For this week's lab, we have to devise our own separation and purification scheme. The mixture contains three compounds, however my problem lies in the fact that the composition isn't given to us. There are four possible combination 1)benzoic acid, benxoin, and 1,4-dibromobenzene
2) fluorene, o-toluic acid, 1,4-dibromobenzene
3) phenanthrene, methyl 4-aminobenzoate, 1,4-dibromobenzene
4) 4-aminoacetophenone, 1,2,4,5-tetrachlorobenzene, 1,4-dibromobenzene
I know that this will require me to remove one component by acid/base extraction because one holds a charge, the other two are neutral and can be separated by boiling point.
I just don't know how to write this procedure without knowing what I'm supposed to issolate. THe manual says the first step should be to dissolve .5g in methylene chloride and then diethyl ether to find which organic solvent is needed. Is this what tells me is in my compound.
ANY HELP AT ALL WOULD BE AMAZING, and the faster the better :) THANKS!
I don't think so. I assume you are to write a generic procedure that will work in ALL cases in which you have an acid and two neutral compounds.
Thank, but how am I supposed to write a procedure without knowing what im expected to react?
To devise a separation and purification scheme for the given mixture, you can follow these step-by-step instructions:
Step 1: Dissolve the mixture in methylene chloride:
- Start by taking a sample of the mixture weighing around 0.5g.
- Dissolve the sample in a suitable amount of methylene chloride (CH2Cl2) to form a solution.
Step 2: Testing solubility with diethyl ether:
- Transfer a small portion of the methylene chloride solution to a separate test tube.
- Add a small amount of diethyl ether (Et2O) to the test tube.
- Observe whether any of the compounds in the mixture dissolve in diethyl ether. Note the solubility observations.
Step 3: Perform acid/base extraction:
- Choose a compound from the list that you suspect to be acidic or basic.
- Add a suitable acid (e.g., hydrochloric acid) or base (e.g., sodium hydroxide) to the methylene chloride solution.
- Vigorously shake the mixture to allow for partitioning.
- Separate the methylene chloride layer from the aqueous layer. Note that the acidic or basic compound will be present in the aqueous layer while the other compounds will remain in the methylene chloride layer.
Step 4: Separate the organic layer:
- Transfer the methylene chloride layer to a clean container.
- Add anhydrous sodium sulfate (Na2SO4) to the container to remove any remaining water traces.
- Allow the mixture to stand for a few minutes, and then filter the solution to remove the sodium sulfate.
Step 5: Concentrate the organic layer:
- Transfer the filtered organic solution to a round-bottom flask.
- Place the flask on a rotary evaporator (or use other suitable methods) to evaporate the solvent (methylene chloride).
- Collect the residue left behind after the solvent evaporation.
Step 6: Purify the separate compounds:
- Based on your observations at each step, you can now determine which compounds are present in the mixture.
- You can perform techniques like column chromatography, recrystallization, or distillation to purify or separate the identified compounds further.
Remember to record your observations, especially regarding solubility and the separation of compounds at each step. These observations can help you in further analysis and identification of the compounds in the mixture.
To devise your own separation and purification scheme, you need to determine the identity of the compounds in the mixture. While the composition of the mixture is not given, you can use the information provided in the question to narrow down the possibilities.
The manual suggests dissolving the mixture in methylene chloride and then diethyl ether to determine which organic solvent is needed. This step can provide some information about the compounds present in the mixture.
Here's one approach you can take to devise your own separation and purification scheme:
1. Dissolve the mixture, approximately 0.5g, in methylene chloride. This step allows you to determine if any of the compounds are soluble in methylene chloride. Record your observations.
2. If all compounds are soluble in methylene chloride, it suggests that none of the compounds are acidic or basic. In this case, you may proceed with separating the compounds based on their boiling points. You can perform a simple distillation to separate the compounds.
3. If one compound is soluble in methylene chloride while the others are not, the soluble compound may be an acidic or basic compound. To further identify and separate the compound, perform an acid/base extraction using a suitable acid or base solution. This will allow you to selectively isolate the charged compound.
4. Once you have the charged compound separated, you can convert it back to its neutral form by adjusting the pH. Then, you can proceed to separate the remaining neutral compounds based on their boiling points using distillation.
Remember, the information provided in the question suggests that one component requires an acid/base extraction because it holds a charge, while the other two compounds are neutral and can be separated by boiling point.
To fully determine the compounds present in the mixture, you may need to perform additional tests like melting point determination or spectroscopic analysis. These tests can help you confirm the identity of each compound in the mixture.
Always refer to your lab manual or consult with your instructor to ensure you follow the specific instructions and safety guidelines for your experiment. Good luck with your lab!