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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.
APPEARS IN
संबंधित प्रश्न
Write the reaction that indicates the presence of -CHO group in glucose
Enumerate the reactions of D-glucose which cannot be explained by its open chain structure.
Maltose is a
(a) Polysaccharide
(b) Disaccharide
(c) Trisaccharide
(d) Monosaccharide
What do you observe when glucose solution is heated with Tollen’s reagent?
What do you observe when glucose is treated with bromine water?
Write the reactions involved when D-glucose is treated with the following reagent:
H2N-OH
The following compound can be called as:
Choose the appropriate answer(s) for the below representation from the options given
Acetylation of glucose yields ____________.
Which of the following statements is incorrect regarding glucose?
The symbols D and L represents ____________.
Glucose does not react with ____________.
Glucose reacts with acetic anhydride to form ______.
Which of the following properties of glucose cannot be explained by its open chain structure?
(i) Glucose does not form hydrogen sulphite with NaHSO3.
(ii) On oxidation with HNO3 glucose gives saccharic acid.
(iii) Glucose is found to exist in two different crystalline forms which are named as α and β.
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.
Reduction of glucose by HI suggest that ____________.
Which is the least stable form of glucose?
The two forms of D-glucopyranose obtained from the solution of D-glucose are called ____________.
The letter D and L in carbohydrates represent ____________.
Why does compound (A) given below not form an oxime?
(A)
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?
What happens when D-glucose is treated with the following reagent?
HI
Account for the following:
What happens when D – glucose is treated with the following reagents
HNO3
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:
