Recrystallization Essay

Different procedures were used to isolate benzil from the ether layer and benzoic acid from the aqueous layers. To isolate benzil, anhydrous MgSO4 was added to the flask containing the ether layer solution. MgSO4 removes the remaining water in the ether layer solution. After making sure that enough amount of MgSO4 present in the solution, the ether solution was filtered by using gravity filtration. During filtration, MgSO4 was removed from the solution and the ether solution was collected in 25 ml flask. To separate benzil from the filtered ether solution, the beaker containing the ether solution was heated until the ether evaporated. After letting the beaker to cool to room temperature, the mass of the beaker with the benzil crystals was measured. From the combined mass of the beaker and the benzil crystals and from the predetermined mass of the beaker, the mass of the collected crystals was calculated to be 0.266 gram.

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

7. Plan: Each student in a group of three will work to purify the product of the reaction with cis-stilbene, trans-stilbene, or styrene. The crude products will be purified through recrystallization. This purification process will be performed several times. When the recrystallization is complete, a vacuum filtration will be executed to filter out the crystals. An NMR spectrum will be taken of the recrystallized product.

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.

Hickey) Organic chemistry lab 2 manual, department of Chemistry University of New Orleans. We observed a yellow residue in the bottom of the flask after the dichloromethane has been boiled off, and 2-propanol (3ml) was added to it and then was heated until the entire residue dissolved and the solution was transferred to a clean Erlenmeyer flask.

After 20 mL of methanol, 2.91 g of 2-naphthol, 1.71 g KOH, and a few boiling chips were combined in a small round-bottom flask and allowed to react, 1.8 mL iodoethane was added. The mixture was boiled for two hours with a reflux condenser; after adding 50 mL of cold water, the flask was sealed with a plastic stopper and parafilm and stored in a freezer for several days.

• Filtration (Separation of solids, or other unwanted material, from fluids.) • Recrystallization (Technique used to purify chemicals.) Reaction scheme / Chemical structure: Physical Data Table: Chemical Name Molecular Weight (g/mol)

The goal of the lab was to separate a neutral compound and an acid from an unknown mixture. The DCM (Dichloromethane) was added to create the organic layer. Both the neutral compound and acid were insoluble in water so aqueous NaOH was added. The acid would be deprotonated into an ion, which is soluble in water. Using the separatory funnel, the organic layer was separated from the aqueous layer. HCl was added so that the ion would protonate back into the acid and precipitate out of solution. Vacuum filtration via Buchner funnel was used to separate the acid (crystals) from the salt, NaCl. Na2SO4 was the drying agent used to remove any residual water from the organic layer. Gravity filtration helped separate the drying agent from the organic layer containing the neutral compound. The organic layer (DCM solvent) was boiled in order to separate the solvent from the neutral compound, which was in the form of crystals. Ethanol was heated up and added to the crystals of the neutral molecule which allowed the removal of impurities. The solution was placed in a hot water bath and the crystals of the neutral molecule precipitated out. The cool temperature helped crystallize the neutral compound into crystals. Finally, the neutral compound crystals were separated via vacuum filtration using a Buchner funnel. The acid and neutral compound and massed via an analytical balance so that the percent recovery can be calculated. Melting point (Mel-temp) was used to determine the

The product attained was a white, dry solid. The small amount of product lost during the second recrystallization was most likely do to impurities, which were filtered away with the methanol. Impurities that contributed to the low percent yield could be due to side reactions such as methyl o-nitrobenzoate and methyl p-nitrobenzoate. Although the percent yield attained was low, the product attained was fairly pure due to similarity in melting point and IR spectrum compared to standardly accepted values for methyl m-nitrobenzoate.

When cooling the acetanilide solution pure acetanilide crystals are formed. During the vacuum filtration, the acetanilide crystals that were caught in the funnel are washed by ice cold deionized water. Recrystallization is used as a purification method because impurities would not solidify with the crystal and can be easily washed away in the vacuum filtration once the crystal is

Methods used to separate miscible solvents include thin layer chromatography (TLC) as well as column chromatography. A method used to separate a mixture of miscible solvents is column chromatography, which is used to purify and separate compounds. The particular speed of the solvents used in the experiment depended upon the properties, being polar or nonpolar, as well as the properties of the prepared column (INSERT SOURCE HERE). With column chromatography, there are two phases that include mobile and stationary phases. In the experiment performed, the glass column used was first packed with a piece of cotton followed by a layer of sand in order to keep the silica gel in place and also to prevent the gel from flowing out of the tube when the particular solvent was added. Based upon whether the

The crude cinnamic acid was dissolved then recrystallized. The goal for recrystallizing crude cinnamic acid was to purify the acid and filter out any impurities. Recrystallization is one method used to purify a compound. Using a hot solvent, the compound is dissolved. It is then cooled to produce pure crystals. “As the crystal develops, impurities are excluded from the crystal lattice, thereby completing the purification process.”1 The key to recrystallization is the solvent used. “The solute must be relatively insoluble in the solvent at room temperature but much more soluble in the solvent at a higher temperature. At the same time, impurities that are present must either be soluble in the solvent at room temperature or insoluble in the solvent at a high temperature.”2 The solvent must be able to dissolve the product and the impurities for recrystallization to take place. Once dissolved, the solution cools first to room temperature before placing it in an ice bath, for “gradual cooling is conducive to the formation of large, well-defined crystals.”2 Once cooled, the solution is placed into the ice bath to further the recrystallization of the compound. The crystals are then

If the solute melts prior to the boiling of the solvent, recrystallization will not be able to occur. For example, if you wanted to purify a sample of Compound X which is contaminated by a small amount of Compound Y, an appropriate solvent would be one in which all of Compound Y dissolved at room temperature because the impurities will stay in solution and pass through filter paper, leaving only pure crystals behind. Also appropriate would be a solvent in which the impurities are insoluble at a high temperature because they will remain solid in the boiling solvent and can then be filtered out. Finally, the solvent should be volatile enough as to evaporate from the surface of the compound and be of low financial cost.

Recrystallisation is a process used to purify impure substances which are present in a solvent. The process uses the principle that most solids become more soluble in solvents, as the temperature is increased. Therefore, as the temperature is raised, the amount of solute which can be dissolved in a solvent increase. Recrystallisation is also known by fractional crystallization. To help predict the outcome of a recrystallisation process a solubility curve can be used, as shown below.