Colorless dye

Permanent Hair Colorants. Permanent colorants produce hair coloration that lasts until the hair grows out. Color is formed inside the hair by hydrogen peroxide-induced coupling reactions of colorless dye precursors. A hiU range of shades can be obtained with this system and the permanent or oxidative hair colorants are considered to be the most important class of hair dyes. 

Colorless dyes of the chlorinated diphenyl ether—ureasulfonic acid type (Mitin [3567-25-7] (158)) and the (polychloro-2-chloromethylsulfonamido)-diphenyl ether type (Eulan (159)) appHed at 1—3% of the fabric weight are the most widely used during the fabrication of woolens. They cannot be removed by dry cleaning and provide protection from fabric pests over the lifetime of the product. 

Although most DIR couplers are based on image dye-forming parents, universal DIR couplers have appeared in the Hterature. These materials react with oxidized developer to produce the inhibitor (or precursor) and either a colorless dye, an unstable dye, or a washout dye (100). Universal DIR couplers could be used in any layer with a need to match only image-modifying properties, not hue, to the given layer. 

Coloring adjunct, 12 31 Coloring, electrolytic, 16 221-222 Color intensity, of spices, 23 159 Colorless dye precursors, 19 295-296 Color matching, of inorganic pigments,... 

The more popular method to control leveling is to use cationic products that act as colorless dyes competing with the colored cationic dyes for the fiber sites. If amounts of colored modified basic dye and colorless modified basic dye equal to the saturation value of (he fiber are uniformly dissolved in the dyebalh. then level dyeing behavior is promoted. 

Suramin is a colorless dye that evolved from Ehrlich s early work with azo dyes such as Trypan Red that cured mice infected with trypanosomes (Ehrlich and Shiga, 1904). It has therefore been viewed as the first synthetic chemotherapeutic drug (it was inactive in humans). A decade later, suramin, which is, however, trypanocidal in humans, was introduced. It is still in use today for this purpose. Even though the drug has since been shown to inhibit various enzyme systems in parasitic protozoa and worms such as filaria (see avermectin later), its mechanism of action and basis of selective toxicity has still not been elucidated. 

Reakt [BASF BASF AG] Colorless dye intennediates for noncarbon cqiying pt. ... 

P-Carotene is digested by humans and animals and degraded oxidatively to colorless retinal 320 nm). This white compound is then coupled with a white protein to allow color vision in the range of 400-700 nm. How did nature know that a colorless dye would eventually become useful in connection with a protein and sunlight ... 

An imaging system based on photopolymerizable microcapsules has recently been developed (8-101. The microcapsules (Figure 1) contain photoinitiators, acrylic monomers, and a colorless dye precursor. 

Photo-crosslinkable monomer containing predissolved initiator, colorless dye precursor, and other necessary ingredients was emulsified in water and then encapsulated. The capsule slurry was machine coated on paper and dried to form a uniform layer of approximately 12 jum thick. The average capsule size was estimated to be 8 m by Coulter Counter. 

Sample Preparation. Photohardenable formulations based on TMPTA in combination with other reagents including photoinitiators (Quanticure ITX or 7-diethylamino-3-cinnamoyl coumarin, depending on the specific experiment) and colorless dye precursors developable upon contact with acidic resin coated paper were used as a test composition. 

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