Q 19P. - Organic Chemistry (Mcmurry)

Question

Of the two vitamins A and C, one is hydrophilic and water-soluble while the other is hydrophobic and fat-soluble. Which is which?

Vitamin A                                             Vitamin C

(Retinol)                                            (Ascorbic acid)

Step-by-Step Solution

Answer

Vitamin A is fat-soluble (hydrophobic) because most of its atom can’t form hydrogen bond with water. Vitamin C is water-soluble (hydrophilic) because it has several polar -OH groups that can form hydrogen bond with water.

Hydrogen Bonding

Hydrogen bonding is defined as the force of attraction existing between hydrogen atom which is attached to highly electronegative atom in a covalent molecule and more electronegative atom of another covalent molecule is called hydrogen bonding. Hydrogen bond is possible mostly inpolar covalent molecule where partial charge separation is there. 

Identification of Vitamin A (Retinol) and VitaminC (Ascorbic acid)

Vitamin A is fat-soluble (hydrophobic) because most of its atom can’t form hydrogen bond with water. Vitamin A is fat-soluble which means that it dissolves in fat, unlike other vitamins that are water soluble.

Vitamin C is water-soluble (hydrophilic) because it has several polar -OH groups that can form hydrogen bond with water.

Vitamin A                                                                Vitamin C

(Retinol)                                                             (Ascorbic acid)

                          Fat-soluble (hydrophobic)water-soluble (hydrophilic)