Iodide coal alkylation with

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 Liotta procedure involved slurrying coal in an aqueous solution of tetrabutylammonium hydroxide to remove acidic protons, followed by addition of methyl iodide as alkylating agent. This mixture was then stirred vigorously for 12-72 hrs. depending upon the extent of alkylation desired. After all lation, the moist coal sample was roto-evaporated to remove excess THF and methyl iodine, followed by exdiaustive extraction with water to remove tetrabutylammonium iodide produced during all lation. Finally, the treated coal was vacuum dried (50 C, 0.1 torr, 24 hours) before use. 

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. 

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). 

SYNTHESIS and CHARACTERIZATION of O-ALKYLATED EXTRACTS. Alkylation occurs when tetrabutylanunonium hydroxide is used to promote the reaction of the alkyl iodide with the coal in tetrahydrofuran.(14) The alkylation reaction occurs primarily on acidic oxygen functionalities such as phenolic hydroxyl and carboxylic acid groups, as shown below. 

The O-methylated extract was derivatized with 99 percent C-enriched methyl iodide. The NMR spectrum of the extract showed a strong absorption at 56 ppm (relative to TMS), which can be attributed to unhindered aryl methyl ethers (67%), a smaller absorption at 60 ppm, attributable to hindered aryl methyl ethers (23%), and a resonance at 51 ppm, assignable to methyl esters derived from carboxylic acids (10%).(16) TTiese results are consistant with those of Liotta l al, who studied the alkylation of whole Illinois No. 6 coal.(12)... 

In the first case [1] Y can be either a hydroxy, alkoxy or nitro group. The first two groups are important but variable constituents in coals and the last is probably minor or non-existent. The second active class of species are the alkyl-pyridines [2]. The final case [3] includes substituents on the benzyl carbon where X can be an ether or carbonyl functional group. The general mechanism of this reaction is most probably the base catalyzed iodination of the benzyl carbon with subsequent displacement of the iodide by the pyridine to form the pyridinium salt. In all three modes of activation, the single aromatic ring can be replaced with polycyclic rings. 

Table III. The Reduction and Alkylation of Illinois No. 6 Coal with Methyl, Butyl, and Octyl Iodide ...

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... 

The preparation of alkyl derivatives of ammonia suggested a further step. Hofmann and Cahours (in London) investigated the corresponding derivatives of phosphine, PH3, some of which had been prepared by P. Thenard. They obtained triethylphosphine, P(C4H5)3, by the very violent reaction between zinc ethyl and phosphorus trichloride in ether, and showed that it forms an oxide and sulphide by direct combination, combines with hydrogen chloride, bromide, and iodide, and with ethyl iodide to form P(C4H5)4l. Hofmann found that triethylphosphine forms a red crystalline compound, P(CaH5)3, CS2, with carbon disulphide, which can be used as a test for this in coal gas. 

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