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प्रश्न
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?
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उत्तर
Following reactions and facts could not be explained by open-chain structures of glucose.
• Despite having the aldehyde group, glucose does not give 2, 4 − DNP test, Schiff's test and it does not form the hydrogen sulphide addition product with \[\ce{NaHSO3}\].
• The pentaacetate of glucose does not react with hydroxylamine indicating the absence of a free −CHO group.
It was proposed that one of the −OH groups may add to the −CHO group and form a cyclic hemiacetal structure. It was found that glucose forms a six-membered ring in which −OH at C − 5 is involved in a ring formation.
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संबंधित प्रश्न
Enumerate the reactions of D-glucose which cannot be explained by its open chain structure.
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?
The following compound can be called as:
The number of asymmetric carbon atom(s) below the figure is/are
Acetylation of glucose yields ____________.
Glucose does not give Schiff’s test because of the formation of cyclic ____________.
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.
Which is the least stable form of glucose?
A solution of D-glucose in water rotates the plane polarised light ____________.
The number of chiral carbons in ß-D(+) glucose is ____________.
Which one of the following reactions is not explained by the open chain Structure of glucose?
In the following reaction, identify A and B:
\[\begin{array}{cc}
\ce{C6H12O6 ->[Acetic anhydride] A}\\
\downarrow \text{Conc. nitric acid}\phantom{...}\\
\ce{B}\phantom{.................}\end{array}\]
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.
The number of asymmetric carbon atoms in the glucose molecule in open and cyclic form is ______.
When D-glucose reacts with HI, it forms ______.
