2.3- Dimethylnaphthalene, oxidation 2.3- naphthalenedicarboxylic

Similar regiospecific syntheses employing PMBs and dialkylnaphthalene have been used to prepare 2,6-dimethylnaphthalene [581-42-0] which is oxidized to the corresponding 2,6-naphthalenedicarboxylic acid [1141-58-4]y also used as a monomer for liquid crystal polymers. 

Naphthalenedicarboxylic acid is a precursor to polyethylene naphthalate (PEN), which is used to improve the properties of polyester bottle resins (see also problem E.1.6). It can be made by the liquid phase oxidation of 2,6-dimethylnaphthalene as described in U.S. 6,114,575, assigned to BP Amoco. Estimate the cost of production for a plant that produces 250,000 metric tons per year (250 kMTA). 

Sulfur, and derivatives of sulfur in a low oxidation state, can also be applied for oxidation of methylated aromatic compounds. Thus, under the conditions of a modified Willgerodt reaction, dimethylnaphthalenes can be converted into methylnaphthoic acids (ca. 40%) and naphthalenedicarboxylic acids (ca. 60%) (molar ratios of Hydrocarbon S NH3 H20 = 1 7 5.6 65 ... 

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