title: Microwave-assisted methanolysis of green coffee oil.
abstract: Optimisation of a microwave-assisted methanolysis was performed to obtain cafestol and kahweol directly from green coffee oil (Coffea arabica). A two-factor (the methanolysis period and temperature), three-level, factorial experimental design (3(2)) was adopted. The methanolysis procedure was performed under microwave irradiation, using closed vessel and accurate fast responding internal fibre-optic temperature probe. The effects on the responses were measured by HPLC. After 3 min of microwave irradiation (hold time) at 100°C, with 500 mg of green coffee oil, a yield higher than 99% was obtained. The yield of this reaction is 26% after 2h when working under conventional heating. The methods described in the literature lead to long reaction times, poor yields and formation of side products. The microwave-assisted technique proved to be faster, avoided undesired side products and gave better conversion, when compared to conventional heating process.
authors.affiliation: Departamento de Química Orgânica, Universidade Federal do Rio de Janeiro, Bloco A, CEP: 21941-909, Rio de Janeiro - RJ, Brazil.
authors.forename: S S
authors.initials: SS
authors.lastname: Oigman
authors.forename: R O M A
authors.initials: RO
authors.lastname: de Souza
authors.forename: H M
authors.initials: HM
authors.lastname: Dos Santos Júnior
authors.forename: A M C
authors.initials: AM
authors.lastname: Hovell
authors.forename: L
authors.initials: L
authors.lastname: Hamerski
authors.forename: C M
authors.initials: CM
authors.lastname: Rezende
mesh_terms: D005591:Chemical Fractionation / Q000295:instrumentation / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D040503:Coffea / Q000737:chemistry*; D004224:Diterpenes / Q000032:analysis / Q000302:isolation & purification*; D000432:Methanol / Q000737:chemistry; D008872:Microwaves; D010938:Plant Oils / Q000032:analysis / Q000302:isolation & purification*; D013696:Temperature
chemical_list: D004224:Diterpenes; D010938:Plant Oils; C053401:kahweol; C053400:cafestol; D000432:Methanol