17539-30-9Relevant academic research and scientific papers
Controlled reduction of aromaticity of alkylated polyaromatic compounds by selective oxidation using H2WO4, H3PO4and H2O2: a route for upgrading heavy oil fractions
Francisco, Manuel,Hutchings, Graham J.,Jenkins, Robert L.,Knight, David W.,Nowicka, Ewa,Sankar, Meenakshisundaram,Taylor, Stuart H.,Willock, David J.
, p. 13885 - 13892 (2021/08/16)
Heavy crude oil fractions which form the residues from fractional distillation are a significant proportion of current hydrocarbon reserves. However, processing residues for use as chemicals or fuels is hampered by the high polyaromatic content of this material. Selective reduction of aromaticity by targeted ring opening and the preservation of alkylated chain side groups are key requirements for the upgrading of alkylated polynuclear aromatic hydrocarbons (PAHs) to more easily processed and higher value molecules. In this study, a H2WO4catalyst combined with H3PO4and H2O2oxidant is applied to the selective oxidation of PAHs containing different lengths of substituent alkylated chain, and different numbers of rings in the fused aromatic core. For a model substrate of 2-ethylnaphthalene, using traditional organic solvents, aliphatic carbon was oxidized more readily compared to aromatic carbon. However, it was found that the oxidation to desired products can be specifically controlled as the selectivity is directed by the choice of solvent, with reactions carried out in acetonitrile giving oxidation only in the aromatic region of the molecule. With larger polyaromatic molecules, a biphasic solvent system is used with Aliquat 336 as a phase transfer agent. Even for this more complex reaction system high conversion to the corresponding alkylated ring opened compounds was obtained.
Selective oxidation of alkyl-substituted polyaromatics using ruthenium-ion-catalyzed oxidation
Nowicka, Ewa,Sankar, Meenakshisundaram,Jenkins, Robert L.,Knight, David W.,Willock, David J.,Hutchings, Graham J.,Francisco, Manuel,Taylor, Stuart H.
, p. 4285 - 4293 (2015/03/14)
Ruthenium-ion-catalyzed oxidation of a range of alkylated polyaromatics has been studied. 2-Ethylnaphthalene was used as a model substrate, and oxidation can be performed in either a conventional biphasic or in a monophasic solvent system. In either case the reaction rates and product selectivity are identical. The reaction products indicate that the aromatic ring system is oxidized in preference to the alkyl chain. This analysis is possible due to the development of a quantitative NMR protocol to determine the relative amounts of aliphatic and aromatic protons. From a systematic set of substrates we show that as the length of the alkyl chain substituent on a polyaromatic increases, the proportion of products in which the chain remains attached to the aromatic system increases. Larger polyaromatic systems, based on pyrene and phenanthrene, show greater reactivity than those with fewer aromatic rings, and the alkyl chains are more stable to oxidation.
