Leuco base
With leuco base (from ancient Greek λευκός leukós "clear" and ancient Greek βάση basé "foundation", "base") or leuco compound is referred to in the chemical compounds useful as an intermediate in the production of dyes are formed and dyed often colorless or less intense than the corresponding Are dyes. The leuco compounds are the reduced form of the dye, which is then oxidized to the dye (e.g. with lead (IV) oxide ).
The reduction of mostly water-insoluble pigments to the water-soluble leuco compound plays an important role in vat dyeing .
Examples
An important example is the dyeing of blue jeans with the vat dye indigo , in which indigo is reduced to the water-soluble leuco compound indigo white and reoxidized with atmospheric oxygen after application to the fiber.
If the redox reaction between the dye and its leuco form is fast and reversible, the compound can be used as a redox indicator .
Example: Redox reaction between the colorless leucomethylene blue and methylene blue
.
Individual evidence
- ^ Brockhaus ABC Chemie , VEB FA Brockhaus Verlag Leipzig 1965, p. 796.
- ^ A b Hans Beyer, Wolfgang Walter: Textbook of organic chemistry . 18th edition. S. Hirzel Verlag, Stuttgart 1978, ISBN 3-7776-0342-2 .