Energy & Fuels 1987, 1, 401-405
401
Ash can be removed efficiently by the low-temperature treatment of coal with n-butylamine; however, the high nitrogen content of SRC is not desirable. Removal of nitrogen by the bond scission of adducts should be attempted. When N-butylaniline (6 g) was treated with tetralin (6 g) at 400 and 450 "C, respectively, under a nitrogen atmosphere (5.1 MPa) for 1h, 23% and 59% of N-butylaniline decomposed to benzene. Needless to say, the use of catalysts can accelerate the denitrogenation reaction.
exceeded 100% at 300 "C for 10 h. 2. Five kinds of coals, including 0-alkylated Taiheiyo coal, were liquefied at 300 "C for 1 and 10 h. High coal conversions were obtained, and increasing hydroxyl oxygen content tended to increase coal conversion. 3. The substitution reaction of phenol with n-butylamine to give N-butylaniline was confirmed. Phenol contributes to hydrogen bonding, and N-butylaniline does not. The substitution reaction may have contributed to the rupture of noncovalent bonds such as hydrogen bonds and the 7-A interactions between coal molecules.
Conclusions 1. When Taiheiyo coal was liquefied by using n-butylamine as a solvent, conversions comparable to those obtained under high-severity conditions were obtained at 300 "C after 10 and 24 h. Under these liquefaction conditions, SRC yields were always larger than conversion to BE and
Acknowledgment. The authors appreciate helpful discussions with their colleague Dr. S. Sat0 and wish to thank A. Saito for his technical assistance and analyses of coals. Registry No. HZC(CHz),NH2,109-73-9;C6HSOH,108-95-2; (H3C(CHz)3)zNH, 111-92-2;H3CCH20H,64-17-5; tetralin, 119-64-2.
Reaction of Illinois No. 6 Coal with (Ethoxycarbony1)carbene' Martin Pomerantz* and Peter Rooney Department of Chemistry, The University of Texas at Arlington, Arlington, Texas 76019-0065 Received March 9, 1987. Revised Manuscript Received July 13, 1987 The reaction of (ethoxycarbony1)carbene (1) formed by the mild thermal decomposition of ethyl diazoacetate (2) with Illinois No. 6 HVCB coal has been studied. Soxhlet extraction (with a toluenemethanol mixture) showed up to 40% more extractables than unreacted coal. Thermogravimetric analysis (TGA) and derivative plots (DTGA) showed significantly more weight loss and, more importantly, lower temperatures at which the weight loss occurred for the treated coal. Diffuse reflectance FT-IR (DRIFT) spectra showed the expected incorporation of the ester functionality of the carbene into the coal along with a decrease in aromatic and a concomitant increase in aliphatic absorptions in the coal. Finally, capillary gas chromatographicand GPC analyses indicated that the major reaction of the carbene was with the coal, since relatively small amounts of the dimers, trimers, and polymers of 1 were formed. These results indicate that the reaction of (ethoxycarbony1)carbenewith coal should prove to be a useful tool in studying the molecular structure of coal.
Introduction Studies of the molecular structure of coal have relied heavily on the chemical reactions of the coal and on the structure of the products produced. Many of these reactions involve high temperatures and fairly severe conditions, and as a result, it is frequently difficult to relate the reaction products to coal structure because of molecular rearrangements and unanticipated reactions. For this reason people have sought mild reactions that would depolymerize the coal and provide tractable, identifiable products. Among the low-temperature reactions studied are oxidations using trifluoroperoxyacetic acid? Na2Cr207?
(1) Presented before the Division of Fuel Chemistry, at the 193rd National Meeting of the American Chemical Society, Denver, CO, April, 1987. (2) Deno, N. C. Department of Energy Report No. DOE/PC/30250T1; Department of Energy: Washington, DC, 1983. Deno, N. C.; Jones, A. D.; Owen, D. 0.;Weinschenk, J. I., 111. Fuel 1985,64,1286. Deno, N. C.; Jones, A. D.; Koch, C. C.; Minard, R. D.; Potter, T.; Sherrard, R. S.; Stroh, J. G.; Yevak, R. J. Ibid. 1982,61 490. Deno, N. C.; Curry, K. W.; Jones, D. A.; Keegan, K. R.; Rakitsky, W. G.; Richter, C. A.; Minard, R. D. Zbid. 1981, 60,210. Verheyen, T. V.; Pandolfo, A. G.; Johns, R. B.; MacKay, G. H. Geochim. Cosmochim. Acta 1985,49, 1603. (3) Stephens, J. F.; Leow, H. M.; Gilbert, T. D.; Philip, R. F. Fuel 1985, 64, 1531. Duty, R. C.; Geier, M.; Harwood, S. Zbid. 1985, 64, 421.
Ag20,4HN03,5and Hz02,6and alkylati~n.~Most other attempts at depolymerization involve high temperatures and much more severe conditionsa8 In this report we examine the reactions of coal with (ethoxycarbony1)carbene(1) formed by the mild thermal decomposition of ethyl diazoacetate (2; eq 1). There are N,CHCOOEt 7Nz + :CHCOOEt (1) 2 1 a few reports in the literature of studies involving reaction of coal with diazo compounds or carbenes. All but one (4) Hayatau, R.; Scott, R. G.; Winana, R. E.; McBeth, R. L.; Botto, R. E. Roc.-Int. Conf. Coal Sci. 1983,322; Chem. Abstr. 1985,102,187669q. ( 5 ) Rudakov, E. S.; Savoskin, M. V.; Rudakova, R. I.; Kucherenko, V.
A. Ukr. Khim. Zh. (Russ. Ed.) 1984, 50, 115; Chem. Abstr. 1985, 102, 116301~.Hayatau, R.; Winans, R. E.; Scott, R. G.; Moore, L. P.; Studier, H. M. In Organic Chemistry of Coal; Larsen, J. W., Ed.; American Chemical Society: Washington, DC, 1978; p 108. (6) Heard, I.; Senftle, F. E. Fuel 1984, 63, 221. (7) Ettinger, M.; Nardin, R.; Mahasay, S. R.; Stock, L. M. J. Org. Chem. 1986, 51, 2840. Stock, L. M.; Willis, R. S. Ibid. 1985, 50, 3566. (8) Gorbaty, M. L., Ouchi, K., Eds. Coal Structure; American Chemical Society: Washington, DC, 1981. Meyers, R. A., Ed. Coal Structure; Academic: New York, 1982. Davidson, R. M. In Coal Science; Gorbaty, M. L., Larsen, J. W., Wender, I., Eds.; Academic: New York, 1982; Vol. 1. 83.
0887-0624/87/2501-0401$01.50/0 0 1987 American Chemical Society
Pomerantz and Rooney
402 Energy & Fuels, Vol. I , No. 5, 1987
have involved the use of diazomethane to analyze for -COOH and phenolic OH groups?Jo and these studies have shown that it is a rather poor analytical method. One recent studyloreports on the reaction of labeled l4CH2N2 and l4CCI2with coal and coal-derived materials. The conclusions, based strictly on the uptake of reagent both before and after exposure to air, were that air-exposed fractions exhibited more ketonic and carboxyl groups a t the expense of phenolic hydroxyl, benzylic methylenes, and other oxidizable moieties. The reactions of carbenes, particularly (ethoxycarbony1)carbene (I), with a very large variety of organic compounds is quite well-known.ll They will add to unsaturated and aromatic molecules to form three-membered and seven-membered rings, they will insert into C-H bonds, they will react with some heteroatoms, and they will undergo various free-radical reactions. Equations 2-4 illustrate the former reactions by showing the reaction of the carbene 1 with ethylene, benzene, and naphthalene, respectively.
le 1 :CHCOOEt
H,C=CH,
8
:CHCOOEt
COOEt
___)
a
COOEt
not isolated
12)
J /, --t
I
fl
COOEt (3)
COOEt
:CHCOOEt)
Table I. Results of the Reaction of N,CHCOOEt (2) with Illinois No. 6 Coal 2, g coal, g amt. recovered,0 g 70 yieldb 7' 0 extracted
coal 1
coal 2
0 1.004 1.015 101 31
1.016 1.002 1.563 88 45
2.028 1.010 2.264 89 63
by 'H NMR spectroscopy) showed that 2 was stable to the overnight stirring procedure. Table I shows the results. It should be noted that the decomposition of 2 apparently begins below 80 "C and N2 evolution is fairly vigorous at 80 "C. This suggests that since ethyl diazoacetak normally requires higher temperatures for decomposition,ll the reaction is being catalyzed, presumably by the mineral matter in the coal. It is also well-known that catalyzed decomposition of 2 gives rise to carbene products.ll In order to be sure that the major reactions were of carbene 1 with the coal, we independently prepared the known products formed when 2 decomposes by itself and when 2 reacts with the dimers of 1. The dimers, namely, diethyl maleate (3) and diethyl fumarate (4), are known to give pyrazoline 5 on reaction with 2, and this, in turn, thermally (above 180 "C) or catalytically, is known to decompose to cyclopropane 6 (eq 5).l1-I3 Capillary gas
-
COOEI
H /L-\H
r
h
C
O
O
E
t
3
In this paper we report on the reactions of 1 (prepared by mild thermal decomposition of 2) with an Illinois No. 6 HVCB bituminous coal (PSOC-1351) and studies of the products involving thermal analyses (TGA, DTGA), diffuse reflectance FT-IR spectroscopy (DRIFT), GPC analysis of the extracts, and some preliminary GC analyses.
Results and Discussion A sample of Illinois No. 6 HVCB bituminous coal obtained from The Pennsylvania State University Coal Research Section (PSOC-1351) was crushed to
