To classify alcohols, which carbon position determines if it is primary, secondary, or tertiary?

When classifying alcohols as primary, secondary, or tertiary, the key factor is the carbon atom that is directly attached to the hydroxyl group (-OH). This carbon's position within the chemical structure determines the classification:

• A primary alcohol has the hydroxyl group attached to a carbon that is connected to only one other carbon (or none at all), indicating that it resides on the terminal end of a carbon chain.

• A secondary alcohol has the hydroxyl group bonded to a carbon that is attached to two other carbons, placing it in a central position within the carbon chain.

• A tertiary alcohol features the hydroxyl group on a carbon that is connected to three other carbons, making it a carbon atom located in a branched or more complex position.

The other factors mentioned in the options, such as carbon chain length, type of substituents, and presence of double bonds, do not determine the classification of alcohols as primary, secondary, or tertiary. Instead, they may affect the properties of the alcohol but not its classification based on the location of the hydroxyl group. Therefore, understanding the relation of the hydroxyl group's placement on the carbon is crucial for proper nomenclature and classification of alcohols.