Disproportionation of Tall Rosin with Palladium Catalyst
1962 Volume 11 Issue 1 Pages 28-35
Details
1962 Volume 11 Issue 1 Pages 28-35
Hays, Ball and their co-workers proposed the following equation for estimation of the content of abietic acid in disproportionated product.
Abietic acid %=α241-α248.5/27.5×100
where;α241 and α248.5 are the specific adsorption coeffici-ents at 241 mμ and 248.5 mμ respectively.
When disproportionation of tall rosin was carried out using active carbon catalyst only, experiments showed that the content of abietic acid from upper equation was influenced by the unsaponifiable matter.
Because α241 of the unsaponifiable matter was much larger than α248.5, and the extinction coefficient of disproportionated product was increased as a whole by the unsaponifiable matter. But, in disproportionation with Pd-catalyst, the content of abietic acid was scarecely influenced by the unsaponifiable matter, because α241-α248.5 was very small. The saponifiable component, which is scarcely soluble in iso-octane was produced in a certain reaction condition of disproportionation. This component having the maximum extinction coefficient at 250 mμ makes larger the extinction coefficient of disproportionated product as a whole, but has influenced little on equation for estimation of content of abietic acid.
The disproportionation of tall rosin with Pd-catalyst was investigated. The active carbon was the best as carrier and 1 part of Pd to about 100 parts of active carbon was suitable ratio. The more catalysts, the lower temperature or the shorter reaction time at the advancing reaction, the larger activity of the recovered catalysts were achieved. In the cyclic reuse of the recovered catalysts, the required amount of the catalysts was about 0.25 % (2 cycles with 0.5%) in the average. In the additional use of catalyst, mixed use of new additional catalyst with the recovered was more effective than that in which the recovered catalyst was used at first and then new catalyst was subsequently added. The requirement of the catalysts were about 0.13% and 0.2% in the average for the former system and the latter respectively.
