Question

Define saturated compounds.

Answer 1

Hint: Saturated compounds are those compounds in which there is a single bond present between two carbon atoms.A saturated compound is a chemical compound that resists the addition reactions, such as hydrogenation, oxidative addition, and binding of a Lewis base.

Complete answer:
Branched and unbranched aliphatic saturated compounds are called alkanes. These are insoluble in water due to their non-polar nature but soluble in non-polar solvents. The boiling point of alkanes is directly proportional to molecular weight which means as the size of the carbon chain increases, the boiling point also increases but remember in case of branched chain although the number of carbon atoms increases but size decreases therefore boiling point also decreases. In other words, the shape approaches to spherical which results in decrease in van der waals forces (as surface area decreases) Melting point of alkanes do not show regular trend. Alkanes with an even number of carbon atoms have higher melting point than the odd number of carbon chains. This is due to the fact that alkanes with an odd number of carbon chains have their carbon atom on the same side of the molecule and in even carbon atom alkane, the end carbon atom is on the opposite side. Thus alkanes with even carbon atoms are packed closely in the crystal lattice to permit greater intermolecular interactions. Saturated compounds undergo complete oxidation to give $C{O_2} $ and water with evolution of heat. Therefore, these are used as fuels. When the supply of oxygen is limited then these compound produces carbon black (used in printing ink) and CO. $C{H_4} + 3{O_2} \to 2CO + 4{H_2} O$
$C{H_4} + {O_2} \to C + 2{H_2} O$

Note:Saturated compounds undergo substitution reaction via free radical mechanism, unbranched chain compounds undergo isomerization on heating in presence of $AlC{l_3} + HCl $ to give branched chain compounds.