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Glucose
Glucose occurs in nature in Free State as well as in combined state. In Free State, it occurs in sweet fruits and honey. Ripe grapes contain – 20% glucose and hence the name grape sugar. In combined state, glucose is present in di- and polysaccharides. Maltose and starch on hydrolysis yield only glucose.
Preparation of glucose
By hydrolysis of Cane-sugar: in laboratory glucose can be prepared by hydrolysis of cane-sugar in the presence of alcohol using dilute hydrochloric acid. Glucose and fructose are formed in equal amounts. Glucose, being less soluble in ethyl alcohol than fructose, crystallizes out.

By hydrolysis of Starch: glucose is obtained, on commercially scale, by hydrolysis of starch by boiling it with dilute sulphuric acid at 393 K under a pressure of 2-3 bar.

Structure of glucose
Glucose is an aldohexose. It is monomer of many of the larger carbohydrates such as starch, cellulose. The reactions of glucose indicate that its molecule contains one primary (-CH2OH) and four secondary (-CHOH) hydroxyl groups. Glucose was assigned the following structure on the basis of evidences that follow:
Evidences that support the structure of Glucose
The molecular formula of glucose is C6H12O6.
Reduction: glucose is reduced to sorbitol, a hexahydric alcohol, on reaction with hydrogen in the presence of nickel as catalyst or on reaction with sodium amalgam in aqueous solution.

Reaction with hydrogen iodide: Glucose on prolonged heating with HI gives n-hexane.

This reaction suggests that the six carbon atoms in glucose are linked linearly.
Oxidation: (i) glucose on oxidation with acid oxidizing agents, such as bromide water. Tollen’s reagent or Fehling’s solution gives Gluconic acid.

This confirms the presence of an aldehydic group in glucose.
(ii) stronger oxidizing agents such as concentrated nitric acid oxidize glucose to glucaric acid (saccharic acid).

Acetylation: when glucose is reacted with acetic anhydride in the presence of sulphuric acid, a pentaacetyl derivative of glucose is obtained.

Formation of pentaacetyl derivative indicates the presence of five –OH groups in glucose molecule.
Ether formation: Glucose reacts with dimethyl sulphate in the presence of alkali to form penta-O-methyl derivative.

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Preparation of glucose
By hydrolysis of Cane-sugar: in laboratory glucose can be prepared by hydrolysis of cane-sugar in the presence of alcohol using dilute hydrochloric acid. Glucose and fructose are formed in equal amounts. Glucose, being less soluble in ethyl alcohol than fructose, crystallizes out.
By hydrolysis of Starch: glucose is obtained, on commercially scale, by hydrolysis of starch by boiling it with dilute sulphuric acid at 393 K under a pressure of 2-3 bar.
Structure of glucose
Glucose is an aldohexose. It is monomer of many of the larger carbohydrates such as starch, cellulose. The reactions of glucose indicate that its molecule contains one primary (-CH2OH) and four secondary (-CHOH) hydroxyl groups. Glucose was assigned the following structure on the basis of evidences that follow:
Evidences that support the structure of Glucose
The molecular formula of glucose is C6H12O6.
Reduction: glucose is reduced to sorbitol, a hexahydric alcohol, on reaction with hydrogen in the presence of nickel as catalyst or on reaction with sodium amalgam in aqueous solution.
Reaction with hydrogen iodide: Glucose on prolonged heating with HI gives n-hexane.
This reaction suggests that the six carbon atoms in glucose are linked linearly.
Oxidation: (i) glucose on oxidation with acid oxidizing agents, such as bromide water. Tollen’s reagent or Fehling’s solution gives Gluconic acid.
This confirms the presence of an aldehydic group in glucose.
(ii) stronger oxidizing agents such as concentrated nitric acid oxidize glucose to glucaric acid (saccharic acid).
Acetylation: when glucose is reacted with acetic anhydride in the presence of sulphuric acid, a pentaacetyl derivative of glucose is obtained.
Formation of pentaacetyl derivative indicates the presence of five –OH groups in glucose molecule.
Ether formation: Glucose reacts with dimethyl sulphate in the presence of alkali to form penta-O-methyl derivative.
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Inorganic Chemistry
Organic Chemistsry
Analytical Chemistry
Biochemistry
Physical Chemistry
Topics
Nucleic Acid Functions
Carbohydrates
Glucose-Cyclic Structure
Disaccharides
Enzymes
Fructose
Functions Of Carbohydrates
Glucose
Hormones
Enzyme Activity Mechanism
Monosaccharides
Nucleic Acids
Polysaccharides
Proteins, Amino Acids
Proteins Structure
The Cell
Vitamins
Biostatistics
Mutarotation
Monosaccharides Properties
Compound Lipids
Derived Lipids
Fatty Acids
Lipids
Simple Lipids
Radiation-Detection Measurement
Synthetic Polymers
Amino Acids
Bioenergetics
Biological Oxidation Reduction
Cell Membrane
Cell Motility, Cytoskeleton
Cerebrospinal Fluid
Chromatography
Proteins Classification
Clonal Selection Theory
Blood Coagulation
Coenzymes
Nerve Impulse Conduction
Connective Tissue
DNA, RNA
Diagnostic Applications
Lipids-Digestion, Absorption
Proteins-Digestion, Absorption
Endoplasmic Reticulum
Enzyme Inhibition
Enzyme Linked Assay
Enzymes Classification
Erythrocytes
Vitamins-Complex Group
Extracellular Enzymes
Fermentation, Putrefaction
Fibrinolysis
Folic Acid
ATP Functions
Bile Salts Functions
Functions Of Blood
Plasma Proteins Functions
Gastric Juice
Hemoglobin
Blood Lacing Hemolysis
Blood Clotting Inhibitors
Intermediary Metabolism
Enzymes Intracellular Location
Leukocytes
Lymph, Sweat, Synovial Fluid
Histocompatibility
Proteins-Transport Mechanism
Metabolism Study
Mitochondria
Muscles
Niacin
Nucleoproteins
Nucleotides
Nucleus
Oxidative Phosphorylation
Oxyhemoglobin
Pancreatic Juice
Peptides Importance
Proteins Properties
Polyacrylamide Electrophoresis
Amino Acids Properties
DNA Properties
Proteins Characterization
Nucleotide Transhydrogenases
Relaxation
Riboflavin
Saliva
Nucleic Acids Structure
Protein Molecule Structure
Thiamine
Transmission At The Synapse
Transport Across Membranes
Variations In Disease
Vitamin A
Vitamin B
Vitamin C
Vitamin D
Vitamin E
Vitamin K




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