Number of Benzenoid compounds possible which can be represented by the molecular formula C₇H₈O is______

Benzenoid Compounds with Molecular Formula C7H8O

The molecular formula C₇H₈O represents compounds that are benzenoid in nature and contain a benzene ring with a functional group attached. Let us understand the concept and determine how many such compounds are possible.

A benzenoid compound refers to a compound containing a benzene ring (C₆H₆) as part of its structure. The molecular formula C₇H₈O indicates that the compound has one benzene ring and one additional carbon, hydrogen, and oxygen atom. This suggests that functional groups like -OH (hydroxyl group), -CHO (aldehyde group), or others may be attached to the benzene ring.

To solve this, we need to find all possible structural isomers that satisfy the molecular formula C₇H₈O while maintaining a benzene ring in the structure. These isomers can include:

1. Cresols: These are methylphenols where a -CH₃ (methyl group) and an -OH group are attached to the benzene ring. There are three possible arrangements depending on the positions of the groups on the ring:
   • Ortho-cresol (2-methylphenol)
   • Meta-cresol (3-methylphenol)
   • Para-cresol (4-methylphenol)
2. Benzyl Alcohol: In this structure, a -CH₂OH group (benzyl group) is attached to the benzene ring.
3. Benzaldehyde: Here, a -CHO (aldehyde group) is attached to the benzene ring.

Combining all possibilities, we have a total of 5 benzenoid compounds that satisfy the molecular formula C₇H₈O:

• Ortho-cresol
• Meta-cresol
• Para-cresol
• Benzyl alcohol
• Benzaldehyde

The concept behind this calculation is based on analyzing the functional groups that can be attached to the benzene ring and their possible positions. By systematically exploring all combinations, we ensure no isomer is missed.