Figure 2 Caffeine is an amine; therefore, it has a basic nitrogen that will react with a proton source such as hydrochloric acid. The compounds will be extracted on the basis of the solubility properties of the acids, bases, and their salts. That is true even if there is a carbonyl or a benzene somewhere else in the molecule. In that case, skip steps 3-4. In the event that any reagent used in this investigation comes in contact with your skin or eyes, wash the affected area immediately with lots of water. It was then weighed at 0.
. MacKenzie, Experimental Organic Chemistry, Prentice-Hall. Do you remember which functional group that would be? If the error were to happen the other way around and some of the dichloromethane layer was picked up with the aqueous extracts, which means less naphthalene would have resulted than expected. The weight of the solid residue in the reaction tube will be determined and the tube will be stoppered. If a neutral compound was present in your unknown, it will remain in the organic layer throughout the extraction procedure.
It then becomes more water-soluble. Later you will isolate any compound that was extracted by the bicarbonate. For example, a mixture of neutral compound and a carboxylic acid can be separated using bicarbonate ion since only carboxylic acid will be ionized by the bicarbonate ion. The contents in the second tube were then transferred back into the original tube using the pipet. The dichloromethane solution will then be dried by adding about 0. Use it to guide you through your spectral analysis of the isolated carboxylic acid, isolated amine, and isolated unfunctionalized compound. This process was repeated a second time by adding an additional 1.
There is a neutral one which doesn't react with any acids or bases. Quite often, the components develop some pressure on being shaken. The lower layer of the mixture, the dichloromethane layer, was then transferred using the pipet into a clean centrifuge tube. The products, a carboxylic acid and a phenol, are insoluble in aqueous solutions and precipitate from solution. Lastly, I know it was hard to get all of the naphthalene out of tube to weigh it, so the weight of naphthalene recovered is low. All of the possible compounds are soluble in ethyl acetate.
© 2009—2019 Adam Cap riola. We are using ethyl acetate in this lab, so avoid excessive exposure. Caution: When shaken, the mixture may develop pressure; be sure to vent it periodically. Drying refers to the removal of water. The acid will precipitate from the solution, as shown here. For example, a reaction is carried out in aqueous solution and the desired product is an organic compound. Suppose you have a mixture of two compounds.
The solid formed by these steps will be separately filtered via vacuum filtration using a 25 mL filter flask. Note that in both cases, the reactions favor the formation of products. The benzoic acid and ethyl 4-aminobenzoate solutions were neutralized, then the prepitate was dried using a Buchner funnel vacuum apparatus. The mixture will be mixed by capping the tube and shaking it by hand to thoroughly mix the two phases. At the end of this sequence you will have extracted the organic solution with three 10 mL portions of 10% aqueous sodium bicarbonate.
The basic compound would become ionic, and more water-soluble. However, if we were to extract with hydroxide ion, both the carboxylic acid and the phenol would be converted into their conjugate bases see figure2. Evaporation of the ether gives the pure, neutral compound. The basic aqueous solution containing the carboxylate salt is acidified, causing the sodium carboxylate salt to convert back to the carboxylic acid, which is not water soluble. During the decanting of dichloromethane, some of the liquid may not have made it would of the tube. The general flowchart of the separation is shown below. The reaction of a phenol, however, favors the reactants since the pKa of phenol 10 is larger than that of the carbonic acid 6.
By this experiment the rate at which benzoic acid was being transferred from the kerosene to the aqueous phase was calculated. The p Ka value of the acids gives a measure of the acidity of each compound. Without this number, we cannot grade your report. Clark, Organic chemistry Laboratory- Standard and Microscale Experiments, Saunders College Publishing. If we want the original compound in a pure form, we need to take that proton away. This will also take place in an ice bath.