Direct hydroxylation of fats and derivatives with a hydrogen peroxide tungstic acid system

Abstract

The direct preparation of threo-l,2-glycols without isolation of intermediates from oleic acid, methyl oleate, and oleyl alcohol by oxidation with a hydrogen peroxide (70%)-tmlgstic acid system at pH 0-1 and 45-55C without solvent has now been shown to be an efficient, high-yield reaction.The threo-isomers are formed from intermediate epoxides by in situ hydration with accompanying inversion. Preincorporation of about 2% of the glycol reaction product into oleic acid or methyl oleate speeds up the oxidation reactions markedly and adds to their control and reproducibility. With oleyl alcohol, addition of reaction product is not necessary.Castor and olive oils are also readily oxidized to almost complete elimination of unsaturation, but the products are only 50-60% 1,2-glycols, owing to intra-and intermolecular polyether information. Addition of reaction product is unnecessary with castor oil, but with olive oil the reaction rate is greatly accelerated by incorporation of 2% of reaction product. Preconditioning (5 hr) of the hydrogen peroxide with the tungstie acid permits slightly faster oxidation rates. Emulsions are also rapidly oxidized under appropriate conditions, but these systems are more complicated to prepare and work up than oxidatmn of the substrates directly. Tentative reaction mechanisms are proposed in which an inorganic polyperoxytungstie acid is the effective oxidizing agent and hydroxyl-containing species are intportant interracial or complexing agents between the substrate and oxidant system.

Oxidative Cleavage of the Double Bond of Monoenic Fatty Chains in Two Steps: A New Promising Route to Azelaic Acid and Other Industrial Products

“…A high conversion can also be achieved for oleic acid when 2 wt % preformed diol is added to the reacting mixture, as suggested by Luong et al 2 Table 3). Probably, the alcohol groups of diol strongly interact with pertungstic acid, forming an adduct with tenside properties acting, therefore, as a phase-transfer agent.…”

“…2 In Table 2 the double-bond conversions, determined by gas-chromatographic analysis, and diol yields obtained at different times, at 70°C, by using stabilized H 2 O 2 (60%) for oleyl alcohol are reported. Yields are normally lower than the conversion not only for the a The double-bond concentration has been determined by determining the iodine number.…”

“…The second step of the reaction, that is, the oxidative cleavage of the diol primarily obtained promoted by the presence of both Co(Ac) 2 and H 2 WO 4 , has not been reported in any scientific paper but only in the patent literature. 1 Some papers 6,7 reported the oxidative cleavage of the double bond with H 2 O 2 in the presence of tungstic and molibdic compounds, as catalysts, but using a phase-transfer agent.…”

Chemical transformations of renewable lubricant feedstocks

“…Since ring opening of fatty epoxides requires harsh reaction conditions [242], the direct synthesis of vic-dihydroxy FAs is of interest. Catalytic hydroxylation of oleic acid by H 2 O 2 affords syn diols via the epoxy intermediate [243,244]. Ring opening of the oxirane ring with HCl or HBr (with formation of chloro-and bromohydrins) introduces halogens in the structure which increase the polarity of the compounds [245].…”

“…6.38 and Table 6.19). Butyl-10,12-dihydroxy-9-behenoxystearate (BDHBS) with a bulky ester behenyl mid-chain moiety exhibits the most favourable low-temperature performance (PP, −47 °C) and highest VI (243). On the other hand, butyl-10,12-dihydroxy-9-octyloxystearate (BDHOS) shows the highest oxidation stability (onset temperature, OT, 221 °C).…”