The history and chemistry of the Murexide dye

1820-1840

The purple dye was still very much a laboratory curiosity in the late 1830s when the reaction was reinvestigated by Justus von Liebig (1803-1873) and Friedrich Wöhler (1800-1882) at Giessen. They renamed the it murexide, an allusion to the Murex mollusc which is the source of the Tyrian purple of antiquity. The big drawback to commercial production was the scarcity of uric acid, there being few boa constrictors about. Duck or chicken excrement could also be used, but the uric acid content was not very high.

The chemistry involves the oxidation of uric acid to give a mixture of alloxan, alloxantin and other fragments with nitric acid and then reaction with ammonia to give murexide.

For the details of the chemical structures of uric acid, its oxidation products and murexide, and a molecular model, click here
and for the actual recipies used, click here.


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