Amide Synthesis

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Amide Synthesis: Acetanilide Abstract: The purpose of the Amide Synthesis is to create a secondary amide of acetanilide by using aniline as a nucleophile to react with a carbonyl carbon made from the resonance of a double bonded oxygen. In this case, the aniline is purified with the use of decolorizing charcoal in order to give a soluble hydrochloride salt. This experiment involved mixing aniline, charcoal, HCl and sodium acetate trihydrate in a vial attached to an air condenser. This solution was then mixed with Anilinium chloride and acetic anhydride to induce a reaction that produced crystals of acetanilide. The final product was collected with vacuum filtration and dried in order to test for its melting point and mass. The melting point resulted from 115-116 o C and a mass of 0.0246g. This was then used to calculate the percent yield of 99.5% while the atom economy was a low 56%. Any sources of error in this experiment can be any decolorizing charcoal pieces

being crushed in the process of this experiment or spilling of the reaction, losing reactants, when added into the small test tubes. Overall because of the similarities in the experimental product and its theoretical it can be said the product was achieved successfully. Chemical Mechanism: Property Table: Compounds Meltin g Point Boilin g Point Density Compound Structure Molecular Weight Aniline -6.3 o C 184.1 o C 1.02 g/cm 3 93.13g/mol Anilinium chloride 196- 200 o C 245 o C 1.22 g/l 129.58g/mol Acetic Anhydride 73.1 o C 139.8 o C 1.08 g/cm 3 102.09g/mol Acetanilide 114.3 o C 304 o C 1.22 g/cm 3 135.17g/mol

Sodium Acetate Trihydride 58.4 o C 122 o C 1.45 g/cm 3 136.08g/mol Introduction: Amides are classified as primary, secondary and tertiary which are just based on how many carbon atoms are attached to the nitrogen atom. In this experiment, aniline, a primary amide will be used to produce a secondary amide called acetanilide. In order to produce this product of acetanilide, aniline has to be purified with a strong acid like HCl to completely protonate the solution into a soluble hydrochloride salt. The purifying agent for this experiment will be the decolorizing charcoal which will absorb the impurities from the aniline and HCl, therefore purifying the mixture. Another important process done in this experiment is the mixture of acetic anhydride and sodium acetate that allows the acyl substitution to occur. An acyl substitution is “when a nucleophile like an amine displaces the leaving group of acyl derivative such as an acid halide or anhydride” (libretexts) in this case. Once the acyl substitution occurs between the acetic anhydride and sodium acetate the mixture can be combined with the solution containing the aniline which should react to produce the desired product of acetanilide. The last experimental process used to complete this experiment is the use of the Hirsch funnel. The Hirsch funnel is a vacuum filtration technique that is used to collect crystals from a solution and separate the crystallized product from the liquid. The vacuum allowed us to collect the produced acetanilide and wash the product of any impurities in order to achieve the purest form of the product. Procedure: The procedure of this experiment starts by placing 100ul of aniline in a small test tube and placed in an Erlenmeyer flask to avoid it from spilling. To this solution, while it is swirling, incorporate 0,5ml of water with a pipette and three drops of concentrated HCl. In addition to 10mg of decolorizing charcoal in pelletized form. Let the solution mix well before transferring it to a 3ml reaction vial. To the reaction vial we add an additional 0,5ml of water, a magnetic spin vane and attach the air condenser. On a separate small test tube, dissolve 150mg of sodium acetate Trihydrate with 0.5ml of water and cover with a cork. Remove the air condenser from the beaker with the previous solution sand add 150ul of acetic anhydride to that solution with the prepared dissolved sodium acetate trihydrate. Reattach the air condenser and stir until a precipitate is formed. Then, let the solution sit at room temperature before placing it in an ice bath for ten minutes. After the ice bath, our product acetanilide should be seen as crystals which will be collected using vacuum filtration. To rinse the collected solid, wash with 0.5ml of cold water and pull air through the funnel to ensure dryness of the product for at least 10 minutes. The next day, the product can be weighed for its mass and test for its melting point and percent yield. Data: Table 1: Number of measured compounds used and final mass results with percent yield Mass of Aniline 0.0168g Mass of Sodium Acetate 0.1600g Melting Point 115-116 o C

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Experimental mass of product 0.0246g Theoretical mass of product 0.0245g Percent Yield 99.5% Atom Economy 56% Calculations: 0.0168 g 93.13 g / mol = .000180 mol .000180 mol x 136.08 = .0245 theoretical massof product % yieldof product = Experiment mass of product Theoretical Mass x 100 0.0245 g 0.0246 g = 0.995 x 100% = 99.5% yield of product massof atoms ∈ product massof reactantsused = % atomeconomy 135.17 ( 93.13 + 136.08 + 12 ) = 56% atomeconomy Discussion: The purpose of the lab Amide Synthesis is to produce a reaction on aniline to create a secondary amide product of acetanilide. This was achieved by having a nucleophile of aniline attach a carbonyl carbon of acetic anhydride. The main processes involved in this experiment is the use of decolorizing charcoal in order to purify aniline as its hydrochloride salt. This was then combined with Anilinium chloride, acetic anhydride and sodium acetate to complete the reaction and produce acetanilide as the product. The product was collected as crystals with the use of the Hirsch Funnel and dried until the next day to calculate the final product mass and melting point. When weighing the product, it gave a total of 0.0246g of acetanilide produced in the experiment. Its melting point was around 115-116 o C which was close to the theoretical melting point of acetanilide of 114.3 o C. This melting point is one of the reasons as to why this experiment can be seen as successful because of the similarities between our experiment product values and its theoretical values. Another value indicating the success of achieving acetanilide as the product is the percent yield of the experiment which resulted in 99.5% percent yield. The high percent yield indicates that a good amount of the reactants used in this experiment were converted into the product of acetanilide. The calculated atom economy was low as it resulted in 56%. The low atom economy was expected because of a high waste of carboxylic acid during the process of this reaction. Any sources of error could’ve been any crushing of the decolorizing charcoal pellets as this could’ve change the reaction process or spilling of the reaction, losing reactants, when added into the small test tubes.

Conclusion: In conclusion, this experiment can be considered a successful experiment because the reaction was completed and the product of acetanilide was achieved. Other indicators of the successfulness of the experiment can be the high percent yield of 99.5% which indicates that mostly all the reactants were converted into producing the product of acetanilide. The total mass of product collected from this experiment was 0.0246g which some of it was then used to determine the melting point of the product of 115-116 o C which was similar to the theoretical value of 114.3 o C. The atom economy calculated was 56% which was low but expected because of a big waste in carboxylic acid during the process of the experiment. any sources of error where the decolorizing pellets being crushed or spilling of the solution. The experiment was a success. Reference: 1. Katz/Schwartz pp. 69-71 Organic Chemistry , Laboratory Manual, Fourth Edition. 2. Libretexts. (2020, August 11). 21.4: Nucleophilic Acyl Substitution Reactions. Retrieved December 12, 2020, from https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Map:_Organic_Chemistry_( McMurry)/21:_Carboxylic_Acid_Derivatives- _Nucleophilic_Acyl_Substitution_Reactions/ 21.04:_Nucleophilic_Acyl_Substitution_Reactions