Beiträge zur Kenntnis der Abietinsäure

The Pschorr Synthesis

“…In every case found, acetic anhydride was the acid anhydride used. In some cases a small amount of anhydrous zinc chloride (8,9,35,52,53,54,60) or stannous chloride (26) was added, but the beneficial effect of these "catalysts" is dubious. For instances in which one or the other of these metal chlorides has been used, the average yield was approximately 10 per cent lower than the aver- age yield for this step of the Pschorr synthesis.…”

“…It appears that such acids with alkyl groups substituted in the 1-, 2-, 3-, or 4-positions tend to undergo decarboxylation easily (9, 33, 53, 65), and that with rare exceptions (75,79,88,97) difficulty is encountered where these acids are substituted with alkoxyl groups at almost any position (16,26,30,31,36,37,39,64,66,67,78,84,85,86,97,103). Decarboxylation of chloro or bromo derivatives is usually attended by poor yields (4,8,47,58,69,79), except in a recent case where quinoline and copper bronze were used (10). Some of the difficulty in decarboxylating halophenanthrenecarboxylic acids can be explained in terms of well-defined reactions.…”

Recent Advances in Applied Microchemistry

“…The number of the quantitative microanalytical methods for the determination of halogens and of sulfur has been enlarged (19,70) by the introduction of the Parr bomb (8, 39, 53), a wet-combustion method (90, 14S), and procedures permitting the volumetric determination of these elements (141,146).…”