Describe how one would obtain the stated pure product from the following mixtures and assume that this cannot be achieved simply by distillation of the original mixture:
1. benzoic acid from a mixture with ammonium benzoate
2. phenylamine from a mixture with nitrobenzene, HCl and tin (IV) chloride.
1. To obtain pure benzoic acid from a mixture with ammonium benzoate, you can follow these steps:
a) Start by adding water to the mixture to dissolve the ammonium benzoate. Since benzoic acid is insoluble in water, it will remain as a solid or precipitate.
b) Filtration can be used to separate the solid benzoic acid from the aqueous solution of ammonium benzoate. Pour the mixture into a filter paper or funnel, and collect the filtrate (the liquid passing through) in a separate container.
c) The collected solid on the filter paper is the benzoic acid. Rinse it with some cold water to remove any impurities.
d) After rinsing, transfer the benzoic acid onto a watch glass or any suitable dish, and allow it to dry completely. This can be achieved by leaving it in a well-ventilated area or using a gentle heat source, such as a desiccator.
e) Once the benzoic acid is dry, it should be in its pure form and can be scraped or collected using a spatula. Store it in a dry, airtight container to prevent any moisture absorption.
2. To obtain pure phenylamine (also known as aniline) from a mixture with nitrobenzene, HCl, and tin (IV) chloride, the following steps can be undertaken:
a) Start by reducing the nitrobenzene to phenylamine. This reduction can be achieved by adding a reducing agent like tin (IV) chloride and hydrochloric acid (HCl) to the mixture. The tin (IV) chloride acts as a catalyst in this reaction.
b) The mixture needs to be heated under suitable conditions and for a specific duration. Typically, refluxing is used, which involves heating the mixture to its boiling point and allowing the vapors to condense and return back to the reaction flask.
c) After the reduction has taken place, the resulting mixture will contain phenylamine along with other reaction byproducts and residues.
d) To isolate phenylamine, you can perform a liquid-liquid extraction. This involves using a suitable organic solvent, such as ethyl acetate or diethyl ether, which is immiscible with water. Add the organic solvent to the mixture and shake or stir vigorously.
e) The organic solvent will selectively extract phenylamine from the mixture, while leaving behind the impurities and remaining reactants. Allow the layers to separate, and carefully drain or pipette the organic layer containing phenylamine into a separate container.
f) The extracted organic layer can then be dried using anhydrous sodium sulfate or a similar drying agent. After the drying agent settles, filter the solution to remove any remaining solid particles.
g) The filtered solution can be concentrated, typically by evaporating the solvent under reduced pressure or using a rotary evaporator. This step will leave behind pure phenylamine as a solid or concentrated solution.
h) To obtain phenylamine in its solid form, you can allow the concentrated solution to cool or induce crystallization by adding a small amount of a suitable solvent in which phenylamine is less soluble (e.g., hexane or petroleum ether).
i) After the phenylamine crystals have formed or precipitated, they can be collected by filtration, washed with a cold solvent, and dried to remove any residual solvent. The resulting solid should be pure phenylamine and can be stored in a sealed container.