Experiment 8: Preparation of Triphenylmethyl Methyl Ether Hayley Williams, willi553@go.stockton.edu CHEM 2125 007 April 10, 2018 Abstract The objective of this experiment was to produce triphenylmethyl methyl ether (TPMME) via an Sn1 substitution reaction. The “reflux” method was applied to run the reaction. Methanol was mixed with triphenylmethyl chloride (TPMCl) and then added to a round-bottom flask to be heated and boiled for fifteen minutes. During the fifteen minutes of boiling, the vapors travelled through a simple distillation apparatus, leaving TPMME in the flask to be crystallized. The TPMME was recrystallized using vacuum filtration and tested for purity using a TLC test. The theoretical yield of the TPMME (2.000g) was used to calculate the % yield (50.45%) based on the mass of the recovered TPMME (1.009g). The results of the TLC tests between the product, starting material and a sample of the two combined, concluded that the TPMME was pure. This was determined because the Rf value of the product (0.568) was very similar to the Rf value of the pure TPMME (0.523) that was separated from the combined sample. Even though the % yield was on the lower side, the sample produced showed to be very pure. Purpose/Theory The purpose of this experiment was to use the reflux method of simple distillation to produce triphenylmethyl methyl ether from triphenylmethyl chloride and methanol. In order to determine the success of the experiment, % yield was calculated and a TLC test was run to ensure the purity of the product. The type of reaction that occurred in this experiment was an SN1 substitution reaction. This reaction works by substituting the chloride with a nucleophile (methanol). The nucleophile attacks the electrophilic carbocation and generates a stable trityl carbocation. The rate of an SN1 reaction depends on the nature of the substrate (alkyl halide), the ability of the leaving group to leave, and the nature of the solvent. The rate of the reaction increases as the stability increases. The trityl carbocation created is very stable because the positive charge can be delocalized over all three rings through ten different resonance structures placing the (+) charge on the circled atom. The chemical reaction mechanisms in this experiment exhibit the loss of a leaving group and a nucleophilic attack as shown in the formula below: The distillation method used in this experiment was the “reflux” reaction, which is essentially heating and boiling a mixture to cause a reaction without losing any solvent. In this experiment in particular, the TPMCl was combined with methanol creating TPMME as it boiled, and the chlorine was removed via the west condenser. After recrystallization of the TPMME, the % yield was calculated after first finding the limiting reagent and the theoretical yield. Once the % yield was determined, a TLC test was run to check the purity of the produced TPMME. If the product was pure, the Rf values of the product would mimic the Rf value of pure TPMME. The Rf value of the pure TPMME was found by combining the starting compound with the product and testing that against both the product and the starting compound alone. The combined TPMCl and the TPMME separated when tested and when the spots aligned almost perfectly with the separated spots, it was confirmed that the TPMME product was pure. Results/Discussion Equations/Sample Calculations Data: TPMCl mass (g) 2.031 g TPMCl mw (g/mol) 278.775 g/mol TPMCl moles used 0.00729 moles TPMME mass (g) 1.009 g TPMME mw (g/mol) 274.363 g/mol TPMME moles 0.00368 moles Theoretical Yield (TPMME) 2.000 g % Yield (TPMME) 50.45% Limiting Reagent TPMCl (0.00729) TLC Test (Solvent: ethyl acetate) Compound Rf Value Starting Compound (TPMCl) 0.181 Product (TPMME) 0.568 Combined (TMPPE+TPMCl) 0.181/0.523 Equations/Sample Calculations cont. The goal of this experiment was accomplished because the SN1 reaction between TPMCl and methanol produced, after applying the refluxing method, pure TPMME. The % yield was calculated by using the above equation. The % yield equation required the calculations of the theoretical yield and limiting reagent in order to be completed correctly. The theoretical yield and limiting reagent calculations are shown above as well. The theoretical yield for the TPMME was 2.000g and the actual mass collected was 1.009g, showing a % yield of 50.54%. This % yield is a little low and it shows that there were some inefficiencies either in the reaction or while carrying out the experiment. When the purity of the TPMME was run through a TLC test, the Rf values showed that the product was mostly pure TPMME. Of the three compounds shown on the TLC test, the combined sample finished with two separated spots (TPMME and starting compound) instead of just one. Each of the separated spots were in alignment with either the starting compound’s spot or the product’s spot. When viewing the TLC plate under the UV lamp, it was clear, without any calculations that the TPMME product was pure. To be sure, the Rf values of each of the four spots were compared. The Rf value of the pure TPMME (0.523), which separated from the starting compound, was very similar to that of the produced TPMME (0.568). The aforementioned spot was confirmed to be TPMME opposed to the starting compound because the Rf values of the second spot and the spot from the starting compound were equal (0.181). To sum everything up, the reaction produced a lower % yield than expected, but the product itself was very pure. Conclusions The main objectives for this experiment were to carry out an SN1 substitution reaction of TPMCl and methanol via the reflux method, determine the % yield of the produced TPMME, and to assess the purity of the produced TPMME. The % yield came out to be 50.45% which is lower than anticipated. The cause for such a low % yield could have been many things, such as failing to remove all of the crystals after recrystallization and also losing crystals while transferring the product from one vessel to another. The purity of the TPMME was tested via a TLC test, which concluded that the product was, indeed, pure. The TPMME’s purity was confirmed when the Rf value of the product (0.568) was nearly identical to that of the pure TPMME (0.523). The closer the product’s Rf value is to that of its known compound, the more pure the product is. All of the goals of this experiment were met successfully. References Experiment #8 Preparation of Triphenylmethyl Methyl Ether pre-lab notes, Dr. Aaron Wohlrab https://blogs.stockton.edu/chem2/files/2016/01/Triphenylmethylmethylether_S16.pdf Zubrick, James. The Organic Chem Lab Survival Manual, 9th ed.; Wiley: NJ, 2014.  An important use of the equation for a reaction is to provide information about the stoichiometry of a reaction. We will need to know this information in order to calculate the theoretical yield and percent yield of your synthesis. 1-methoxybutane (butyl methyl ether) was synthesized by the following reaction: Use the data from the Aldrich Catalog below to calculate the following Sodium methoxide FW 54.02 , d 0.945 1-Bromobutane, FW 137.03, d 1.276 Butyl methyl ether, FW 88.15 , d 0.744 (4pts)A student used 20 ml of 1- bromobutane in this experiment. How many grams and how many moles of bromobutane did she use? (4pts)She used 45 ml of a 25% (wt./wt.% solution) of sodium methoxide in methanol. Use the density of this solution to calculate the mass of sodium methoxide she used. Use the mass to calculate the number of moles of sodium methoxide she used. (4pts)Compare the number of moles of reactants and decide which is the limiting reagent. In other words, how many moles of product are theoretically possible? (4pts)How many grams of product are theoretically possible? This is commonly called the theoretical yield. (4pts)If a student obtained 12 g of product, what is the % yield?