Elucidation of aliphatic structures in low-rank coals with ruthenium tetroxide oxidations

✍ Scribed by Edwin S. Olson; John W. Diehl; Michael L. Froehlich; David J. Miller

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 662 KB
• Volume: 66
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(87)90337-1

✦ Synopsis

The oxidation of low-rank coals with ruthenium tetroxide was investigated with the objective of elucidating the aliphatic bridging groups and hydroaromatic groups present in the organic structure. The reaction was carried out in a two-phase system with a phase transfer catalyst. An accurate quantitative method was developed for the analysis of the carboxylic acid products. Six of the products were determined by isotope dilution with standard acids followed by gas chromatography-mass spectrometry of methyl esters prepared from the acid mixture. A suite of low-rank coals were oxidized in this system and product yields were compared. Higher yields of the aliphatic acids were obtained from the higher-rank subbituminous coals. A series of lithotypes of Beulah lignite were oxidized. The yields of the aliphatic acids obtained from lithotypes were in the order: vitrain> durain> fusain, and aromatic acids were obtained from the lithotypes in the opposite order. A method was developed to distinguish whether the aliphatic acids originated from hydroaromatic or bridging groups. A priordehydrogenation experiment resulted in a 50% change in the amount of succinic acid obtained in the oxidation but very little change in the amount of adipic acid. This finding implies that half of the succinic acid originates from hydroaromatics and half from bridging groups, whereas very little of the adipic acid results from hydroaromatic groups.