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17th August 2011 @ 02:07
Incomplete reaction. Pyrrole formed.


See also: Paal-Knorr Synthesis of 1-aryl-2,5-dimethyl Pyrrole Core (PMY 1-1)

Condensation of 4-fluoroaniline and 2,5-hexanedione to form 1-(4-fluorophenyl)-2,5-dimethyl-1H-pyrrole in toluene at reflux.

Reaction Scheme PY12.png

Experiment start time: 12.20 EST 17/08/2011
4-fluoroaniline (333 mg, 3 mmol, 1 equiv.) and 2,5-hexanedione (342 mg, 3 mmol, 1 equiv.) were stirred in toluene (5 mL) at reflux. After 1 hour a new product was observed by TLC. At 4 hours baseline starting materials still remain. After 24 hours the product spot appeared larger but the reaction was still incomplete. The reaction was cooled. Diethyl ether (10 mL) and the mixture was dried (MgSO4) and filtered before concentration under reduced pressure to obtain a brown oil (561 mg). Crude 1H NMR consistant with pyrrole, 4-fluoroaniline, and 2,5-hexanedione (62:17:22 respectively by NMR). After overnight at room temperature, brown oil is now a brown crystalline solid. Attempted recrystallisation (EtOH/H2O) resulted in a oil. Has not crystallised (0833 EST 22/08/11).

TLC (10% EtOAC/petrol) visualised by UV and vanillin:
Reaction TLC PY12TLC.jpg

TLC after drying (middle spot):
Crude product TLC

Mass Spectrometry (ESI +/-):
No mass ions consistant with SM or products were observed. 11.41 EST 18/08/2011

1H NMR Spectra

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