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 5 °C under stirring. A sodium nitrate solution (2.1 g in 5 mL of 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 while cooling for 10 minutes before being allowed to warm to room temperature. Zinc powder (4.0 g) was added to the reaction mixture in small portions so that the mixture gently refluxed, the reaction mixture was then heated to reflux for one hour. The mixture was then allowed to cool and allow the excess zinc to settle. While still hot, the solution was decanted in stirred cold water (200 mL), causing the crude product to precipitate. The zinc residue was washed with hot 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 (2 x 10 mL water) and air dried. . The crude product was recrystallized from ethanol to give a yellow solid in 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 (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 in… midway through the paper… the final peaks in the spectrum are much higher wavenumbers due to the lighter elements involved. The CH stretch is at 2976.58 cm-1 and the NH stretch is at 3265.02 cm-1. All these peaks correspond well to the literature values2. Conclusion Product 3 was isolated in a low yield of 27% and with some solvent impurities, as shown by analytical techniques, but was indeed successfully synthesized. When repeating this experiment more care must be taken during purification to remove solvent impurities and minimize loss of crude product.References1. H. E. 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 1Figure 2 1H-NMR spectrum of the product 3.Figure 3 13C-NMR spectrum of the product 3.Figure 4 IR spectrum of the product 3.