Energy & Fuels 1989,3, 381-385 recovery and lengthened the induction time of the less oleophilic solids. The effect of salt concentration on the more oleophilic solids appeard to be due to compression of the electrical double layer surrounding individual particles, whereas the effect on the less oleophilic particles seemed to be due to adsorption of hydrated cations. Because of these differing effects, it was possible to improve the separation of highly oleophilic Upper Freeport coal and mineral pyrite by increasing the salt concentration of the agglomeration system, whereas it was not possible to improve the separation of weakly oleophilic Illinois No. 6 coal and mineral pyrite. Surprisingly, a larger recovery of pyrite
38 1
than coal was achieved when mixtures of mineral pyrite and Illinois No. 6 coal were agglomerated with heptane, which indicates that pyrite may be more oleophilic than coal under some conditions.
Acknowledgment. Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. W-7405-Eng-82. This work was supported by the Assistant Secretary for Fossil Energy, through the Pittsburgh Energy Technology Center. Registry No. NaC1,7647-14-5; graphite, 7782-42-5; heptane, 142-82-5;pyrite, 1309-36-0.
Additive Effects of Solvent-Refined Coal Fractions and Aromatic Compounds on the Hydrogenolysis of Diar ylmethanes Shigeru Futamura,* Seiya Koyanagi, and Yoshio Kamiya Department of Reaction Chemistry, Faculty of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113 Japan Received October 24, 1988. Revised Manuscript Received February 28, 1989 The solvent system promoting hydroliquefaction of coal and the additive effect of some aromatic compounds on the hydrogenolysis of diarylmethanes in hydrocarbon solvents were investigated. Solvent-refined coal (SRC) promoted this latter reaction in tetralin, but no additive effect of SRC was observed in the thermal decomposition of bibenzyl under the same conditions. It was shown that SRC acted not only as a hydrogen donor but also as a hydrogen shuttler. The additive effect of recovered SRC was greatly affected by the hydrogen donatability of solvent. The hydrogen-shuttling effects of some quinones and azaaromatics were investigated on the basis of the structural analysis of SRC. Phenanthridine was shown to be the most effective hydrogen shuttler. The optimum molar mixing ratio of hydrogen shuttler to tetralin was determined to be 15.
Introduction It has been established that coal fragmentation proceeds successively in processes of coal liquefaction. In relation to its mechanism, Whitehurst and co-workers have discussed the role of asphaltols.' Kleinpeter and co-workers have noted that light solvent-refined coal (SRC) is an excellent hydrogen-transfer agent.2 The authors have also reported that SRC promotes the hydrogenation of aromatic compounds in tetralin.3 Further investigation has revealed that SRC not only donates ita inherent hydrogen but also mediates the hydrogen transfer from tetralin to the diarylmethane.4 The structural analysis of raw and recovered SRC's was carried out, and some imino linkages in SRC were suggested as the possible moiety shuttling hydrogen. This paper clarifies the action mechanism of SRC in hydrogen-transfer reactions and presents the SRC-mimetic hydrogenolysis of diarylmethanes, using aromatic compounds as the hydrogen shuttler. (1)Farcasiu, M.; Mitchell, T. 0.; Whitehurst, D. D. CHEMTECH 1977, 7,68&686. (2) Kleinpeter, J. A.; Burke, F. P.; Dudt, P. J.; Jones, D. C. Final Report to EPRI, No. AP-1425,1980. (3) Kamiya, Y.; Ohta, H.; Fukushima, A.; Aizawa, M.; Mizuki, T. Proc.--lnt. Conf. Coal Sci. 1983; 196-198. (4) Koyanagi, S.; Futamura, S.;Kamiya, Y. Proceedings of the Conference on Coal Science; Fuel Society of Japan: Tokyo, 1986; pp 206-208. 206-208.
0887-0624/89/2503-0381$01.50/0
Table I. Elemental Analyses of the Fractionated Miike SRC's SRC raw SRC-1 SRC-2 SRC-3 eluent ether-methanol THF pyridine w t % eluent 54 38 8 anal., % C H N 0 (diff) ash H/C
86.9 5.7
87.2 5.9
87.0 6.0
1.2
1.1
1.1
6.0 0.2 0.80
5.8
5.9
0.82
0.83
78.3 5.6 1.9 11.4 2.8 0.86
Experimental Section Materials. The diarylmethanes were synthesized according to the method described in a previous paper? The additives and the solvents were commercially purchased and purified if necessary by conventional methods. The SRC's were prepared from Miike (C, 84.5%; H, 6.1%), Akabira (C, 83.4%; H, 6.2%), and Yallourn (C, 67.4%; H, 5.9%) coals as follows: each coal (20 g) was reacted in tetralin (60 ml) at 400 "C at 9.0 MPa of hydrogen for 30 min. The reaction mixtures were subjected to Soxhlet extraction for 15 h using tetrahydrofuran (THF) as the solvent. The residues obtained in the vacuum distillation (3 mmHg, a t 250 "C, for 1 h) of the T H F extracts were used as SRC (raw SRC) in the hydrogenolysis of the diarylmethanes. Column chromatographic separation of the SRC derived from Miike coal, which will be ( 5 ) Futamura, S.; Koyanagi, S.; Kamiya, Y. Fuel 1988,67,14361440.
0 1989 American Chemical Society
Table 11. Additive Effect of SRC on the Hydrogenolysis of Di-1-naphthylmethane(DNM) % convn
SRC (amt/g) none Yallourn (0.1) Akabira (0.1) Yallourn (0.4) Akabira (0.4) Miike (0.4) none Yallourn (0.1) Akabira (0.1) Yallourn (0.4) Akabira (0.4)
of DNM 8 13 12 38 38 36 5 9 6 17 20
% yield of 1-MN 6 9 9 19 20 19
solvent
% selectivity
( % convn)
of 1-MI 47 38 40 26 26 27
Tet (8) Tet (8) Tet (8) Tet(l2) Tet (12) Tet (16) 1-MN (0.3) 1-MN (3) 1-MN (2) 1-MN (6) 1-MN (7)
Key: DNM 7.5 mmol; solvent 75 mmol; 460 "C; initial hydrogen pressure 2.0 MPa; 30 min; Yallourn SRC (C, 83.3%, H, 6.0%); Akabira SRC (C, 86.2%, H, 6.3%); 1-MN = 1-methylnaphthalene; Tet = tetralin; 1-MI = 1-methylindan. designated only as SRC unless otherwise noted, was carried out by eluting ether-MeOH (98:2 v/v) (SRC-1, 54 wt %), THF (SRC-2,38 wt %), and pyridine (SRC-3,8 wt %). Table I shows the elemental analyses of the SRC's. Hydrogenolysis of Diarylmethanes. Prescribed amounts of a diarylmethane, a hydrogen-donor solvent, and an additive were put into a W-mL stainless-steel, magnetically stirred autoclave. After being pressurized by 2.0 MPa of hydrogen, the autoclave was heated up to the reaction temperature and maintained during the prescribed period of time. After the reaction, the autoclave was cooled to room temperature by an electric fan. Product Analysis. The products were identified by GC-MS (JEOL JMS-DXBOO equipped with a glass column of 5% OV-1 on Chromosorb W, 4 mm in diameter and 1 m in length). Quantitative analysis of the products recovered with THF was carried out by GC (Shimadzu GC-4C equipped with a stainless column of 5% SE-30 on Chromosorb P, 4 mm in diameter and 4 m in length). The structural change of SRC was monitored by means of 'H and 13C NMR spectroscopy, GPC, and elemental analysis.
Results Solvent-Dependent Additive Effect of SRC. As Table I1 shows, the addition of SRC promotes the hydrogenolysis of di-1-naphthylmethane. The additive effect does not seem to depend on the SRC origins, reflecting their similar chemical compositions,6 but it is greatly affected by the hydrogen donatability of the solvent. The addition of Yallourn or Akabira SRC (0.40 g) caused about a 2-fold larger conversion of di-1-naphthylmethane in tetralin than in 1-methylnaphthalene, respectively. The additive effect of SRC is greatly affected by the mechanisms for decomposition of model compounds. As Figure 1 shows, the conversion of bibenzyl was almost constant, independent of the amount of SRC added. In this reaction, nearly the same selectivities of toluene (80%) were obtained. The formation of benzene and ethylbenzene was negligible. On the other hand, SRC addition promoted the hydrogenolyses of the diarylmethanes to different extents, depending on their aromatic ring sizes. The additive effect of recovered SRC (SRC recovered after the first use of raw SRC in the hydrogenolysis of 9-benzylphenanthrenewith the same method for preparing raw SRC) is also solvent-dependent (Table 111). In tetralin, recovered SRC and raw SRC showed comparable additive effects and similar conversions of tetralin were obtained. Under the reaction conditions, the rearrangement of tetralin to 1-methylindan also occurred, and the (6)Kamiya, Y.J . Fuel SOC.Jpn. 1978, 57, 12-20.
, Futamura et al.
382 Energy & Fuels, Vol. 3, No. 3, 1989
_loo
0.4
0
0.8
SRC/G
Figure 1. Additive effect of SRC on the hydrogenolysis of diarylmethanes and the thermal decomposition of bibenzyl in tetralin at 430 OC: (0)diphenylmethane; (m)1-benzylnaphthalene; (A)9-benzylphenanthrene; (0)bibenzyl. Original
193 z p i O 5
2
XI00 MW
2
XI00 MW
Recovered
la
a105
,/I,
20
25
,
30
:.\*.: 60-
35
,
45 E
Figure 2. GPC profiles of the raw and recovered SRC fractions: (-) raw SRC; (--) SRC-1; (---) SRC-P; (----) SRC-3. Conditions: SRC concentration 1.0 g dm-3 (THF); UV detector a t 260 nm.
naphthalene selectivity almost doubled in the presence of SRC. On the other hand, in decalin, a modest conversion of 9-benzylphenanthrene was obtained in the presence or absence of recovered SRC. Tables IV and V show that the conversion of di-lnaphthylmethane does not correlate with the amount of Ha(6 = 2.0-4.5 ppm) in the fractionated SRC. The weight ratio of the hydrogen consumed in the hydrogenolysis of di-1-naphthylmethane to H, lost from SRC falls to 1.5-2.3. Structural Analysis of SRC. Figure 2 shows the GPC profiles of the raw and recovered SRC's. Basically, similar molecular size distributions were obtained before and after the reactions for all the SRC's although the structures sensitive to light at 260 nm grew for SRC-3 after the reaction. Next, the recovered SRC was analyzed by 13C NMR spectroscopy in order to detect the chemical structures shuttling hydrogen in dehydrogenated SRC. Figure 3 shows the 13CNMR spectrum of the lighter fractions filtered from a colloidal THF-d8 solution of the recovered SRC. It was confirmed by the control experiments that the sharp peaks were not derived from contaminants in the solvents or reagents. The carbon atoms at 139 and 154 ppm can be assigned to the azomethine carbons and the
Energy & Fuels, Vol. 3, No. 3, 1989 383
Additive Effects on Hydrogenolysis
Table 111. Additive Effect of the SRC's Derived from Miike Coal on the Hydrogenolysis of 9-Benzylphenanthrene (9-BP)' % selectivity % selectivity solvent additive % convn of 9-BP To1 Phen DHP % convn of solvent 1-MI NoH 19 71 70 13 13 61 20 tetralin none 52 83 88 11 20 38 44 tetralin raw SRC recovered SRC 42 86 75 11 18 44 40 tetralin 17 ... 75 Nd 7 decalin none 90 3 7 raw SRC 35 ... deca1in 77 Nd 7 recovered SRC 20 decalin
...
a Key: 9-BP 7.5 mmol; solvent 75 mmol; SRC 0.4 g; 430 "C; initial hydrogen pressure 2.0 MPa; 5 h; To1 = toluene; Phen = phenanthrene; DHP = 9,lO-dihydrophenanthrene;1-MI = 1-methylindan; NpH = naphthalene; Nd = not detected.
~
Table IV. Additive Effect of the Fractionated SRC's Derived from Miike Coal on the Hydrogenolysis of Di-1-naDhthulmethane" additive % convn % yield % convn % selectivity SRC of DNM of 1-MN of Tet of 1-MI none 8 6 8 47 raw SRC 36 19 16 27 SRC-1 49 33 16 26 17 26 SRC-2 41 19 30 25 10 26 SRC-3 ~~
~
OKey: DNM 7.5 mmol; tetralin 75 mmol; SRC 0.4 g; 460 OC; initial hydrogen pressure 2.0 MPa; 30 min. Table V. Amounts of Hydrogens Bonded to the a-Position on the Aromatic Ring in 0.4 g of the SRC Derived from Miike Coal amt of hydrogen HJmg in H,/mg in consumed needed in the original recovered H,/mg hydrogenolysis of SRC (A) SRC ( B ) (A-B) DNM/mg raw SRC 7.75 4.83 2.92 5.40 2.63 6.15 7.55 4.92 SRC-1 3.26 4.95 8.00 4.74 SRC-2 3.02 1.99 3.30 SRC-3 5.01
carbons at the ipso positions in phenolics. These findings urged us to investigate the hydrogenshuttling abilities of quinones as precursors of phenolics and three-ring aza aromatic compounds, which have been sparsely documented in the literature. Their hydrogenshuttling abilities were also compared with those of some aromatic hydrocarbons. Hydrogen-Shuttling Effect of Aromatic Compounds. Table VI shows the hydrogen-shuttling effect of some aromatic hydrocarbons, quinones, and aza aromatics on the hydrogenolysis of 9-benzylphenanthrene. The data in Table VI show that the hydrogen-shuttling abilities of the compounds with the equally condensed aromatic nucleus are higher for aza aromatics and quinones than for hydrocarbons. Among the hydrocarbons, anthracene is the most effective, and pyrene, which has attracted much attention as a hydrogen ~huttler,'-~ has shown a slightly better hydrogen-shuttling ability than naphthalene, phenanthrene, and chrysene. Under the reaction conditions, 77% of the anthracene was converted to afford 9,lO-dihydroanthracene and 1,2,3,4-tetrahydroanthracenein 52 and 46% selectivities, respectively. Dihydropyrenes and dihydrochrysenes were given in 69 and 78% selectivities from pyrene and chrysene, respectively. As for quinones, anthraquinone was apparently the best shuttler. The least active 1,4-naphthoquinone was more effective than the hydrocarbons such as naphthalene, (7) Davies, G. 0.; Derbyshire, F. J.; Price, R. J. Inst. Fuel 1977, 50, 121-126.
(8) Mochida, I.; Takeshita,K. ACS Symp. Ser. 1980, No. 139,259-272. (9) Derbyshire, F. J.; Whitehurst, D. D. Fuel 1981,60, 655-662.
Figure 3. 13CNMR spectrum of the lighter fractions filtered from the colloidal THF-d8 solution of the recovered SRC. 50
I
30
Y
m
0
0.1
0.2
0.3
[HYDROGEN SHUTTLERI I [ TETRAL I N I
Figure 4. Concentration effect of hydrogen shuttler on the 9-benzylphenanthrene conversion at 430 OC: (0)phenanthridine; (B)
phenanthrenequinone; (A)phenanthrene.
phenanthrene, and chrysene. All the quinones, however, were converted almost quantitatively to afford the corresponding monophenols in 50-60% selectivities. The aza aromatics used in this study showed different reactivities toward hydrogenation of their own aromatic nuclei. In the tetralin-acridine system, 87% of acridine was converted to afford 9,lO-dihydroacridine and 1,2,3,4tetrahydroacridine in 18 and 60% selectivities,respectively. As for the tetralin-quinoline system, 52% of quinoline was converted to 1,2,3,4- and 5,6,7,8-tetrahydroquinolinesin 69% combined selectivity. On the other hand, in the tetralin-phenanthridine system, the phenanthridine conversion was not more than 10% and 5,6-dihydrophenanthridine was formed in 60% selectivity. Therefore, there is no correlation between the 9benzylphenanthrene conversion and the amounts of the
384 Energy & Fuels, Vol. 3, No. 3, 1989
Futamura et al.
Table VI. Hydrogen-Shuttling Effect of Additives on the Hydrogenolysis of 9-Benzyluhenanthrene" % selectivity % convn % selectivity
additive none naphthalene phenanthrene anthracene chrysene pyrene quinoline 1-azaphenanthrene 4-azaphenanthrene phenanthridine acridine 1,4-naphthoquinone phenanthrenequinone anthraquinone
% convn of 9-BP
19 20 21
30 22
25 22 23 23 33 40 24 27 30
To1 71 70 71 73 72 74 76 71 69 65 76 96 83 93
Phen 70 71
DHP 13
76 73 74 73
...
...
72 73 79 76 83
additive
11 11
13 9 8 7 7
...
15
tetralin 13 13
MI 61 55 68 48 52 51 47 50 52 43 37 42 38 35
12 21
77 15 18 52
16 18
19 18 17 23 25 20 22 29
...
23 5 87 93 97 99
NPH 20 17 38 24 28 36 27 28 39 53 48 53
"Key: 9-BP 7.5 mmol; additive 7.5 mmol; tetralin 75 mmol; 430 'C; initial hydrogen pressure 2.0 MPa; 5 h. Scheme I. Hydrogen Shuttling
1-
9-BP
SH(Solvent)
Scheme 11. Hydrogen-Transfer Processes Where the Three-Ring Aromatic Compounds and Their Dihydro Derivatives Are Involved
broducts
perhydro derivatives of the hydrogen shuttlers formed during the reactions. Figure 4 shows the 9-benzylphenanthrene conversion as a function of the molar ratio of hydrogen shuttler to tetralin. The 9-benzylphenanthrene conversion levels off at [hydrogen shuttler]/[tetralin] L 0.2.
Discussion SRC addition did not promote the thermal decomposition of bibenzyl or increase the toluene selectivity, suggesting that SRC is not so active a hydrogen donor toward the stabilization of benzyl radicals derived from bibenzyl when compared with tetralin. On the other hand, SRC promoted the hydrogenolysis of the diarylmethane, depending on its aromatic ring sizes. The diarylmethane decomposes via ipso hydrogenation in hydrogen-donor s o l ~ e n t s .It~ is most likely that SRC mediates the monohydrogen transfer from tetralin to the diarylmethane; viz., SRC acts as a hydrogen shuttler (Scheme I). As for recovered SRC, hydrogen shuttling could also occur on some of their dehydrogenated moieties since SRC can be recycled effectively in hydrogen-donor solvents such as tetralin. The additive effect of recovered SRC is much lower in less hydrogen donatable solvents such as decalin and 1-methylnaphthalene. Almost no hydrogen transfer could proceed from 1-methylnaphthalene or decalin to the dehydrogenated SRC. There is almost no correlation between the conversion of di-l-naphthylmethane and the amount of Ha in the SRC (Tables IV and V), but the data in Table V show that 3 5 4 0 % of H, in the fractionated SRC's were consumed during the reactions. This apparent contradiction can be explained on the basis of the dual nature of SRC: some specific structures in the dehydrogenated SRC formed in the donation of its inherent hydrogen can facilely accept hydrogens from solvent; viz., SRC gains hydrogen-shuttling moieties in itself by losing its donatable hydrogens. We assume at present that the hydrogen-shuttling moieties would be some aromatic nuclei, not radicals, since they rapidly donate their @-hydrogensto afford unsaturated structures. The selectivity of 1-methylindan derived from tetralin similarly decreased on adding SRC or aro-
m * m e a HH
8
H
X=CH, N HDZHydrogen donor HA=Hydrogen acceptor
matic compounds. On the contrary, the selectivity of 1methylindan increased on adding bibenzyl, which acted as a source of benzyl radical^.^ Therefore, accumulation of radicals derived from SRC is unlikely under the reaction conditions. A decrease in the 1-methylindan selectivity on SRC addition suggests that the initial transfer of a-hydrogen in tetralin to SRC would occur more selectively since 1methylindan is derived only from the 2-tetralyl radical and isomerization between the 1- and 2-tetralyl radicals is negligible.1° Among the fractionated SRC's, SRC-1 was the most effective, suggesting that less polar fractions in SRC with smaller molecular sizes mediate the hydrogen transfer from tetralin. It is most unlikely that the ash contained in SRC acted as a catalyst since SRC-3 containing all the ash in raw SRC was the least effective. Figure 2 indicates that decomposition and condensation of SRC are negligible under the reaction conditions. Scheme I1 shows the stepwise hydrogenation pathways of the aromatic compounds. The effectiveness of the'hydrogen shuttler should be determined by two factors such as the hydrogen accepting ability of the shuttler itself (HD = tetralin in eq 1and 5) and the hydrogen-releasing ability of the hydroaromatic radical (HA = the diarylmethane in eq 2 and 6). Therefore, the quinones can be excluded as stable hydrogen shuttlers under coal liquefaction conditions. The superdelocalizability gives a good measure to estimate the reactivity of the diarylmethane toward hydrogen~lysis.~ The quantum chemical data in Table VI1 also indicate that the hydrogen-accepting ability decreases in the order acridine > anthracene > pyrene > phenanthri(IO) Franz, J. A.; Camaioni, D. M. Fuel 1980,59, 803-805.
Energy & Fuels, Vol. 3, No. 3, 1989 385
Additive Effects on Hydrogenolysis Table VII. Superdelocalizability Values (Sr(R))"of Aza Aromatics and Aromatic Hydrocarbons aromatic compd quinoline phenanthridine 1-azaphenanthrene 4-azaphenanthrene acridine 9-benzylphenanthrene
SdR) (position) 1.0527 ( 4 4 1.1045 (6-1 1.0214 ( 4 4 1.0151 (5) 1.4732 (9-) 0.9803 (9-)
aromatic compd naphthalene phenanthrene chrysene pyrene anthracene
Sr(R) (position) 0.9944 (1-) 0.9974 (9-) 1.0440 (6-) 1.1150 (1-) 1.3132 (9-)
a Superdelocalizability values toward radical reactions, which were calculated according to the simple Huckel theory.
dine > quinoline > chrysene > 1-azaphenanthrene > 4azaphenanthrene > phenanthrene > naphthalene. If the hydroaromatic radical formed in eq 1 and 5 is more susceptible to further hydrogenation (eq 3 and 7) rather than to hydrogen donation to 9-benzylphenanthrene (HA = 9-benzylphenanthrene in eq 2 and 61, considerable amounts of hydrogen from tetralin are consumed in vain to afford the dihydro derivatives of the shuttlers. Such is the case for anthracene and acridine. Thermochemical data predict that eq 2 is more exothermic than eq 6 , due to the larger resonance energies of phenanthrene and its aza analogues." In fact, perhydro derivatives are produced in lower yields for phenanthrene and phenanthridine than for anthracene and acridine. This could be one of the reasons why phenanthridine is a better shuttler than anthracene. The perhydro derivatives of the aromatic compounds such as 9,lO-dihydroanthracene and 9,lO-dihydrophenanthrene are good hydrogen donors for stabilization of coal fragment radicals, but in the bimolecular monohydrogen-transfer reactions encountered in hydrogen shuttling, those dihydroaromatics are considered to be less effective hydrogen donors than the hydroaromatic radicals. The heat of reaction should be more negative for the hydrogen transfer from such a radical to the diarylmethane, due to the larger gain in resonance energy. Direct and indirect overhydrogenation reactions of the shuttler such as disproportionation of these dihydro derivatives formed in eq 3 and 7 are undesirable to promote smooth hydrogen shuttling. The saturation of the 9-benzylphenanthrene conversion at [hydrogen shuttler]/[tetralin] 1 0.2 (Figure 4) could be ascribed to the occurrence of the reversible hydrogen ex(11) Futamura, S.; Koyanagi, S.; Kamiya, Y. Fuel 1989,68, 130-132.
change between the hydroaromatic radical and the hydrogen shuttler except for the case of phenanthrenequinone. Pyrene shows an unexpectedly lower hydrogen-shuttling ability although its hydrogen-accepting ability is a little higher than that of phenanthridine, which contradicts the results on the liquefaction of Monterey and Belle Ayr coals.12 The rather low conversion of pyrene and the small consumption of tetralin may suggest that the hydrogen exchange between the hydropyrenyl radical and pyrene occurs reversibly even at [pyrene]/ [tetralin] = 0.1. These facts reveal that phenanthridine could act as an effective hydrogen shuttler since overhydrogenation of phenanthridine and adduction of phenanthridine-derived compounds into the hydrogenolyzates from 9-benzylphenanthrene occur only to a small extent, contrasting with quinoline-1,2,3,4-tetrahydroquinolinemixtures.13-15 SRC is a better hydrogen shuttler on the basis of weight than any of the aromatic compounds used in this research. SRC acts not only as a hydrogen donor but as a hydrogen shuttler, suggesting some involvement of phenanthridine-like imino bondings in SRC. Conclusions It has been shown that SRC and phenanthridine are effective hydrogen shuttlers in the hydrogenolysis of diarylmethanes, which can be ascribed to their superior hydrogen-shuttling abilities and higher stabilities under reaction conditions.
Acknowledgment. We are grateful to Professor M. Hida and Associate Professor T. Yamagishi a t Tokyo Metropolitan University for the GC-MS measurements. Registry No. DNM, 607-50-1; 9-BP, 605-05-0; tetralin, 11964-2;decalin, 91-17-8;naphthalene, 91-2@3;phenanthrene, 85-01-8; anthracene, 120-12-7; chrysene, 218-01-9; pyrene, 129-00-0; quinoline, 91-22-5; 1-azaphenanthrene, 85-02-9; 4-azaphenanthrene, 230-27-3;phenanthridine, 229-87-8; acridine, 260-94-6; 1,4-naphthoquinone, 130-15-4; phenanthrenequinone, 84-11-7; anthraquinone, 84-65-1. (12) Derbyshire, F. J.; Varghese, P.; Whitehurst, D. D. Fuel 1982,61, 859-864. (13) McNeil, R. I.; Young, D. C.; Cronauer, D. C. Fuel 1983, 62, 806-812. - - . - - -. (14) Hellgeth, J. W.; Taylor, L. T.; Squires, A. M. hoc.-Znt. Conf. Coal Sci. 1983, 172-175. (15) Derbyshire, F. J.; Odoerfer, G . A.; Whitehurst, D. D. Fuel 1984, 63, 56-60.
