Extraction
In this lab, extraction was used to separate and purify a mixture of benzoic acid and benzocaine. For a successful extraction process to occur the liquids must obtain the following properties. The liquids being used must be insoluble when mixed together therefore forming layers, acquire different densities to allow separation, have different solubilities, and the liquids should not react with the compounds to allow isolation of the compounds. Dichloromethane and hydrochloric acid were used to extract benzocaine while benzoic acid was extracted with the use of dichloromethane and sodium hydroxide. In both cases, the dichloromethane will be the bottom layer in the funnel since it is chlorinated..
To start the lab, 2.035 grams of benzocaine and benzoic acid mixture was obtained and dissolved into forty milliliters of dichloromethane and put into the separatory funnel. Benzocaine was extracted first by adding six molar hydrochloric acid to the funnel, shaking the funnel until pressure no longer forms, and allowing the layers to separate after shaking. After shaking the funnel, a large white emulsion formed between the two layers and small amounts of water were added to get rid of this emulsion. Once the layers were distinctly separated, the dichloromethane and aqueous layers were drained into two separate flasks. The addition of hydrochloric acid binds an extra hydrogen to the amine group in benzocaine giving the nitrogen a positive charge. To get rid of the positive charge, six molar sodium hydroxide was added to get benzocaine and water. A possible error occured when adding the sodium hydroxide to the acidic solution. The addition of sodium hydroxide was suppose to make the solution basic yet the solution had a pH of one. The solution was then heated to get rid of the oil that had formed, cooled, put in an ice bath, and put through vacuum filtration in order to get the pure benzocaine crystals.
The dichloromethane layer that was previously extracted was put back into ...
