Early Dyestuffs

Artificial dyes in the laboratory of the Lancashire calico-printer John Lightfoot included his own invention of aniline black he also pioneered new methods for mordanting and the use of vanadium in aniline black printing.104A general account has been given of the role of rosaniline in the development of the synthetic dye industry.105 A paper on quinones focuses chiefly on the case of anthraquinone and the synthesis of alizarin from anthracene.106 

---

As early as 2500 bce m India indigo was used to dye cloth a deep blue The early Phoenicians discovered that a purple dye of great value Tyrian purple could be extracted from a Mediterranean sea snail The beauty of the color and its scarcity made purple the color of royalty The availability of dyestuffs underwent an abrupt change m 1856 when William Henry Perkin an 18 year old student accidentally discovered a simple way to prepare a deep purple dye which he called mauveme from extracts of coal tar This led to a search for other synthetic dyes and forged a permanent link between industry and chemical research... 

Phthalocyanine Dyes. In addition to their use as pigments, the phthalocyanines have found widespread appHcation as dyestuffs, eg, direct and reactive dyes, water-soluble dyes with physical or chemical binding, solvent-soluble dyes with physical or chemical binding, a2o reactive dyes, a2o nonreactive dyes, sulfur dyes, and wet dyes. The first phthalocyanine dyes were used in the early 1930s to dye textiles like cotton (qv). The water-soluble forms Hke sodium salts of copper phthalocyanine disulfonic acid. Direct Blue 86 [1330-38-7] (Cl 74180), Direct Blue 87 [1330-39-8] (Cl 74200), Acid Blue 249 [36485-85-5] (Cl 74220), and their derivatives are used to dye natural and synthetic textiles (qv), paper, and leather (qv). The sodium salt of cobalt phthalocyanine, ie. Vat Blue 29 [1328-50-3] (Cl 74140) is mostly appHed to ceUulose fibers (qv). 

In the United States all other processes have been completely phased out and virtually all benzoic acid is manufactured by the continuous hquid-phase air oxidation of toluene. In the late 1950s and the early 1960s both Dow Chemical and Snia Viscosa constmcted faciUties for Hquid-phase toluene oxidation because of large requirements for benzoic acid in the production of phenol and caprolactam. Benzoic acid, its salts, and esters are very useful and find appHcation in medicinals, food and industrial preservatives, cosmetics, resins, plasticizers, dyestuffs, and fibers. 

An early method developed for the assay of detergents based upon the sodium salts of the higher homologues of the alkanesulphonic acids,21 involved treatment of an aqueous solution of the detergent with methylene blue in the presence of chloroform. Reaction takes place between the ionic dyestuff (which is a chloride) and the detergent ... 

These are thermoset polymers made from phenol or, less commonly, phenolic-type compounds such as the cresols, xylenols, and resorcinol, together with formaldehyde. They had been known for some time - G.T (later Sir Gilbert) Morgan discovered them in the early 1890s when attempting (unsuccessfully) to make artificial dyestuffs by reaction of phenol with formaldehyde. But this knowledge had not been exploited before 1907, the year in which Leo... 

The above reactions can be used to prepare a variety of multi-purpose intermediates that are of great value in dyestuffs manufacture. Many of these intermediates were prepared and found to be of value in dye manufacture before the orientation of their substituents was established. This early lack of basic knowledge resulted in these intermediates being given trivial names that have persisted in the dyestuffs industry. 

The other source of modem dmgs was the European dyestuff industry of the nineteenth and early twentieth centuries. The goal of this industry was to make useful dyes, principally for fabrics. In the course of handling novel molecules, scientists occasionally make unexpected observations (serendipity) that suggest novel utilities. For example, the commonly used sweetener aspartame was discovered by accident when a scientist licked a finger containing a bit of this substance. It turned out to be surprisingly sweet. 

The nitration of aromatic hydrocarbons is one of the most widely studied and well-documented reactions in organic chemistry. Aromatic nitro compounds are of huge industrial importance in the synthesis of pharmaceutical drugs, agrochemicals, polymers, solvents and perfumes, and for the synthesis of other industrially important chemicals containing amine and isocyanate functionality. However, early research into aromatic nitration was fuelled exclusively by their use as explosives and intermediates in the synthesis of dyestuffs. The former is the subject of this chapter. 

The class of 2-amino-4H-pyrans has been known for several decades. The first representatives 1 and 2 are from the late 1950s to the early 1960s. Spiro-conjugated pyranopyrazole 1 was obtained in studies on pyrazolone dyestuffs (56ACS587), while pyranopyranone 2 served as a precursor for the blood anticoagulant warfarin (62JOC3086). 

Toxicology of Certain Azo Dyes. It has been known for over 100 years that certain amines used to manufacture synthetic dyes caused bladder cancer, especially 2-naphthylamine, benzidine and 4-aminodiphenyl. All the major dyestuff manufacturers abandoned the use of these amines in the production of dyes in the early 1970s. 

The compounds to be discussed in this chapter, plus some related ones, are given in Table 1. The Colour Index is the source of the early, definitive information on dyestuffs. Chemical Abstracts uses it as its chief reference source for the chemical constitution of trade-named dyes. 

The importance of phthalocyanines, apart from their early use as models for hemes and chlorophylls, lies in the fact that metal complexes of the phthalocyanine system produce extremely intense and useful dyestuffs. Much research has therefore been devoted to physical and spectroscopic studies of these molecules (B-81MI30700). Phthalocyanines are extremely stable, are stable to light, and are insoluble in most solvents, so they are very useful dyestuffs. 

The simplest way of coloriog cellulosic fibers is with direct dyes. The dyeing mechanism follows exactly the outline just described where the addition of sail is used to allow dyestuff to be absorbed on the fiber. This is done carefully to ensure that level dyeing is achieved, especially during the early stages of dyeing. 

Both 2 1 chromium and cobalt complex azo dyestuffs have little or no affinity for cellulosic fibres and until the early 1960s their use was restricted to wool and nylon. With the introduction by ICI of their Procion range of fibre-reactive dyes, however, their use was extended to cellulosic fibres on which they give prints having excellent fastness to light and wet treatments. Before that time the development of metal complex dyes for cellulose had followed a similar pattern to that of the development of such dyes for wool but, in this case, the most important metal was copper. Early work in this field has been reviewed by several authors.1 The after-treatment of dyeings on cotton obtained from dyestuffs such as (11) with copper salts was used for many years to improve fastness... 

---