...Khanh Nguyen Thanhthao Vo September 17, 2014 RECRYSTALLIZATION INTRODUCTION The purpose of this experiment is to study how to perform recrystallization technique in order to purify compounds and to apply TLC and melting point detection technique to test the purity of the recrystallized sample. In chemistry, recrystallization is the purification technique for solid compounds, using an appropriate solvent, to coax out either the desire compound or the impurities. The name “recrystallization” is given because of the crystals often formed when the experiment is successfully performed.2,3 Recrystallization works based on the difference in solubility when the temperature changes. Therefore, picking the solvent to dissolve the compound is a very tricky and important part. For single-solvent recrystallization, which is performed in this experiment, the chosen solvent should not dissolve the sample while cold, so that the crystal can be formed when the temperature drops. However, the solvent should dissolve the sample completely while hot in order to release all the impurity crystals being trapped up in the solid form of the desired compound. Furthermore, the impurities should have higher solubility than the desired compound in that chosen solvent, so that all the impurities would remain in the solution while recrystallization takes place.2,3 In case no single solvent can be found, a system of two solvents can also be used for recrystallization. Generally speaking, in this solvent pair,...
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...University of Santo Tomas, España, Manila Organic Chemistry Laboratory Recrystallization of Acetanilide Experiment 4 Author: Janina Erika G. Sese Group 8 – 2C Medical Technology (A.Y. 2015-2016) Members: Kathleen Danielle Marie A. Robles, Amiel C. Sabangan, Hanz Jefry A. Saliendra, Andrea Betina M. Vega, Anna Denise Z. Yang ------------------------------------------------- Date Submitted: October 28, 2015 ------------------------------------------------- ABSTRACT Recrystallization is the simplest and most widely used operation for purifying organic solids that differ in their solubility at different temperatures. In this experiment, three test tubes with water, hexane and, ethanol, respectively, were used to dissolve pure acetanilide. These test tubes were placed in a water bath for one to five minutes, then, were cooled through running water for the selection of the best solvent to use in recrystallization. Crude acetanilide was obtained by mixing two milliliters aniline and 20 milliliters distilled water with three milliliters acetic anhydride, which was cooled with running water. It was then filtered and dried for the procurement of crude acetanilide. This was mixed with 20 milliliters of the chosen solvent and heated through water bath until the solid was dissolved. Next, it was immediately filtered while hot. The filtrate was collected and was cooled with running water leading to the recrystallization of pure acetanilide. This was again filtered with a tared filter paper...
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...RECRYSTALLIZATION OF CRUDE ACETANILIDE FROM ACETYLATION OF ANILINE ABSTRACT Recrystallization is a process of dissolving the solid to be crystallized in a hot solvent or solvent mixture and then cooling the solution slowly. The purpose of this experiment is to purify crude acetanilide product by recrystallization. Crude acetanilide is produced by the acetylation of aniline. The crude acetanilide is brought to boil in water, the chosen recystallization solvent. Activated charcoal is added when there is change in color; then, filtration is done to collect the solution. Once the solution reaches the room temperature, it is placed in an ice bath. Finally, the crystals were collected through filtration and washings with water. INTRODUCTION Only solids that can pass the vapor phase without passing through the liquid phase can be purified by sublimation. Solids that do not have this property can be purified by recrystallization. Recrystallization is the most important method for purifying solid organic compounds. It is a very efficient method of purification, and an important industrial technique still relevant in the chemical world. (Williamson and Masters, 2010). Figure 1: process of recrystallization A pure, crystalline organic substance has a well-defined crystal lattice, a three-dimensional array held by London forces. Most organic solids melt between the range of 22℃ and 250℃. An impure organic solid does not have a well-defined lattice and needs to undergo...
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...Synthesis of Acetanilide and Purification by Recrystallization Par, B., Ramos, S., Reynaldo, H., Roque, P., Servidad, Y., and Soriente, P. 2D-Pharmacy, Group No. 7, Department of Pharmacy, Faculty of Pharmacy, University of Santo Tomas, España Boulevard, 1015 Manila, Philippines Abstract Recrystallization is the primary method of purification used to isolate organic compounds in a supersaturated solution by the difference of solubility at different temperature that results to the separation of the compound from the solution. The purpose of this experiment is to synthesize acetanilide by the acetylation of aniline and to obtain pure acetanilide by purification of the collected crude acetanilide by crystallization. The recrystallizing solvent was chosen among ethanol, water and hexane. The acetanilide was synthesized and formed by acetylation of aniline and acetic anhydride, and it was then cooled to hasten the formation of crystals. After cooling, the mixture was filtered and dried to obtain the crude acetanilide. The crude acetanilide and the chosen recrystallizing solvent was mixed and heated in the water bath until the solid dissolved. The solution was filtered while hot and its filtrate was cooled in an ice bath. The filtrate was then filtered to collect the crystal residue formed. The crystals were washed with distilled water and allowed to dry to obtain the pure acetanilide. The weight of pure acetanilide was measured and the melting point of the pure acetanilide...
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...The purpose of this experiment was for the student to be able to perform the dehydrobromination of meso-stilbene dibromide in order to produce an alkyne, diphenylacetalyene. The dehydrobromination of meso-stilbene dibromide requires removal of two hydrogen bromides—in other words, a double elimination. In order for the elimination of the halogen to happen, the hydrogen being attacked and the leaving group need to be on the same plane. More specifically, the molecule has to be in an anti-periplanar orientation in order to have the elimination reaction happen more efficiently. Even though a molecule in a syn-periplanar orientation also has the hydrogen and leaving group in the same plane, the fact that both groups are on the same side makes the molecule sterically hindered. The staggered conformation of the meso-stilbene dibromide is orbitally more favorable than the eclipsed conformation making the anti-periplanar orientation the more favorable orientation for an elimination reaction. Fortunately, the fact that meso-stilbene dibromide had a single bond allowed for this molecule to develop the anti-periplanar orientation by having rotated the bond until the hydrogen and the leaving group were on opposite sides of the molecule. When producing alkynes, there are two steps involved in the reaction: the formation of an intermediate alkene with a vinyl halide followed by the elimination of the halide to result in an alkyne. For the creation of the intermediate vicinal bromide in this...
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...Experiment 5 - Cold Work, Recovery, Recrystallization and Grain Growth Objective To study the effects of cold working on the microstructure and mechanical properties of 70/30 Cartridge Brass. Background A small percentage of the energy expended in plastically deforming a material remains stored in the metal as an increase in internal energy. Changes are produced in both its physical and mechanical properties. Principally, there is a marked increase in hardness and electrical resistivity with the amount of cold working. Microstructurally, this increment in internal energy is associated with an increase in the dislocation density as well as the density of point defects, such as vacancies and interstitials. For most metals, the dislocation density increases from the values of 106-107 lines/cm2 (typical of the annealed state) to 108-109 after a few percent deformation and up to 1011 -1012 lines/cm2 after heavy deformation. At a more macrostructural level, the grains become markedly elongated in the direction of working and heavily distorted. This distortion is evident from a bending of annealing twins and from unevenness in etching caused by local strain inhomogeneities. While the increased hardness and strength that result from the working operation can be important, it is often necessary to return the metal to its initial condition by annealing. This usually means holding the cold worked metal at a temperature above about 1/3 of the absolute melting point for a period of time. The...
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...Lab #1 Recrystallization Robert Stephenson January 23rd, 2008 Purpose: Purify compounds using recrystallization which will consist of two parts: (A) Recrystallize acetanilide from water (simple recrystallization). (B) Recrystallize cinnamic acid from ethanol and water (mixed solvent recrystallization). Introduction: Several methods have been developed over time in order to purify various organic compounds. One of the most basic and effective techniques known is recrystallization. Despite its decreased practice, recrystallization still remains one of the top methods in obtaining scalable amounts of ultra-pure organic materials. This technique essentially relies on the different solubility’s of compounds to be purified in a solvent. The impure material will thus dissolve in a hot solvent, allowing the removal of these impurities through filtration, which will then allow the desired compound to crystallize as it cools. Solvents and solubles are important factors in recrystallization; the substance should have a high solubility at elevated temperatures, and low solubility at low temperatures. Additionally, the solvent should have the capability of dissolving or not dissolving impurities, which will determine the occurrence of filtration. Compared to insoluble impurities, which are filtered once the compound dissolves in the hot solvent, soluble impurities are filtered out in solution as the compound is left behind. In some cases, decolorizing carbon...
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...solution if necessary to keep it hot all times during the filtration.8. Rinse the flask in which the solid was heated with 20 ml of boiling water then pour this water also through the ilter.9. Allow the filtrate to cool, undisturbed , to room temperature, and then place it in an ice bath. If crystallization has not occurred, attempt to induce it by any of the methods discussed previously.10. Collect the crystals by filtration.11. Allow the crystals to dry in air.12. When crystals are completely dry, weigh them , label and turn in to your instructor to be used for melting point determination in Activity 8. | Choosing a solventThe first consideration in purifying a solid by recrystallization is to find a suitable solvent. There are four important properties that you should look for in a good solvent for recrystallization. 1. The compound should be very soluble at the boiling point of the solvent and only sparingly soluble in the solvent at room temperature. This difference in solubility at hot versus cold temperatures is essential...
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...samples. We recrystallized the salicylic acid because this would then allow us to see the differences in purity between normal salicylic acid and the recrystallized. The recrystallized in theory should be more pure because the crystallisation processes purifies the sample. This would show up on the TLC and the melting point. We recrystallized salicylic acid so that it could be compared with the aspirin samples. From the recrystallization we worked out the percentage recovery. The calculation consisted of the original weight of acid (2g) divided by the weight of the acid after recrystallization which was 1.3g. Then it should be multiplied by 100 to get a percentage. We achieved 51.5% after recrystallization. This was considerably lower than we had expected. Although we knew that the weight of the acid would be reduced we did not expect it to be so dramatic. Recrystallized substances are normally purer than standard samples because the impurities or contaminants get removed by the filtering, evaporating and separation that occurs during the recrystallization. Results After recrystallizing the salicylic acid we calculated the percentage recovery. The result we achieved was not what we had expected. We had expected some of the acid to have been lost and the recovery be reduced. The results we got showed that only 51.5% of the acid remained after the crystallisation. This was surprising because almost half of the original substance of salicylic acid had gone. The original mass...
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...Name: Srikant Tulsi Reg # 10/0705/0497 Experiment # 4 Date: 5/11/2014 Partners: Shefali Seecharran Pride Ade-Thomas Claude Fraser Title: Synthesis of 9,10-Dihydroanthracene-9,10-Endo-α,β – Succinic Anhydride Reactions: Reaction Mechanism Physical Properties Table: Chemical | Formula | M.W (g/mol) | Quantity (g or ml) | Amount( moles) | Molar Equivalent | M.P(OC) | B.P (OC) | Density\(g/cm3) | Yield (g) | % yield | Anthracene | C14H10 | 178.23 | 2.018 g | 0.0113 | 1 | 215 | 339 | 1.28 | | | Xylene | C8H10 | 106.16 | 2.5 ml | 0.0022 | 1 | -47.4 | 138.5 | 0.864 | | | Maleic Anhydride | C4H2 O3 | 98.06 | 1.001 g | 0.0102 | 1 | 52.8 | 202 | 1.480 | | | Hexane | C6H14 | 86.18 | - | - | | -96 | 68 | 0.655 | | | DCM | C10Cl2 | 84.93 | - | - | | -96.7 | 39.6 | 1.327 | | | Ethyl Acetate | C4H8O2 | 88.11 | - | - | | -83.6 | 77 | 0.897 | | | 9,10-Dihydroanthracene-9,10-Endo-α,β – Succinic Anhydride | C18H12O3 | 276.29 | - | - | | 262-264 | | | 2.326 | 82.43 | Calculations: * Calculating the number of moles of Anthracene Mass of Anthracene Used is 2.018 g Molar Mass is 178.23 g/mol Number of moles = MassMolar mass = 2.018 g 178.23gmol = 0.0113 moles * Calculating the number...
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...ring. At the other is a secondary or tertiary amine. These two ends are separated by a central chain of atoms usually one to four units long. The aromatic part is typically and ester of an aromatic acid which is important to the bodily detoxification of these compounds. In our experiment, we created a topical anesthetic, Benzocaine, by the direct estherification of p-aminobenzoic acid. This was accomplished by reaction with absolute ethanol catalyzed by concentrated sulfuric acid and later neutralized with a 10% sodium carbonate solution. Neutralization raised the pH of the overall reaction system to about 8 creating a precipitate of Benzocaine. Recrystallization of the crude product was performed to increase purity. Our experiment produced a 0.0705g crude sample of Benzocaine with a melting point of 86.55 – 88oC. Recrystallization produced a 0.0411g pure sample with a melting point of 89.5 – 90.9oC. Pure Benzocaine melts at 90oC. Benzocaine is an odorless, white, rhombohedric crystal with low water solubility. It is sensitive to light exposure and to temperatures above 30° C. As a drug, it has a low potency...
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...the vacuum and carefully pour 50 mL of water on the product to wash it. Reapply the vacuum and repeat this process 3 times. | Product was washed 3 time with water without releasing the vacuum. | 7 | Finally press the product as dry as possible on the filter using cork or 50 mL beaker, then press it between sheets of filter paper ( Save sample for mpt.) | A filter paper was placed on top of the crystals and a 50 ml beaker was placed on top of paper and pressed down. | 8 | Recrystallize the rest of the product using 5 mL of ethanol for each 4 g dibenzalacetone. | 4 mL of ethanol was added to the solution. | 9 | Add the product dissolve in hot ethanol then cool to room temp. Place it in ice bath (the yield after recrystallization should be about 2 g) | The product was added to the hot ethanol after it was completely dissolved was placed inside ice bath. | 10 | Perform...
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...Name: Srikant Tulsi Reg # 10/0705/0497 Experiment # 4 Date: 5/11/2014 Partners: Shefali Seecharran Pride Ade-Thomas Claude Fraser Title: Synthesis of 9,10-Dihydroanthracene-9,10-Endo-α,β – Succinic Anhydride Reactions: Reaction Mechanism Physical Properties Table: Chemical | Formula | M.W (g/mol) | Quantity (g or ml) | Amount( moles) | Molar Equivalent | M.P(OC) | B.P (OC) | Density\(g/cm3) | Yield (g) | % yield | Anthracene | C14H10 | 178.23 | 2.018 g | 0.0113 | 1 | 215 | 339 | 1.28 | | | Xylene | C8H10 | 106.16 | 2.5 ml | 0.0022 | 1 | -47.4 | 138.5 | 0.864 | | | Maleic Anhydride | C4H2 O3 | 98.06 | 1.001 g | 0.0102 | 1 | 52.8 | 202 | 1.480 | | | Hexane | C6H14 | 86.18 | - | - | | -96 | 68 | 0.655 | | | DCM | C10Cl2 | 84.93 | - | - | | -96.7 | 39.6 | 1.327 | | | Ethyl Acetate | C4H8O2 | 88.11 | - | - | | -83.6 | 77 | 0.897 | | | 9,10-Dihydroanthracene-9,10-Endo-α,β – Succinic Anhydride | C18H12O3 | 276.29 | - | - | | 262-264 | | | 2.326 | 82.43 | Calculations: * Calculating the number of moles of Anthracene Mass of Anthracene Used is 2.018 g Molar Mass is 178.23 g/mol Number of moles = MassMolar mass = 2.018 g 178.23gmol = 0.0113 moles * Calculating the number...
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...Throughout the experiment, many decisions had to be made. One of the major decisions being to choose the right solvent to perform recrystallization in. It was decided, between the choice of ethanol and ethyl acetate, that ethanol was to be used for recrystallization. This was decided by testing the solubility of the product in both solutions. In ethyl acetate, the product readily dissolved, while in ethanol it needed heat to dissolve. The Aldol condensation reaction consisted of mixing two unknowns, A345 (a liquid) and a B192 (a solid). Through a series of chemical tests, A192 is concluded to be a methyl ketone and B192 is an aldehyde. According to the Tollens Test, which tests for aldehydes, B192 turned gray while the liquid did not. In the Chromic acid test, which also tests for aldehydes, B192 turned into a green liquid while A345 had no reaction....
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...combination thereof whereas the dynamic load is most often of fatigue type arising out of vibrations and rotating force. [1] 2.2 Processing of Fasteners Processing is generally done in 4 stages: 2.2.1. Material Selection Material selection depends totally on application of Fastener, which is further decided on Physical Properties and Chemical composition. 2.2.2. Fabrication of Fasteners [3] This process can be done with the help of different process like Hot/Cold rolling, drawing,etc which again depends on type of Bolt to be processed. Rolling can be classified based on the temperature of metal to be rolled. If the temperature of the metal to be rolled is above recrystallization temperature, it is termed as hot rolling; this is 50-100o C above the recrystallization temperature and if the temperature of metal is below recrystallization temperature then it is termed as cold rolling. Hot rolled products are malleable which can be used for complicated shapes and cold rolled products must have simple shape but are more precise to the required dimensions. 2.2.3. Heat Treatment [4] Engineering properties are modified by heat treatment processes so that structural components are able withstand specified operating conditions and have desired useful life. Process includes the heating and cooling of metals to change their physical and mechanical properties, without letting it change its shape. Heat treatment could be said to be a method for strengthening materials but could also be used to alter...
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