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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.
\[\begin{array}{cc}
\phantom{...}\ce{CHO}\phantom{..................}\ce{CHO}\phantom{......}\ce{O}\phantom{..........}\\
\phantom{........}|\phantom{.......................}|\phantom{..........}||\phantom{...............}\\
\phantom{}\ce{(CHOH)4 ->[Acetic anhydride] (CH - O - C - CH3)4}\\
\phantom{.}|\phantom{.......................}|\phantom{...................}\\
\phantom{.....}\ce{CH2OH}\phantom{................}\ce{CH2 - O - C - CH3}
\phantom{.....}\\
\end{array}\]
APPEARS IN
संबंधित प्रश्न
Enumerate the reactions of D-glucose which cannot be explained by its open chain structure.
Glucose on reaction with HI gives n-hexane. What does it suggest about the structure of glucose?
Differentiable between the following:
Amylose and Amylopectin
Write the reaction involved when D-glucose is treated with the following reagent:
(CH3CO)2O
Choose the appropriate answer(s) for the below representation from the options given
The number of asymmetric carbon atom(s) below the figure is/are
Oxime is formed by treating glucose with ____________.
Which one of the following compounds is different from the rest?
Glucose is found to exist in two different α and β crystalline forms. These forms can be obtained by:
(i) The α form of glucose is obtained by crystallisation from a concentrated solution of glucose at 303 K.
(ii) The β form of glucose is obtained by crystallisation from a concentrated solution of glucose at 303 K.
(iii) The β form is obtained by crystallisation from hot and saturated aqueous solution at 371 K.
(iv) The α form is obtained by crystallisation from hot and saturated aqueous solution at 371 K.
Which of the following reactions of glucose can be explained only by its cyclic structure?
A solution of D-glucose in water rotates the plane polarised light ____________.
The number of chiral carbon atoms present in cyclic structure α-D(+) glucose:
Assertion: D (+) – Glucose is dextrorotatory in nature.
Reason: ‘D’ represents its dextrorotatory nature.
On the basis of which evidences D-glucose was assigned the following structure?
\[\begin{array}{cc}
\ce{CHO}\\
|\phantom{....}\\
\phantom{..}\ce{(CHOH)4}\\
|\phantom{....}\\
\phantom{..}\ce{CH2OH}
\end{array}\]
Account for the following:
What happens when D – glucose is treated with the following reagents
Bromine water
Glucose with excess of phenyl hydrazine forms ______.
The number of asymmetric carbon atoms in the glucose molecule in open and cyclic form is ______.
Give a reason for the following observations:
Penta-acetate of glucose does not react with hydroxylamine.
