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 . Introduction Pyrrole has been a molecule of great interest due to its heterocyclic aromatic properties. The lone pair on the nitrogen is delocalised within the ring, causing the heterocycle to be electron-rich . This causes the ring to become increasingly nucleophilic, and therefore makes it susceptible to attack from electrophiles . The addition of these new substitutions makes more important molecules , which have a huge contribution to not only the chemical industry, but also the biological. 1 Substituted pyrrole molecules are fantastic precursors to make complex molecules, such as medicines, agrochemicals and dyes. Indole, an important benzo-pyrrole, is the basis of the important protein, tryptophan and has functions as a neurotransmitter in the brain. The neurotransmitter, serotonin, is important in making modern drugs such as sumatriptan which treats migraines.2 Pyrrole synthesis can be achieved by a vast number of methods. Some of the most common processes used in today’s laboratory include the Hantzch pyrrole method, Paal-Knoor Knorr synthesis and the Knoorr synthesis; the latter which will be studied in this experiment. Other complex methods explored include Robinson’s utilization of the reaction between an aldehyde and a hydrazine . However, this method requires high temperatures which are not economically favourable to maintain and so the other classic methods are gene... ... middle of paper ... ...ential of the reaction and products. References Works Cited 1. V. Amarnath, D. C. Anthony, K. Amarnath, W. M. Valentine, L. A. Wetterau, D. G. J. Org. Chem. 1991, 56, p. 6924-6931. 2. J. Clayden, N. Greeves, S. Warren, P. Wothers. Organic Chemistry. 8th ed. 2007, Oxford University Press, p. 1186-1191. 3. G. M. Robinson, R. Robinson. J. Chem. Soc. 1918, p. 639-645. 4. A. H. Corwin. Heterocyclic Compounds. 1950, 1, p. 287. 5. Y. Byun, D. A. Lightner. J. Heterocyclic Chem. 1991, 28. p. 1683-1692. 6. Professor Chris Willis, School of Chemistry, University of Bristol 7. Professor Kevin Booker-Milburn, 2nd Year Heterocyclic notes, School of Chemistry, University of Bristol 8. H. Fischer. Organic Syntheses Coll. 1943, 2, p. 202; H. Fischer. Organic Syntheses Coll. 1935, 15, p. 17. 9. C. Schmuck, D. Rupprecht. Synthesis 2007, 2007, 20, p. 3095-3110.
2. Cooper, M. M., Cooperative Chemistry Laboratory Manual, McGraw-Hill: New York, NY, 2009, p. 60.
Wittig reactions allow the generation of an alkene from the reaction between an aldehyde/ketone and an alkyl halide (derived from phosphonium salt).The mechanism for the synthesis of trans-9-(2-phenylethenyl) anthracene first requires the formation of the phosphonium salt by the addition of triphenylphosphine and alkyl halide. The phosphonium halide is produced through the nucleophilic substitution of 1° and 2° alkyl halides and triphenylphosphine (the nucleophile and weak base). An example is benzyltriphenylphosphonium chloride, which was used in this experiment. The second step in the formation of the of the Wittig reagent, which is primarily called a ylide and derived from a phosphonium halide. In the formation of the ylide, the phosphonium ion in benzyltriphenylphosphonium chloride is deprotonated by the base, sodium hydroxide to produce the ylide as shown in equation 1.
In a separate beaker, acetone (0.587 mL, 8 mmol) and benzaldehyde (1.63 mL, 16 mmol) were charged with a stir bar and stirred on a magnetic stirrer. The beaker mixture was slowly added to the Erlenmeyer flask and stirred at room temperature for 30 minutes. Every 10 minutes, a small amount of the reaction mixture was spotted on a TLC plate, with an eluent mixture of ethyl acetate (2 mL) and hexanes (8 mL), to monitor the decrease in benzaldehyde via a UV light. When the reaction was complete, it was chilled in an ice bath until the product precipitated, which was then vacuum filtrated. The filter cake was washed with ice-cold 95% ethanol (2 x 10 mL) and 4% acetic acid in 95% ethanol (10 mL). The solid was fluffed and vacuum filtrated for about 15 minutes. The 0.688 g (2.9 mmol, 36.8%, 111.3-112.8 °C) product was analyzed via FTIR and 1H NMR spectroscopies, and the melting point was obtained via
The goal of this lab is to exemplify a standard method for making alkyne groups in two main steps: adding bromine to alkene groups, and followed by heating the product with a strong base to eliminate H and Br from C. Then, in order to purify the product obtained, recrystallization method is used with ethanol and water. Lastly, the melting point and IR spectrum are used to determine the purity of diphenylacetylene.
Physical Chemistry Laboratory Manual, Physical Chemistry Laboratory, Department of Chemistry, University of Kentucky, Spring 2006.
We thank the University of Oklahoma and the chemistry faculty for providing the space, instructions, and equipment for the development of this report and experiment.
The reaction of (-)-α-phellandrene, 1, and maleic anhydride, 2, gave a Diels-Alder adduct, 4,7-ethanoisobenzofuran-1,3-dione, 3a,4,7,7a-tetrahydro-5-methyl-8-(1-methylethyl), 3, this reaction gave white crystals in a yield of 2.64 g (37.56%). Both hydrogen and carbon NMR as well as NOESY, COSY and HSQC spectrum were used to prove that 3 had formed. These spectroscopic techniques also aided in the identification of whether the process was attack via the top of bottom face, as well as if this reaction was via the endo or exo process. These possible attacks give rise to four possible products, however, in reality due to steric interactions and electronics only one product is formed.
Gallagher et al. has established a library of compounds on 6-6 fused bicyclic pyridine. Here 2, 6-difluoropyridine 5.3 underwent nucleophilic substitution with 3-amino-1-propanol to provide 5.4 in 95% yield. It was mesylated and cyclized to give the pyridinium salt 5.5 and eventually mild basic hydrolysis of 5.5 furnished 5.6 in 85% yield (Scheme 5.2).32
Schreuder, Jolanda A. H.; Roelen, Corné A. M.; van Zweeden, Nely F.; Jongsma, Dianne; van der Klink, Jac J. L.; Groothoff, Johan W.
The product was recrystallized to purify it and the unknown filtrate and nucleophile was determined by taking the melting points and performing TLC. Nucleophilic substitution reactions have a nucleophile (electron pair donor) and an sp3 electrophile (electron pair acceptor) with an attached leaving group. This experiment was a Williamson ether synthesis usually SN2, with an alkoxide and an alkyl halide. Conditions are favored with a strong nucleophile, good leaving group, and a polar aprotic solvent.
23. S. Alwarappan, S. Boyapalle, A. Kumar, C.-Z. Li and S. Mohapatra, J. Phys. Chem. C, 2012, 116, 6556–6559
Castka, J. F., Metcalfe, H. C., Davis, R. E., & Williams, J. E. (2002). Modern Chemistry. New York: Holt, Rinehart and Winston.
Miller SL, and Urey HC. 1959 Organic Compound Synthesis on the Primitive Earth. Science 130,
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/
One of the most important uses of organic compounds is in medicine. All living things have four organic molecules - carbohydrates, proteins, lipids and nucleic acids. Without carbon chains and nucleic acids, DNA would not exist. Enzymes which produce chemica...