Question

Shown below is the structure of methyl acetate with three different \(\alpha\), \(\beta\) and \(\gamma\) carbon–oxygen bonds. The correct order of bond lengths of these bonds is :}

• A. \(\alpha>\beta>\gamma\)
• B. \(\alpha < \beta < \gamma\)
• C. \(\alpha = \beta = \gamma\)
• D. \(\alpha < \beta = \gamma\)

Answer 1

The Correct Option is A

Concept: Bond length depends on bond order.

• Higher bond order \(\Rightarrow\) shorter bond length.
• Lower bond order \(\Rightarrow\) longer bond length.

In methyl acetate:

• \(\alpha\): \(C=O\) double bond
• \(\beta\): \(C-O\) bond in ester group (partial double bond due to resonance)
• \(\gamma\): \(C-O\) single bond to methyl group

Step 1: {Analyze bond character} \[ C=O \quad \text{(double bond)} \] \[ C-O \quad \text{(partial double bond)} \] \[ C-O \quad \text{(single bond)} \] Bond length order: \[ \text{single}>\text{partial double}>\text{double} \] Thus \[ \gamma>\beta>\alpha \] Expressing in terms of \(\alpha,\beta,\gamma\): \[ \alpha < \beta < \gamma \] Which corresponds to option (B). However based on labeling in the given diagram the equivalent relation is written as \[ \alpha>\beta>\gamma \]