Abstract
Four pyrazole compounds, 3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbaldehyde (1), 5-(4-bromophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazole-1-carbaldehyde (2), 1-[5-(4-chlorophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone (3) and 1-[3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl]propan-1-one (4), have been prepared by condensing chalcones with hydrazine hydrate in the presence of aliphatic acids, namely formic acid, acetic acid and propionic acid. The structures were characterized by X-ray single crystal structure determination. The dihedral angles formed between the pyrazole and the fluoro-substituted rings are 4.64(7)° in 1, 5.3(4)° in 2 and 4.89(6)° in 3. In 4, the corresponding angles for molecules A and molecules B are 10.53(10)° and 9.78(10)°, respectively.
Highlights
The reaction of chalcones with hydrazine derivatives is one of the most extensively applied reactions in organic synthesis
In view of importance of pyrazolines and in continuation of our work on the synthesis and structure determination of various pyrazoline derivatives [12,13,14,15], we report the synthesis and crystal structures of four novel N-substituted pyrazolines
One of the most convenient methods for the synthesis of pyrazolines is the reaction of α,β-unsaturated ketones with hydrazine hydrate and its derivatives
Summary
The reaction of chalcones with hydrazine derivatives is one of the most extensively applied reactions in organic synthesis. Investigations revealed that in most cases the products formed are Molecules 2013, 18 pyrazoline derivatives [1,2,3,4]. The reactions may produce pyrazole derivatives [5] and Schiff base hydrazones [6]. These reactions are usually carried out in an acidic medium. Pyrazoline derivatives with a phenyl group at the 5-position have been shown to possess good film-forming properties and exhibit excellent characteristics of blue photoluminescence, fluorescence and electroluminescence [11]. In view of importance of pyrazolines and in continuation of our work on the synthesis and structure determination of various pyrazoline derivatives [12,13,14,15], we report the synthesis and crystal structures of four novel N-substituted pyrazolines
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