Chemistry Of Carbohydrates -1

Chemistry Of Carbohydrates -1

By Virendra Joshi

​What are carbohydrates?

​

Carbohydrates are organic substances containing C, H

and O. Hydrogen atoms are present usually in the ratio of

2:1 as it occurs in a water molecule. Example: glucose,

fructose, lactose, starch etc. There may be exception to the

above, e.g. C2H4O2 is acetic acid and not a carbohydrate

though H and O are in the ratio of 2:1.

​Define carbohydrates in chemical term.

​

Carbohydrates are defined chemically as aldehyde or

ketone derivatives of the higher polyhydric alcohols or

compounds which yield these derivatives on hydrolysis.

​How will you classify carbohydrates?

​

Carbohydrates are classified into four major groups:

• Monosaccharide (“simple sugars”): They cannot be

hydrolyzed into simpler forms.

• Disaccharides: They yield two molecules of same or

different monosaccharide units on hydrolysis.

• Oligosaccharides: They yield three to six molecules of

monosaccharides on hydrolysis.

• Polysaccharides (glycans): They yield more than 6

molecules of monosaccharides on hydrolysis.

​How are monosaccharides further classified?

Monosaccharides are further classified into two groups

depending on:

• The number of carbon atoms they possess, e.g. trioses,

tetroses, pentoses, hexoses, etc.

• Whether aldehyde (-CHO) or ketone (-CO) group is

present, e.g. aldoses, ketoses.