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Method to Produce Sorbic Acid and Pentadiene from Renewable Biostock


Background: Sorbic acid has been used extensively as a preservative in a vast array of food. The benefits of sorbates as food preservatives are two-fold: sorbates inhibit a wide spectrum of bacteria yeasts and molds and they have extremely low toxicity. Several protocols for producing sorbic acid and sorbates are known. However the most common method of producing commercial quantities requires a decomposition step that yields unwanted colored byproducts. Multiple purification steps are required to yield product that is food grade or better. 13-pentadiene or piperylene is a volatile flammable linear five-carbon hydrocarbon. It is used widely as a monomer in the production of plastics adhesives and resins. It is produced commercially as a byproduct of ethylene production and no other means of producing 13-pentadiene in commercial quantities is known. A method of making sorbic acid that overcomes the formation of byproducts and yield losses of known methods while also resulting in the creation of 13-pentadiene is needed. Technology Description: UW–Madison researchers have developed a method of making 24-hexadienoic acid (i.e. sorbic acid) and 13-pentadiene (i.e. piperylene) via an acid-catalyzed ring-opening of 6-methyl-56-dihydro-2-pyrone (i.e. parasorbic acid). The parasorbic acid can be made from a renewable precursor 4-hydroxy-6-methyl-2-pyrone (HMP). The method comprises converting a renewable feedstock HMP into parasorbic acid (PSA) and then opening the ring of the PSA by contacting the PSA with a solid acid catalyst. This can be performed with acid-catalyzed ring-opening to yield sorbic acid or with decarboxylation of the opened ring to yield pentadiene. The conversion of HMP to PSA is accomplished by hydrogenating the HMP in the presence of a catalyst comprising one or more noble metals. The conversion takes place in a solvent selected from the group of C1- to C6-alcohols and C1- to C6-carboxylic acids and the ring-opening reactions take place in a polar aprotic solvent or a mixed solvent of water and a polar aprotic solvent. A more specific three-step approach begins by hydrogenating 4-hydroxy-6-methyl-2-pyrone (HMP) to yield 4-hydroxy-6-methyltetrahydro-2-pyrone (4-HMTHP). Then the 4-HMTHP is dehydrated by contacting it with a solid acid catalyst to yield parasorbic acid. Finally the ring of the PSA is opened by contacting the PSA with a solid acid catalyst to yield sorbic acid or pentadiene. Applications: 1) Production of biorenewable chemicals including sorbic acid and pentadiene


1) Provides a streamlined method of producing both 24-hexadienoic acid and 13-pentadiene from renewable feedstock 2) Presents an opportunity to convert dihydro-4-dydroxy-6-methyl-2H-pyran-2-one to 3-penten-2-one a useful and reactive unsaturated ketone as an intermediate

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