Essay Acid Base Extraction

This experiment combined all the knowledge of the previous labs performed throughout the semester. An unknown mixture containing an organic acid or base and an organic neutral compound in nearly equal amounts needs to be separated to its separate components. An understanding of solubility, extraction, crystallization and vacuum filtration is necessary in order to

In the first acid extraction of benzocaine, the compound was dissolved in the organic solvent of dichloromethane. When the mixture was shaken with HCl, benzocaine’s amine group gained a proton and became more soluble in water than dichloromethane. This allowed the newly formed hydrochloric salt to migrate to the aqueous layer. However, the addition of NaOH to the acidic aqueous layer regenerated benzocaine by deprotonation, making it insoluble in the aqueous layer. The precipitation of an ionic salt was therefore recovered by vacuum filtration and had a tested melting point range of 85.1C-87.4C compared to 88C-90C, the literature melting point of benzocaine. The similarity in melting point ranges, but low percent yield of 30.37% proves that the extract was somewhat successful. Lower yields may be the result of spillage performed in the lab. In the second basic extraction, the organic layer now included benzoic acid and benzamide. When treated with NaOH to deprotonate benzoic acid, the newly formed sodium benzoate transitioned to the aqueous layer as a sodium salt. Benzoic acid is regenerated once again after the addition of HCl and became insoluble in the aqueous layer after protonation. Its precipitation was then filtered out for a 65.87% recovery. Compared to its literature melting point of 122.41C, the resulting 120.9C-123.5C melting range of the sample also supports the accuracy of the separation due to its similarities and high percent yield. In conclusion, the usage of base and acid liquid extraction was mostly successful in this experiment because it was able to efficiently and properly isolate the impure mixture into two separate components of benzocaine and benzoic acid. By performing the techniques of extraction and vacuum filtration, the similarities between literature and tested

There are millions of different organic compounds. Most of them are found in mixtures and in order to achieve a pure form they need to be separated, isolated, and purified. However, there are endless numbers of possible mixtures, which make it impossible to have a pre-designed procedure for every mixture. So chemists often have to make their own procedures. The purpose of this experiment was to prepare the student to the real world by them designing their own procedure which will help them understand the techniques of separation and purification better. The goal was to extract two of the components of the

In order to isolate benzoic acid, benzocaine and 9-fluorenone, each component needed to be separated from one another. All three compounds began together in one culture tube, dissolved in methylene chloride and formed into a homogenous mixture. In this culture tube, two milliliters of aqueous three molar hydrochloric acid was added, which immediately formed two layers, the top acidic aqueous layer was clear in color and contained benzocaine, and the bottom organic formed was yellow and contained benzoic acid and 9-fluorenone. Benzocaine’s amino group is protonated by the aqueous layer hydronium. This protonation forms the conjugate acid of benzocaine, benzocaine hydrochloride. Thus, the conjugate acid, benzocaine hydrochloride is a salt in which is soluble in water and furthermore can be isolated from the organic mixture. When testing out the pH levels in benzocaine, the pH test strip was dark blue in color, indicating a pH level of around 5 to 7. When isolating benzoic acid, two milliliters of aqueous three molar sodium hydroxide was added, which deprotonates the carboxylic group in benzoic acid, forming its conjugate base, sodium benzoate. As with benzocaine hydrochloride, sodium benzoate is a water soluble ionic salt in the aqueous layer that can then be separated from the bottom organic layer containing the 9-fluorenone. The pH test strip was a vibrant red for benzoic acid, indicating a pH of 2. Now the 9-fluorenone is left, deionized water is added to remove any excess

lab bench. Place a beaker from the drawer on the stir plate. Drag the bottle of NH3 to the 5 mL graduated cylinder (the smallest one) by the sink and fill the cylinder by dropping the bottle on the cylinder. Now drag the 5 mL graduated cylinder to the beaker on the stir plate and add the 5 mL of

The problem that was trying to be solved in this study deals with analyzing unknown solutions. In this particular case, a chemical company has several unknown solutions and to correctly dispose of them they need to know their properties. To figure out the properties several qualitative tests were performed throughout the study (Cooper 2012).

After about 1 minute of shaking, the two layers separated. The organic layer on the top layer (consisted of ethyl acetate and naphthalene) collected for further experiment; by adding Sodium Sulfate into organic phase and filtering the Na2So4 from the solution using the wool. The dried organic layer was weighed to get its mass and the residue of Na2SO4 were rinsed with ethyl acetate under vacuum (rotary evaporator). The acid extract on the bottom layer which is a combination of benzoic acid and NaOH were collected in the 50 mL Erlenmeyer beaker for the recovery of acid.

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.

Upon the addition of water, it was noted that a layer separation occurred and the water layer remained on top, with the 2-methylphenol layer on the bottom layer. Then, conversion calculations were performed to determine the appropriate amount of 3M NaOH to be added to the 2-methylphenol solution. From the calculations, it was determined that 1.08 mL were to be added. 3M NaOH itself was a cloudy solution in appearance and upon the addition of 3M NaOH to the 2-methylphenol solution, it was noted a color change occurred and it became a yellow-green solution. Following this, the same calculations used previously, were used to determine the appropriate amount of sodium chloroacetate, which was found to be 0.38 g (3.26 mmol). Sodium choloroacetate was a white, crushed solid that was then combined with 1 mL of water and was swirled until the sodium chloroacetate completely dissolved. This sodium choloracetate solution was then transferred to the 2-methylphenol solution by the use of a medicine

In this experiment, 0.31 g (2.87 mmol) of 2-methylphenol was suspended in a 10 mL Erlenmeyer flask along with 1 mL of water and a stir bar. The flask was clamped onto a hotplate/stirrer and turned on so that the stir bar would turn freely. Based on the amount of 2-methylphenol, 0.957 mL (0.00287 mmol) NaOH was calculated and collected in a syringe. The NaOH was then added to the 2-methylphenol solution and allowed to mix completely. In another 10 mL Erlenmeyer flask, 0.34 g (2.92 mmol) of sodium chloroacetate was calculated based on the amount of 2-methylphenol and placed into the flask along with 1 mL of water. The sodium chloroacetate solution was mixed until dissolved. The sodium chloroacetate solution was poured into the 2-methylphenol and NaOH solution after it was fully dissolved using a microscale funnel.

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

Experiment 4A: Determination of a Partition Coefficient for Benzoic Acid in Methylene Chloride and Water, and Experiment 4B: Solvent Extraction I: Acid-Base Extraction Using the System Benzoic Acid, Methylene Chloride, and Sodium Bicarbonate Solution

Distillation is a method of separating two volatile chemicals on the basis of their differing boiling points. During this lab, students were given 30 mL of an unknown solution containing two colorless chemicals. Because the chemicals may have had a relatively close boiling point, we had to employ a fractional distillation over a simple distillation. By adding a fractionating column between the boiling flask and the condenser, we were able to separate the liquids more efficiently due to the fact that more volatile liquids tend to push towards the top of the fractionating column, thereby leaving the liquid with the lower boiling point towards the bottom. After obtaining the distillates, we utilized a gas chromatograph in order to analyze the volatile substances in the gas phase and determine their composition percentage of the initial solution. Overall, through this lab we were able to enhance our knowledge on the practical utilization of chemical theories, and thus also demonstrated technical fluency involving the equipment.

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.

In this experiment were used three separation techniques: extraction, sublimation and recrystallization. During the first method, 0.70 g sample of salicylic acid-naphthalene mixture was dissolved in 10 ml of diethyl ether. The solution was placed in a separatory funnel and 10 ml of saturated aqueous sodium bicarbonate solution was added to it. After the initial gas was