Paint and Coating Technology : What is polar and non-polar solvents?

Friday, April 15, 2022

What is polar and non-polar solvents?

Polar solvent: Polar solvent is a type of solvent that has large partial charges or dipole moments. The bonds between the atoms have very different but measurable electronegativities. A polar solvent can dissolve ions and other polar compounds.

Non-polar solvent: Nonpolar solvents have nonpolar bonds owning to the fact that there small or negligible difference of electronegativity (less than 0.4) between the bonded atoms. Nonpolar solvents dissolve only nonpolar solutes.

Polar Protic solvents:

Polar protic solvents are capable of hydrogen bonding because they contain at least one hydrogen atom connected directly to an electronegative atom (such as O-H or N-H bonds).

Example:Water (H2O), formic acid (CH2O2), hydrogen fluoride (HF), ethanol (C2H5OH), ammonia (NH3), methanol (CH3OH), acetic acid (CH3COOH), etc.

Polar aprotic solvents: Aprotic solvents lack acidic protons. Thus, they cannot act as proton donors in hydrogen bonding. Unlike polar solvents, they lack hydroxyl and amine groups.

Polar aprotic solvents are of particular interest because of their ability to dissolve salts, although they cannot donate protons. Many hydrocarbons and chlorocarbons are classified as aprotic solvents.

Example: acetone (H3C-(C=O)-CH3),Ethyl acetate, DMSO, Dimethyl sulphoxide ((CH3)2S=O),DMF, N,N-dimethylformamide (C3H7NO),HMF (hydroxymethylfurfural),

Oxolane/tetrahydrofuran (THF),Crown ethers, Acetonitrile (CH3C≡N),

Nonpolar Solvents: Nonpolar solvents have nonpolar bonds owning to the fact that there small or negligible difference of electronegativity (less than 0.4) between the bonded atoms. Nonpolar solvents dissolve only nonpolar solutes, as suggested by the general solubility principle, “Like dissolves like”, with some exceptions.