Question:medium

One of the products formed in the following reaction is

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Grignard reagents are aggressive proton-seekers! If a compound contains an active hydrogen like in $\text{H}_2\text{O}$, R-OH, $\text{R-NH}_2$, or R-COOH, the Grignard reagent will immediately abstract it to form an alkane (R-H), bypassing any potential carbon-carbon coupling pathways.
Updated On: Jun 29, 2026
  • FigA
  • FigB
  • FigC
  • FigD
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The Correct Option is A

Solution and Explanation

Step 1: Identify the two reactants.
The figure shows cyclohexylmagnesium bromide \(C_6H_{11}MgBr\) reacting with cyclohexylamine \(C_6H_{11}NH_2\). One is a Grignard reagent and the other carries an N-H group.
Step 2: Recall what Grignard reagents do with acidic H.
The carbon bonded to magnesium behaves as a strong base, a carbanion \(R^-\). Any active hydrogen on O, N or S is grabbed at once. This is the Zerewitinoff type acid-base reaction.
Step 3: Spot the active hydrogen.
Cyclohexylamine has N-H bonds. These protons are acidic enough to be pulled off by the cyclohexyl carbanion.
Step 4: Write the proton transfer.
\[ C_6H_{11}MgBr + C_6H_{11}NH_2 \rightarrow C_6H_{11}H + C_6H_{11}NHMgBr \] The reaction is simply an acid-base step, not a coupling.
Step 5: Name the products.
The carbanion picks up a proton to become cyclohexane \(C_6H_{12}\); the rest forms a magnesium amide salt.
Step 6: Match the option.
One of the products is plain cyclohexane, which is the structure in option 1 (FigA).
\[ \boxed{\text{Cyclohexane } (C_6H_{12}),\ \text{FigA}} \]
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