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प्रश्न
How will you distinguish 1° and 2° hydroxyl groups present in glucose? Explain with reactions.
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उत्तर
On oxidation with nitric acid, glucose as well as gluconic acid both yield a dicarboxylic acid, saccharic acid. This indicates the presence of a primary alcoholic (–OH) group in glucose.
\[\begin{array}{cc}
\phantom{.......}\ce{CHO}\phantom{..............}\ce{COOH}\phantom{............}\ce{COOH}\phantom{....}\\
\phantom{......}|\phantom{...................}|\phantom{..................}|\phantom{........}\\
\phantom{.....}\ce{(CHOH)4 ->[Oxidation] (CHOH)4 <-[Oxidation] (CHOH)4}\\
\phantom{......}|\phantom{...................}|\phantom{..................}|\phantom{........}\\
\phantom{......}\ce{CH2OH}\phantom{............}\ce{\underset{acid}{\underset{Saccharic}{COOH}}\phantom{............}\ce{\underset{acid}{\underset{Gluconic}{CH2OH}}}\phantom{..}}\\
\end{array}\]
Acetylation of glucose with acetic anhydride gives glucose pentaacetate which confirms the presence of five –OH groups. Since it exists as a stable compound, five –OH groups should be attached to different carbon atoms.
\[\begin{array}{cc}
\phantom{...}\ce{CHO}\phantom{..................}\ce{CHO}\phantom{......}\ce{O}\phantom{..........}\\
\phantom{........}|\phantom{.......................}|\phantom{..........}||\phantom{...............}\\
\phantom{}\ce{(CHOH)4 ->[Acetic anhydride] (CH - O - C - CH3)4}\\
\phantom{.}|\phantom{.......................}|\phantom{...................}\\
\phantom{.....}\ce{CH2OH}\phantom{................}\ce{CH2 - O - C - CH3}
\phantom{.....}\\
\end{array}\]
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संबंधित प्रश्न
Write the reaction that indicates the presence of -CHO group in glucose
What happens when glucose is treated with hydroxylamine?
Maltose is a
(a) Polysaccharide
(b) Disaccharide
(c) Trisaccharide
(d) Monosaccharide
What do you observe when glucose solution is heated with Tollen’s reagent?
The following compound can be called as:
The spatial arrangement of the given molecule is denoted by:
Glucose reacts with acetic anhydride to form ______.
Reduction of glucose by HI suggest that ____________.
A solution of D-glucose in water rotates the plane polarised light ____________.
The two forms of D-glucopyranose obtained from the solution of D-glucose are called ____________.
Which one of the following reactions is not explained by the open chain Structure of glucose?
In the following reaction, identify A and B:
\[\begin{array}{cc}
\ce{C6H12O6 ->[Acetic anhydride] A}\\
\downarrow \text{Conc. nitric acid}\phantom{...}\\
\ce{B}\phantom{.................}\end{array}\]
Account for the following:
What happens when D – glucose is treated with the following reagents
Bromine water
Consider the following reactions:
(i) \[\ce{Glucose + R-OH ->[Conc. HNO3] [A] ->[X eq of][(CH3CO)2O] Acetyl derivative}\]
(ii) \[\ce{Glucose ->[Ni/H2] [A] ->[Y eq of][(CH3CO)2O] Acetyl derivative}\]
(iii) \[\ce{Glucose ->[Z eq of][(CH3CO)2O] Acetyl derivative}\]
'X, 'Y' and 'Z' in these reactions are respectively:
Match List - I with List - II.
| List I | List II | ||
| (A) | Glucose + HI | (I) | Gluconic acid |
| (B) | Glucose + Br2 water | (II) | Glucose pentacetate |
| (C) | Glucose + acetic anhydride | (III) | Saccharic acid |
| (D) | Glucose + HNO3 | (IV) | Hexane |
Choose the correct answer from the options given below:
The reagents with which glucose does not react to give the corresponding tests/products are:
- Tollen’s reagent
- Schiff’s reagent
- HCN
- NH2OH
- NaHSO3
Choose the correct options from the given below:
