Some organic compounds dissolve in water and some are not. There are some reasons which will decide solubility of organic compounds in water. This lesson we identify those soluble compounds and why they dissolve in water.
In this tutorial, we study which organic compounds are soluble in water and why they dissolve? Sometimes we can see rather than solubility, organic compounds react with water and dissolve or make precipitates.
Now, we take each organic compound type to study their solubility in water.
Alkane, alkene and alkyne belong to the hydrocarbon type. In hydrocarbons, there are only carbon - hydrogen bonds in the organic compound. So polarization is weak to make strong intermolecular forces between water molecules. Therefore, alkane , alkene and alkyne are not soluble in water.
Benzene is not soluble in water because benzene cannot make strong intermolecular forces such as hydrogen bonds or dipole dipole interactions.
All alkyl halides are insoluble in water. Alkyl halides can form dipolar - dipolar interactions. But it is not enough to dissolve due to non-polar hydrocarbon group.
Methanol, ethanol dissolve very well in water. Propanol dissolve little bit. Butanol is completely insoluble in water. When alkyl group gets longer or larger, solubility of alcohols decreases.
Phenol can make hydrogen bonds due to -OH bond. But due to large phenyl group, phenol does not dissolve in water.
Aldehyde and ketone which have less molecular mass, will dissolve in water. Formaldehyde, Ethanal, butanal are soluble aldehydes. Benzaldehyde is insoluble in water. Acetone (propanone), butanone are soluble ketones.
Carboxylic acids are soluble in water because they can form hydrogen bonds with water. But when alkyl group gets larger, solubility decreases. Formic acid, ethanoic acid, propanoic acids are water soluble. Remember that, carboxylic acids dissolve in water and dissociate to give an acidic solution.
All aromatic carboxylic acids are insoluble in water. Benzoic acid forms a white precipitate in the water. Benzoic acid can form hydrogen bonds, but due to large phenyl group, (phenyl group is a non-polar part) benzoic acid does not dissolve in water.
Carboxylic acid chlorides readily dissolve in water and reacts with water to give carboxylic acid and hydrochloric acid (HCl). Benzoyl chloride reacts with water to produce benzoic acid which is a white precipitate.
Amine can make hydrogen bonds with water. Amine which have less molecular mass are soluble in water. But solubility is low when alkyl group is large. Methanamine (methylamine), ethanamine, propylamine are soluble in water.
Aniline is insoluble in water due to large phenyl group. It can form hydrogen bonds.
Amides can form hydrogen bonds due to -NH2 group. Amides which have smaller alkyl group have high solubility in water.
Now, we are going to list very useful organic compounds which dissolve in water very well.