Predict the product when D-glucose is treated with

Predict the product when D-glucose is treated with
(1) Sodium borohydride
(2) Excess of phenyl hydrazine (PhNHNH2), ethanol (C2H5OH), and heated
(3) Excess of acetic anhydride, and
(4) Methanol in the presence of an acid

The Correct Answer and Explanation is :

Let’s break down the reactions of D-glucose under the conditions provided:

(1) Sodium Borohydride (NaBH₄)

• Reaction: Sodium borohydride is a mild reducing agent that primarily reduces aldehydes and ketones to alcohols. D-glucose has an aldehyde group at the anomeric carbon (C1 in its open-chain form).
• Product: When D-glucose is treated with sodium borohydride, the aldehyde group at C1 is reduced to a primary alcohol, forming sorbitol (a sugar alcohol). Sorbitol is the reduction product of glucose.

(2) Excess Phenylhydrazine (PhNHNH₂), Ethanol (C₂H₅OH), and Heat

• Reaction: Phenylhydrazine reacts with the carbonyl group (aldehyde or ketone) in sugars to form hydrazones. In this case, excess phenylhydrazine will react with the aldehyde group at C1 of glucose to form a phenylhydrazone derivative.
• Product: The primary product will be glucosazone, a yellow crystalline solid, which is a hydrazone derivative of glucose. Heating accelerates the formation of glucosazone from glucose.

(3) Excess Acetic Anhydride

• Reaction: Acetic anhydride is a reagent that acetylates hydroxyl groups in alcohols. D-glucose contains several hydroxyl groups (OH groups) that can react with acetic anhydride.
• Product: The reaction will lead to the formation of acetates. Excess acetic anhydride will acetylate all the hydroxyl groups of glucose, resulting in the formation of glucose pentaacetate. The product is an esterified derivative of glucose with five acetate groups attached.

(4) Methanol in the Presence of Acid

• Reaction: In the presence of acid, methanol can esterify the hydroxyl groups of glucose, resulting in the formation of methyl esters. The reaction occurs due to the acidic catalysis of ester formation.
• Product: The primary product would be methyl D-glucoside, formed by esterifying the hydroxyl group of glucose with methanol.

Summary of Products:

1. Sorbitol (Reduction to alcohol)
2. Glucosazone (Hydrazone derivative)
3. Glucose pentaacetate (Acetylation)
4. Methyl D-glucoside (Esterification with methanol)

Now, I will generate an image representing the chemical structures of these products.

Here is the image showing the chemical structures of the products from the reactions of D-glucose:

1. Sorbitol (formed by reduction with sodium borohydride).
2. Glucosazone (formed with phenylhydrazine).
3. Glucose pentaacetate (formed with excess acetic anhydride).
4. Methyl D-glucoside (formed with methanol in the presence of acid).