Methanol is polar, organic solvent. According to rule 'like dissolves like', this can extract organic, polar phytochemicals. Then why we extract our plant material initially with methanol and then fractionate it with non polar solvents (hexane, chloroform, carbon tetrachloride etc.) along water?
Polar solvents are best for dissolving polar reactants (such as ions); nonpolar ... it's this absence of charge which makes these molecules “non-polar”. ... to list) where a polar protic solvent such as water, methanol, or ethanol can .... It is more polar than hydrocarbons, but is still not miscible at all with water. Polar solvents have large dipole moments (aka “partial charges”); they contain bonds between atoms with very different electronegativities, such as oxygen and hydrogen.
Non polar solvents contain bonds between atoms with similar electronegativities, such as carbon and hydrogen (think hydrocarbons, such as gasoline). Bonds between atoms with similar electronegativities will lack partial charges; it’s this absence of charge which makes these molecules “non-polar”. Protic solvents have O-H or N-H bonds. Why is this important? Because protic solvents can participate in hydrogen bonding, which is a powerful intermolecular force. Additionally, these O-H or N-H bonds can serve as a source of protons (H+).
Aprotic solvents may have hydrogens on them somewhere, but they lack O-H or N-H bonds, and therefore cannot hydrogen bond with themselves.Solvents can cause considerable confusion in reactions, because they’re listed along with the reagents of a reaction but often don’t actually participate in the reaction itself
If you notice - we seldom use absolute MeOH - normally one uses 80% conc. MeOH at this conc dissolves a lot of biomolecules specially secondary metabolites of a wide range of classes - that is why for prelim screening we use MeOH follwowed by a solvent partition for particular biochemical.
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