Polyanion , coal iodide

The rich chemistry of the coal polyanion and the presumably close relationship between the structures of the coal polyanion and the initial coal molecules prompted us to study the reaction conditions and the reaction products carefully and then to examine the reaction of the coal polyanion with 90%-enriched butyl-l- C iodide. 

Coal Alkylation with Butyl-1- C Iodide. Potassium (26.1 mmol) was added to a stirred solution of naphthalene (3.14 mmol) in tetrahydrofuran (45 mL) under argon. After 45 min, -325 mesh coal (1.00 g) and an additional wash quantity of tetrahydrofuran (10 mL) were added. The mixture was stirred for 5 days. The excess potassium (2.98 mmol) was removed. A small quantity of insoluble coal (0.041 g) was unavoidably lost in the removal of the metal. A solution of 90%-enriched butyl-1- C iodide (6.88 g) in tetrahydrofuran (10 mL) was added to the stirred solution in 15 min. This quantity corresponds to a twofold excess of the amount of reagent needed for the alkylation of a coal polyanion with 21 negative charges per 100 carbon atoms and naphthalene dianion. Potassium iodide began to precipitate from the reaction mixture almost immediately. The alkylation reaction was allowed to proceed for 2 days. Potassium iodide rapidly settled from the reaction mixture when stirring was interrupted. 

The reaction of the. coal polyanion with methyl iodide occurs at least fivefold more rapidly than the reaction with butyl or octyl iodide, as judged by the rate of precipitation of potassium iodide. However, the results shown in the table reveal that there are only very minor differences in the solubility of the reaction products. In addition, we observed that the coal polyanions prepared from the insoluble residues of the first alkylation reaction were considerably more reactive. These polyanions reacted very rapidly with methyl iodide and reacted with butyl iodide to produce butene-1. 

The alkylation reactions of the coal polyanions also were investigated. The reactions of the polyanion with methyl, butyl, and octyl iodide were compared in tetrahydrofuran. The reaction could be monitored quite readily by the rate at which potassium iodide precipitated from solution. We estimate that methyl iodide is at least fivefold more reactive than butyl or octyl iodide under these conditions. This result, of course, suggests that the Sj 2 reactions of the coal polyanion are more... 

As already mentioned, several investigators have pointed out that naphthalene or tetrahydrofuran may be incorporated into the coal product (9, 10, 11), In this work we found that chromatographic procedures could be used to separate unbound naphthalene and its reductive alkylation products from the coal alkylation products. The spectroscopic work indicates that the principal resonances of naphthalene and tetrahydrofuran are absent from the butylated coals. Moreover, the mass balance shows that no important quantity of naphthalene or tetrahydrofuran could be incorporated. We supplemented this negative evidence by a comparison of the reaction products obtained from the same coal in a reaction in liquid ammonia. In the most pertinent case the Illinois No. 6 coal was treated with potassium in liquid ammonia. The polyanion was alkylated with butyl iodide. The product distribution obtained by GPC and the spectroscopic properties of these fractions were very closely related to the properties of the reaction products obtained in the reaction with naphthalene in tetrahydrofuran. Recently Larsen and his group found that neither " C-labeled naphthalene nor tetrahydrofuran was incorporated in chemically significant amounts in the coal products separated from the reaction mixture by chromatography (12). 

---