Important information about 4 questions (L5)
1. What is the main structural feature of the azo dyes that causes them to be colored compounds?

2. Methyl Orange is an acid-base indicator. In dilute solution at pH greater than 4.4, it is yellow. At pH = 3.2 the solution appears red. Draw a structure of the species that is formed at the lower pH of the acid proton adds to the azo nitrogen atom adjacent to the aromatic ring containing the -SO3 group. Why does the proton add to this particular nitrogen when two other nitrogen atoms are available in the molecule?

3. In the formation of diacetylferrocene, the product is always the one in which each ring is monoacetylated. Why is no diacetylferrocene produced in which both acetyl groups are on the same aromatic ring?

4. Ferrocene cannot be nitrated using the conventional HNO3-HzSO4 mixed acid conditions, even though nitration is an electrophilic aromatic
substitution reaction. Explain.