The novel synthetic route of 3,5-dimethyl-1-(3-phenylpropyl)-1H-pyrazole under solid–liquid phase transfer catalysis conditions assisted by an ultrasound application—A study of some kinetic parameters

•A study of some kinetic parameters of synthesizing 3,5-dimethyl-1-(3-phenylpropyl)-1H-pyrazole.•Phase transfer catalysis assisted by ultrasonic irradiation.•Interfacial mechanism.•THAB as effective catalyst.•Excess bromo benzene as good supporting organic solvent.•Aromatic involved NH center avails for alkylation with simple phase transfer catalysts.

The kinetic study for synthesis of 3,5-dimethyl-1-(3-phenylpropyl)-1H-pyrazole was studied successfully by reacting the 3,5-dimethyl pyrazole with 1-bromo-3-phenyl propane under phase transfer catalysis and ultrasonic irradiation conditions using aqueous solution of NaOH (5 g or 0.25 g/ml), excess amount of bromobenzene and tetrahexyl ammonium bromide as a phase transfer catalyst. The reaction was carried out at 40 °C under pseudo-first order conditions and was monitored by gas chromatography (GC). Kinetic reaction found to follow ‘pseudo first order’ rate law. From the experimental data, a rate expression had been developed to explain the kinetic behavior of the reaction from which the apparent rate constant (kapp) of the organic phase was attained. The effects of agitation speed, amount of sodium hydroxide, effect of quaternary ammonium salts, amount of catalyst and temperature on the reaction were also studied.

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