Question

The following carbohydrate is:

A. $\alpha$ ketohexose
B. an aldohexose
C. an $\alpha $ - furanose
D. an $\alpha $ - pyranose

Answer 1

Hint: For this problem, we have to study the structure of all the carbohydrates to identify the correct carbohydrate. Also, we know that carbohydrates are the polysaccharides.

Complete step by step answer:
- In the given question, we have to identify the given structure and explain the name of the carbohydrate.
- As we know that the beta position of the compound is the position when the functional group is attached in the same direction whereas alpha position is the position in which the functional group is attached to the opposite direction.
- And in the given structure the beta position is present because the -OH group at first carbon and fifth carbon are attached at the same upper direction as shown below:

- So, we can say that option C and D will be an incorrect answer.
- Now, among option A and B hexose is a 6 membered ring structure which is also known as furanose when an oxygen atom is also attached whereas the five-membered rings are known as furanose.
- Now, 'Aldo' group is used when there is a presence of aldehyde group in the structure and the 'keto' is used when the functional group ketone i.e. -C=O is present.
- So, we can see that at the 6 carbon the aldehyde group is attached due to which the complete name of the compound will be aldohexose.
So, the correct answer is “Option B”.

Note: Option was not correct because for the keto group there should be the presence of double bond between carbon and oxygen which was not present. Sugars such as glucose, mannose are considered as the aldohexose.