Everything You Need to Know About Nitro and Nitroso Dyes: From Synthesis to Application
Introduction
Nitro and nitroso dyes are a class of organic compounds that contain one or more nitro (NO2) or nitroso (NO) groups attached to an aromatic ring. These groups act as chromophores, which means they absorb light at certain wavelengths and reflect others, producing different colors. Nitro and nitroso dyes have been used for various purposes since the 19th century, such as dyeing textiles, paper, leather, wood, cosmetics, food, and pharmaceuticals. They also have some biological activities, such as antibacterial, antifungal, antiviral, or anticancer properties. However, they also have some drawbacks, such as toxicity, environmental pollution, poor lightfastness, or limited color range.
Nitro And Nitroso Dyes Pdf Free
In this article, we will explore the structure and color, history, uses, types, properties, synthesis, formulation, and biological activities of nitro and nitroso dyes. We will also discuss some of the advantages and disadvantages of these dyes and provide some suggestions for further research or application.
Structure and color of nitro and nitroso dyes
Nitro and nitroso dyes exhibit benzenoid-quinonoid tautomerism (1.25), which means they can exist in two different forms: a benzenoid form with a double bond between two carbon atoms in the ring, or a quinonoid form with a double bond between a carbon atom and an oxygen atom in the ring. The quinonoid form is more stable and more colorful than the benzenoid form because it has more conjugated double bonds that can delocalize electrons. The color of nitro and nitroso dyes depends on the number and position of the NO2 or NO groups on the ring, as well as the presence of other substituents that can affect the electron distribution. Generally, more NO2 or NO groups produce darker colors, while ortho (adjacent) positions produce brighter colors than meta (separated by one carbon) or para (opposite) positions.
Nitro and nitroso dyes can also form chelate complexes with metals, which means they can bind to metal ions through two or more coordination sites. This can enhance the color intensity and stability of the dye by increasing the conjugation length and preventing oxidation or reduction reactions. 71b2f0854b