“ Ortho-coumaric acid (o-oxycinnamic acid) is obtained from coumarin as shown above, or by boiling coumarin for some time with sodium ethylate. It melts at 208° C. and is easily soluble in hot water and in alcohol. It cannot be converted into coumarin by heating alone, but it is readily transformed on heating with acetic anhydride or acetyl chloride. ”

“ It can also be prepared by heating a mixture of phenol and malic acid with sulphuric acid, or by passing bromine vapour at 107° C. over the anhydride of melilotic acid. It forms rhombic crystals (from ether) melting at 67° C. and boiling at 290° C., which are readily soluble in alcohol, and moderately soluble in hot water. ”