(i) Chemical properties of monosaccharides : When a & p isomeric forms of D-glucose are dissolved in water. Their optical rotation changes with time and approaches the final equilibrium value. +53°. This change is known as mutarotation. Mutarotation occurs because of slow conversion of α -D glucose and β-D glucose via open chain form until equilibrium is established giving a constant rotation +53°.
Acetals traditionally derive from the product of the reaction of an aldehyde with excess of alcohol, whereas the name ketal derives from the product of the reaction of a ketone with excess alcohol.
(ii) Chemical properties of proteins :
• Proteins when hydrolyzed by acidic agents, like cone. HC1 yield amino acids in the form of their hydrochlorides.
• Sanger’s reaction : Proteins react with FDNB reagent to produce yellow coloured derivative, DNB amino acid.
• Xanthoproteic test: On boiling proteins with cone. HN03, yellow colour develops due to presence of benzene ring.
• Folin’s test: This is a specific test for tyrosine amino acid, where blue colour develops with phosphomolybdotungstic acid in alkaline solution due to presence of phenol group.
