COMPUTATION STUDY OF TRANSITION STATES IN SYNTHESIS OF CHALCONE WITH VARIOUS SOLVENT USING DFT METHODS (DENSITY FUNCTION THEORY)
Chalcone compounds and their derivatives show significant biological activity where the presence of a double bond and carbonyl group in the chalcone compound can function as a drug design. Chalcone derivatives also act as anti-bacterial, anti-inflammatory, anti-parasitic, anti-tumor, anti-malaria, a...
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Format: | Theses |
Language: | Indonesia |
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Online Access: | https://digilib.itb.ac.id/gdl/view/68270 |
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Institution: | Institut Teknologi Bandung |
Language: | Indonesia |
Summary: | Chalcone compounds and their derivatives show significant biological activity where the presence of a double bond and carbonyl group in the chalcone compound can function as a drug design. Chalcone derivatives also act as anti-bacterial, anti-inflammatory, anti-parasitic, anti-tumor, anti-malaria, anti-HIV, anti-hyperglycemic and antioxidant agents. Many chalcone syntheses use the various method with so many biological activities. The reaction method that is often or commonly used to synthesize chalcone compounds is the Claisen-Schmidt condensation method. This research uses acetophenone and benzaldehyde as reactants. The use of solvents in an organic chemical reaction has an important role and significantly affects the obtained product results, so in calculating the solvent effect, it is necessary to consider the polarity. Chalcone synthesis occurs through four reaction steps: the formation of enolate ion reactions, nucleophilic addition reactions, proton transfer reactions, and dehydration reactions. The transition state, which is difficult to know its shape in laboratory research, can be predicted using a computational system. This computational calculation uses the DFT (Density Functional Theory) method. This research use B3LYP as the computational method with def2-SVP as the base set and the CPCM for the dissolving process in the ORCA program. This study carried out calculations under two conditions: the state in the gas phase and using a solvent. The solvents used in the computational method in this research are water, ethanol and toluene. Each solvent represents its polarity. As we know, water is the most polar solvent, and toluene is the least. This research aims to find the energetics of the chalcone synthesis reaction and understand the transition state that occurs.
The research methodology of this calculation includes two devices, namely hardware and software. The hardware used is a laptop, while the software used has Termius, Avogadro, Chemcraft, Gausview, WinSCP, and the Orca program for calculations. The research stages started with literature study, initial structure formation, analysis of stable structure, estimation of transition state structure and measure of the resulting energetics. The construction of the initial structure of the compound begins with the creation of a Z-matrix, the determination of the charge, and the multiplicity of the molecules. Optimization calculation is carried out to get the most stable structure of a molecule. The transition state is predicted based on the intermediate in the reaction and then calculated to determine the movement and the resulting energetics.
Gibbs Free Energy is the generated energy in the computational calculations. We use Hartree as the unit of energy. The calculation results obtained four transition states, each with a different activation energy value. The activation energy obtained in transition state 1 is 123.65 kJ/mol for aqueous solvent, 123.63 kJ/mol for ethanol solvent, 121.45 kJ/mol for toluene solvent and 119.14 kJ/mol for non-solvent calculation. The activation energy obtained at transition state 2 is 47.31 kJ/mol for aqueous solvents, 47.01 kJ/mol for ethanol solvents, 40.94 kJ/mol for toluene and 32.08 kJ/mol for calculations without solvents. The activation energy obtained at transition state 3 is 291.92 kJ/mol for aqueous solvents, 290.19 kJ/mol for ethanol solvents, and 271.00 kJ/mol for toluene solvents and 252.08 kJ/mol for non-solvent calculations. The activation energy obtained at transition state 4 is 124.78 kJ/mol for aqueous solvent, 124.97 kJ/mol for ethanol solvent, 133.55 kJ/mol for toluene solvent and 136.77 kJ/mol for non-solvent calculation. For transition states 1, 2 and 3, it can be concluded that the more polar the solvent, the greater the activation energy obtained. Meanwhile, for transition state 4, the more non-polar the solvent, the higher the energy produced. The effect of this solvent can be explained by the interaction of each species involved with the solvent. |
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