Answer
🔬 Identification of Hydroxyl Group Attachment in a Steroid Molecule
The molecule shown in the image is a steroid backbone with four fused rings, labeled A, B, C, and D, and a long hydrocarbon tail. One of the most defining features is the hydroxyl group (–OH) attached to the ring structure.
In steroid nomenclature, the carbon numbering begins in ring A and proceeds through the tetracyclic skeleton in a standard, well-defined sequence.
📌 Determining the Carbon Number for the OH Group
- The OH group is clearly attached to the first carbon of the steroid backbone in ring A.
- This carbon is known as C-3 in the conventional steroid numbering system.
The C-3 carbon is a secondary carbon bonded to two other carbon atoms and is typically the site for hydroxyl substitution in many biologically active steroids like cholesterol and estradiol.
✅ Final Answer
The hydroxyl (OH) group is bonded to carbon number 3 (C-3) of the steroid skeleton.