Question

In the structure of glucose if the OH group on carbon atom 4 is above the plane of the ring then,it is alpha or beta or D glucose or May be alpha or beta

Answer 1

The position of the hydroxyl group (OH) on carbon atom 1 in the cyclic form of glucose determines its alpha or beta designation. An OH group above the plane indicates a beta anomer, while below the plane indicates an alpha anomer. The D or L configuration of glucose is dictated by the orientation of the OH group on carbon 5.

Step-by-step explanation:

When considering the structure of glucose in its cyclic form, the position of the hydroxyl group (OH) around the anomeric carbon (carbon 1) determines whether it's an alpha or beta anomer. If the OH group on the anomeric carbon is below the plane of the ring, it is said to be in the alpha (α) position. On the other hand, if the OH group is above the plane of the ring, it is in the beta (β) position. Therefore, in the case where the OH group on carbon atom 4 is above the plane of the ring, this does not determine whether glucose is alpha or beta. Instead, it is the position of the OH group on carbon atom 1 that is critical. The alpha or beta designation does not directly determine whether the glucose is D-glucose; that is determined by the orientation of the hydroxyl group on the last chiral center, which is carbon 5 in the case of glucose.

Answer 2

The correct answer is May be alpha or beta.

Step-by-step explanation:

Alpha D glucose and Beta D glucose structural configuration based the position of -OH group of C1 carbon or anomeric carbon.

if the C1 OH and C6 CH2OH are present in the same plane of the ring then the glucose molecule will exist in beta configuration.

On the other hand if C1 OH and C6 CH2OH are present in the opposite side of ring with respect to each other then the glucose molecule will exist in alpha configuration.

The position of -OH group of C4 atom above or down the plane does not matter for the structural appearance of glucose in alpha or beta configuration.

From that point of view it can be said that according to the question the glucose molecule will exist either in alpha or beta configuration.