SINTESIS SENYAWA OMEGA-6 TERKONJUGASI ASAM 8,10,12-OKTADEKATRIENOAT DARI MINYAK JARAK

BAYU REFINDRA FITRIADI, Prof. Dr. Hardjono Sastrohamidjojo

2013 | Tesis | S2 Ilmu Kimia

Telah dilakukan sintesis senyawa omega-6 terkonjugasiasam 8,10,12- oktadekatrienoat dari minyak jarak. Senyawa asam 8,10,12-oktadekatrienoat diperoleh melalui beberapa tahap reaksi yaitu: (I) isolasi metil risinoleat dari minyak jarak melalui reaksi transesteriflkasimenggunakan KOH, (2) Reaksi hidrolisis metil risinoleatmenggunakanKOH, (3) reaksi oksidasi ikatan rangkap dari asamrisinoleatmenggunakanpereaksiKMn04encerpada suasanaasampada suhu 0-5°C,dan (4) reaksi dehidrasigugus hidroksilmenggunakanpereaksiP20S pada suhu 140°C selama 3,5 jam. Konfmnasi struktur dari senyawa yang dihasitkandilakukandenganspektrometerIR, IH-NMR,UV-Visdan GC-MS. Reaksi transesteriftkasiminyakjarak menggunakanKOHmenghasilkan komponen utama metil risinoleat dengan rendemen 77%. Reaksi hidrolisis terhadap metil risinoleat menghasilkanasam risinoleat dengan rendemen 74%. Reaksi oksidasi asam risinoleat menghasilkansenyawaasam 9,10,12-trihidroksi stearat (THSA) dengan rendemen total 75% berupa dua diastereoisomerdari bentuk a dan p. Produk a berbentuk kristal putih dengan titik leleh 106°C sedangkan produk p berbentuk padatan putih dengan titik leleh 125°C.Reaksi dehidrasiterhadapasam 9,IO,12-trihidroksistearatmenghasilkansenyawaomega- 6 terkonjugasi asam 8,IO,12-oktadekatrienoatberupa cairan kecoklatandengan rendemen 81%. Gugus karboksilat pada asam 9,IO,12-trihidroksistearat tidak terpengaruholeh adanyareaksidehidrasi.

Synthesis of conjugated omega-6 compounds 8,10,12-octadecatrienoic acid ITomcastor oil has been done. 8,10,12-octadecatrienoicacid was synthesized through several steps of reaction, i.e. (I) isolation of methyl ricinoleate fi'om castor oil by transesterification in the presence of potassium hydroxide, (2) hydrolysis of methyl ricinoleate with potassium hydroxide, (3) oxidation to double bond of ricinoleic acid using dilute potassium permanganate in alkaline condition at 0-5°C, and (4) dehydration of hydroxyl group of trihydroxy stearic acid using P20s at 140°C for 3.5 hours. Structural characterization was done by meansofIR, IH-NMR,UV-Vis danGC-MSspectrometers. Transesterificationof castor oil using KOH produced methyl ricinoleate as main component in 77% yield. Hydrolysis of methyl ricinoleate produced ricinoleic acid in total yield of 74%. Oxydation of ricinoleic acid produced 9,10,I2-trihydroxystearic acid (THSA) in total yield of 75% which were found as two diastereoisomers Le., a dan p. a product was produced as white crystal with melting point of 106°C, while p product was obtained as white powder with melting point of 125°C. Dehydration reaction to 9,10,12-trihydroxy stearic acid produced conjugated omega-6 compounds 8,I0,12-octadecatrienoic acid which was produced as brownish liquid, in 81% yield. Carboxylic group of 9,10,12- trihydroxystearic acid was not affectedby dehydrationreaction.

Kata Kunci : omega-6 terkonjugasi, asam 8,10, 12-oktadekatrienoat, reaksi dehidrasi