How many different D-2-ketohexoses are there?

Question

Quizplus · Accepted Answer

D-2-ketohexoses are six-carbon sugars with a carbonyl group (ketone) at the second carbon in the D configuration. To determine how many different D-2-ketohexoses there are, we need to consider the possible configurations of the four remaining carbons.

If we start with a D-aldohexose (six-carbon sugar with an aldehyde at the first carbon in the D configuration) and convert the aldehyde group to a ketone group at the second carbon, we can create four possible isomers:

1. D-fructose (the ketohexose with the same structure as the ketone form of D-glucose)
2. D-psicose (also known as D-allulose)
3. D-sorbose
4. D-tagatose

All four of these isomers are D-2-ketohexoses, so there are a total of 4 different D-2-ketohexoses.

Therefore, the best choice is B.

How Many Different D-2-Ketohexoses Are There