Bøger af Sanjay S

Quinones are organic compounds that are formally derived from aromaticcompounds such as benzene or naphthalene. During the conversion, an evennumber of (CH) groups are oxidised into (C=O) groups and necessary doublebonds are rearranged to get fully conjugated cyclic dione structure1. Apart fromthis, organic molecules such as phenols and catechols having electron donatingsubstituents are easily oxidized to quinones. The electron donating substituentsincrease the nucleophilicity of the ring and contributes to the large redoxpotential needed to break the aromaticity (quinones are conjugated but notaromatic).Many natural and artificial colouring substances (dyes and pigments) are quinonederivatives. They are next to azo dyes in importance as dyestuffs with particularemphasis on blue colours. Alizarin {1,2-dihydroxy-9,10-anthraquinone} (8),extracted from the madder plant, was the first natural dye to be synthesized fromanthracene. This was used as the prominent red dye for dyeing textile fabrics.