Glucose structure open chain

Glucose structure open chain.

The structure of glucose may be discussed under the following heads : (a) Open chain formula ; (b) Configuration ; (c) Cyclic structure ; (d) Haworth representation.

A. Open-chain Formula.

The open-chain formula of glucose is constructed from the following facts:

1. Molecular formula.

Elemental analysis and molecular weight determination have established that glucose has the molecular formula C6H12O6.

2. Presence of 6-carbon unbranched chain.

The complete reduction of glucose with concentrated hydrogen iodine and red phosphorus gives n-hexane. This proves that the glucose molecule is made of an unbranched six-carbon chain.

3. Presence of 5 OH groups.

Glucose reacts with acetic anhydride to form a pentadactyl derivative. This shows the presence of five hydroxyl groups. Since glucose is a stable compound, no two OH group are attached to the same carbon. In other words, the five OH groups are on different carbons.

4. Presence of C=O group.

Glucose reacts with hydroxylamine to form an oxime. It suggests the presence of a carbonyl group.

5. Presence of terminal CHO function.

On mild oxidation with bromine water, glucose is converted to gluconic acid which when reduced with an excess of Hl yields n-hexanoic acid.

Glucose structure open chain
This shows that glucose contains a six-carbon straight chain with CHO at one end, which has been oxidized to COOH.

6. Construction of open-chain formula.

Knowing that glucose has a straight 6-carbon chain with a terminal CHO, the five OH groups can be placed on each of the remaining five carbons. Supplying hydrogen atoms to these carbons to satisfy their tetracovalency, the open-chain structure of glucose can be written as:

Glucose structure open chain

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