Reactivity of O-methylated Illinois No. 6 coal towards alkyllithiums/methyl iodide

• Published in: Fuel (Guildford) 1985-01, Vol.64 (10), p.1349-1354
• Main Authors: Chambers, R.Rife, Hagaman, Edward W., Woody, Madge C., Smith, Kyle E., Mckamey, Donna R.
• Format: Article
• Language: English
• Subjects: alkyllithium; Applied sciences; coal; Coal and derived products; Energy; Exact sciences and technology; Fuels; reactivity; Structure, chemical and physical properties
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/0016-2361(85)90333-3

An O-methylated Illinois No. 6 vitrain was treated repeatedly with a series of C-H indicator bases of known pK a and quenched with 13,14C-methyl iodide. The extent of 14CH 3 incorporation depended strongly upon base strength, increasing in the order 9-phenylfluorenyllithium < fluorenyllithium < trityllithium. A significant number of methyl groups ( 0.7–1.2 100 coal carbons) were introduced with fluorenyllithium and trityllithium as the base. Additional methyl groups were added upon a second and third treatment with base and alkylating agent. After three treatments, the number of added methyl groups had doubled. The extent of base reagent incorporation was established by parallel experiments using 14C-enriched bases. CP/MAS 13C n.m.r. of the first coal alkylation product using trityllithium and 13C-enriched methyl iodide was consistent with predominantly C-alkylation. From these results, a unified picture for coal structure emerges which contains a distribution of reactive C-H sites, distinguishable on the basis of their acid-base properties. Possible reactive sub-structures are considered.