}$ |

Memory Aid:

• Ionic salts (Na⁺, K⁺): Attack through more electronegative atom (O in $\ce{NO2-}$, C in $\ce{CN-}$)
• Covalent salts (Ag): Attack through the atom bonded to metal (N in both cases)