Synthesis of 9-(4-Methoxyphenyl)-3,3,6,6-tetra-3,4,5,6,7,9- hexahydro-2H-xantene-1 using Lime and Lemon Juice as the Environmentally Friendly Catalyst and Its Antioxidant Activity

The 9-(4-Methoxyphenyl)-3,3,6,6-tetra-3,4,5,6,7,9-hexahydro-2H-xantene-1 compound, which is addressed as compound 1 in this study, is the derivatives of 1,8-dioxo- octahydroxantene. This compound has a carbonyl group and double bond on beta carbon toward the carbonyl group and benzene ring. The presence of this chromophore helps the compound creates intermediate stabilized by resonance from its interaction with free radicals and has the potential to be an antioxidant. Compound 1 was synthesized from p- methoxybenzaldehyde and dimedone through Knoevenagel condensation reaction using an acid as catalyst. The lime and lemon juice was selected as a catalyst to support green chemistry principle. The obtained product includes white powder with a melting point of 222-224oC. The IR analysis results, GC-MS, and 1H-NMR data show that the compound structure of Compound 1. Meanwhile, the antioxidant activity test using the DPPH method reveal that Compound 1 has the antioxidant activity with IC50 of 22.74 ppm

Assisted ultrasonic wave of vanillin derivatives synthesis and antioxidant activity using DPPH method

In recent years, the need for compounds with antioxidant activities have expanded. Generally, the natures of these compounds involve the presence of conjugated double bonds, phenolic groups, and resonance effects on the structure. One of the compounds with the phenolic group is vanillin. It can be modified into the derivative of 1,8-dioxo-octahydroxantene compound due to its aldehyde content. Meanwhile, 1,8-dioxo-octahydroxantene compound has two 2- cyclohexenone rings bound in the pyran ring and one phenolic group, expected to carry more excellent antioxidant activity than vanillin. The 9-(4-hydroxy-3-methoxyphenyl)-3,4,5,6,7,9- hexahydro -1H-xantene-1,8(2H)-dione (Compound 1) was synthesized from 1,3- cyclohexanedione and vanillin through Knoevenagel's condensation reaction aided with an acid catalyst with a single reaction phase. Besides, green chemistry was adopted in this study using environmentally friendly catalysts from lime juice and ultrasonic wave. The synthesized compounds' structure was confirmed through the spectrophotometer IR, GC-MS, and 1H-NMR spectrometer, while its antioxidant activity was tested using the DPPH method. The reaction occurred with and without lime juice catalyst, producing yields of 6.65% and 70.58%, respectively. The results of the antioxidant activity test suggest that Compound 1 carries substantially robust antioxidant activities, with IC50 of 0.99 ppm

Thermodynamic and Infrared Spectroscopy Analysis of Tert-butyl Chloride and Hydroxide Nucleophilic Substitution Reaction Using Computational Method

Reaksi substitusi nukleofilik adalah salah satu reaksi yang penting dan umum dipelajari pada kimia organik. Mekanisme bagaimana reaksi sebenarnya berlangsung dan spesi apa yang berperan pada sistem sehingga terbentuk produk, diulas pada penelitian ini. Pada penelitian ini, dimodelkan reaksi substitusi nukleofilik senyawa tersier butil klorida oleh ion hidroksida. Pemodelan komputasi pada penelitian ini, digunakan software Putty, Marvin, NWChem, Avogadro, dan ECCE Viewer. Hasil akhir perhitungan komputasi, didapatkan besaran termodinamika berupa energi aktivasi 230.9478 kcal mol-1, entalpi reaksi -7101.74808 kcal mol-1, entropi reaksi -40.178 cal/mol-K dan energi bebas Gibbs sebesar 4877.32262 kcal mol-1. Lebih lanjut, kestabilan dan reaktivitas molekul pada reaksi ini, dianalisis menggunakan pemodelan molekul dan spektroskopi infra merah.   Kata kunci: kimia komputasi, substitusi nukleofilik, tersier butil kloridaThe nucleophilic substitution reaction is one of the important and commonly studied in organic chemistry reaction. The mechanism of how the reaction actually takes place and what species play a role in the system so that the product is formed is reviewed in this study. In this study, was modeled the nucleophilic substitution reaction of a tertiary compound butyl chloride by hydroxide ions. Computational modeling in this study, used software Putty, Marvin, NWChem, Avogadro, and ECCE Viewer. The final results of computational calculations obtained thermodynamic quantities in the form of activation energy 230.9478 kcal mol-1, reaction enthalpy -7101.74808 kcal mol-1, reaction entropy -40.178 cal/mol-K and Gibbs free energy of 4877.32262 kcal mol-1. Furthermore, the stability and reactivity of the molecules in this reaction were analyzed using molecular modeling and infrared spectroscopy.   Keywords: computational chemistry, nucleophilic substitution, tertiary butyl chlorid

Bifunctional Catalytic Activity of γ-NiOOH toward Oxygen Reduction and Oxygen Evolution Reactions in Alkaline Solutions

Nickel oxyhydroxides (NiOOHs) are well-known for their superior activity toward oxygen evolution reaction (OER) in alkaline solutions. However, their activity toward oxygen reduction reaction (ORR) has been largely unexplored. There exist three NiOOH polymorphs: α-, β-, and γ-NiOOH, characterized by different interlayer spacing. Although still debated, γ-NiOOH with a large layer spacing has been indicated as the active phase for OER. Here, a highly crystalline γ-NiOOH was prepared in a carbon matrix by the in situ electrochemical transformation of nickel dithiooxamide Ni(dto) in 1 M KOH solution. The catalyst prepared in this way showed low overpotential not only for OER, but also for ORR in alkaline solutions. The onset potential for ORR is ~0.81 V vs. RHE, and the reaction proceeds via the 2e− transfer pathway. The high OER catalytic activity and relatively low ORR overpotential make this nanocomposite catalyst a good candidate for bifunctional OER/ORR catalyst, stable in alkaline solutions

Isolasi dan Optimasi Transesterifikasi Minyak Biji Pepaya (Carica papaya) sebagai Sumber Energi Terbarukan

AbstrakLimbah biji pepaya Indonesia sebanyak 134.904,75 ton, mengandung minyak yang  berpotensi ditransesterifikasi menjadi metal serta berpotensi sebagai biodiesel. Penelitian ini bertujuan untuk menentukan: (1) kondisi optimum sintesis biodiesel dengan dua tahapan reaksi, (2) karakter metil ester sintetis melalui transesterifikasi, dan (3) komponen metil ester sintetis serta potensinya sebagai biodiesel. Tahapan penelitian eksperimental laboratoris ini, yaitu: (1) ekstraksi minyak biji  pepaya, (2) sintesis metil ester dari minyak biji pepaya, (3) karakterisasi metil ester sintetis dan uji potensi biodiesel meliputi penentuan densitas, viskositas, indeks bias, dan uji bilangan asam, dan (4) identifikasi komponen metil ester sintetis dengan GC-MS. Rendemen tertinggi metil ester sintetis diperoleh 75,82% b/b pada konsentrasi katalis KOH 1% b/b dengan karakteristik viskositas 4,76 cSt, massa jenis 0,85 g/mL, bilangan asam 0,70 mg KOH/g, dan indeks bias 1,44, maka metil ester sintetis telah memenuhi SNI 04-7182-2006 dan berpotensi sebagai biodiesel. Hasil uji GC-MS menunjukkan adanya metil palmitat 14,58%, metil oleat 78,87%, dan metil stearat 4,57%

Synthesis of biodiesel from waste cooking oil using heterogeneous catalyst of Na₂O/γ-Al₂O₃ assisted by ultrasonic wave

The synthesis of biodiesel via transesterification needs to be improved by the heterogeneous catalysts. So, the study aimed to determine the best conditions for the synthesis of biodiesel produced through a transesterification reaction using waste cooking oil with a Na2O/γ-Al2O3 catalyst assisted by ultrasonic wave. The steps were: catalyst preparation, oil preparation, esterification, trans-esterification reactions using methanol and various Na2O/γ-Al2O3 catalysts, and characterization. The results showed that the refined waste cooking oil using FTIR was known that there was still a carbonyl group indicating the presence of triglycerides. Free Fatty Acid content of waste cooking oil after esterification was 0.40%, so that the transesterification reaction could be carried out. The XRD results of the catalyst showed a conformity with the reference and it was determined by the Scherrer formula that the crystal size of the catalyst was 30.59 nm. The best condition for biodiesel synthesis was obtained at a catalyst ratio of 1:1 as much as concentration 3% w/w for 15 minutes of ultrasonication, 65 ℃, and molar ratio of methanol: oil (12:1), for the yield of 83.51%. After identification through GC-MS, it was known that the main components in the transesterified biodiesel from waste cooking oil were methyl elaidate (38.54%), methyl palmitate (30.90%) and methyl linoleate (16.61%)