Advertisements
Advertisements
प्रश्न
Enlist the properties of glucose that can not be explained on the basis of open chain structure of it
Advertisements
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
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
Maltose is a
(a) Polysaccharide
(b) Disaccharide
(c) Trisaccharide
(d) Monosaccharide
What do you observe when glucose solution is heated with Tollen’s reagent?
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:
(CH3CO)2O
Oxime is formed by treating glucose with ____________.
Which of the following statements is incorrect regarding glucose?
Which one of the following compounds is different from the rest?
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.
The reaction of glucose with red P + HI is called ____________.
Which is the least stable form of 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 ____________.
Choose the correct relationship for glucose and fructose:
Which one is correct?
In the following reaction, identify A and B:
\[\begin{array}{cc}
\ce{C6H12O6 ->[Acetic anhydride] A}\\
\downarrow \text{Conc. nitric acid}\phantom{...}\\
\ce{B}\phantom{.................}\end{array}\]
Three structures are given below in which two glucose units are linked. Which of these linkages between glucose units are between C1 and C4 and which linkages are between C1 and C6?
| (I) |  |
| (II) |  |
| (III) |  |
How will you distinguish 1° and 2° hydroxyl groups present in glucose? Explain with reactions.
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?
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
When D-glucose reacts with HI, it forms ______.
Give the reaction of glucose with hydrogen cyanide. Presence of which group is confirmed by this reaction?
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:
