Fructose is an important ketohexose. It is obtained along with glucose by the hydrolysis of disaccharide, sucrose.
Fructose also has the molecular formula C6H12O6.
The ring, thus formed is a five-membered ring and is named as furanose with analogy to the compound furan. Furan is a five-membered cyclic compound with one oxygen and four carbon atoms.
The cyclic structures of two anomers of fructose are represented by Haworth structures as given
Comparison of Glucose and Fructose