The Knorr Synthesis of Pyrroles Experimental A mixture of ethyl acetoacetate 1 (7.52 g, 7.5 mL) in glacial acetic acid (18 mL) was prepared and cooled to 5oC while stirring. Sodium nitrate solution (2.1 g in 5 mL deionised water) was added at such a rate that the temperature of reaction did not exceed 7oC. Once this addition was complete the mixture was stirred with cooling for 10 minutes before being allowed to warm to room temperature. Zinc dust (4.0 g) was added to the reaction mixture in small portions so that the mixture refluxed gently, the reaction mixture was then heated to reflux for one hour. The mixture was then allows to cool and the excess zinc to settle. While still hot the solution was decanted into stirred cold water (200 mL) precipitating the crude product. The zinc residue was washed with warm glacial acetic acid (2 x 5 mL) and this was added to the aqueous solution. This suspension was allowed to stand for 10 minutes, before being filtered, washed (water 2 x 10 mL) and air dried. The crude product was recrystallised from ethanol to yield a yellow solid 3. 26% yield (1.83 g); Elemental analysis for C12H17NO4: C: 54.918%, H: 6.704%, N: 5.122% (Theoretical: C: 60.24%, H: 7.16%, N: 5.85%, Loss:26.75%); Mr 239.2 g mol-1; ν/cm-1: 1259.48 (N-C), 1667.41 (C=C), 1688.41 (C=O), 2976.58 (C-H), 3265.02 (N-H); 1H-NMR (400 MHz, CDCl3), δ/ppm: 1.24 and 1.38 (dt, 3H, C-CH3, C12 and C15), 2.51 and 2.56 (ds, 6H, 2 x =C-CH3, C6 and C7), 4.31 (m, 4H, 2 x -CH2-, C11 and C14), 5.3 (s, 1H, N5-H); 13C-{1H}-NMR (400 MHz, CDCl3), δ/cm-1:11.98 (C6 and C7), 14.43 (C12 and C15), 59.50 and 60.29 (C11 and C14), 133.5 (C3), 117.5 (C1), 131.3 (C2), 138.6 (C4), 165.47 (C8 and C9) . Results and Discussion Product 3 was formed i... ... middle of paper ... ...nal peaks in the spectrum are at much higher wavenumbers because of the lighter elements involved. The C-H stretch is at 2976.58 cm-1 and the N-H stretch is at 3265.02 cm-1. These peaks all correspond well with the literature values2. Conclusion Product 3 was isolated in a low yield of 27% and with some solvent impurities as shown by the analytical techniques but it was indeed synthesised successfully. On repeating this experiment more care should be taken when purifying to remove the solvent impurities and minimise loss of crude product. References 1. H. E. Gottleib, V. Kotlyar and A. Nudelman, J. Org. Chem., 1997, 62, 7512. 2. E. Fabiano and B. T. Golding, J. Chem. Soc. Perkin Trans., 1991, 3371. Appendix 1 Figure 2 1H-NMR spectrum of product 3. Figure 3 13C-NMR spectrum of product 3. Figure 4 IR spectrum of product 3.
In a small reaction tube, the tetraphenylcyclopentadienone (0.110 g, 0.28 mmol) was added into the dimethyl acetylene dicarboxylate (0.1 mL) and nitrobenzene (1 mL) along with a boiling stick. The color of the mixed solution was purple. The solution was then heated to reflux until it turned into a tan color. After the color change has occurred, ethanol (3 mL) was stirred into the small reaction tube. After that, the small reaction tube was placed in an ice bath until the solid was formed at the bottom of the tube. Then, the solution with the precipitate was filtered through vacuum filtration and washed with ethanol. The precipitate then was dried and weighed. The final product was dimethyl tertraphenylpthalate (0.086 g, 0.172mmol, 61.42%).
Every 5 minutes, a small amount of mixture was dissolved in acetone (0.5 mL) and was spotted onto a thin layer chromatography (TLC) plate, which contained an eluent mixture of ethyl acetate (2 mL) and hexanes (8 mL). The bezaldehyde disappearance was monitored under an ultraviolet (UV) light. Water (10 mL) was added after the reaction was complete, and vacuum filtrated with a Buchner funnel. Cold ethanol (5 mL) was added drop-by-drop to the dried solid and stirred at room temperature for about 10 minutes. Then, the solution was removed from the stirrer and place in an ice bath until recrystallization. The recrystallized product was dried under vacuum filtration and the 0.057 g (0.22 mmol, 43%) product was analyzed via FTIR and 1H NMR
The solvent should be easily removed from the purified product, not react with the target substances, and should only dissolve the target substance near it’s boiling point, but none at freezing. A successful recrystallization uses minimum amount of solvent, and cools the solution slowly, if done to fast, many impurities will be left in the crystals. Using the correct solvent, in this case ice water and ethyl acetate, the impurities in the compound can be dissolved to obtain just the pure compound. A mixed solvent was used to control the solubility of the product. The product is soluble in ethanol an insoluble in water. Adding water reduced solubility and saturates the solution and then the crystals
Data Table 3 indicates the observations from these tests. Though a control test for each test wasn’t prepared, due to the starting reagents being unattainable, the results clearly show that the product is unsaturated. An unsaturated compound means that there is/are bonds in its structure. The product was also analyzed by infrared spectroscopy and gas chromatography. The spectrums obtained allowed one to determine the composition of 1-methylcyclohexene; any impurities and excess products were observed as well. From the infrared spectrum, there is a little peak around 3300-3500 cm-1; this indicated a very little presence of alcohol in the product and thus, most of the alcohol has been successfully removed. If one compared the IR spectrum of the product to the starting material, 2-methylcyclohexanol, one could clearly see the change in peak size of the O-H stretch. The infrared spectrum of 1-methylcyclohexene also depicted a C-H stretch and an alkene functional group at 500-1500 cm-1 and 2932.54cm-1, respectively. From the gas chromatography spectrum (Data Table 4), the area percentages show that there were three products - peaks 22 through 24 - that were formed from the dehydration experiment. Nevertheless, there are two predominant products, as shown from their high percentages, 3-methylcyclohexene (~24%) and 1-methylcyclohexene
This experiment involves performing various techniques, including heating under reflux, separation, drying, distillation, gas chromatography (GC), infrared spectroscopy (IR spectroscopy), and nuclear magnetic resonance (1H NMR). Heating under reflux is important to overcome any activation barrier of energy that may be present in order to complete the reaction.
Procedure: A sand bath was set atop a hot plate set at power level 5, while a 10 mL round bottom was prepared with the addition of 14 (0.33 mL) drops of olive oil and 1 mL of cyclohexene. Once the contents of the 10 mL round bottom were mixed thoroughly, a boiling chip was added, and the round bottom was attached to a reflux condenser apparatus. The reflux was run for 20 minutes starting at the point in time when the mixture within the round bottom flask (that was submerged in the heated sand bath) began to boil. While the running the reflux, a 5 ¾ inch Pasteur pipette was obtained and clamped vertically with the tip facing downward. A small amount of glass wool was placed inside of the pipette and pushed down to block the narrowing end by a wooden boiling stick. A total of 100 mg (0.100 g) of celite was weighed out and was carefully added into the pipette as an additional layer atop the glass wool stopper.
A bath was prepared using a 400 mL beaker filled halfway with water. The bath was then sat on a hot plate and lest to boil. 2g of salicylic acid was placed in a 125 mL Erlenmeyer flask with 3 mL of acetic anhydride, and 3 drops of concentrated sulfuric acid. The solutions were mixed and placed in the boiling water bath. The solution was left in the boiling bath for 30 minutes. The 125 mL Erlenmeyer flask was removed and placed on the side to cool to room temperature. Once cooled the solution was placed into a 150 mL Beaker that was filled with 20 mL of ice water. As the beaker was placed in the ice bath, it was simultaneously scraped with a glass rod until crystals formed at the bottom of the beaker. The crystal solution was poured into a Buchner
The purpose and goal of this experiment is to separate a mixture of fluorene and 9-fluorenone through the method of column chromatography, and then determine the purity of the isolated compounds through thin-layer chromatography (TLC), as well as melting point analysis. Through column chromatography, gravity is utilized to move the solvent and compounds down the column, where the changes in the solvent polarity assists in eluting the desired compounds to separate fractions. Each fraction solvents can then be evaporated to obtain the compounds of interest. Through TLC, a thin layer of polar and hydrophilic silica gel on an inert sheet is used to spot the sample on the bottom of the sheet and is then developed in a jar of eluent, where through
The solutions were then stirred with separate stirring rods to mix the NaCl solution and the deionised water into a homogeneous solution.
After figuring out the mass of the empty beaker to be 72.5 grams, 100 milliliters of water were heated using a hot plate. The water warmed just below boiling. Once the beaker of water was removed from the hot plate, 12.1 grams of copper (II) sulfate was added. Once the copper (II) sulfate was stirred, 1.5 grams of iron filling was added to the beaker and set to allow the copper to settle on the bottom of the beaker. Once the beaker was cool enough to touch and the copper was settled to the bottom, we began the decanting process. Decanting was used to remove the limiting reagent, the iron sulfate compound, to dry out the excess reagent, the copper. The copper was decanted twice again with water to clean off any left over iron sulfate compound. Then the copper was covered with acetone and put in an oven for 15 minutes to dry completely. Once the copper was dried, the electronic balance was used again to measure the mass of the beaker and the copper. Once this mass was calculated to be 75.2 grams, the empty beaker’s mass of 72.5 grams was subtracted from it to give us the total mass of the copper, which was 2.68 grams. We knew a reaction occurred when a solid formed at the bottom of the
Remove the extra solvent on a steam bath under a hood while flushing the flask with N2 gas, leaving the crude extract. Weigh extract.
In order to separate the mixture of fluorene, o-toluic acid, and 1, 4-dibromobenzene, the previously learned techniques of extraction and crystallization are needed to perform the experiment. First, 10.0 mL of diethyl ether would be added to the mixture in a centrifuge tube (1) and shaken until the mixture completely dissolved (2). Diethyl ether is the best solvent for dissolving the mixture, because though it is a polar molecule, its ethyl groups make it a nonpolar solvent. The compounds, fluorene and 1, 4-dibromobenzene, are also nonpolar; therefore, it would be easier for it to be dissolved in this organic solvent.
The conical vial was placed in a small beaker and allowed to cool to room temperature. The mixture was Cooled thoroughly in an ice bath for 15-20 minutes and crystals collected by vacuum filtration on a Hirsch funnel. The vial was rinsed with about 5 mL of ice water and transferred into to the Hirsch funnel and again washed with two additional 5mL portions of ice water. Crystals were dried for 5-10 minutes by allowing air to be drawn through them while they remained on the Hirsch funnel. The product was transferred to a watch glass plate and allow the crystals to dry in air. Crude acetaminophen product was weighed and set aside a small sample for a melting point determination and a color comparison after the next step. Calculation of the percentage yield of crude acetaminophen (MW = 151.2). was done and recorded in the lab notebook.
Complex formation of the zinc ion with different accelerators is critical to get efficient curing. A preceding reaction with stearic acid forms the hydrocarbon-soluble zinc stearate and liberates water before the onset of crosslinking
The Knorr synthesis of the pyrrole, 2,4-diethoxycarbonyl-3,5-dimethylpyrrole, was achieved using an α-amino ketone, ethyl acetoaminoacetate and reacting it with its predecesso r, ethyl acetoacetate in a double condensation reaction . The product was analysed by 1H NMR, 13C NMR, mass spectrometry and IR spectroscopy giving positive results .