Color Dyes – A dye is a substance that modifies the color of the medium in which it introduces. Dyes can be of natural origin (animal, plant, or mineral), so it is necessary to use separation methods (solvent extraction, distillation, chromatography, etc.) to extract them. It is also often possible to produce them by chemical synthesis. Dyes are present in food and, in particular, in drinks and sweets. They are also used to dye clothes and are the main constituent of inks.

Synthesis Of Color Dyes In The 19th Century

During the nineteenth century, the chemical synthesis of dyes began with the discovery of mauveine by Perkin in 1856. Chemists succeeded in synthesizing dyes hitherto extracted from plants or animals. Stains are becoming much more affordable because chemical synthesis costs far less money than removing them. In 1897, the German company BASF industrialized the synthetic production of indigo discovered by Baeyer in 1880. Quinoline yellow, whose main component C 18 H 9 Na 2 O 8 S 2 is the first food coloring to synthesize. It is the full development of organic chemistry, that is, substances containing the majority of the elements carbon C and hydrogen H within a carbon chain.


Like a dye, a pigment modifies the color of the medium that receives it, but unlike the latter, it comes in the form of an insoluble powder. It is, therefore, necessary to choose a medium that can maintain the pigments without settling. Thus, such a medium is called a “binder”, for example, consist of oil. The pigments can be of organic origin (vegetable or animal) but are most often of mineral nature. Pigments found in cosmetic products, even if they are mainly present in paints.

Subtractive Mixtures

Reminder On Subtractive Synthesis

Pigments and dyes absorb part of the light they receive, transmitting (in the case of dye solutions) or diffusing (for pigments) the other amount of this light. If a mixture of color substances absorbs several colors, the visible color is the sum of all the colors not absorbed: a subtractive synthesis. For example, combining color dyes or pigments makes it possible to achieve a subtractive synthesis of light with cyan, magenta, and yellow as primary colors. A subtractive mixture, therefore, results from combining the primary colors of the subtractive synthesis. The color of a combination results from a subtractive synthesis of the colors of the colored materials used to create it.

Conjugated Double Bonds

To fully understand the concept of conjugated double bonds, it is necessary to take the time to explain the topological formulas. Indeed, the more complex the molecule, the more extended and tedious its representation in expanded, semi-developed, or even simple procedures.

The Molecule Is Represented As Follows

  • The carbon chain is arranges in a broken line which have branches.
  • Multiple bonds are present.
  • The atoms other than C and H appear by their symbol and the hydrogen atoms they possibly carry.

One of the advantages of skeletal formulas is that they allow you to visualize conjugated double bonds well. We call “conjugated double bonds” an alternation of double bonds and single bonds. The particularity of these systems of conjugated double bonds lies in the increased absorption of radiation, exceptionally light radiation. It is this property that makes this type of molecule colorful.


Color dyes originated way back in history. However, these color dyes are developing in terms of color mixtures. These mixtures include several colors with various dyes mixing.