~ 1106 ~ International Journal of Chemical Studies 2018; 6(5): 1106-1110 P-ISSN: 2349–8528 E-ISSN: 2321–4902 IJCS 2018; 6(5): 1106-1110 © 2018 IJCS Received: 16-07-2018 Accepted: 17-08-2018 Bayu Ardiansah, Department of Chemistry, FMIPA, Universitas Indonesia Kota Depok, Indonesia Lina Mardiana, Department of Chemistry, FMIPA, Universitas Indonesia Kota Depok, Indonesia Ridla Bakri Department of Chemistry, FMIPA, Universitas Indonesia Kota Depok, Indonesia Siti Sarah Qomariah Department of Chemistry, FMIPA, Universitas Indonesia Kota Depok, Indonesia Correspondence Bayu Ardiansah, Department of Chemistry, FMIPA, Universitas Indonesia Kota Depok, Indonesia Synthesis and radical scavenging evaluation of 4- (3-(2-hydroxyphenyl)-4, 5-dihydro-1H-pyrazol-5- yl)-2-methoxyphenol Bayu Ardiansah, Lina Mardiana, Ridla Bakri and Siti Sarah Qomariah Abstract Sodium impregnated on activated chicken eggshells (Na-ACE) has been utilized as an eco-friendly and green catalyst for the synthesis of a pyrazoline derivative, 4-(3-(2-hydroxyphenyl)-4, 5-dihydro-1H- pyrazol-5-yl)-2-methoxyphenol via chalcone intermediate. The highest yield of chalcone (65%) was obtained from the reaction with 25% wt. catalyst at 60 o C for 8h. Meanwhile, the best yield of pyrazoline (54%) was isolated from the reaction with 20% wt. catalyst at 60 o C for 4h reaction time. The structure of organic compounds was confirmed using FT-IR, UV-Vis and LC-MS. In free radical scavenging evaluation, pyrazoline derivative exhibit antiradical activity with IC50 value of 20.45 μg/ml. Keywords: Free radical, chalcone, pyrazoline, solid catalyst, Na-ACE 1. Introduction Pyrazoline is a class of heterocyclic compounds which is rarely found in natural products. Pyrazoline and its derivatives have been known to have various biological activities such as anti-inflammatory [1] , antitumor and antimalarial [2] , analgesic [3] and antibacterial [4] . With their biological advantages and potential as drug candidates, it is necessary to develop green synthesis methods of pyrazoline derivatives. Synthesis of pyrazolines can be carried out by reacting α, β-unsaturated carbonyl compounds with hydrazine or its derivatives in acidic or alkaline conditions [5] . Chalcone, a type of α, β- unsaturated carbonyls, is a multifunctional organic compounds in the synthesis of various heterocycles [6] . Chalcone is an intermediate of flavonoids with C6-C3-C6 carbon skeleton. It can be synthesized through Aldol condensation reactions using several types of catalysts like NaOH [7] , KOH [8] , acidic ionic liquids [9] , activated carbon [10] and kaolin [11] . These catalysts can promote the formation of chalcones in good yields, but some of them have limitations such as corrosive, require complex reactor/ equipment setting and use of toxic solvents [12, 13] . Thus, environment-friendly materials or protocols are needed for the synthesis of chalcone and pyrazoline compounds. In this study, pyrazoline compound, 4-(3-(2-hydroxyphenyl)-4, 5-dihydro-1H-pyrazol-5-yl)-2- methoxyphenol will be synthesized from the reaction between chalcone compound 3-(4- hydroxy-3-methoxyphenyl)-1-(2-hydroxyphenyl) prop-2-en-1-one and hydrazine hydrate. Meanwhile, chalcone compound will be prepared from the reaction between 2- hydroxyacetophenone and vanillin via Aldol condensation (Scheme 1 and 2). Sodium impregnated on activated chicken eggshells (Na-ACE) will be used as heterogeneous catalyst to speed-up these reactions. The material has been prepared under same conditions in our previous work. Furthermore, the ability of chalcone and pyrazoline compounds to inhibit free radical will be evaluated in vitro using DPPH method. Scheme 1: Synthesis of chalcone