In 1840 the Dutch professor Gerardus Johannes Mulder mentioned levulinic acid for the first time. He synthesized it by heating fructose with hydrochloric acid. The former term “levulose” for fructose gave levulinic acid its name. Although levulinic acid has been well known since the 1870s, it has never reached a commercial use in significant volume. First commercial production of levulinic acid began as a batchwise process in an autoclave by A.E. Statley in the 1940s. In 1953 the US company Quaker Oats developed a continuous process for the production of levulinic acid. In 1956 it was identified as a platform chemical with high potential and in 2004 the US Department of Energy identified levulinic acid by screening approximately 300 substances as one of the 12 potential platform chemicals in the biorefinery concept.
Synthesis
The original synthesis of levulinic acid is done by heating hexoses or starch in dilute hydrochloric acid or sulfuric acid. The yield depends on the nature of the acid, acid concentration, temperature and pressure. In addition to formic acid further, partly insoluble, by-products are produced. These are deeply colored and their complete removal is a challenge for most technologies. Many concepts for the commercial production of levulinic acid are based on a strong acid technology. The processes are conducted in a continuous manner using lignocellulose as inexpensive starting material which is impregnated by dilute mineral acid and transferred to a high pressure reactor where it is heated with steam to allow the reaction to form levulinic acid to take place. After cooling the reaction mixture and filtering off the solid by-products, the levulinic acid that is formed is separated from the mineral acid catalyst by extraction without neutralization of the acid catalyst. This allows the acid catalyst to be recycled, while the levulinic acid can be purified from the acid-free organic solvent. Pure levulinic acid is isolated by evaporation of the extraction solvent and distillation of the levulinic acid. Companies who developed technology based on this concept include Biofine, DSM, Segetis, and GFBiochemicals. GFBiochemicals started the commercial production of levulinic acid in 2015 at a production scale of 2,000 MT/a in Caserta, Italy. 2Caserta is the world's largest operational production plant for levulinic acid.
Reactions and applications
Levulinic acid is used as a precursor for pharmaceuticals, plasticizers, and various other additives. The largest application of levulinic acid is its use in the production of aminolevulinic acid, a biodegradable herbicide used in South Asia. Another key application is the use of levulinic acid in cosmetics. Ethyl levulinate, a primary derivative of levulinic acid, is extensively used in fragrances and perfumes. Levulinic acid is a chemical building block or starting material for a wide variety of other compounds including γ-valerolactone and 2-methyl-THF.
Other occurrence and niche uses
Levulinic acid is used in cigarettes to increase nicotine delivery in smoke and binding of nicotine to neural receptors.
Safety
Levulinic acid is relatively nontoxic, with an of 1850 mg/kg.
