The nature of a constituent of quebracho tannin.
Putnam, Robert Conrad
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Tanning is defined as a process of skin treatment whereby the hot water shrinkage point of the skin is raised, the fibres of the skin substance are prevented from mutually adhering on drying, and the skin substance is protected from putrefaction under ordinary conditions in air. There are various kinds of tanning processes such as vegetable tanning, chrome tanning, formaldehyde tanning, oil tanning and synthetic tanning. In vegetable tanning the materials used for the actual preservation process are obtained from the bark or wood or other parts of various trees or plants. Vegetable tannins may be conveniently divided into three groups. The first of these is the class of depsides or gallotannins which are hydrolysable and yield gallic acid. The second group consists of hydrolysable tannins which yield ellagic acid. The third group consists of non-hydrolysable tannins called phlobatannins. The latter yield red-colored insoluble products called "phlobaphenes" on boiling with acid. Catechin tannin is a phlobatannin and the structure of catechin is known, but not the structure of its tannin. The structure of no phlobatannin is known at present. Many have speculated as to their general structure on very slim evidence and some tannins have been synthesized which appear qualitatively similar to phlobatannins, but no real proof of structure has been forthcoming. [TRUNCATED]
Thesis (Ph.D.)--Boston University
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