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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
Draw the simple Fisher projection formulae of D - (+) - glucose and D - (-) - fructose
Maltose is a
(a) Polysaccharide
(b) Disaccharide
(c) Trisaccharide
(d) Monosaccharide
Enlist the properties of glucose that can not be explained on the basis of open chain structure of it
Glucose on reaction with HI gives n-hexane. What does it suggest about the structure of glucose?
Differentiable between the following:
Amylose and Amylopectin
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.
Answer the following question.
What is the basic structural difference between glucose and fructose?
Which of the following statements is incorrect regarding glucose?
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.
Which of the following pairs represents anomers?
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.
Assertion: D (+) – Glucose is dextrorotatory in nature.
Reason: ‘D’ represents its dextrorotatory nature.
What happens when D-glucose is treated with the following reagent?
HI
Consider the following reactions:
(i) \[\ce{Glucose + R-OH ->[Conc. HNO3] [A] ->[X eq of][(CH3CO)2O] Acetyl derivative}\]
(ii) \[\ce{Glucose ->[Ni/H2] [A] ->[Y eq of][(CH3CO)2O] Acetyl derivative}\]
(iii) \[\ce{Glucose ->[Z eq of][(CH3CO)2O] Acetyl derivative}\]
'X, 'Y' and 'Z' in these reactions are respectively:
The number of asymmetric carbon atoms in the glucose molecule in open and cyclic form is ______.
When D-glucose reacts with HI, it forms ______.
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:
