The alkyl group (R ) tends to stabilise the `gt C = O` group by reeasing the electrons (+I effect) towards the `sp^(2)` hybridised carbon atom. As a result, the polarity of te bond is ligkely to decrease and stability will therefore, increase. Ketones with two such groups are more stable than the corresponding aldehydes having only one alkyl group. Consequently their boiling points are slightly higher. For example, boiling points of isomeric propanal and propanone are 322 K and 329 K respectively.
