Sains Malaysiana 44(8)(2015): 1183–1188

Separation of Geraniol from Citronellol by Selective Oxidation of Geraniol to Geranial

(Pengasingan Geraniol daripada Sitronelol melalui Pengoksidaan Memilih Geraniol kepada Geranial)

DANIEL CHONG JUN WENG¹, JALIFAH BINTI LATIP¹*, SITI AISHAH BINTI HASBULLAH¹ & HARJONO SASTROHAMIDJOJO²

¹School of Chemical Sciences & Food Technology, Faculty of Science and Technology

University Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan, Malaysia

²Department of Chemistry, Gadjah Mada University, Yogyakarta, Indonesia

Diserahkan: 4 Disember 2014/Diterima: 9 April 2015

ABSTRACT

Rhodinol is a mixture of geraniol and citronellol. It is the second fraction in fractional distillation of commercially grown Cymbopogon nardus (C. nardus). The physical and chemical similarities of these two compounds made them inseparable. The individual use of each compound is of great importance. A selective oxidation (hydrogen peroxide activated by platinum black) of geraniol (in rhodinol) to geranial was done while remaining citronellol intact in order to separate the two compounds into different chemical functionality. A yield of 81% geranial achieved while minimizing citronellal formation from citronellol to 17%. Chemical separation using sodium hydrogen sulfite (NaHSO₃) was done to separate the aldehydes from the unreacted citronellol. Purification using fractional distillation was done to obtain pure geraniol and remove minor fraction of citronellal.

Keywords: Geranial; geraniol; oxidation; rhodinol; selective

ABSTRAK

Rodinol adalah sebatian yang terdiri daripada geraniol dan sitronelol. Dengan menggunakan kaedah penyulingan berperingkat, rodinol adalah pecahan kedua Cymbopogon nardus (C. nardus). Kedua-dua sebatian ini tidak boleh diasingkan disebabkan ciri fizikal dan kimia yang seiras. Kegunaan geraniol dan sitronelol sebagai sebatian yang berasingan adalah penting daripada segi industri. Dalam kajian ini, pengoksidaan memilih (hidrogen peroksida yang diaktifkan oleh platinum hitam) geraniol (dalam rodinol) kepada geranial dilakukan sementara sitronelol kekal utuh supaya kedua-dua sebatian ini boleh diasingkan dengan keadaan fungsi kimia yang berlainan. Tindak balas ini memberikan hasil sebanyak 81% geranial dan berjaya meminimumkan penghasilan sitronelal daripada sitronelol kepada 17%. Dengan menggunakan cara pengasingan kimia, hidrogen sulfit (NaHSO₃) digunakan untuk mengasingkan aldehid daripada sitronelol. Akhirnya, pecahan kecil sitronelal diasingkan daripada geraniol tulen dengan menggunakan penyulingan berperingkat.

Kata kunci: Geranial; geraniol; memilih; pengoksidaan; rodinol

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*Pengarang untuk surat-menyurat; email: jalifah@ukm.edu.my