CYCLISATION-ACETYLATION KINETICOF (R)-(+)-CITRONELLAL BY Zn2+-NATURAL ZEOLITE AS SOLID SOLVENT CATALYST

ABSTRACT Kinetic in cyc/isation-acetylation of (R)-(+)-citronellal with acetic anhydride was investigated over Zn2+_ Natural zeolite (Zn2+-Natzeo)as a catalyst. (R)-(+)-citronellalhas been isolated from citronella oil by fractional distillation under reducing pressure. Enantiose/ectivecapillary GC on a Supelco/3-DEX225 column has been used for analysis the enantiomers ratio of citronellal. Catalyst Zn2+-Natzeo has prepared through acid activation of natural zeolite from Malang using HF 1% and HCI 6 M, followed by ion-exchange with 3 M NH4CIand calcination at 450 °C for 1 h under nitrogen to obtainedH-natural zeolite (H-Natzeo). H-Natzeo was modifiedto Zn2+-Natzeoby ion exchange with 0.1 M ZnC/2" Cyclisation-acetylation reaction was carried out by heating (R)-(+)-citronellal (CIT), acetic anhydride (AA), and 1 g catalyst in glass batch reactor with vigorous stirring at 80°C. Molar ratio CIT/AA that used, i.e. 0.250.51.01.2and 1.5.As the reaction proceeded, 1 mL sample was taken off at 10203060120180min and extractedusing n-hexane for every molar ratio. Structure analysis of product was conducted by GC-MS. Kinetic of the cyclisation-acetylation reaction was analyzed according to the Langmuir-Hinshelwood mechanism. Increasing molar ratio of CIT/AA will decrease the isopulegyl acetate (lPA) and neo-isopulegyl acetate (NIPA) formation. Rate constant of cyclisation-acetylation reaction catalyzed by Zn2+-Natzeo was 30.964-47.619 mmol(min. g catrf at 80°C, 30 min and the ratio adsorption equilibrium constant Kcr,lKAA was 7.09. Keywords: Cyclisation-acetylation,(R)-(+)-citronellal,Zn2+-naturalzeolite, kineti

Interaction Between Li+ Cation With Crown Ethers Of Bz15c5, DBz16c5 And DBz18c6: Molecular Modeling Base On Mndo/D Semiempirical Method = Pemodelan Interaksi Ion Li dengan Eter Mahkota Bz15C5, DBz16C5 dan DBz18C6...

ABSTRACT The aim of this research is to find information about the substituent effect to the structure of crown ether benzo-15-crown-5 (Bz15C5), dibenzo-16-crown-5 (DBz16C5) and dibenzo-18-crown-6 (DBz18C6), and also crown ether selectivity to coordinate a Li metal cation. The presence of substituent could change the conformations flexibility of crown ether during interact with metal cation. In this research semi empirical MNDO/d method was used for calculations. Firstly, geometry optimization was conducted to crown ethers structure using MNDO/d methods. The next steps were running the geometry optimization of complexes between cation Li+ with crown ethers. Data were produced from these calculation are the parameter of crown ether structures, structures of the complexes, and the binding energy of the cation-crown ethers. The presence of electron-withdrawing substituents decreased the binding energy while that of electron-donating one increase the binding energy (value of dE more negative). The substituents which are increase the degree of symmetry of the cation-crown ether complexes could give the increase of crown ether selectivity to bind the cation. Selectivity of crown ether to bind the cation depends on the structural match between ionic radii of crown ether cavity (the ion-cavity size concept). Bz15C5 what has higher selectivity to bind Li+ than DBz16C5 and DBz18C6. Keywords: selectivity, crown ether, MNDO/

Solvation Structure Determination Of Ni2+ Ion In Water By Means Of Monte Carlo Method = Penentuan Struktur Solvasi Ion Ni2+ di dalam Air dengan Metode Monte Carlo

ABSTRACT Determination of solvation structure of Ni2+ ion in water has been achieved using Monte Carlo method using canonic assemble (NVT constant). Simulation of a Ni2+ ion in 215 H2O molecules has been done under NVT condition (298.15 K). The results showed that number of H2O molecules surround Ni2+ ion were 8 molecules in first shell and 17 molecules in second shell, interaction energy of Ni2+-H20 in first shell was -68.7 kcal/mol and in second shell was -9.8 kcal/mol, and there were two angles of 0-Ni2+-0, i.e. 74° and 142°. According to those results, the solvation structure of Ni2+ ion in water was cubic antisymetric. Keywords: Water simulation, Monte Carlo simulatio

DESIGN OF HYDROXY XANTHONES DERIVATIVES AS ANTICANCER USING QUANTITATIVE STRUCTURE-ACTIVITY RELATIONSHIP

ABSTRACTObjective: The objective of the research is to design a new hydroxy xanthone derivative has anticancer activity using quantitative structure-activityrelationship (QSAR).Methods: The QSAR designed new compounds were calculated by parameterized model 3 methods and analysis of multi-linear regression (MLR).Result: The result showed that the best model as follows:LogIC = –9.132 qC1 + 28.853 qC5 + 2.456 qC6 – 7.375 qC10 – 5.112 qC11 + 3.900This result has appropriate some statistical parameters (n=24; PRESS=0.999; r502=0.782; SEE=0. 235; R=0. 885; Fcal/FConclusion: This Model could be used to design of halogen-substituted hydroxy xanthone scaffold and predict their inhibitory concentration (ICtab=4.68).) asanticancer in the range of 0.001 - 0.484 μM.Keywords: Anticancer, Quantitative structure-activity relationship, Xanthone.5

The Interaction Of Co2+-Ammonia Modelling: The Comparative Study Between Ab Initio And Electron Correlation Methods = Pemodelan Interaksi Co24-Amoniak: Perbandingan antara Metode Ab Initio dan Korelasi Elektron

ABSTRACT Research on comparison between Hartree-Fock method and electron correlation methods as well as the effect of size of basis sets on representing interaction of Co2+-NH3 observed from complex energy parameters and optimum geometric parameters have been carried out. The first step is screening basis sets based on charge transfer effect and BSSE value. The selected basis set does not yield charge transfer at 1,4 A < rco2._N < 8 A, and yield small BSSE value. Electron correlation methods used are Moller-Plesset order 2 (MP2), Moller-Plesset order 3 (MP3), Configuration Interaction, Doubles (CID), dan Configuration Interaction, Singles and Doubles (CISD) whereas the basis set used is the result of the screening. LANL2DZ ECP-6-31G* and LANL2DZ ECP-6-311++G(3df,3pd) basis sets are used with Unrestricted Hartree-Fock (UHF) and Moller-Plesset order 2 (MP2) methods to study the effect of size of basis sets. The result of the research showed that the best basis set is LANL2DZ ECP for Co2+ and 6-31G* for NH3. The application of electron correlation method and large basis set can increase the quality of interaction representation of Co2+- NH3. Moller-Plesset (MP) perturbation method gives larger contribution to correlation energy than Configuration Interaction (CI) method. Keywords: solvation modelling, ammonia, cobal

The Keto-Enol Tautomerism of Curcumin and Some 4-substituted Curcumin Derivatives : A Theoretical Study Based on Computational Chemistry Approach

Heat formation (DHf) for the enol and diketo tautomers of curcumin and some 4-substituted curcumin derivatives has been studied using semiempirical AM1 quantum-chemical calculations. The calculations on curcumin, 4-methylcurcumin, 4-ethylcurcumin, 4-npropylcurcumin, 4-isopropyl-curcumin, 4-n-butylcurcumin, and 4-benzylcurcumin showed that the more steric hindrance resulted from the subtituents, the more stable they were in the form of diketo tautomers than enol tautomers. Whereas, calculations on 4-phenylcurcumin, 4-(o-methoxyphenyl)-curcumin, and 4-(p-methoxyphenyl) curcumin showed that though steric hindrance influenced the keto-enol tautomerism, they were found more stable in the form of enol tautomers. This phenomenon was estimated to be related with conjugation effect of the aromatic groups with the enol moiety of the main bone structure.Keywords : 4-Substituted curcumin, the keto-enol tautomerism, AM1, semiempirical calculations

EXTRACTION OF STRONTIUM(II) BY CROWN ETHER: INSIGHTS FROM DENSITY FUNCTIONAL CALCULATION

The structures, energetic and thermodynamic parameters of crown ethers with different cavity size, electron donating/withdrawing substituent groups and donor atoms have been determined with density functional method at B3LYP level of theory in gas and solvent phase. Small core quasi-relativistic effective core potentials was used together with the accompanying SDD basis set for Sr2+ and DZP basis set was used for crown ether atoms. Natural bond orbital (NBO) analysis was evaluated to characterize the distribution of electrons on the complexes. The interaction energy is well correlated with the values of Strontium charge after complexation, the second order interaction energies (E2) and HOMO-LUMO energy gab (∆Egab). The interaction energy and thermodynamics parameters in gas phase are reduced in solvent phase as the solvent molecules weaken the metal-crown ether interaction. The thermodynamic parameters indicated that less feasibility to extract Sr2+ ion directly from pure water without presence of organic solvent. The theoretical values of extraction energy for Sr(NO3)2 salt from aqueous solution in different organic solvent is validated by the experimental trend. This study would have strong contribution in planning the experiments to the design of specific host ligand and screening of solvent for extraction of metal ion

PEMODELAN INTERAKSI ETER MAHKOTA BZ15C5 TERHADAP KATION Zn2+ BERDASARKAN METODE DENSITY FUNCTIONAL THEORY

Selektivitas eter mahkota Bz15C5 dalam mengikat kation logam Zn2+ pada fasa gas dan fasa larutan menggunakan metode perhitungan DFT dengan himpunan basis LANL2MB. Kajian pengaruh mikrosolvasi dan substituen terhadap selektivitas eter mahkota juga dilakukan. Pemodelan mikrosolvasi dalam penelitian ini yakni penambahan dua molekul air pada kompleks eter mahkota-kation. Selektivitas eter mahkota terhadap kation dikaji dengan analisis parameter struktur, parameter energitika dan muatan bersih atom. Selektivitas kompleks eter mahkota-kation dalam fasa larutan dilakukan dengan menggunakan Polarized Continuum Model (PCM). Hasil kajian menunjukkan bahwa pada fasa gas selektivitas eter mahkota dalam mengikat kation dipengaruhi oleh kesesuaian ukuran diameter kation logam dengan kavitas eter mahkota. Selain ukuran kavitas, selektivitas eter mahkota juga dipengaruhi oleh substituen yang terikat pada cincin benzo-eter mahkota. Substituen pendonor elektron dapat meningkatkan selektivitas eter mahkota dalam mengikat kation, sehingga energi interaksi kompleks yang dihasilkan semakin meningkat. Sedangkan substituen penarik elektron menurunkan energi interaksi kompleks. Pada fasa larutan energi interaksi kompleks menjadi menurun akibat pengaruh molekul pelarut yang melemahkan interaksi kation-eter mahkota. Dalam pelarut air, polaritas ligan Bz15C5 tersubstitusi mempengaruhi energi interaksi pembentukan kompleks. Semakin tinggi polaritas ligan eter mahkota, maka energi interaksi pembentukan kompleks ligan-kation makin rendah. Namun, semakin rendah polaritas ligan akan memudahkan interaksi ligan dengan kation dalam membentuk kompleks, sehingga energi interaksi yang dihasilkan meningkat

Metilasi Asam Galat Menggunakan Agen Metilasi Dimetil Sulfat (DMS) atau Dimetil Karbonat (DMC)

Methylation of gallic acid has been conducted by the use of dimethyl sulfate (DMS) or dimethyl carbonate (DMC)  as methylating agents. Methylation of gallic acid using DMS was carried out by various methods, i.e. mild condition at ambient temperature, reflux and sonication. The best method was achieved by methylation under reflux yielded 48.9% efficiency of 3,4,5-trimethoxybenzoic acid.            Methylation of gallic acid with DMC was performed with several variations on the type and amount of base and phase transfer catalyst (PTC). In addition, green methods sonochemistry and microwave irradiation have also been done. Unfortunately, the methylation of gallic acid failed to give 3,4,5-trimethoxybenzoic acid. Methylation of gallic acid using green reagent DMC gave high yield at mole ratio of gallic acid : DMC : K2CO3 : KI : PTC of tetrabuthyl ammonium bromide (TBAB) = 5 : 320 : 20 : 5 : 8 under reflux for 10 hours and produced 75.96% of methyl 3,4,5-trimethoxybenzoate. Atom economy of gallic acid methylation method using DMC is 37.95%, which is not very different from that of DMS method (30.47%). However, the methylation method using DMC produced by products, which  have the lower toxicity compared to that of methylation using DMS

THEORETICAL STUDY ON 15-CROWN-5 COMPLEX WITH SOME METAL CATIONS

The capability of 15-crown-5 ethers to form complexes with some metal cations (Li+, Na+, K+, Zn2+, Cd2+ and Hg2+) was investigated by an ab initio quantum mechanical method. The calculations were performed at the RHF/lanl2mb level of theory. The interaction energies were used to evaluate the metal binding capability of the crown ether. The effect of nature of the metal on the binding properties was also studied. The results of the calculations showed that the interaction energy of the complexes increased in proportion with the ratio of ion charge, electronegativity and ionization potential to the cation diameter. In addition, based on the extraction distribution coefficient in the gas phase, it is found that the 15-crown-5 could not extract metal cations investigated