What are the basic dyes?
Basic dyes refer to salts composed of positively charged pigments and hydrochloric acid, oxalic acid, or double salts composed of zinc chloride, which are dissolved in water and dissociated into dye cations and acid radical anions. Basic dyes are also called salt-based dyes.
What is the history of basic dyes?
In 1856, H. W. Perkin synthesized the world's first synthetic dye aniline violet, which belongs to basic dyes. Afterwards, basic violet 22, basic blue 9, basic green 5, rhodamine and many other varieties appeared successively. The chemical structure types of basic dyes include diaryl methane, triaryl methane, azo type and nitrogen-containing heterocyclic compounds (such as oxazine and thiazine, etc.).
What are the properties of basic dyes?
Basic dyes are soluble in water and more soluble in acetic acid and ethanol. If alkali is added to the basic dye solution, a precipitate will be formed, and then acid will be added. The precipitate dissolves again to form a salt. Since basic dyes are cationic dyes, they cannot be mixed with anionic dyes or anionic surfactants. Basic dyes can be reduced to colorless compounds or leucosomes by reducing agents, and return to their original color when exposed to air or oxidized.
What is the dyeing principle of basic dyes?
The chromatin in the nucleus contains deoxyribonucleic acid (DNA), which is an acidic substance that can ionize H+ and make it negatively charged. Therefore, it can be firmly combined with the positively charged auxochrome group ionized by the basic dye through the attractive force between the charges, thus being dyed in color. In the experiment of "observation of plant cell mitosis", if hydrochloric acid is used for dissociation and dyeing without rinsing, since hydrochloric acid is a strong acid and deoxyribonucleic acid is a weak acid, the presence of hydrochloric acid will inhibit the ionization of deoxyribonucleic acid, As a result, the deoxyribonucleic acid cannot be combined with the positively charged auxochrome group in the basic dye, so that the chromatin cannot be dyed.
What are the applications of basic dyes?
Basic dyes have a complete spectrum and extremely colorful colors. With high color yield, it was widely used in the coloring of cotton, wool, silk, paper, bamboo, leather, feathers and grass products at first. Later it was used in the dyeing of acetate fiber and acrylic fiber. The color base of basic dyes can also be used as oil-soluble dyes for stationery (such as ballpoint pen oil, ink pad oil, colored pencils, etc.) Paint, ink, plastic, rubber product coloring and synthetic fiber raw pulp coloring.
What are the directions for use of basic dyes?
Basic dyes have less hydrophilic groups, so they are difficult to dissolve in water. When dissolving basic dyes, first dissolve them with alcohol or acetic acid, and then dilute them with water. Basic dyes are sensitive to temperature and the temperature of dissolution and dilution and dyeing bath should not be too high.
