Chapter 20: Q5P. (page 1049)

Question: Phenols are less acidic than carboxylic acids, with values of around 10. Phenols are deprotonated by (and therefore soluble in) solutions of sodium hydroxide but not by solutions of sodium bicarbonate. Explain how you would use extractions to isolate the three pure compounds from a mixture of p-cresol (p-methylphenol), cyclohexanone, and benzoic acid.

Short Answer

Expert verified

Answer

The extractions to isolate the three pure compounds from a mixture of p-cresol (p-methylphenol), cyclohexanone, and benzoic acid is shown as follows:

Step by step solution

Extractions

Extraction separates a mixture of compounds and forms a pure compound. Common types of extractions are liquid-liquid extraction and solid-phase extraction.A target compound is isolated by using the extraction method.

Extractions to isolate the three pure compounds

A mixture of p-cresol (p-methylphenol), cyclohexanone, and benzoic acid is shaken with ether and aqueous sodium bicarbonate for extraction. A mixture of p-cresol (p-methylphenol) and cyclohexanone is formed with ether and $C_{6} H_{5} C O O N a$ is formed with a sodium bicarbonate solution. This $C_{6} H_{5} C O O^{-} N a^{+}$ on adding HCl and extracting forms a pure benzoic acid compound.

After that, a mixture of p-cresol (p-methylphenol) and cyclohexanone is shaken with aq. NaOH and by treating with ether, cyclohexanone is produced. Next, by evaporation, a pure cyclohexanone compound is formed. A mixture of p-cresol (p-methylphenol) and cyclohexanone is shaken with aq. NaOH and again treated with aq. NaOH, forming $C H_{3} C_{6} H_{5} C O^{-} N a^{+}$ . Further, adding HCl and filtering produces a pure p-cresol compound.