Aromatic Amines and Azo Compounds

This diazotisation reaction must be done at about 5 °C as the nitrous add made from the sodium nitrite and dilute hydrochloric acid decomposes easily above about 10 °C. 

Another coloured dye is Ponceau red (El24), which is used in colouring tinned fruit. 

Some compounds found in nature contain an amino group and a carboxylic acid group attached to the same carbon atom. Such compounds are called amino acids there are about 20 of them in Nature, and they are the building blocks of the proteins which are vital to you, not only as muscle builders but also as the enzymes which catalyse the reactions going on in every living cell. 

For any amino acid except the first one, glycine (where R = H), the amines have an assymetric carbon atom in their molecules. Two optical 

Three amino acids are shown joining together, but proteins join many hundreds together and there are twenty difterent variations for the R group. 

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