Understanding Benzoic Acid Mass Spectrum Fragmentation
Benzoic acid has the chemical formula $\text{C}_7\text{H}_6\text{O}_2$. Its molecular weight is approximately 122 amu.
In mass spectrometry, molecules are ionized and fragment. The base peak represents the most abundant fragment ion, indicating high stability.
Identifying the Base Peak Fragment
A common fragmentation pathway for benzoic acid involves the loss of the entire carboxyl group ($\cdot\text{COOH}$) from the molecular ion ($M^+$).
- Molecular ion mass: approx. 122 amu.
- Mass of $\cdot\text{COOH}$: approx. 45 amu.
- Fragment mass ($M - \cdot\text{COOH}$): $122 - 45 = 77$ amu.
This fragmentation yields the phenyl cation ($\text{C}_6\text{H}_5^+$), which is a stable aromatic ion.
Conclusion on Base Peak m/z
Due to the stability of the phenyl cation ($\text{C}_6\text{H}_5^+$), the fragment with $m/z = 77$ is typically the most abundant ion in the mass spectrum of benzoic acid, making it the base peak (100% relative abundance).
Therefore, the $m/z$ value for the base peak is 77.
Important Questions from Organic Structure Stability
The major product formed in the following reaction is
The compound, which upon mono-nitration using a mixture of HNO$_3$ and H$_2$SO$_4$, does NOT give the meta-isomer as the major product, is
Identify the CORRECT product in the following reaction:
- Which one among the following structures is the most stable conformer of (Z)-pent-2-ene?
The total number of tautomers for the following molecule (including the structure provided below) is ____________
