Question 18 (Textile Engineering & Fibre Science)
A textile dye should have in its structure atleast
| (A) | One azo and one reactive group |
| (B) | Two chromophores |
| (C) | One chromophores and one auxochrome |
| (D) | One solubilising and one reactive group |
[Show Answer]
C
Frequently Asked Questions | FAQs
What is the chromophore of a dye?
A chromophore is the part of a molecule that is responsible for its color. In the context of dyes, the chromophore is the part of the molecule that absorbs visible light and gives the dye its characteristic color. The chromophore typically contains one or more unsaturated carbon-carbon double bonds, which allow the molecule to absorb light in the visible spectrum.
The type and arrangement of the chromophore in a dye molecule determines the color of the dye. For example, dyes with a conjugated system of alternating double bonds, such as azo dyes, tend to absorb light in the blue and green parts of the visible spectrum and appear yellow, orange, or red. Dyes with a conjugated system of double bonds and heteroatoms, such as anthraquinone dyes, tend to absorb light in the green and blue parts of the spectrum and appear blue or green.
In addition to the chromophore, dyes often contain other functional groups, such as auxochromes, which help to enhance the color and stability of the dye. Auxochromes are functional groups that interact with the chromophore and modify its absorption spectrum. For example, hydroxyl and amino groups are common auxochromes in dyes, which can shift the absorption spectrum of the chromophore towards longer wavelengths and enhance the color of the dye.
What is auxochrome in dye?
In dye chemistry, an auxochrome is a functional group that is attached to a chromophore to modify the color and improve the properties of the dye. An auxochrome is a group of atoms that can either donate or withdraw electrons from the chromophore, which can affect the absorption spectrum and shift the wavelength of light that the dye absorbs.
Auxochromes can be divided into two main types: electron-donating and electron-withdrawing groups. Electron-donating groups, such as amino (-NH2), hydroxyl (-OH), and alkyl (-CH3), increase the electron density around the chromophore, which can shift the absorption spectrum of the dye towards longer wavelengths and enhance the color. Electron-withdrawing groups, such as nitro (-NO2), carbonyl (-C=O), and sulfonyl (-SO2), decrease the electron density around the chromophore, which can shift the absorption spectrum towards shorter wavelengths and produce a different color.
The choice of auxochrome can have a significant impact on the properties of the dye, including its color, solubility, and stability. By selecting the appropriate auxochrome, dye chemists can tailor the properties of the dye to suit specific applications, such as textile dyeing, printing, and coloring of plastics or paints.