Mechanochemical Preparation of Organic Nitro Compounds
Technical Report,14 Feb 2017,13 Feb 2019
New Jersey Institute of Technology University Heights United States
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Aromatic compounds such as toluene are commercially nitrated using a combination of nitric acid with other strong acids. This process relies on the use of highly corrosive chemicals and generates environmentally harmful waste, which is difficult to handle and dispose of. In this study aromatic nitration using solvent-free mechanochemical processing of environmentally benign precursors has been achieved and investigated. Mononitrotoluene MNT was synthesized by milling toluene with sodium nitrate and molybdenum trioxide as a catalyst. Several parameters affecting the desired product yield and selectivity were identified and varied. MNT yields in excess of 60 percent have been achieved in different tests. The desired product yield and selectivity were found to depend on the ratios of the reactants and the catalyst. A parametric study addressed the effects of milling time, temperature, milling media, and catalyst additives on the MNT yield and on the formation of various by products. Toluene conversion as a function ofmilling time exhibited a maximum, which occurred earlier for smaller milling balls. Milling temperature had only a weak effect on MNT formation, but affected the formation of other aromatic by products. Replacing various fractions of MoO3 with fumed silica led to an increased yield of MNT for up to 30 percent of silica. The yield dropped when higher percentages of MoO3 were replaced. The degree of refinement of MoO3 attained inthe mill has been quantified by measuring the surface area of the inorganic fraction of the milled material. The surface measurements were correlated with the product yield. Feasibility of secondary nitration for toluene as well as of mechanochemical nitration of anisole and naphthalene has also been shown experimentally.
- Organic Chemistry