title: Production of conjugated linoleic acids through KOH-catalyzed dehydration of ricinoleic acid.
abstract: Production of conjugated linoleic acids (CLA) using castor oil as starting material involves conversion of ricinoleic acid to methyl 12-mesyloxy-octadec-9-enoate (MMOE) followed by dehydration. This process usually uses 1,8-diazabicyclo-(5.4.0)-undec-7-ene (DBU) as an expensive dehydrating reagent. The present study reports that potassium hydroxide (KOH) can serve as a dehydrating reagent in replacement of DBU. The results showed that conversion of MMOE to CLA catalyzed by KOH was an efficient reaction, with a 77% conversion efficiency at 80 degrees C. The CLA isomeric profile produced in KOH-catalyzed dehydration reaction was similar to that catalyzed by DBU. The CLA mixture produced in KOH-catalyzed dehydration of MMOE at 80 degrees C contained 72% 9c,11t-18:2 and 26% 9c,11c-18:2 while in that catalyzed by DBU, 9c,11t-18:2 and 9c,11c-18:2 accounted for 78 and 16%, respectively. It was found that the temperature of dehydration was an important factor in the determination of CLA isomer composition and yield of conversion. Elevating the temperature from 78 to 180 degrees C decreased not only the conversion efficiency but also production of total c,t-18:2 and c,c-18:2 isomers regardless of dehydration catalyzed by either DBU or KOH. It is concluded that KOH may replace DBU as a dehydrating reagent in conversion of MMOE to CLA when the reaction conditions are optimized.
authors.affiliation: State Key Laboratory of OXO Synthesis & Selective Oxidation, Lanzhou Institute of Chemical Physics, The Chinese Academy of Sciences of Lanzhou, and Department of Chemistry, Henan Normal University, Henan, People's Republic of China
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Yu
authors.initials: Y
authors.lastname: Huang
authors.forename: Han Qing
authors.initials: HQ
authors.lastname: Wang
authors.forename: Zhen-Yu
authors.initials: ZY
authors.lastname: Chen
mesh_terms: D002368:Castor Oil / Q000737:chemistry; D002384:Catalysis; D006878:Hydroxides / Q000737:chemistry*; D007202:Indicators and Reagents / Q000737:chemistry; D007536:Isomerism; D019787:Linoleic Acid / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry*; D012277:Ricinoleic Acids / Q000737:chemistry*
chemical_list: D006878:Hydroxides; D007202:Indicators and Reagents; D017680:Potassium Compounds; D012277:Ricinoleic Acids; D002368:Castor Oil; D019787:Linoleic Acid; C030521:ricinoleic acid; C029943:potassium hydroxide