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प्रश्न
Give scientific reasons:
The disaccharide sucrose gives negative Tollens test while the disaccharide maltose gives a positive Tollens test.
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उत्तर
- The structure of sucrose contains glycosidic linkage between C-1 of α-glucose and C-2 of β-fructose.
- Since the potential aldehyde and ketone groups of both the monosaccharide units are involved in the formation of the glycosidic bond (i.e., α, β-1,2- glycosidic bond), sucrose is a non-reducing sugar and gives negative Tollen’s test.
- The glycosidic bond in maltose is in between C-1 of one glucose ring and C-4 of the other (i.e., α -1,4-glycosidic linkage).
- The hemiacetal group at C-1 of the second ring is not involved in the glycosidic linkage. Hence, maltose is a reducing sugar and gives positive Tollen’s test.
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संबंधित प्रश्न
Give scientific reasons:
Hydrolysis of sucrose is called inversion.
Give two evidences for presence of formyl group in glucose.
Glucose on oxidation with dilute nitric acid gives _______________
The glycosidic linkage in maltose is formed between _______________
Write the name of the polysaccharide used for the commercial preparation of glucose.
Write chemical reaction for following conversions
glucose into gluconic acid
What is the action of the following reagents on glucose?
acetic anhydride
Define carbohydrates.
Write a chemical reaction to convert glucose into glucose cyanohydrin.
Which of the following type of carbohydrates cannot be hydrolyzed?
Identify the substances having glycosidic bond and peptide bond, respectively in their structure:
Which of the following carbohydrate is sweet to taste?
______ is the prosthetic group of glycoproteins.
Fructose is the fruit sugar and chemically it is ketohexose but it has a ______ rather than a ______.
From the following identify the materials that are made up of cellulose.
i. Plant cell wall
ii. Exoskeleton of arthropods
iii. Paper from plant pulp
iv. Cotton fibre
Which among the following compounds is obtained when glucose reacts with hydrogen cyanide?
By which of the following feature we can identify the relatively small DNA molecules of plasmids?
Identify a non-reducing carbohydrate from the following.
Match the Column I and Column II select the correct option.
| Column I | Column II | ||
| i. | Monosaccharides | a. | Stored energy in animals |
| ii. | Glycogen | b. | Polymer made from ß-glucose molecules |
| iii. | Cellulose | c. | Exoskeleton of arthropods |
| iv. | Chitin | d. | Building blocks of carbohydrates |
| e. | Plant hormone |
Monosaccharides are ______ in nature.
Which reagent among the following is used to confirm presence of aldehydic carbonyl group in glucose?
Which among the following type of linkages is present in cellulose?
Glucose and gluconic acid treated with dilute nitric acid forms saccharic acid. What does this indicate?
Which following reagent is used to detect presence of five hydroxyl groups in a glucose molecule?
What is the number of hydroxyl groups present in lactic acid?
When 2 moles of stachyose is hydrolyzed, the number of moles of galactose obtained is ____________.
Which among the following sugars does not reduce Tollen's reagent?
How many hydroxyl groups are present in Erythrulose?
The correct corresponding order of names of four aldoses with configuration given below Respectively is:
Assertion: A solution of sucrose in water is dextrorotatory. But on hydrolysis in the presence of little hydrochloric acid, it becomes levorotatory.
Reason: Sucrose hydrolysis gives equal amounts of glucose and fructose. As a result of this change in sign of rotation is observed.
Which of the following are epimers?
Why carbohydrates are generally optically active?
Classify the following into monosaccharides, oligosaccharides and polysaccharides.
Starch
Write the structure of α-D (+) glucopyranose.
Glucose on oxidation with bromine water yields gluconic acid. This reaction confirms the presence of ______.
The two monosaccharides in a disaccharide are held together by ______ bonds.
The glycosidic linkage present in maltose is ______.
Why carbohydrates are generally optically active.
Why carbohydrates are generally optically active.
Assign D/L configuration to the following monosaccharides:
Describe the action of the following reagent on glucose:
Bromine water
Carbohydrates that do not undergo hydrolysis further are called ______.
Explain the hydrolysis of sucrose.
CH2 OH - CO - (CHOH)4 - CH2 OH is an example of ______.
Why carbohydrates are generally optically active.
Why carbohydrates are generally optically active.
Why are carbohydrates generally optically active?
\[\ce{CH2OH - CO - (CHOH)4 - CH2OH}\] is an example of ______.
Which of the following is used to separate glucose and fructose from hydrolysate of sucrose?
