Find best premium and free Magento themes at Design4Mage
Basic dyes
Basic dyes are one of the most common types of the dyes. Basic dyes are the class of dyes, that are most commonly synthetic. Their primary nature is to act as bases, and are actually aniline dyes. Initially their color base prevents them from being water soluble. They can be made so with the base being converted into a salt. At the chemical level, basic dyes are typically cationic or positively charged. Basic dyes display cationic functional groups like -NR3+ or =NR2+. Since basic dye is a stain that is cationic or positively charged and it is the reason that it reacts well with material that is anionic or negatively charged.

Basic dyes consists of amino groups, or alkylamino groups, as their auxochromes. Synthetic dye that was discovered by Perkin incidentally was a basic dye. Some prominent examples of basic dyes are the following, methylene blue, crystal violet, basic fuchsin safranin, etc. An example of a basic dye that has amino groups as their auxochrome is pararosanilin or basic red 9 (according to the strict colour index system of classification) example of alkylamino groups is methylene blue or basic blue 9. Basic Blue 9 is a very popular dye that has vast use. The following table gives a few vital information regarding the dye basic blue 9.


Common name Methylene Blue
Other name Methylene Blue
Suggested name Swiss blue
C I name Basic blue 9
Solvent blue 8
C I number 52015
Ionisation Thiazin
Solubility aqueous 3.55%
Solubility ethanol 1.48%
Class Basic
Colour Blue
Empirical formula C16H18N3SCI
Formula weight 319.9









  • Mechanism of basic dyes
Basic dye is a stain that is cationic (+ ve charged) and so will react with material that is (-ve) negatively charged. The cytoplasm of all bacterial cells have a slight negative charge when grown in a medium of near neutral pH and will therefore attract and bind with basic dyes. Some examples of basic dyes are crystal violet, safranin, basic fuchsin and methylene blue. It’s applied to wool, silk, cotton and modified acrylic fibres. Usually acetic acid is added to the dyebath to help the take up of the dye onto the fibre. Basic dyes are also used in the coloration of paper.

Basic dye is a class of dyes, usually synthetic, that act as bases, and which are actually aniline dyes. Their color base is not water soluble but can be made so by converting the base into a salt. The basic dyes, while possessing great tinctorial strength and brightness, are not generally light-fast; therefore their use in the dyeing of archival materials is largely restricted to those materials not requiring this characteristic. Basic dyes were at one time used extensively in dyeing leather, mainly because they are capable of combining directly with vegetable-tanned leather without the use of a mordant. Basic dyes show virtually no migration in acrylic fibers under normal dyeing conditions, compatibility is of major importance in selecting dye combinations with optimum level dyeing behavior.

Basic dyes possess cationic functional groups such as -NR3+ or =NR2+. The name 'basic dye' refers to when these dyes were still used to dye wool in an alkaline bath. Protein in basic conditions develops a negative charge as the -COOH groups are deprotonated to give -COO-. In an electric field the chromophore ion travels to the cathode or negative pole; it is positively charged. Generally forms salts with negatively charged (acidic) substances in tissue (chromatin, ergastoplasm, cartilage matrix, some granules). Affinity for such dyes, is called basophilia. Basic dyes perform poorly on natural fibres, but work very well on acrylics.

The most common anionic group attached to acrylic polymers is the sulphonate group, -SO3-, closely followed by the carboxylate group, -CO2-. These are either introduced as a result of co-polymerisation, or as the residues of anionic polymerisation inhibitors. It is this anionic property which makes acrylics suitable for dyeing with cationic dyes, since there will be a strong ionic interaction between dye and polymer (in effect, the opposite of the acid dye-protein fibre interaction).

  • Significance of basic dyes

  • High Tinctorial strength
  • Moderate substantivity
  • Relatively economical
  • Wide shade range
  • Includes some of the most brilliant synthetic dyes
  • Shows good brightness
AND
    • Poor shade stability
    • High acid content
    • Coloured backwaters
    • Very poor lightfastness
    • Preferential dyeing
Uses of basic dyes
Basic dyes have an extensive use for dyeing of cut flowers, dried flowers, dyeing of jute, coir etc. But perhaps now theoptimum use lies in the dyeing of acrylic fibre. For dyeing this range, a new range of 'modified' basic dyes were developed. It became perfectly suitable for dyeing of this material. If the reason behind the success of Basic dyes is analysed, it would be seen that the positively charged cations of the Basic dyes gets attracted towards the negatively charged anions in the acrylic fibre. Acylic polymers have anionic groups attached to it.
They are most commonly the sulphonate group, -SO3-, followed closed by the carboxylate group, -CO2-. This reaction of the cation and anion results in salt linkages. Basic dye do not show absolutely any migration in acrylic fibers under normal dyeing conditions. Other popular applications include dyeing leather. They are preferred in leather dyeing as they can get combined easily with vegetable-tanned leather thus doing away with mordant. Basic dyes also find its use in colouration of papers.