The gas is carbon dioxide.
Isoborneol (also called isoborneol) is usually produced by the reaction of camphor and acetic anhydride in the presence of acetic acid. During this process, the esterification reaction of the ketone carbonyl group of camphor and acetic anhydride may produce gas. . Considering this reaction, the gas is carbon dioxide. The reaction of acetic anhydride with camphor releases carbon dioxide because this is a typical esterification reaction in which an alcohol (here the alcohol part of camphor) combines with an acid anhydride (here acetic anhydride) to form an ester, and a gas is released. In many esterification reactions, the gas released is carbon dioxide.