Disproportionation of Tall Rosin under Hydrogen Atomosphere

Disproportionation of tall rosin with Pd-active carbon catalyst under hydrogen atomosphere was investigated. The required amounts of the catalyst in disproportionation under hydrogen atomosphere was one fifth of that in nitrogen, and the extinction coefficient of ultraviolet absorption spectra of the reaction product under hydrogen became smaller on the whole than that under nitrogen. As phenolic matter is said to lower the yield of polymer, estimation of phenolic matter was made with a result that only a trace of phenolic matter was found qualitatively. The reaction was not affected by the amount of hydrogen within the limit of conditions in experiment. The deterioration of activity of catalyst under hydrogen atomosphere was less than that of nitrogen, and therefore cyclic reuse of the catalyst was possible for five times. When 0.1% of recovered catalyst is used, 0.03% of new catalyst should be added for each cycle. In this case, the consumption of catalyst of each run would become nearly 0.03% at last. Wood and gum rosins were disproportionated easily compared with tall rosin.