Synthesis
The general procedure for the synthesis of 3-acetylthiophene from 3-ethynylthiophene was as follows: a mixture of 3-ethynylthiophene (232 mg, 2.0 mmol) and S-COPNA (NP) resin (59 mg, 0.2 mmol) in H2O (4 mL) was subjected to refluxing conditions (bath temperature of 120°C) and the reaction was stirred for 8 h at 600 rpm. After completion of the reaction, the catalyst was removed by filtration and washed sequentially with H2O and heptane. A drop of saturated NaHCO3 solution was added to the organic layer, followed by evaporation of the organic solvent under reduced pressure. The residue was purified by column chromatography using heptane-acetone (20:1) as eluent to give finally 3-acetylthiophene (225 mg, 84% yield).
Purification Methods
Recrystallise the thiophene from pet ether (b 30-60o) or EtOH. The 2,4-dinitrophenylhydrazone crystallises from CHCl3, m 265o, and the semicarbazone crystallises from EtOH, m 174-175o. [Campaigne & Le Suer J Am Chem Soc 70 1555 1948, Beilstein 17/9 V 399.]
References
[1] Applied Organometallic Chemistry, 2012, vol. 26, # 12, p. 722 - 726
[2] Tetrahedron Letters, 2017, vol. 58, # 10, p. 955 - 958
[3] Tetrahedron Letters, 2014, vol. 55, # 8, p. 1444 - 1447
[4] ChemSusChem, 2013, vol. 6, # 3, p. 430 - 432
