Question

I have an unknown mixture of Benzoic acid, Dimethyl Terephthalate, and Naphthalene dissolved in Dichloromethane. I need to separate the mixture to find the composition using some sort of acid base reation and a distillation. How would I do that? I think that I could use steam distillation to remove the naphthalne but im not really sure on that. Any help would be apprectiated. I start with 25mL of the unknown mixture.

Answer 1

The compounds will be extracted on the basis of the solubility properties of the acids, bases, and their salts.

Hydrochloric acid should be added and extraction of dimethylterephthalate will be performed in two steps: mixing and separation. The extracted dimethylterephthalate can then be isolated by adding aqueous sodium hydroxide which will turn the solution basic which will cause the dimethylterephthalate to precipitate. The benzoic acid should be extracted by adding sodium hydroxide to the dichloromethane solution and using the process of separation. The benzoic acid will then be isolated using aqueous hydrochloric acid to turn the solution acidic which will make the benzoic acid precipitate. These two precipitates will be collected using vacuum filtration. The dimethylterephthalate will be recrystallized using boiling water, and will then be weighed and measured for its melting point. The benzoic acid will also be recrystallized using boiling water, and will then be weighed and measured for its melting point. Anhydrous sodium sulfate can be added to the left over dichloromethane solution. The mixture will react and then be filtered, and the solid residue of naphthalene will be weighed.