Solvents include hydrocarbons such as pentane, hexane and toluene; alcohols such as methanol, ethanol, isopropanol and phenol; esters such butyl acetate; aldehydes and ketones such as formaldehyde, acetone and methyl ethyl ketone; dimethyl sulfoxide; carbonates such as propylene carbonate; N-methyl formamide, tetramethylurea, dimethylacetamide, N-methylpyrrolidone, hexamethylphosphoric triamide an