Chapter 21, Problem 98E

Interpretation Introduction

Interpretation: The test for the presence of glucose with an aldehyde group is given to be found only in the open chain form but not in the cyclic form. This phenomenon is to be explained.

Concept introduction: Carbohydrates are naturally occurring organic compounds. As the name implies carbohydrates are hydrates of carbon and have general formula of ${\text{C}}_{\text{X}}{\left({\text{H}}_{\text{2}}\text{O}\right)}_{\text{Y}}$. Basically, carbohydrates are $\text{polyhydroxy}$ aldehyde and ketones, for examples, glucose and fructose. Glucose is a reducing sugar as it has an aldehyde group and its presence is detected by Tollen’s, Benedicts or Fehlings test.

To determine: An explanation corresponding to the fact that the test for the presence of glucose with an aldehyde group is found only in the open chain form but not in the cyclic form.