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प्रश्न
Enlist the properties of glucose that can not be explained on the basis of open chain structure of it
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उत्तर
Although the open chain structure of D (+) − Glucose explains most of its reactions, it fails to explain the following facts:
a) D (+)-Glucose does not undergo certain characteristic reactions of aldehydes
eg., Glucose does not form NaHSO3 addition product, aldehyde-ammonia adduct 2, 4 − DNP derivative and does not respond to Schiff’s reagent test.
b) Glucose reacts with NH2OH to form an oxime but glucose pentaacetate does not react
with NH2OH, which implies that the free aldehyde group is absent in glucose pentaacetate
c) D(+)-Glucose exists in two stereoisomeric crystalline forms, i.e. α-glucose and
β-glucose, called anomers. α-D(+)-Glucose is obtained when a concentrated aqueous or
alcoholic solution is crystallised at 303 K. It has a melting point of 419 K and has a
specific rotation of +111° in a freshly prepared aqueous solution.
However, when glucose is crystallised from water above 371 K, β-D(+)-glucose is
obtained. It has a melting point of 423 K and has a specific rotation of +19.2° in a
freshly prepared aqueous solution. This behaviour could not be explained by the open
chain structure of glucose.
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संबंधित प्रश्न
Write the reaction that indicates the presence of -CHO group in glucose
Draw the simple Fisher projection formulae of D - (+) - glucose and D - (-) - fructose
Glucose on reaction with HI gives n-hexane. What does it suggest about the structure of glucose?
What do you observe when glucose solution is heated with Tollen’s reagent?
Fill in the blanks by choosing the appropriate word/words from those given in the brackets:
(iodoform, acetaldehyde, positive, greater, acidic, acetone, disaccharide, negative, increases, glucose, decreases, chloroform, polysaccharide, lactose, lesser, basic, cationic hydrolysis, anionic hydrolysis)
Sucrose is a _________ and yields upon hydrolysis, a mixture of ________ and fructose.
What do you observe when glucose is treated with bromine water?
The following compound can be called as:
Oxime is formed by treating glucose with ____________.
Acetylation of glucose yields ____________.
Glucose does not give Schiff’s test because of the formation of cyclic ____________.
Which of the following statements is incorrect regarding glucose?
The symbols D and L represents ____________.
Glucose reacts with acetic anhydride to form ______.
The reaction of glucose with red P + HI is called ____________.
The number of chiral carbon atoms present in cyclic structure α-D(+) glucose:
The α-D glucose and β-D glucose differ from each other due to difference in carbon atom with respect to its ____________.
The two forms of D-glucopyranose obtained from the solution of D-glucose are called ____________.
Which one is correct?
In the following reaction, identify A and B:
\[\begin{array}{cc}
\ce{C6H12O6 ->[Acetic anhydride] A}\\
\downarrow \text{Conc. nitric acid}\phantom{...}\\
\ce{B}\phantom{.................}\end{array}\]
Assertion: D (+) – Glucose is dextrorotatory in nature.
Reason: ‘D’ represents its dextrorotatory nature.
Write the reactions of D-glucose which can’t be explained by its open-chain structure. How can cyclic structure of glucose explain these reactions?
Account for the following:
What happens when D – glucose is treated with the following reagents
Bromine water
Account for the following:
What happens when D – glucose is treated with the following reagents
HNO3
Give a reason for the following observations:
Penta-acetate of glucose does not react with hydroxylamine.
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:
