Carboxyl as a noun is a univalent functional group consisting of a carbonyl and a hydroxyl functional group (-co.oh); characteristic of carboxylic acids. while Carboxylic as an adjective is of, or relating to the carboxyl functional group.
Part of speech: noun
Definition: A univalent functional group consisting of a carbonyl and a hydroxyl functional group (-CO.OH); characteristic of carboxylic acids.
Part of speech: adjective
Definition: Of, or relating to the carboxyl functional group.
We hope you now know whether to use Carboxyl or Carboxylic in your sentence.