relevant role. They can be transformed into methyl esters for production of biodiesel or functionalized to produce surfactants, plasticizers, monomers, and new solvents [2,3]. These include cis-9-octadecenoic acid (oleic acid, OA in Scheme 1), which is a very interesting raw material, since it is renewable, inexpensive, and available in different geographical areas.Its most common transformations are epoxidation, hydroxylation, and oxidative cleavage of the double bond. The latter reaction is particularly interesting because it selectively produces azelaic acid (AA) and pelargonic acid (PA) (Scheme 1).Azelaic acid has important applications in textiles (polyesters and polyamides) and pharmaceuticals (antiacne). Industrially, oxidative cleavage of the double bond is carried out by ozonolysis [4]. However, use of ozone and molecular oxygen at high temperatures represents a serious drawback of this process, since these oxidants present combustion hazards. It is therefore required to find new processes that meet the standards of sustainability.A valid alternative is hydrogen peroxide, because it is capable of oxidizing with excellent atom economy and is safer than gaseous reactants [5]. Many of the known strategies couple H 2 O 2 with catalytic systems such as RuO 2 , Na 3 PO 4 {[WO(O 2 ) 2 ]}, H 2 WO 4 /Co(OAc) 2 , and Re 2 O 7 [6][7][8][9][10][11][12][13][14][15][16]. These synthetic routes (path i of Scheme 1) typically include a first step of dihydroxylation that gives 9,10-dihydroxystearic acid (DSA). In a second step (ii) a new catalyst is introduced, either in the same reaction environment [14] or on the purified diol [15], for oxidative cleavage of the CH(OH)-CH(OH) bond.Recently, an efficient one-pot strategy (iii in Scheme 1) was proposed with a catalyst based on the quaternary ammonium salt Q 3 {PO 4 [WO(O 2 ) 2 ] 4 } [17]. Even in this case, there are some disadvantages, namely high catalyst Abstract This work describes two sustainable methods for production and purification of azelaic acid (AA) to replace the current process of ozonolysis of oleic acid (OA). The first proceeds in two steps, coupling smooth oxidation of OA to 9,10-dihydroxystearic acid (DSA) with subsequent oxidative cleavage by sodium hypochlorite. An alternative methodology is also proposed, using a chemocatalytic system consisting of H 2 O 2 /H 2 WO 4 for direct oxidative cleavage of the double bond of OA at 373 K. A convenient technique for separation and purification of azelaic acid is also proposed.
