Three nitrogen containing molecules, ammonia, NH3, phenylamine, C6H5NH2 and N-methylethylamine, CH3CH2NHCH3, are drawn below respectively in Fig. 1.1.
Fig. 1.1
i) List the three amine molecules drawn in Fig. 1.1 in order of increasing base strength.
[1]
ii) Explain your answer to part (b) (i).
[6]
Phenylamine, C6H5NH2 shown in Fig. 1.1 in part (a) can be produced from nitrobenzene, C6H5NO2.
Name the type of reaction and suggest suitable reagents and conditions for this conversion.
Azo dyes are organic compounds, which are largely used in the treatment of textiles and leather products, as well as in food. Phenylamine, C6H5NH2, can be used in the manufacture of azo dyes.
The manufacturing process is outlined below.
Step 1
Phenylamine is dissolved in HCl to produce a diazonium salt. A diazonium salt contains two nitrogen atoms joined together by a triple bond. The reaction for this process is as follows:
C6H5NH2 + HCl + HNO2 → C6H5N2+Cl- + 2H2O
Step 2
This solution is then slowly added to an alkaline solution of a phenol coupling agent to form the dye.
i) The diazonium salt, C6H5N2+Cl-, is an unstable compound. Suggest a condition that could be added to ensure that the salt would not break down during the reaction.
[1]
ii) Draw the structure of the diazonium salt formed in Step 1, showing the displayed formula of the nitrogen containing group.
[1]
Phenol, C6H5OH, is an aromatic organic compound which is also crucial in the manufacture of azo dyes.
The final step of the azo dye production involves pairing up the diazonium salt with a phenol compound as a coupling agent.
Suggest a structure for the azo dye if the coupling agent used is 2,6-dimethylphenol.
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