Microwave-Assisted Synthesis of Arylidene Acetophenones

An efficient synthesis of arylidene acetophenones have been achieved by using the microwave heating in comparison to the conventional heating. In this work compound 1-phenyle-3-(4-droxyphenyle)-2-propen-1-one, 1-(4-chlorophenyle)-3-phenyle-2-propen-1-one, and 1-(4-chlorophenyle)-3-(4-hydroxyphenyle)-2-propen-1-one have been synthesized by the condensation reaction between aromatic aldehydes and substituted acetophenones under microwave irradiation. The compounds of aldehydes and acetophenones were used as benzaldehyde, parahydroxybenzaldehyde, acetophenone, and parachloroacetophenone. The result shows that the time taken for the reaction was reduced from the conventional 1-2 hours to 60–120 seconds. The yield of the compounds in the conventional heating was moderate while the highest yield of 90–98% was observed in MWI method. The structure of the compounds was characterized by their IR, 1H-NMR spectral data. 1. Introduction High-speed synthesis with microwave has attracted a considerable amount of attention in recent years [1]. The use of microwave heating to accelerate organic chemical transformations was first reported by the groups of Gedye et al. and Giguere et al. [2, 3], although it can be traced back to the 1950s. While most of the early pioneering experiments in the area of microwave-assisted organic synthesis (MAOS) were performed in domestic, sometimes modified, kitchen microwave ovens, the current trend is to use dedicated instruments which have only become available in the last few years for chemical synthesis. The aim of this work was to highlight the comparative synthesis of organic compound in microwave heating and conventional heating. Microwaves are a form of electromagnetic energy that can be transferred to the subject compound by the interaction of the electric-field component of the wave with charged particles in the compound. Microwave energy absorbed by the compound will be converted into heat; however, not all materials can be heated by microwaves. The compounds, which absorb the microwave radiations, are termed dielectrics and characterized by possessing very few free charge carriers and exhibiting a dipole movement [4]. When the microwaves are applied to dielectric compounds with an oscillating electric field, the dipoles within the material attempt to realign themselves and flip around the applied field. Under microwave irradiation at 2.45？GHz, the dipoles realign themselves approximately 2.5 billion times per second due to the alternating electromagnetic field [5]. The dipole movement generates friction inside dielectric