A convenient laboratory or pilot plant scale preparation of pure maleopimaric acid from tall oil rosin is described. The method involves refluxing 1 00 parts of rosin with 17.5 parts of maleic anhydride in 750 parts of glacial acetic acid, reducing the solvent volume to 125 parts, crystallizing the product as an acetic acid solvate, and removing the solvent of crystallization by heating under vacuum. Molar yields averaged 72% for tall oil rosin, based on the total abietic-type acids content. The effects of rosins from different sources, time, proportions of maleic anhydride and acetic acid, temperature, strong acid, and other solvents were investigated.
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