Organic Chemistry Experiment 4 †Recrystallization Essay

INTRODUCTIONRecrystallization is the primordial method for purifying solid extreme compounds. Compounds obtained from natural sources or from re achievement mixtures almost always comprise impurities. The impurities may include some combination of insoluble, soluble, and colored impurities. To obtain a pure compound, these impurities must be removed. Each is removed in a separate step in the recrystallization procedure. 8Acetylation of aniline by acetic anhydride was performed to synthesize the arrant(a) acetanilid. The obtained rude phenylacetamide contained acetic acid as well as unreacted acetic anhydride. The said impurities of the crude acetanilide were removed using activated charcoal, filtration and recrystallization.EXPERIMENTALA. Compounds tested aniline aniline is a clear to slightly yellow liquid with a characteristic odor. It does not readily evaporate at room temperature. aniline oil is slightly solublein pissing and mixes readily with most organic solvents. Ani line is used to make a wide variety of products such as polyurethane foam, unpolished chemicals, synthetic dyes, antioxidants, stabilizers for the rubber industry, herbicides, varnishes and explosives. 2 Aniline is prepared commercially by the catalytic hydrogenation of nitrobenzene or by the action of ammonia on chlorobenzene. The reduction of nitrobenzene can also be carried out with iron borings in aqueous acid. 6 Preparation of AnilineC6H5NO2 + 3 H2 C6H5NH2 + 2 H2O(a)(b) predict 1. (a) Hydrogenation of nitrobenzene (b) Bechamp reductionAcetic anhydrideAcetic anhydride is clear, pallid liquid with a strong, pungent, sour vinegar-like odor, lachrymator. 5 Acetic anhydride is an important solvent and ethanoyl radicalation agent. 4 It is used in the manufacture of acetyl compound, cellulose acetates, acetylizer and solvent in examining wool fat, glycerol, fatty and volatile oils, resins, detection of rosin, in organic synthesis, such as dehydrating agent in nitrations, sulfona tions and other reactions where removal of pissing is necessary. 5 Acetic anhydride is prepared by the carbonylation of methyl group acetate. in that respect is a two-stage process for the preparation of acetic anhydride, in which, in a first step, methyl commonplace or, preferably, iodide is carbonylated to provide the corresponding acetyl halide, such acetyl halide in turn being reacted with methyl acetate, in a second step, to provide acetic anhydride, which corresponds to the following reaction scheme, in the event that methyl iodide is the beginning material 7 Step 1CH3I + CO CH3COIStep 2CH3COI + CH3COOCH3 (CH3CO)2O + CH3I systema skeletale 2. Carbonylation of methyl acetateB. social function1. Choosing the Recrystallizing SolventA corn-grain amount of pure acetanilide was placed into each of three test tubes. Methanol, hexane, and water were added to each test tube respectively. Each was shaken and was placed in a warm bathe (37oC-40oC) for 1-5 minutes and thusly was cooled.Figure 3. Pure acetanilide in test tubes containing different solvents methanol, hexane, water respectively.2. Acetylation of Aniline by Acetic AnhydrideAniline solution was made by mixing 2mL of aniline with 20mL of di saveed water. 3mL of acetic anhydride was then added to the solution to form acetylation. The over-all solution was then placed in an ice bath to form crystals of crude acetanilide.Figure 4. 2mL of aniline mixed with 20mL of distilled waterFigure 5. 3mL of acetic anhydride added to the aniline solutionFigure 6. crystallisation of crude acetanilide in an ice bath 3. Purification of Crude Acetanilide by RecrystallizationThe crude acetanilide crystals were filtered through a wet filter paper. The residue was then dried and weighed. In a separate Erlenmeyer flask, the crude acetanilide residue was placed and 20mL of the recrystallizing solvent was added. The solution was then heated on a hot plate until the entire solid dissolved completely. When the solution b ecame colored, it was removed from the heat and bountiful amount of activated charcoal was added. The heating process continued until the solution became colorless. While the solution was still hot, it was quickly filtered using a fluted filter paper. Its filtrate was then cooled by placing the receiver in a beaker with cold water. The crystals that formed were collected and were washed. When thecrystals completely dried up, it was then weighed.Figure 7. Filtration of the crude acetanilide crystalsFigure 8. Crude acetanilide residue mixed with the recrystallizing solventFigure 9. Heating process of the solutionFigure 10. Addition of the activated charcoal to the solutionFigure 11. Continued heating process of the solution until colorlessFigure 12. Filtration and recrystallization of the acetanilideFigure 13. Weighing of the dried acetanilide crystalsRESULTS AND DISCUSSION1. Choosing the Recrystallizing SolventAmong the three recrystallizing solvents methanol, hexane, and water, wa ter was chosen to be used in the recrystallization of the acetanilide. Table 1. Solubility of pure acetanilide in divers(a) solvents At room temp. During heating Upon coolingWater Insoluble soluble InsolubleMethanol Soluble Soluble SolubleHexane Insoluble Insoluble Insoluble2. Acetylation of Aniline by Acetic AnhydrideThe crude acetanilide was obtained by the acetylation of the aniline. The crude acetanilide obtained was 7.2 grams in its weight. 3. Purification of Crude Acetanilide by RecrystallizationPure acetanilide was obtained by the recrystallization of the crude acetanilide. From the 7.2 grams of crude acetanilide, 1.2 grams of pure acetanilide was gathered.Theoretical YieldAniline2mL x 1.0217 g/mL = 2.0434 g2.04 g x 1 mol x 135.17 g =93.13 g 1 mol2.96 g AcetanilideAcetic Anhydride3mL x 1.082 g/mL = 3.246 g3.246 g x 1 mol x 135.17 g =102.09 g 1 mol4.30 g Acetanilide Aniline is the limiting reagent.Percentage Yield= Actual Yield x 100Theoretical Yield= 1.20 grams x 1002.96 gra ms= 40.54 %The experiment conducted was able to perform different chemical processes. In choosing the recrystallizing solvent, solubility test was conducted among mingled solvents methanol, hexane, and water. The solubility test resulted to the conclusion of choosing water as the recrystallizing solvent. The experiment also included the acetylation of aniline by acetic anhydride toform the crude acetanilide. In the experiment, 7.2 grams of crude acetanilide was obtained. Since the crude acetanilide has impurities, it was purified by some(prenominal) processes heating of solution, activated charcoal addition, and recrystallization. When recrystallization has already occurred in the solution, the pure acetanilide was then obtained. 40.54% of the pure acetanilide was gathered with its weight of 1.2 grams.REFERENCES1 Acetylation of Aniline using Acetic Anhydride. http//prolabscientific.com/Acetylation-of-Aniline-using-Acetic-Anhydride-p-23917.html. 2 Agency for noxious Substances & Disease Registry Toxic Substances Portal Aniline. http//www.atsdr.cdc.gov/toxfaqs/tf.asp?id=449&tid=79. 3 Bayquen, A. V., Cruz, C. T., de Guia, R. M., Lampa, F. F., Pea, G. T., Sarile, A. S., & Torres, P. C. (2009). Laboratory Manual in Organic Chemistry. 839 EDSA, South Triangle, Quezon City C & E Publishing, Inc. 4 chemical substance Book Acetic Anhydride. http//www.chemicalbook.com/ChemicalProductProperty_EN_CB2852742.htm. 5 Chemical Book Acetic anhydride (108-24-7). http//www.chemicalbook.com/ProductMSDSDetailCB2852742_EN.htm. 6 Encyclopdia Britannica Aniline. http//global.britannica.com/EBchecked/topic/25473/aniline. 7 Gauthier-Lafaye et al. Carbonylation of methyl acetate. http//www.google.com.ph/patents?hl=en&lr=&vid=USPAT4500474&id=ymY2AAAAEBAJ&oi=fnd&dq=carbonylation+of+methyl+acetate&printsec=abstractv=onepage&q=carbonylation%20of%20methyl%20acetate&f=false. 8 Recrystallization. http//www.chem.umass.edu/samal/269/cryst1.pdf.