Isolation of dehydroabietic acid by reaction-crystallization coupled with ultrasound wave
The preparation of 2-aminoethanol salt of dehydroabietic acid from disproportionated rosin by reaction-crystallization coupled with ultrasound wave was studied by using disproportionated rosin and 2-aminoethanol as raw materials, ethanol as reaction solvent, and pure dehydroabietic acid could be obtained by extraction, crystallization, recrystallization and acidification.The effects of concentration of ethanol, reaction temperature, reaction time, ultrasound intensity and agitating velocity on the yield of dehydroabietic acid were investigated by orthogonal experiment, and the optimal conditions for isolation were obtained as follows: reaction time 50 min, reaction temperature 35℃, ultrasound power 500 W, concentration of ethanol 50%, agitating velocity 400 r·min-1.Under these conditions, the yield of dehydroabietic acid was 55.37%, and the purity was 99.53%.At the same time, the effect of the conversion of phase state during the aminating reaction-crystallization on the chemical equilibrium and selectivity was investigated.When reaction temperatures were 35℃ and 70℃, respectively, the reaction was heterogeneous and homogeneous, and the purities of dehydroabietic acid prepared were 99.53% and 95.66%.The dehydroabietic acid prepared was analyzed and confirmed with GC, GC-MS, elemental analysis, UV, FT-IR, melting point instrument and polarimeter as well, and the results were in good agreement with the values in literature.