Recrystallization

Experiment 55 consists of devising a separation and purification scheme for a three component mixture. The overall objective is to isolate in pure form two of the three compounds. This was done using extraction, solubility, crystallization and vacuum filtration. The experiment was carried out two times, both of which were successful.

After the process of recrystallization was completed, the melting points and weights were taken for each solid. Some melting points recorded for the solids were very close to the values listed in the literature. However, others differed by sizeable margins from the values listed in the literature. The range observed for the melting point of naphthalene was 78-81°C. This coincides with

In the experiment, we tested three different water temperatures, boiling water (212*F), room temperature water (68* F), and ice water (40* F), and tested the amount of time it took for the Alka-Seltzer tablet to dissolve. In the boiling water, the Alka-Seltzer tablet dissolved in twenty-four seconds, in the room temperature water, the tablet dissolved in fifty seconds, and in the ice water, the tablet dissolved in one hundred seconds.

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.

This experiment was designed by conducting a substitution reaction to construct a complex compound (2-methylphenoxyacetic acid) from two simple parts; also known as synthesis - converting simple molecules into more complex molecules. A purification technique known as crystallization was used to purify the product. Suction filtration was used to filter out the product. The experiment was completed over a three-day experimental period.

In a 25-mL round-bottom flask, 1-chlorobutane (5 mL, 4.32 g, 0.046 mol), sulfuryl chloride (1.6 mL, 2.7 g, 0.02 mol), 2,2’-azobis-(2-methylpropionitrile) (0.03 g), and a boiling chip were added. After a condenser and gas trap were attached to the flask, the mixture was heated to a gentle reflux in a steam bath for 20 min. The flask was then allowed to cool down quickly in an ice bath for a short time before a second portion of the 2,2’-azobis-(2-methylpropionitrile) (0.03 g) was added to the flask. The mixture was refluxed for another 10 min. before the flask was cooled in a beaker of water. The reaction mixture was then poured into a small separatory funnel already filled with water (10 mL),

Purpose: The purpose of this laboratory was to gain an understanding of the differences between the freezing points of pure solvent to that of a solvent in a solution with a nonvolatile solute, and to compare the two.

This experiment explored the multi-step synthesis of synthesis acetylsalicylic acid commonly known as aspirin. A common procedure used in organic chemistry labs is multi step synthesis. this procedure involves a cascade of reactions that ultimately lead to a desire product. The series of reactions begins with commonly found or readily available reagents which are synthesized into products which can be used for a secondary reaction, and so on and so forth until the final desired product is synthesized (Ryerson Department of Chemistry, 2017).

7 screw cap test tubes were labeled as 0µmol/L, 1.5µmol/L, 2.5µmol/L, 3.5µmol/L, 4.5µmol/L, 5.5µmol/L and 6.5µmol/L. Then, 0µL, 75µL, 125µL, 175µL, 225µL, 275µL and 325µL volume of 0.1mM MDA stock solution was orderly added into screw cap test tubes. 2.0mL of 1% TBA was added into screw cap test tubes. Distilled water was added into screw cap test tubes until total volume reached 5.0mL. They were mixed on whirl mixer. Then, they were wormed on a block heater at 100˚c for 30 minutes. After, they were allowed to cool in cold water for 5minutes. 7 centrifuged tubes were labeled as 0µmol/L, 1.5µmol/L, 2.5µmol/L, 3.5µmol/L, 4.5µmol/L, 5.5µmol/L and 6.5µmol/L. Then, the contents were orderly transferred to centrifuge tubes. They were centrifuged

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

My research primarily involves elucidating the effect of diagenetic recrystallization on metal isotopes (Mg, Ca, and Sr) in marine carbonates and evaluating their reliability as geochemical proxies to reconstruct the paleoclimatic conditions and chemical evolution of seawater through geologic period. Geochemical cycling of Mg on the earth’s surface involves transfer of Mg from continental rocks to the ocean followed by reincorporation of Mg into the lithosphere via hydrothermal exchange at the mid-oceanic ridges and through precipitation of carbonate minerals. Since the exogenic cycle of Mg is directly linked to the global carbon cycle it is invaluable for reconstructing the climatic variability (e.g. pCO2 and temperature). The Mg isotopic composition (δ26Mg) of seawater is useful to decouple long-term variability of Mg concentration and δ26Mg of the input and output fluxes to the ocean. The δ26Mg of marine carbonates is a promising proxy for seawater δ26Mg. However, diagenetic recrystallization of calcite, which is known to impact the trace elemental and isotopic composition of carbonates significantly, can complicate the carbonate-based geochemical proxy interpretation. Therefore, it is critical to quantify the diagenetic effect on the concentrations and isotopic composition of trace elements (e.g. Mg, Ca, Sr) in carbonates to facilitate accurate proxy reconstruction.

Determining the percent recovery of the sample indicates the efficiency of the recrystallization and sublimation processes (“Experiment 2: Purification…”, n.d.). It also indicates the purity of the sample; a higher percent recovery implies a low concentration of impurities, while a lower percent recovery implies the opposite (GlaxoSmithKline, 2013). In the recrystallization of naphthalene, the high percent recovery of naphthalene after the purification is an indication that less impurities are present in the initial sample. In the sublimation process, caffeine recovery is 10.94%. The low recovery percentage indicates a higher concentration of impurities in the initial sample. During the preparation of the caffeine sample, pencil was used in

In comparison to other crystallization media, when xylitol was crystallized in the presence of PVA16000, the crystallization medium exhibited a high viscosity (nearly solidified). Thus, additional distilled water was added to allow more xylitol to be dissolved and thus liquefy the solution. Therefore, the final concentration of PVA16000 (0.03%, w/v) was lower than other additives used (from 0.06% to 1.2%, w/v). Concentrations higher than 0.03% (w/v) generated extremely viscous solutions and thus were not investigated.

Solubility of API in solution can be achieved at elevated temperatures than at room temperature or below by heat transfer mechanism that enhances dissolution. But attention has to be paid not to exceed minimally required temperature, because API degradation may cause at elevated temperature that lead to product deterioration. In addition, if volatile solutes or solvents were used, the heat would lead to loss of these agents in atmosphere and reduce product yield.

The objectives of this experiment are to conduct the preparation of aspirin and perform recrystallisation to purify the compound using suction filtration. Besides, this experiment also requires reinforcing the skill of determination melting point of recrystallised compound.