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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
How many moles of acetic anhydride will be required to form glucose pentaacetate from 2M of glucose?
(a) 2
(b) 5
(c) 10
(d) 2.5
What happens when glucose is treated with hydroxylamine?
Glucose on reaction with HI gives n-hexane. What does it suggest about the structure of glucose?
Answer the following question.
What is the basic structural difference between glucose and fructose?
Write the reaction involved when D-glucose is treated with the following reagent:
Br2 water
Write the reactions involved when D-glucose is treated with the following reagent:
H2N-OH
Write the reaction involved when D-glucose is treated with the following reagent:
(CH3CO)2O
The spatial arrangement of the given molecule is denoted by:
Oxime is formed by treating glucose with ____________.
Acetylation of glucose yields ____________.
Glucose does not react with ____________.
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.
Reduction of glucose by HI suggest that ____________.
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 ____________.
Choose the correct relationship for glucose and fructose:
The letter D and L in carbohydrates represent ____________.
Which one of the following reactions is not explained by the open chain Structure of glucose?
In the following reaction, identify A and B:
\[\begin{array}{cc}
\ce{C6H12O6 ->[Acetic anhydride] A}\\
\downarrow \text{Conc. nitric acid}\phantom{...}\\
\ce{B}\phantom{.................}\end{array}\]
Why does compound (A) given below not form an oxime?
(A)
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:
There are 5 OH groups in glucose
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.
