Heterocyclic Tautomerism. II. 4-Acylpyrazolones. X-Ray Crystal Structures of 4-Benzoyl-5-methyl-2-phenylpyrazol-3(2H)-one and 4-Acetoacetyl-3-methyl-1-phenylpyrazol-5-ol

Abstract

The colourless crystalline form of the benzoylpyrazolone (2) has molecules with the NH structure (2c) stabilized by intermolecular hydrogen bonds. At room temperature crystals are monoclinic: P21/c, a 13.508(5), b 9.124(4), c 11.451(3)Ǻ, β 90.80(3)°, Z4; the structure was refined to R 0.059, Rw 0.048. The acetoacetylpyrazolone (3) has the OH structure (3c) with two intramolecular hydrogen bonds. At 193 K crystals are triclinic: Pī , a 7.142(2), b 13.704(8), c 14.699(7)Ǻ, α 117.36(3), β 96.87(3), γ 93.73(3)°, Z 4; the structure was refined to R 0.049, Rw 0.054.

Spectroscopic Studies of the Keto and Enol Tautomers of 1-Phenyl-3-Methyl-4-Benzoyl-5-Pyrazolone

“…Chemical structures of the two forms of PMBP are shown in Scheme 1. Other possible structures of PMBP have also been proposed by many workers (3)(4)(5)(6). We suggest that in the crystal state, the compound mainly exists in the two forms shown above.…”

“…Many studies deal with the tautomerism of 1-phenyl-3-methyl-5-pyrazolone and its 4-acyl derivatives (1)(2)(3). One of its important substituents is 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP).…”

Keto and Enol Tautomers of 4-Benzoyl-3-methyl-1-phenyl-5(2H)-pyrazolone

“…Further, a number of studies (Akama, Saito, Hayashi, Sato, Tanaka & Kanno, 1993;Zeigan, Engelhardt & Uhlemann, 1981;Maquestiau, Van Haverbeke & Muller, 1975;Wamhoff, Schramm & Korte, 1971) have been made on the ketoenol tautomerism of (1). The structures of the keto form of (1) (O'Connell, Ramsay & Steel, 1985) and a Cu complex of (1) (Miao, Liu & Li, 1991) have been determined, but the crystal structure of the enol form has not yet been determined. This work describes the crystal and molecular structure of the enol form, and provides a more precise structure of the keto form.…”

Novel triorganotin(IV) complexes of β-diketonates bearing two heterocycles in their structures

“…1 H (CDCl 3 ) NMR (293K): d, 2.22s, 2.44s (3H, C3-CH 3 ), 6.53br,6.61br,7.40m,7.64m,7.76m (23H, H 5 , C(@O)C 4 H 3 O and N-C 6 H 5 ). 13 7.05br, 7.10t, 7.30-7.50m, 7.60m 7.70t, 7.87br (23H, Sn-C 6 H 5 , C(@O)C 4 H 3 S and N-C 6 H 5 ). 13 6.56dbr, 7.21br, 7.26t, 7.42t, 7.63br, 7.78d (8H, C(@O)C 4 H 3 O and N-C 6 H 5 ).…”

“…13 7.05br, 7.10t, 7.30-7.50m, 7.60m 7.70t, 7.87br (23H, Sn-C 6 H 5 , C(@O)C 4 H 3 S and N-C 6 H 5 ). 13 6.56dbr, 7.21br, 7.26t, 7.42t, 7.63br, 7.78d (8H, C(@O)C 4 H 3 O and N-C 6 H 5 ). 13 7.11t, 7.25t, 7.39t, 7.59d, 7.73t (8H, C(@O)C 4 H 3 S and N-C 6 H 5 ).…”