BlogIIT-JEEImportant Topic of Chemistry: Glucose Structure

Important Topic of Chemistry: Glucose Structure

Glucose Structure


Before we look at the structure of glucose, it’s important to know a few things about it. Glucose is a carbohydrate and a vital biomolecule that aids the body’s metabolism. It has the chemical formula C6H12O6 and is a simple sugar. It is made up of six carbon atoms, twelve hydrogen atoms, and six oxygen atoms in simple terms.

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    Glucose is a readily available monosaccharide, often known as dextrose or blood sugar. Plants and the majority of algae primarily produce glucose during the photosynthesis process.

    As previously stated, the glucose molecule is a vital carbohydrate required to create Adenosine Triphosphate (ATP), also known as the body’s energy molecule. Because both an excessive and insufficient amount of glucose leads to sickness in the human body, the level and amount of glucose are closely regulated.

    What is Glucose, and How Does It Work?

    Glucose is a simple sugar with a molecular formulaC6H12O6 that belongs to the carbohydrate family. It has six carbon atoms as well as an aldehyde group. As a result, it’s known as an aldohexose. It comes in two varieties: open-chain (acyclic) and ring (cyclic).

    Glucose is the primary source of energy for living creatures. With the help of water, sunshine, and carbon dioxide, plants and algae prepare glucose during the photosynthetic process. It can be found in fruits and honey. Glycogenolysis is the process through which animals obtain glucose.

    Structures of Glucose in Various Forms

    The following conditions are used to explain the structure of glucose in detail.

    1. The formula for an Open-Chain
    2. Cyclic Structure Configuration
    3. Representation by Haworth

    Structure of Glucose Formula for an Open-Chain System

    The following information can be used to create the open-chain formula for glucose:

    • Molecular Formula: The molecular formula of glucose is C6H12O6 based on the examination of elements in glucose and the molecular weight of glucose.
    • There is a 6-carbon unbranched chain present: The fact that glucose is reduced when combined with concentrated hydrogen iodide and red phosphorous to give n-hexane is proof that glucose is a molecule made up of an unbranched six-carbon chain.
    • Presence of 5 OH groups: Pentadactyl derivatives are formed when glucose reacts with acetic anhydride. This indicates that there are five hydroxyl groups present. Because glucose is such a stable molecule, no two OH groups can bind to the same carbon. Or, to put it another way, the five OH groups are present on the various carbons.
      When glucose combines with hydroxylamine to generate an oxime, the C=O group is present. It shows that there is a carbonyl group present.
    • Presence of terminal CHO function: When glucose is mildly oxidized with bromine water, it is transformed into glucose acid, which is then reduced with a large amount of HI to create hexanoic acid.

    D/L-Glucose Configuration

    Emil Fischer used reasoning similar to the ones listed below to prove the configuration of D/L-glucose.

    • Construction of four possible D-pentoses: Using the usual configuration of D-glyceraldehyde as a starting point, two possible D-aldotetroses can be made by putting a CHOH immediately below CHO, to the right of Oh, and the left of Oh.
    • Configuration II or IV of D-Arabinose: D-arabinose’s terminal CHO and CH2OH groups are oxidised by nitric acid, giving two optically active dicarboxylic acids. Forms II and IV can produce two optically active diacids, whereas forms I and III can only produce meso acids with a plane of symmetry. As a result, D-arabinose is classified as either II or IV.
    • In each case, rough degradation of D-glucose and D-mannose yields D-arabinose: The CHOH underneath CHOH is eliminated during ruff deterioration. As a result, by adding a new CHOH below CHO in form II of D-arabinose, the configuration of two aldohexoses, D-glucose and D-mannose, can be obtained.
    • The dicarboxylic acid produced by D-glucose and L-glucose is the same: This suggests that the sole difference between these two sugars is the position of the terminal groups (CHO and CH2OH). As a result, changing the terminal groups in D-glucose should provide a different aldohexose.
      When VII is rotated through 1800C in the plane of the paper, it produces aldohexoses VIII, which is not the same as V. A similar approach with formula VI does not result in the formation of new sugar.

    Glucose’s Physical Properties

    Glucose is a crystalline white solid with a melting point of 1460 degrees Celsius. When this glucose molecule is crystallized with cold water, glucose monohydrate is formed, with the chemical formula C6H12O6.H20 melting point of 860 degrees Celsius. It’s highly soluble in water, only slightly soluble in ethanol, and completely insoluble in ether. Sucrose is roughly three-quarters as sweet as cane sugar. It is optically active; the most common natural form is (+)- glucose.

    How to Draw a Glucose Molecule’s Open Chain Structure

    To draw an acyclic form of glucose, follow the steps below.

    • Step 1: Make a drawing of six carbon atoms.
    • Step 2: For all carbon atoms, save the first, and draw extended arms.
    • Step 3: Draw a hydrogen-to-carbon bond with four hydrogen atoms on one side and one on the other.
    • Step 4: Fill in the remaining places with an OH group. (It’s critical to transpose.)
    • For the left side, (OH) to —> (HO) to show that oxygen is bound to carbon)
    • Step 5: Add two single-bonded hydrogen bonds and one double-bonded carbon to the ends.


    In water, what is the structure of glucose?

    The open-chain (acyclic) and ring (cyclic) forms of the glucose molecule exist, resulting from an intramolecular interaction between the aldehyde C atom and the C-5 hydroxyl group to generate an intramolecular hemiacetal. Both forms are in equilibrium in aqueous solutions, with the cyclic one dominating at pH 7.

    How many atoms does glucose have?

    It is made up of six carbon atoms, twelve hydrogen atoms, and six oxygen atoms in simple terms. Glucose is a readily available monosaccharide, often known as dextrose or blood sugar.

    What is the source of glucose?

    Glucose or sugar is found in the foods we eat. Carbohydrates, including fruit, bread, pasta, and cereals, are common sources of glucose. These foods are broken down into sugar in our stomachs and then absorbed into the bloodstream.

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