From an Orgo Chem II Lab on Diazonium Salts (Properties of Amines): Chemicals us

Question

From an Orgo Chem II Lab on Diazonium Salts (Properties of Amines):

Chemicals used:

4-nitroaniline

6M HCL

12M (concentrated) HCL

NaNO3

2-napthol

10% sodium hydroixe

potassium

ice

Lab Questions:

1) You may have noticed that a lot of organic substances are white or pale yellow and just plain bland when it comes to their color. What is it about the structure of para red that gives rise to it having such a strong color?

2) Describe the general overall shape of para red.

3) In the reaction between potassium iodide and your diazonium salt, which substance acted as the nucleophile?

4) It sure doesn’t look like p-nitroaniline is water soluble. Explain how it was able to dissolve in the HCl solution. Be as specific as possible. You may include a reaction, but you still need to explain using your words.

5) It sure doesn’t look like 2-naphthol is water soluble. Explain how it was able to dissolve in the NaOH solution. Be as specific as possible. You may include a reaction, but you still need to explain using your words.

6) What was the purpose of adding concentrated hydrochloric acid during the last step of the procedure? Try to be as specific as possible.

Thank you in advance!!!

Explanation / Answer

1)The colur of any organic compounds depend upon its absorption pattern which inturn depends on the energy diffrence between HUMO and LUMO gap.if the energy required to bring transition lies in between visible region , the compond appears coloured.Further conjugation lowers energy diffrence and hence makes compound coloured.Besides, colour is intensified by the presence of Auxochromes like NO2 and -OH group.

3)Iodide ion acts as a nucleophile.

4) p-NITRO ANNILNE is not water soluble as such. However, if HCl is added to it ,it forms salt (p-nitro anniliuim hydrochloride) which makes it water soluble( Acid base chemistry).

5) BETA NAPTHOL being acidIc in nature readily forms salt with base (NaOH),makes it water soluble.

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