What is meant by a first order reaction? Give an example of such a reaction.

Explanation

Monosaccharides when treated with excess of phenyl hydrazine give osazone. During the formation of osazone C- 1 and C-2 carbons of the monosaccharides participate in the reaction. But the other carbon atoms do not take part in the reaction in any way and hence they remain unaffected. The structures of glucose and fructose clearly reveal that they only differ in the structures of C-1 and C-2 but the structures of C-3, C-4 , C-5 and C-6 in both the compounds are identical. This is the reason for which they react with excess phenyl hydrazine to yield the same osazone.