Department of Chemistry Virginia Commonwealth University CHEZ 302 – Organic Chemistry II LabExperiment #8: Synthesis of an Ester Submitted by: Joseph Thomas Morrison Start date: March 28th, 2013 Completion date: March 28th, 2013 Submission date: April 4th, 2013 Pages in lab notebook: 21-23 ___________________________ Signature Results…………………………………………………………………. 10. 11... References………………………………….…………. Objective……………………………………………………………... Table of Contents………………………………………………………. 4. 7.. Discussion………………………………………………………………. Synthetic Equations…………………………………………...…………………………………… 2...………………... Title Page…………………………. 9.. Experimental Procedure………………….. 5. 3... Physical Properties……………………………………. 8. 6.....…………………………. Attachments IR Spectrum of Product (Methyl Salicylate) ... Calculations……………………………………………………………..2 Table of Contents 1.…………………………….. . An additional objective of this experiment was to validate the product (methyl salicylate) using the techniques of percent yield calculation and IR (infrared spectroscopy). and rotary evaporation while driving the reaction equilibrium toward the products by using an excess of methanol.3 Objective The objective of this experiment was to form methyl salicylate from salicylic acid and methanol in the presence of an acid catalyst through a facilitated esterfication chemical reaction using the techniques of heating under reflux. separation. gravity filtration. 4 Synthetic Equations Theoretical Yield of Methyl Salicylate ( )( )( ) Percent Yield of Methyl Salicylate [ ] Overall Reaction of Salicylic Acid and Methanol to Methyl Salicylate . 93 g/mol Boiling Point: 39.sigmaaldrich.. N.p.33 g/mL [1] Sigma-Aldrich. 2013.6 °C Density: 1.08 g/mol Boiling Point: 337 °C Density: 1.com>. .http://www.84 g/mL Hazards: Corrosive and toxic.5 Physical Properties Note: All physical properties of liquids and solids from this experiment were obtained from Sigma Aldrich. Structure: Name: Sulfuric Acid Molecular Weight: 98.7 °C Density: 0.04 g/mol Boiling Point: 64. Web.7918 g/mL Hazards: Flammable and toxic. <.d. n. Structure: Name: Methylene Chloride Molecular Weight: 84. 13 Mar. [1] Liquids Name: Methanol Molecular Weight: 32. .01 g/mol Boiling Point: 851 °C Density: 2. Structure: Solids Name: Salicylic Acid Molecular Weight: 138.15 g/mol Boiling Point: 220-224 °C Density: 1. Structure: Name: Sodium Bicarbonate Molecular Weight: 84. Structure: Name: Methyl Salicylate Molecular Weight: 152.174 g/mL Hazards: Toxic by ingestion.20 g/mL Hazards: Irritant.12 g/mol Melting Point: 159 °C Hazards: Toxic by ingestion.6 Hazards: Carcinogen. 7 Structure: Name: Sodium Sulfate (Anhydrous) Molecular Weight: 142.04 g/mol Melting Point: 884 °C Hazards: Irritant. Structure: . 309 mols) was added to the flask. loss) of the product occurred. 5. 0.9 grams. A reflux condenser was attached and the mixture was heated at reflux for 45 minutes. A layer of oil formed on the top of the refluxing mixture.8 Experimental Procedure To a 50 mL round-bottom flask. The organic layer was dried over sodium sulfate and then gravity filtered into a pre-weighed 100 mL round-bottom flask (39. The product was weighed and the percent yield was determined.5 mL of methanol (9. The combined methylene chloride extracts were washed with 15 mL of water.2 grams. 0. 10 mL of ICE water was added to the mixture and the contents of the flask were transferred to a separatory funnel.9 grams of salicylic acid (4.235 mols).035 mols) was added. 12.3 grams. The mixture was shaken gently during the extractions and washings.393 mols).094 mols) was slowly added with swirling.9 grams. .9 grams. 0.0 mL of concentrated sulfuric acid (9. and the flask was swirled to dissolve the solid. A white solid formed in the flask. or evaporation (and.5 grams) and the solvent was evaporated using a rotary evaporator. The product was an oil – and care was taken not to evaporate past the point where the solvent was gone. The reaction mixture was allowed to cool to room temperature. 4. 0. The mixture was swirled occasionally during the reflux period. The product (methyl salicylate) was extracted into two 15 mL portions of methylene chloride (19. therefore. An IR and an NMR were run on the product. When the solid was dissolved. 0. followed by 15 mL of 5 % aqueous sodium bicarbonate solution (33. 9 Calculations Theoretical Yield of Methyl Salicylate ( ( )( ) )( ) Percent Yield of Methyl Salicylate [ ] . 4 ppm. Percent Yield The percent yield of phenacetin from the experiment was determined to be 35. and a CH2R group (CH3) respectively.10 Results IR Results The IR spectrum showed peaks at 3100 cm-1.39 % . C=O amide. CONR2 group (CH3). 1500 cm-1. and a 3H triplet at 1.1 ppm.4 ppm. and 1050 cm-1. 2H doublet at 6. 1640 cm-1. which represented hydrogen(s) attached to a aromatic group (CH). and a C-O ether respectively. 2H quartet at 4.4 quartet at 1. NMR Results The NMR spectrum showed a 2H doublet at7.0 ppm. 3H singlet at 2. C=C aromatic. aromatic group (CH).8 ppm. which represented a C=CH aromatic stretch. OC6H5 group (CH2). 4 quartet at 1.4 ppm. In this experiment. As stated earlier in this report.8 ppm. however this peak was not observed in the NMR spectrum which indicated that human error or equipment error was a possible factor in the non-existent peak. a phenol.1 ppm. These results were representative of the results expected from the NMR spectrum of pure phenacetin with one exception. 1500 cm-1. the NMR spectrum showed a 2H doublet at7. which represented hydrogen(s) attached to a aromatic group (CH).39 %. percent yield calculation. was be de-protonated by sodium methoxide. aromatic group (CH).4 ppm. These results were representative of the results expected from the IR spectrum of pure phenacetin. vacuum filtration and recrystallization incorporating a mixed-solvent system. C=C aromatic. p-acetamidophenol (acetaminophen).0 ppm. and a C-O ether respectively.11 Discussion The objective of this experiment was to form phenacetin from acetaminophen through a facilitated Williamson ether synthesis chemical reaction using the techniques of heating under reflux. IR (infrared spectroscopy). As stated earlier in this report. and NMR (nuclear magnetic resonance). OC6H5 group (CH2). and a CH2R group (CH3) respectively. and 1050 cm-1. which represented a C=CH aromatic stretch. the IR spectrum showed peaks at 3100 cm-1. It was expected that there would be a 1H singlet at 8 from the amide N-H. 2H quartet at 4. 2H doublet at 6. The resulting phenoxide ion then reacted with bromoethane (ethyl bromide) to give . and a 3H triplet at 1. An additional objective of this experiment was to validate the product (phenacetin) using the techniques of melting point determination. CONR2 group (CH3). The melting point of the product was determined to be 109-110 °C which was significantly lower than the literature melting point of phenacetin (134136 °C) which supported the hypothesis that impurities were present in the product. 3H singlet at 2. 1640 cm-1. C=O amide. Phenacetin was successfully formed during this experiment with a determined percent yield of 35. Overall.39 %). The product was also validated using the techniques of melting point determination. IR (infrared spectroscopy). Because of the nature of a Williamson ether synthesis. human error in the form of the addition of non-equimolar amounts of acetaminophen and sodium methoxide mistakenly was probable. and NMR (nuclear magnetic resonance). the experiment’s objectives were successfully completed. . phenacetin was obtained from the experiment using the techniques of heating under reflux. Of which.12 phenacetin (p-ethoxyacetanilide). The results of the Williamson ether synthesis also showed that equipment error was probable due to the missing peak in the NMR spectrum (amide N-H) but the represented C=O amide peak in the IR spectrum. percent yield calculation. The results of the Williamson ether synthesis showed that human error was probable due to the significantly low melting point (109110 C) and the significantly low percent yield of phenacetin (35. vacuum filtration and recrystallization incorporating a mixed-solvent system. Therefore. adding equimolar amounts of acetaminophen and sodium methoxide was crucial in preventing unwanted side reactions and to obtain the pure phenacetin product. d. N. . 13 Mar. n.13 References [] Sigma-Aldrich.http://www. <.com>.. 2013.sigmaaldrich. Web.p.