Pemisahan enantiomer 1-(3,4-Dimektosi Fenil) -2-profil isobutirat dengan HPLC kolom kiral pirkle

MARYATI, Dr. H. Chairil Anwar

2001 | Tesis | S2 Kimia

Telah dilakukan reaksi adisi metileugenol dengan asam isobutirat 98% dengan perbaadingan mol metjleugenol : asam jsobutirat = 1 : 27 &an katalis asam sulfat, pada temperatur penangas minyak 180°C dan walctu refluks 5 jam. Sisa asam dihilangkan dengan destilasi, ester yang didapat diekstrak dengan dietileter dan dinetralkan dengan NaHC03 jenuh. Hasil yang diperoleh diidentifikasi dengan GC-MS, IR diul H'NMR. HasiI analisis menunjukkan adanya senyawa 1 -(3,4-dimetoksi feni1)-Zpropil isobutirat. Pemisahan enantiomer 1 -(3,4-dimetoksi fenil)-2-propil isobutirat dilakukan dengan HPLC menggunakan fasa diam kiral Pirkle, (R)-(3,4-dinitro benzoil) fenilglisin dengan eluen campuran heksana - isopropil alkohol (PA) pa& perbandingan 95 : 5 (v/v) dan suhu 22°C. Sebagai pembanding digunakan ester 1(3,4-dimetoksi fenil)-2-propil format yang menunjukkan dua puncak yaitu R dan S. Enantiomer 1 -(3,4-dimetoksi fenil)-2-propil isobutirat lebih cepat terelusi dibandingkan dengan 1(3,4-dimetoksi €enil)-2-propil format, diduga karena keasaman asam isobutirat lebih rendah dari asam format. Interaksi antara fasa dim dan enantiomer ditunjukkan dengan komputasi berdasarkan perhitungan mekanika molekuler. Diastereomer R-R mempunyai energi yang lebih rendah (lebih stabil) dibanding R-S, dan enantiomer R akan keluar dari kolom sebagai puncak kedua.

The addition reaction of methyleugenol with isobutyrate acid of 98% with HzS04 as catalyst was carried out at 18OoC, for 9 hours. The mol ratio of methyleugenol : isobutyric acid was 1 : 27. The mixture was distilled and the residue was extracted by diethylether, neutralized by saturated sodium bicarbonate. Isobutyrate ester was yielded (30%) after evaporation of solvent. Gas chromatography analisis showed that purity was 5 I ,80 %. Structure determination of isobutyrate ester was done by IR, GC-MS and H'Nh4R which was showed that product is mixture of l-(3,4-dimetoksi fenil>2-propyl-isobutirate. Separation of enantiomeric mixture of 1 -(3,4-dimethoxy phenyl)-2-propyl isobutyrate was done by HPLC using Pirkle's chiral column, (R)-(3,4-dinitro benzoil) phenylglysin and eluent a hexana-isopropyl alchohol at the ratio 95 / 5 (v/v) and temperatue 22°C. 1-(3,4- dimetoksi phenyl)-2-propyl- formate used as standard of comparison. Elution of 1 -(3,4-&methoxy phenyl)-2-propyl isobutirate was faster than 1 -(3,4- dimetoxy phenyl)-2-propyl-formate. This phenomena was estimated becouse acidity of isobutyrate acid is lower than formic acid. Interaction between stationary phase and enantiomers was proved by computasional of molecular machanics. The energi of R-R diastereomer is lower than R-S. The R-R diastereomer seems to be more stable than R-S, and R-enantiomer eluted as a second peak.

Kata Kunci : Pemisahan Enantiomer,HPLC,Senyawa Ester Kiral