Q22 of 26 Page 1

(i) Which of the following biomolecule is insoluble in water? Justify.


Insulin, Haemoglobin, Keratin.


(ii) Draw the Haworth structure for α-D-Glucopyranose.


(iii) Write chemical reaction to show that glucose contains aldehyde as carbonyl group.


(i)


• Keratin is the biomolecule which is insoluble in water.


• Keratin is a family of fibrous structural proteins which is the key structural material for building up the outer layer of our skin.


• It is also the key structural component of hair and nails.


• Keratin monomers assemble into bundles to form intermediate filaments, which are tough and insoluble and form strong unmineralized tissues( found in reptiles, birds, mammals etc.)


(ii)


• In glucose ring there are 5 carbon atoms (main chain) and 1 O atom .


• α-D-Glucopyranose the –OH group on C-1 atom on the ring is present below the plane of the ring(which is the only difference with β D-Glucopyranose).


• The Haworth structure for α-D-Glucopyranose is :



(iii)


• Like aldehydes glucose responds to the following reactions ;


• Reduces Fehling's reagent, reacts with hydroxylamine to form oxime & reacts with HCN to form cyanohydrins also reduces tollen’s reagent .


• But the most important reaction which indicates of the presence of an aldehyde group is the reaction where glucose gets oxidised gluconic acid on reaction with mild oxidising agents like bromine water.


More from this chapter

All 26 →
20

(a) Exemplify the following reactions:

(i) Rosenmund reduction reaction.


(ii) Kolbe electrolysis reaction


(b) Arrange the following compounds in increasing order of their reactivity towards HCN:


Acetaldehyde, Acetone, Di-tert-butyl ketone.


OR


(a) Predict the products of the following reactions:


(i)




(b) Arrange the following compounds in increasing order of acid strength: Benzoic acid, 4-Nitrobenzoic acid, 4-Methoxybenzoic acid.


 21

(i) Identify the monomer in the following polymeric structure: [ CH2-CH=CH-CH2-CH2-CHCN]n


(ii) On the basis of forces between their molecules in a polymer to which class does neoprene belong?


(iii) Can both addition and condensation polymerization result in the formation of a copolymer?


 23

John had gone with his mother to the doctor as he was down with fever. He then went to the chemist shop with his mother to purchase medicines prescribed by the doctor. There he observed a young man pleading with the chemist to give him medicines as he had nasal congestion. The chemist gave him cimetidine. John advised and also explained to the young man that he should only take the medicines prescribed by the doctor.

Answer the following questions:


(a) Did the chemist give an appropriate medicine? Justify your answer.


(b) John’s action was appreciated by his mother. List any two reasons.


 24

(a) Write the mechanism of hydration of ethene to form ethanol.

(b) How are the following conversions carried out?


(i) Propanol to propan-2-ol.


(ii) Propanol to 1-propoxypropane


(c) Give the structure and the IUPAC name of the major product obtained in the following reaction:



OR


(a)Write the mechanism of the reaction of HI with methoxymethane.


b) Identify A and B in the following reactions:


(i)



(ii)



(c) Give the structure and the IUPAC name of the major product obtained in the following reaction:



conc. H2SO4