The Knorr synthesis of pyrrolesExperimentalA mixture of ethyl acetoacetate 1 (7.52 g, 7.5 ml) in glacial acetic acid (18 ml) was prepared and cooled to 5°C with stirring. Sodium nitrate solution (2.1 g in 5 mL deionized water) was added at a rate such that the reaction temperature did not exceed 7 °C. 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 is then allowed to cool and the excess zinc is decanted. While still hot, the solution was decanted into cold stirred water (200 mL), precipitating the crude product. The zinc residue was washed with hot glacial acetic acid (2 x 5 ml) and added to the aqueous solution. This suspension was left to stand for 10 minutes, before being filtered, washed (2 x 10 ml water) and air dried. . The crude product was recrystallized from ethanol to give a yellow solid in a yield of 3.26% (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%) ; M. 239.2 g mol-1; ν/cm-1: 1259.48 (NC), 1667.41 (C=C), 1688.41 (C=O), 2976.58 (CH), 3265.02 (NH); 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 middle of paper......the final peaks of the spectrum are at many higher wavenumber levels due to the lighter elements involved. The CH section is at 2976.58 cm-1 and the NH section is at 3265.02 cm-1. These peaks all match well with literature values2.ConclusionProduct 3 was isolated in a low yield of 27% and with some solvent impurities as shown by analytical techniques, but it was indeed synthesized successfully. When repeating this experiment, one should be more careful during purification. to remove impurities from the solvent and minimize loss of raw product.References1. SE Gottleib, V. Kotlyar and A. Nudelman, J. Org. Chem., 1997, 62, 7512.2. E. Fabiano and BT 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.