Reflux
The reflux procedure is ‘the process of boiling reactants while continuously cooling the vapour and returning it back to the flask as a liquid’ (chem.wisc.edu, 2014). The reactants are needed to be heated for a long period of time with the sulfuric acid, which acts as a catalyst to speed the reaction up, in order for the reactants to react and be converted into the products, which in this case is the ester. However the reactants are very volatile which means that it is easily evaporates and won’t produce the products. Reflux is then needed and used to cool any of the reactant and product vapour evaporating to be heated by reflux once again.
Separation/Purification
There are a few different steps into separating and purifying the ester from the mixture.
At the end of reflux, both the reactants and products are present in the pear-shaped flask. This is because the acid used was very weak and did not fully react with the alcohol therefore once the mixture has reached a chemical equilibrium, the concentration will remain the same. This means that not all the reactants are going to be converted into products. Washing the mixture with 20mL of distilled water allowed the separation between the aqueous layer (water-soluble substances) and the organic layer (ester) in the separating funnel. Therefore washing the mixture with distilled water is needed to separate the aqueous layer, which is discarded, with the ester.
There will still be a small amount of acid which wasn’t
The objective of this extraction experiment was to achieve a comprehensive understanding, as well as master the practice, of the technique of separating various individual components of a compound.
The crude product was washed by taking the reaction product in the separatory funnel and adding 23 mL of deionized H2O. The mixture was shaken and allowed to settle until layers were observable. The top layer was the desired product and approximately 25 mL of aqueous layer was extracted from the separatory funnel. Next, 25 mL of 5% NaHCO3 was added to the separatory funnel in order to neutralize the acid. This mixture was swirled, plugged with the stopper and inverted. Built-up gas was released by turning the stopcock to its opened and closed positions, releasing CO2 by-product. This was done four times in one minute intervals. The solution was allowed to settle until layers were observable. The bottom layer that contained salt, base and water was extracted from the separatory funnel. The crude product was washed again as mentioned previously.
It was observed that the solution turned a strong purple tint as the reflux continued, turning extremely dark at certain points. At the end of the 15 minutes, the reflux was stopped and the round bottom flask was allowed to cool to room temperature. Afterwards, the flask was placed in an ice bath in order to allow a precipitate to form, and it was observed that an extremely slight precipitate formed at the bottom of the flask. The mixture was then poured into a Buchner funnel attached to a Buchner flask in order to perform a vacuum filtration. The collected precipitate was further washed with 10 mL of cold DI water and 10 mL of cold ethanol.
alcohol (2-methyl-2-butanol, MW _ 88.2, d _ 0.805 g/mL) and 25 mL of concentrated hydrochloric acid (d _ 1.18 g/mL). Do not stopper the funnel. Gently swirl the mixture in the separatory funnel for about 1 minute. After this period of swirling, stopper the separatory funnel and carefully invert it. Without shaking the separatory funnel, immediately open
As the acid was being added, the mixture was being stirred over a stir plate. Once completed, the reaction mixture was poured from the round bottom flask into a 500 mL separatory funnel and its top (organic) layer was extracted into another beaker. The bottom (aqueous) layer was placed back into the funnel and extracted twice with 50.0 mL of ethyl ether each. The newly extracted layers were combined and dried over magnesium sulfate (MgSO4). The dried solution was the decanted into a beaker to remove the MgSO4 salts and the product solution was collected via Buchner vacuum filtration. The resulting product was transferred into an Erlenmeyer flask with an inverted beaker on top and stored in a drawer.
After the mixture finished refluxing, the flask was then cooled on ice. A sulfuric acid solution was then prepared by pouring 4.5 mL of concentrated H2SO4 over 50 grams of ice and then diluted to 75 mL by adding enough tap water to reach 75 mL. The sulfuric acid solution was then cooled on ice.
There are various techniques to separate a mixture of compounds from each other. One of the commonly used way to isolate compounds from a mixture of two compounds is called extraction. This method of extracting two compounds from each other relies on the different solubility of the compounds in two different solvents.
Me and my lab partner, obtained a mixture of a un known proportion from the instructor and then flow the guide line in our lab manual to separate the mixture by applying the separation method motioned in our lab manual pages 33-40 . In this experiment, the separation methods were decantation,
Techniques and equipment used throughout the experiment include a reflux apparatus, separatory funnel for isolation, vacuum filtration, and simple distillation. The reflux condenser is used to allow thorough distillation of the product with the use of heat to accelerate and stir while vapors
A 0.5 g of sodium tungstate dihydrate was weighed and transferred into a 50-mL round-bottom flask with a magnetic stir bar. Approximately 0.6mL of Aliquat 336 was then transferred carefully into the round bottom flask using a 1mL syringe. The round bottom flask and its contents were then set up in an oil bath. 11mL of 30% hydrogen peroxide and 0.37 g of potassium bisulphate were added to the reaction mixture in the round bottom flask and stirred using a magnetic stirrer. Lastly, 2.5mL of cyclohexene was added using automatic dispenser and the mixture stirred. A condenser was fitted on the round bottom flask, clamped and attached to water horses. The reaction mixture was then heated on the oil bath and the reflux process initiated for an hour while stirring the mixture vigorously. Half way while rinsing, any trapped cyclohexene in the condenser was rinsed. After 1 hour, the round bottom flask was rinsed
14 mL of 9 M H2SO4 was added to the separatory funnel and the mixture was shaken. The layers were given a small amount of time to separate. The remaining n-butyl alcohol was extracted by the H2SO4 solution therefore, there was only one organic top layer. The lower aqueous layer was drained and discarded. 14 mL of H2O was added to the separatory funnel. A stopper was placed on the separatory funnel and it was shaken while being vented occasionally. The layers separated and the lower layer which contained the n-butyl bromide was drained into a smaller beaker. The aqueous layer was then discarded after ensuring that the correct layer had been saved by completing the "water drop test" (adding a drop of water to the drained liquid and if the water dissolves, it confirms that it is an aqueous layer). The alkyl halide was then returned to the separatory funnel. 14 mL of saturated aqeous sodium bicarbonate was added a little at a time while the separatory funnel was being swirled. A stopper was placed on the funnel and it was shaken for 1 minute while being vented frequently to relieve any pressure that was being produced. The lower alkyl halide layer was drained into a dry Erlenmeyer flask and 1.0 g of anhydrous calcium chloride was added to dry the solution. A stopper was placed on the Erlenmeyer flask and the contents were swirled until the liquid was clear. For the distillation
a. O3: The O has an oxidation number of 0, because the oxidation number of an element is always 0 regardless of its subscript.
When the heat was added to the flask the residue dissolved and the reactant mixture was clear.
In this part of experiment, alcohol(2ml) and CH3COOH(1ml) will react to produce an ester, the ester's odor can then be compared with that of the ester bank to determine the identity of the ester. This is done by mixing the reagents in the solution with a glass stirring rod and then to further dissolve the solution, it
The compounds are separated by collecting aliquots of the column effluent as a function of time.