Judul: Studi Mekanisme Reaksi Brominasi Metileugenol
Abstrak: Podofilotoksin merupakan senyawa yang dapat digunakan sebagai antikanker yang dapat disintesis secara kimia. Metode dari jalur ini melibatkan beberapa langkah reaksi, salah satunya brominasi metileugenol. Brominasi metileugenol menghasilkan beberapa produk yang menunjukkan keberadaan produk samping yang menurunkan rendemen produk utama, yaitu 1-bromo-2- (1,2-dibromoisoprop-2-il)-4,5-dimetoksibenzena. Dengan meragamkan ekuivalen bromin yang ditambahkan dalam reaksi tersebut, dapat ditentukan mekanisme reaksinya serta kondisi optimum untuk mendapatkan rendemen 1-bromo-2-(2,3- dibromopropil)-4,5-dimetoksibenzena terbaik. Reaksi dilakukan dengan penangas es, dan bromin diteteskan. Senyawa 1-bromo-2-(1,2-dibromoprop-2-il)-4,5- dimetoksibenzena terbentuk sebagai produk utama sejak awal reaksi sedangkan 1- bromo-2-(2,3-dibromopropil)-4,5-dimetoksibenzena baru menjadi produk utama setelah metileugenol habis bereaksi. Br2 2.6 ekuiv menghasilkan 1-bromo-2-(2,3- dibromopropil)-4,5-dimetoksibenzena dengan rendemen tertinggi (71%).
Keyword: ekuivalen Br2, metileugenol, reaksi brominasi

Judul: Effect of Solvent on Brominated Methyleugenol with 1,13 Equivalent of Br2
Abstrak: Brominasi metileugenol (1) dengan 0,1–1,2 ekuivalen Br2 dalam kloroform (CHCl3) telah dilaporkan menghasilkan 1-bromo-2-(1,3-dibromoprop-2-il)-4,5-dimetoksibenzena (4) sebagai produk utama. Senyawa 4-(2,3-dibromopropil)-1,2-dimetoksibenzena (2) diperoleh sebagai produk tambahan, tetapi 1-bromo-2-(2,3-dibromopropil)-4,5-dimetoksibenzena (3) tidak dihasilkan. Untuk mengevaluasi mekanisme pembentukan produk 4 yang tidak lazim, penelitian ini mengevaluasi reaksi brominasi 1 pada 11 pelarut dengan kepolaran yang berbeda. Brominasi menggunakan 1,13 ekuivalen Br2, yaitu jumlah Br2 yang tepat menghabiskan reaktan 1 dalam CHCl3. Dalam pelarut etil asetat, komposisi produk brominasi hampir sama dengan dalam CHCl3. Produk 2 merupakan produk utama brominasi dalam diklorometana (DCM). Brominasi dalam dietil eter (Et2O), diisopropil eter, n-heksana, karbon tetraklorida, tetrahidrofuran (THF), dan metanol (MeOH) tidak membentuk 3. Produk 4 sangat dominan dalam Et2O. Reaksi dalam THF dan MeOH membentuk produk samping. Reaksi dalam t-butanol tidak menghasilkan produk 2, sementara dalam aseton, produk 2, 3, dan 4 tidak teramati. Berdasarkan hasil penelitian ini, komposisi produk brominasi 1 dipengaruhi oleh pelarut. Reaksi dalam pelarut Et2O dan DCM perlu diteliti lebih lanjut untuk mendapatkan kondisi optimum pembentukan produk 4 dan 2., Bromination of methyleugenol (1) with 0,1–1,2 equivalents of Br2 in chloroform (CHCl3) has been reported to yield 1-bromo-2-(1,3-dibromoprop-2-yl)-4,5-dimethoxybenzene (4) as the main product. 4-(2,3-dibromopropyl)-1,2-dimethoxybenzene (2) was obtained as an additional product, but 1-bromo-2-(2,3-dibromopropyl)-4,5-dimethoxybenzene (3) was not produced. To evaluate the unusual formation mechanism of product 4, this study focused on the bromination reaction of 1 in 11 solvents with different polarities. The bromination uses 1,13 equivalents of Br2, i.e., the right amount of Br2 depletes reactant 1 in CHCl3. In ethyl acetate solvent, the composition of the brominated product is almost the same as in CHCl3. Product 2 is the main bromination product in dichloromethane (DCM). Bromination in diethyl ether (Et2O), diisopropyl ether, n-hexane, carbon tetrachloride, tetrahydrofuran (THF), and methanol (MeOH) did not form 3. Product 4 is very dominant in Et2O. The reaction in THF and MeOH forms by-products. The reaction in t-butanol did not produce product 2, while in acetone, products 2, 3, and 4 were not observed. Based on the results of this study, the composition of brominated product 1 is influenced by the solvent. The reaction in Et2O and DCM solvents needs further investigation to obtain the optimum conditions for forming products 4 and 2.
Keyword: brominated, Br2, methyleugenol, solvent

Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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