Jurnal Kimia Sains dan Aplikasi 25 (9) (2022): 316–321 316 ISSN: 1410-8917 e-ISSN: 2597-9914 Jurnal Kimia Sains dan Aplikasi 25 (9) (2022): 316–321 Jurnal Kimia Sains dan Aplikasi Journal of Scientific and Applied Chemistry Journal homepage: http://ejournal.undip.ac.id/index.php/ksa Synthesis of Cardanol-Based Acetaldehyde Novolac Resin from Cashew Nut Shell Liquid (CNSL) Soerya Dewi Marliyana a,* , Sayekti Wahyuningsih a , Nisa Nur Hayati a a Department of Chemistry, Faculty of Sciences and Mathematics, Sebelas Maret University, Surakarta, Indonesia * Corresponding author: msoerya@staff.uns.ac.id https://doi.org/10.14710/jksa.25.9.316-321 Article Info Abstract Article history: Received: 15 th August 2022 Revised: 22 nd November 2022 Accepted: 24 th November 2022 Online: 23 rd December 2022 Keywords: CNSL; isolation; cardanol; novolac resin Polymers are currently in the limelight. Phenolic resin is one of the polymer products obtained from the polymerization process, either from natural or synthetic sources. One of the natural compounds that can be applied to polymers is cardanol. This study aimed to synthesize cardanol-based acetaldehyde novolac resin from Cashew Nut Shell Liquid (CNSL). Isolation of cardanol from CNSL was done by liquid-liquid extraction method with acetone and purified by gravity column chromatography in a mixture of n-hexane and ethyl acetate in a ratio of 9:1. HPLC analysis showed that cardanol compounds had aliphatic chains with different levels of saturation and the yield was 18.48%. The cardanol- acetaldehyde novolac resin was synthesized through a condensation polymerization reaction with a cardanol-acetaldehyde mole ratio (1:0.5), using HCl as a catalyst. FTIR and 1 H-NMR analysis were employed to identify the novolac resin structure. The product was a brownish-orange solid with a yield of 12.80 mg (40%) and followed ortho-ortho substitution. Cardanol is one of the natural phenol sources that might be utilized to manufacture novolac resins. 1. Introduction Cardanol is a promising natural resource since it is obtained from a by-product of the cashew nut industry known as cashew nut shell liquid (CNSL). Utilization of CNSL as a source of cardanol is secure and more environmentally friendly [1]. This compound can be employed as a source of natural phenol in manufacturing phenol-formaldehyde resins because it contains a C15 unsaturated hydrocarbon chain with one to three meta- position double bonds in the phenol group [2, 3]. Cardanol has a series of unsaturated hydroxy groups, aromatic rings, and hydrophobic alkyl groups, which make it a potential renewable polymer material [4]. Cardanol has been extensively researched as a modifier for phenolic resins due to its simple polymerization and structural similarity to phenol. Cardanol can react with formaldehyde under various conditions to produce resole or novolac resins, depending on the catalyst used [5]. Cardanol structure is shown in Figure 1. The production of novolac resin is done with a certain mole ratio using an acid catalyst such as adipic acid, oxalic acid, succinic acid, sulfuric acid, hydrochloric acid, or tricarboxylic acid, for instance, citric acid [6, 7]. Tiwari et al. [8] have synthesized novolac resin by reacting cardanol and formaldehyde with a mole ratio of 1:0.8 using citric acid as a catalyst. Sangeetha [6] synthesized novolac resin using cardanol-formaldehyde (1:0.9) with a malonic acid catalyst. Figure 1. The chemical structure of cardanol [9] Most novolac resins are derived from cardanol and formaldehyde, although the acquired products are unsatisfactory. Synthesis of novolac resin using cardanol-formaldehyde still has some drawbacks, such as weak chemical stability, low flexibility, and poor adhesion; therefore, novolac resin must be modified to improve its chemical stability, flexibility, and adhesion [10, 11]. A modification was developed by reacting cardanol and acetaldehyde to obtain a novolac resin with Jurnal Kimia - Sains & Aplikasi Check for updates saturated R = monoena R = diena R = triena R =