Judul: Sintesis Flavonol melalui 2’-Hidroksikalkon
Abstrak: Flavonol is a class of flavonoids commonly found in fruits and vegetables. Flavonol is very useful, especially in food sector and health. In this study, flavonol unsubstituted was successfully synthesized from an intermediate material 2’-hydroxychalcone. The 2’-hydroxychalcone was synthesized by Claisen-Schmidt condensation method between o-hydroxyacetophenone and benzaldehyde using 4 different catalysts, namely KOH 60%, solid pellet of KOH-grinding technique, BF3-Et2O, and NaH in DMF. The KOH 60% was the best catalyst, giving the highest yield (57%). Afterward, the flavonol was synthesized in 1-stage oxidation cyclization of o-hydroxyacetophenone using Algar-Flynn-Oyamada (AFO) reaction, giving 76%. The flavonol total yield from 2’-hydroxychalcone was 43%. All synthesized products were characterized by their melting points and their spectra. The success of the synthesis flavonol opens the way to synthesis of useful flavonol derivatives such as quercetin and kaempferol.
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Judul: Sintesis Flavon dari Fenol dan Benzoil Klorida
Abstrak: Flavone is a class of flavonoid, commonly found in plants with wide bioactivity spectrum. A widely used flavone synthesis route is through acidcatalyzed oxidative cyclization of β-diketone. In this study, unsubstituted flavone had been synthesized via 5-step from phenol, with 22% yield and successfully increased the yield of previous study on Fries rearrangement of phenyl acetate and benzoylation of o-HAP steps. Phenol was acetylated resulting 93% phenyl acetate. AlCl3-catalyzed Fries rearrangement in 1.5 hour and at 120 °C converted phenyl acetate into o-hydroxyacetophenone (o-HAP) with 40% yield. AlCl3 as catalyst produced o-HAP with higher and reproducible yield compared with BF3·Et2O and ZnCl2. Benzoylation of o-HAP followed by Baker-Venkataraman rearrangement of the ester product using KOH in dried pyridine produced β-diketone 1-(2- hydroxyphenyl)-3-phenylpropane-1,3-dione. The yield of ester and β-diketone were 71% and 85%, respectively. Finally, oxidative cyclization of β-diketone with sulphuric acid as catalyst produced 99% of flavone. The flavone product had been characterized spectroscopically and its melting point as well.
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Judul: Perubahan Garis Pantai di Pesisir Utara Babo, Teluk Bintuni, Provinsi Papua Barat.
Abstrak: Garis pantai dapat berubah secara terus menerus dan pemantauan perubahannya dapat dilakukan menggunakan teknologi pengindraan jauh. Penelitian ini bertujuan mengidentifikasi perubahan garis pantai dan faktor penyebabnya di Pesisir Utara Babo, Teluk Bintuni, Provinsi Papua Barat tahun 1990 – 2019 menggunakan data satelit Landsat. Ekstraksi garis pantai dilakukan menggunakan metode Normalize Difference Vegetation Index (NDVI) dan Tasseled Cap untuk menghasilkan fitur garis pantai. Sedangkan perubahan garis pantai dihitung menggunakan Digital Shoreline Analysis System (DSAS) dengan metode Net Shoreline Movement (NSM) dan End Point Rate (EPR). Tinggi gelombang dan kecepatan arus di bagian dalam Teluk Bintuni cenderung lebih kecil dibandingkan di bagian mulut teluk. Hasil analisis DSAS menunjukkan bahwa di wilayah Pesisir Utara Babo tahun 1990-2019 sebagian besar mengalami abrasi, sedangkan akresi hanya terjadi di beberapa lokasi. Abrasi terbesar terjadi pada subzona D1 (Desa Tanah Merah) yaitu sebesar 56.91 m pada tahun 1990-2000 dengan laju perubahan 5.26 m/tahun dan akresi terbesar terjadi pada subzona D3 (Desa Tofoi) sebesar 97.16 m pada tahun 2000-2010 dengan laju perubahan 8.90 m/tahun. Perubahan garis pantai terbesar selama rentang tahun 1990-2019 terjadi pada subzone D3 dengan nilai sebesar 226.2 dan laju perubahan 7.91. Perubahan garis pantai di wilayah ini dominan dipengaruhi oleh fenomena pasang surut, selain itu hantaman gelombang, arus susur pantai (longshore current), masukkan sedimen dari sungai dan adanya alih fungsi lahan juga mempengaruhi terjadinya abrasi dan akresi.
Keyword: abrasi, akresi