Lance Feig CH 128L Experiment Report Purpose The purpose of this lab was to synthesize methyl benzoate from benzoic acid and methanol through Fischer esterification. The identity of the product was verified through IR, GC, and 1H-NMR analysis, where the experimental readings were compared to known readings of methyl benzoate. Furthermore, a percent yield of the product was calculated. In Fischer esterification, a carboxylic acid is converted to an ester by replacing the carboxyl alcohol group (-OH) with an ether (-OR). The acid catalyst protonates the carbonyl oxygen, making the carbonyl carbon more electrophilic. This promotes the attack of the alcohol nucleophile. Fischer esterification is an equilibrium reaction because the water product …show more content…
Then, the product was filtered over cotton to remove the solids. Some of the product was absorbed by the cotton, which decreased the percent yield. The product was a thick liquid, so some remained stuck to the side of the decanted beaker, which also decreased the percent yield. For future experimentation, the amount of cotton used could be reduced or the sample could be decanted without the use of filtering. In addition, a pipette could be used to transfer the sample to reduce the amount of sample left behind. Second, the product was separated from an aqueous layer in the separatory funnel twice. It was probable that some organic solvent was left in the aqueous layer, which would reduce the percent yield as it was discarded. For future experimentation, an additional separation could be performed on the collected aqueous layers to maximize the extracted organic solvent. However, the yield of methyl benzoate was likely lower than the calculated 47.40% since a majority of the product was diethyl ether solvent. As noted in the GC analysis, over 90% of the product was diethyl ether according to the peak areas. Due to an external situation, the solvent was evaporated by heating the product on the hot plate. This was less effective than the preferred method of blowing air over the top of the
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The percent yield was 22.33%. In most cases, that means that a lot of possible product was lost. However, in this case, that was not true. When Benzaldehyde reacted with the Wittig reagent, it produced two products: E-Stilbene and Z-Stilbene. The Z product was a liquid, while the E product was a solid.
The sulfuric acid was used to protonate the oxygen on the carboxyl group of benzoic acid. This promoted the addition of the nucleophile (the methanol) to the double bonded carbon to oxygen. After the nucleophile attacks the double bond, a two-proton transfer occurs and water leaves the molecule to form an ester. The benzoic acid and methanol are in equilibrium with the product. This ester product equilibration leaves a lot of starting material unreacted.
The goal of this experiment was to synthesize the unknown ester through Fischer Esterification. This procedure involves treating a carboxylic acid with an alcohol and a strong acid catalyst. This procedure was also catalyzed with heat at 160oC-180oC, to keep the temperature from exceeding the boiling points of the compounds in use. The acid catalyst protonated the double bonded oxygen atom to force the atom to pull two electrons away from the double bond in order to stabilize the atom’s charge. As this electron shift occurred, the alcohol attacked the carbocation that lost its double bond.
The strawberry was then smashed with our fists for 2 minutes. Next, we opened the bag carefully and added 10 mL of the extraction buffer into the bag, we again pressed out all of the air from the bag extremely carefully so as to not spill the strawberry or extraction buffer and sealed the bag once again. We then mixed the 2 together by using our fists. Next, we placed the cheesecloth in the funnel and put the funnel into the beaker. Then, we opened the bag and slowly began to pour the mixture into the funnel and began to filtrate into the test tube until it was 1/8th full.
In this experiment, the fundamental objective was to synthesize an ester by utilizing the Fischer esterification technique. This method included by using acetic acid and an unknown alcohol #110 as the reactants. Afterward, the reaction was processed, and the product was isolated and purified respectively by isolation and distillation. Then, IR spectroscopy was characterized the product, which demonstrated prominent peaks at 1737.54 cm-1, 1381.
To go in more depth, 98.2% is a high yield, despite the inaccuracies due to time constraints, and the inability to the recrystallize the benzoic acid. As mentioned earlier, product might have been lost during the many filtration procedures in the experiment, as not all of the product was poured out from the flask, onto the filter. Since, recrystallization could not be done, the benzoic acid was immediately transferred onto the watch glass, and it is when transferring some product could have been left on the filter. Overall, pouring product into the filter, and trying to get every particle of product from the flask for each filtration procedure in the experiment, is rather difficult, and is impossible to get every bit of product. Another key possibility, though it fortunately did not occur in the experiment, a green, or purple result
Before proceeding with the experiment, the theoretical yield was calculated to be 0.945 g. After preparation of the product, the theoretical yield was used to determine the percent yield, which was found to be 79%. Due to this reasonable yield, it was concluded that the synthesis of methyl orange had been successful. Data Table 1 gives the results and observations that were recorded throughout the preparation of methyl orange. According to literature, methyl orange is an azo dye that forms orange crystals. However, the product that formed was orange with gold crystals.
Additionally, the Grignard may not have completely reacted with the benzophenone, which may not have hydrolyzed entirely. Unreacted bromobenzene and Grignard reagent would have resulted in the formation of a biphenyl side product. Because Grignard reagents readily reacts with protic solvents, an anhydrous environment was required. Exposure to atmospheric humidity may have decomposed the reagent, thus further limiting TPM yield. Furthermore, during the liquid-liquid extraction, the alkoxide salt may not have reacted completely with HCl, causing it to be loss in the aqueous
The product obtained in this experiment was a slightly yellow tinted liquid. The percent yield was 28.99%. This is indicative of a successful product. This percentage indicates, not only was product formed, but the correct amount of anhydrous sodium sulfate was added, which removed the water molecules from the product. Another factor contributing to the percent yield is the amount of time the product was left under gentle air.
The mass of the crude product was 0.77 g, where the purified product was 0.03g. Comparing the pure product to the amount of isoborneol used, the percent yield was found to be 2.4%. To improve this low percent yield the procedure should be again be examined. Reducing the amount of product lost during transfers, filtration, and sublimation would improve yield. Better transfer would involve more through washes of glassware. Moreover, the yield of the sublimation process was very low (3.9%).
Loss of product occurred due to multiple transfers between glassware and during both vacuum filtrations. During the first filtration, the mother liquor was cloudy signifying that crystals had gotten under the filter paper and were lost. Washing the crystals with methanol made the mother liquor even cloudier meaning that the methanol was warm enough to dissolve the desired product and impurities (337). The crystals formed after the recrystallisation were a bright yellow color due to the possible reaction of the methyl benzoate with the sulfuric acid. Once they were rinsed with methanol, the yellow color disappeared.
.048 1.0 94.1 Experiment Two Methanol (MeOH) And Water (H2O) .049 .045 Methanol – 1.5 Water – 0.5 92 Conclusion Both experiments were of fair solubility, but in the case of recrystallization of Benzoic Acid, Water was the best solvent to recrystallize acid the most. Experimental data determined that there was a difference of .003g between using the single solvent in comparison to the paired solvent.
Abstract The unknown concentration of benzoic acid used when titrated with standardized 0.1031M NaOH and the solubility was calculated at two different temperatures (20◦C and 30◦C). With the aid of the Van’t Hoff equation, the enthalpy of solution of benzoic acid at those temperatures was determined as 10.82 KJ. This compares well with the value of 10.27KJ found in the literature.
Not enough time was given for the precipitate to settle in the beaker, hence when the supernatant is removed; there is a large amount of product lost. This is especially so in step 25, because a large amount of solvent is decanted. It will require much longer than the given time of 10 minutes to allow most of the precipitate to settle at the base of the beaker. Hence instead of decanting the mixture, centrifugation can be used to remove the solution instead. The amount of product lost will be significantly lower by carrying out this process.