Alizarin yellow R is an azo dye that changes color from yellow to red between pH 10.2 and 12.2.

(a) Outline a synthesis of alizarin yellow R from aniline, salicylic acid (o-hydroxybenzoic acid), and any other reagents.
(b) Draw the structure of alizarin yellow R as it exists in its yellow form at pH = 9. Note that the conju-gate acid of a diazo group has a plc near 5.
(c) Draw the structure of alizarin yellow R as it exists at pH > 12. Why does it change color?

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CO,H O2N N-N он alizarin yellow R