CIE A Level Chemistry复习笔记7.6.6 Azo Compounds
Azo Compounds
- Azo (or diazonium) compounds are organic compounds that have an R1-N=N-R2 group
- They are often used as dyes and are formed in a coupling reaction between the diazonium ion and an alkaline solution of phenol
Azo compounds are characterized by the presence of an R1-N=N-R2 group
Coupling of benzenediazonium chloride with phenol in NaOH
- Azo compounds can be formed from the coupling reaction of a benzenediazonium chloride salt with alkaline phenol
- Making an azo dye is a multi-step process
Formation of azo compounds table
Reaction mechanism of the formation of azo compounds
- The delocalised electrons in the π bonding systems of the two benzene rings are extended through the -N=N- which acts as a bridge between the two rings
- As a result of the delocalisation of electrons throughout the compound, azo compounds are very stable
Making other azo dyes
- Other dyes can be formed via a similar route as described above
- For example, the yellow dye can be formed from the coupling reaction between benzenediazonium chloride and C6H5N(CH3)2instead of phenol (C6H5OH)
The yellow azo dye is formed via a coupling reaction between benzenediazonium chloride and C6H5N(CH3)2
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