Basic Dyes

Basic dyes are water-soluble cationic dyes that are mainly applied to acrylic fibers, but find some use for wool and silk. Usually acetic acid is added to the dyebath to help the uptake of the dye onto the fiber. Basic dyes are also used in the coloration of paper. These are very bright dyes and are most commonly synthetic.

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.

These 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 fuchsia safranin, etc. An example of a basic dye that has amino groups as their auxochrome is pararosanilin or basic red 9 and example of alkylamino groups is methylene blue or basic blue 9.

Basic Dyes for Inks

Basic Dyes for Paper

Basic Dyes for Agrochemicals

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

Basic chemical structure of Basic Blue 9:

• Moderate substantivity
• High Tinctorial strength
• Relatively economical
• Includes some of the most brilliant synthetic dyes
• Shows good brightness
• Wide shade range

• High acid content
• Poor shade stability
• Colored backwaters
• Very poor light fastness
• Preferential dyeing

The new improvised dyes, based on the similar chemistry of basic dyes, shows a bit longer molecular structures than the typical conventional basic dyes, and result in significantly improved properties. Key advantages over conventional basic dyes:-

• Better Lightfastness
• Covers all fibres
• Clear backwaters
• Excellent substantivity

• Dyeing of cut flowers, dried flowers, dyeing of jute, coir etc.
• Dyeing of acrylic fibre
• Dyeing of leather.
• Coloration of papers

Note : For dyeing acrylic fibre, 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.