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Transition‐Metal‐Free Direct C‐H Arylation of Thiophene in Aqueous Media via Potassium Peroxymonosulfate
Author(s) -
Özenler Sezer,
Kaya Hakan,
Elmaci Nuran,
Yildiz Umit Hakan
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201901508
Subject(s) - chemistry , monomer , tetramer , trimer , thiophene , aqueous solution , nuclear magnetic resonance spectroscopy , catalysis , bromide , absorbance , potassium persulfate , transition metal , dimer , polymer chemistry , photochemistry , inorganic chemistry , organic chemistry , polymer , chromatography , enzyme
Abstract This study covers the use of potassium peroxymonosulfate (PPS) which, is a mild and inexpensive catalyst, for direct coupling of C–H/C–H for water soluble thiophene. The 3‐(4‐methyl‐3′‐ thienyloxy)propyltriethylammonium bromide (M1) has been selected as model monomer that reacted PPS in 2.0, 0.20 and 0.020 monomer to PPS ratio. The reaction has been monitored via NMR spectroscopy revealing the monomer consumption and formation of dimers to tetramers as well as completion of reaction within 15 minutes. Resultant product is easily collected without tedious work up steps. The computational calculation has optimized the regularity of the coupling as head to tail, tail to tail, head to tail (HT‐TT‐HT) for tetramer. The regularity of tetramer which is further satisfied via NMR analysis showing emergence of new peaks at 3.56 and 4.48. The shifts in the UV maximum of reactive species have been monitored by absorbance spectroscopy showing time dependent red shift corresponds to growing from monomer to tetramers. The reaction has self‐stopped due to low solubility of moderate condensates (higher than trimer), however further experiments have performed in water‐organic mixtures showed great promises to obtain higher condensates.