EXP. 8: SUPPLEMENTARY LAB QUESTIONS 1. The reagent used to couple with the diazo

Question

EXP. 8: SUPPLEMENTARY LAB QUESTIONS 1. The reagent used to couple with the diazonium salt is often a derivative of aniline or pheno: Explain why Reaction of 7-amino-2-naphthol with benzenediazonium ion at pH 9 results in s ortho to the hydroxyl group. At pH 5 the substitution occurs ortho to the amino Explain how the pH determines the ring in which substitution occurs. 2. H2N 7-amino-2-naphthol 3. What two starting compounds would be used to prepare Orange I1? NaO,S Below pH 10.0, Orange Il exists as an orange solution. As the pH is raised past 10.0, the solution turns violet. Explain; in your answer, refer to structural changes in the dye at these different pH values. 4. In the synthesis of the azo dye Methyl Orange, immediately after the coupling reaction a proton is transferred from the dimethylamino group to the azo linkage. Why does this occur? 5. Why did we set the UV-VIS parameters to include the region up to 700 nm? (the default for UV spectroscopy is 200-500 nm)

Explanation / Answer

there are five questions.....I am solving only first question !

PLease post remaining questions separately . I will be happy to help ...

1) For coupling Reaction with Diazonium, We need a strongly activated or strongly electron rich rings like phenol or aniline, because the Electrophile Diazonium is a weak electrophile.

So coupling or the electrophilic reaction needs electron rich rings for effective reaction

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