Synthesis of Phenacetin in Survey of Organic Chemistry Laboratory | CHM 2435, Lab Reports of Organic Chemistry

Download Synthesis of Phenacetin in Survey of Organic Chemistry Laboratory | CHM 2435 and more Lab Reports Organic Chemistry in PDF only on Docsity! CHM 2435 Name Experiment 8 Synthesis of Phenactin Report Sheet Date A. Complete the following reaction by writing in the inorganic by-products on the right side of the equation. OH H N O NaOH+ + CH3CH2I+ + (organic product from first equation) ONa H N O H2O ONa H N O O H N O NaI B. Calculation of Percent Yield 1.0 M Sodium Acetaminophen Hydroxide Ethyl Iodide Product Volume used 15.5 mL 2.1 mL Mass used 2.12 g 4.1 g ** (2.1 mL x 1.95 g/mL ) Molecular weight 151.18 g/mol 155.97 g/mol 179.24 g/mol Molec formula = C8H9NO2 Molec formula = C2H5I Mol form= C10H13NO2 Moles used 0.0140 0.0155 †† 0.026 - (grams divided by molecular weight), except for NaOH, which is volume in L times molarity Limiting reagent acetaminophen (will get used up first) Theoretical yield (moles) 0.014 Equal to the number of moles of limiting reagent (if 1:1 relationship between limiting reagent and product) Theoretical yield (grams) 2.5 g (theoretical moles product x molecular weight product) Actual yield (grams) 1.86 g Percent yield 76% (actual yield/theoretical yield x 100) ** the volume (in mL) times the density (g/mL) gives the mass. density of iodoethane = 1.95 g/mL †† the volume (in L) times the molarity gives the moles C. Melting point of product 121.1-122.5 °C QUESTIONS: 1. Compare the melting point of your product to the literature melting point (133-136 °C). Is your product pure? Why or why not? Just comparing the values, it does not seem like it, since my melting point is ~ 12 °C lower than the literature value. However, my melting point has a range of only 1.4 °C, so it must be fairly pure (as pure compounds have melting point ranges of 3 °C or less) 2. Comment on your percent yield - was it high or low?? If you were to repeat the experiment, what would you change to get a better percent yield? It was not bad.. To get a better percent yield I would let the reaction go longer (maybe it did not go to completion), use more EtI (since some of it may have evaporated away), and cool the flask longer after the reaction (to be sure all the solid formed). 3. Why don’t we simply add all the chemicals at once, instead of adding the sodium hydroxide, heating, and then adding the ethyl iodide. This would be easier, right? This would be bad - the hydroxide can directly react with the ethyl iodide to give ethanol and a free iodide ion. By heating the acetaminophen and hydroxide alone, most of the hydroxide should be react to the give the acetaminophen anion and water, so that the only thing that will attack the ethyl iodide will be the desired compound (the acetaminophen anion). 4. One way to tell if an organic reaction is going to proceed or not is to compare the pKa’s of the acids on either side of the arrow. The reaction will proceed from left to right if the ACIDIC species on the right of the arrow is a WEAKER acid than the acid on the left of the arrow. For instance, HCl completely dissociates (reacts) in water since the it is a stronger acid than H3O+ : HCl + H2O Cl H3O ++ Ka 1.6 x 102 5.5 x 101 Note that in this case water is acting as the base, but we compare the conjugate acid of water (H3O+) to HCl, not H2O itself. The conjugate acid can easily be found simply by putting a hydrogen on the base (so H2O goes to H3O+).