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Energy & Fuels 1997, 11, 174-182
Aqueous High-Temperature Chemistry of Carbo- and Heterocycles. 30.1 Aquathermolysis of Phenyl-Substituted Hydroxyquinolines Alan R. Katritzky*, Elena S. Ignatchenko, and Steven M. Allin Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200
Michael Siskin and David L. Ferrughelli Corporate Research, Exxon Research and Engineering Company, Annandale, New Jersey 08801
Jo´zsef Ra´bai* Institute of Organic Chemistry, Eo¨ tvo¨ s University Budapest, P.O. Box 32, H-1518 Budapest 112, Hungary Received May 28, 1996. Revised Manuscript Received August 19, 1996X
A range of phenylquinolones and hydroxy-substituted phenylquinolines was synthesized and subjected to aquathermolysis in water alone, in 15% aqueous formic acid, and in 15% aqueous sodium formate at 315 and 460 °C. Thermal controls were obtained using cyclohexane as solvent. It was thought that the hydroxy substituent might provide a “handle” of activation for subsequent ring opening, denitrogenation, and possible biaryl cleavage pathways. At 350 °C all substrates tended to give mainly quinolines via deoxygenation as the main pathway. At 460 °C all substrates gave complex product slates with some ring opening to lower molecular weight products. Some denitrogenation was observed via ring opening and further reaction. Decarbonylation to yield indoles was also noted as a competing reaction pathway to quinoline ring opening. The indoles subsequently underwent ring opening reactions.
Introduction Quinolines and isoquinolines have been previously subjected by us to aquathermolysis under a variety of resource conversion conditions to model the reactions of N-heterocycles in coals and oil shale kerogens. In the liquid phase in the presence of 10% aqueous formic acid, quinoline undergoes mainly reduction to 1,2,3,4-tetrahydroquinoline,2 whereas isoquinoline undergoes mainly ring opening to yield denitrogenated products such as xylene, ethylbenzene, and indane.2 The selective reduction of quinoline to mainly 1,2,3,4-tetrahydroquinoline is also observed as the main reaction route in 15% aqueous formic acid (water-carbon monoxide) under supercritical conditions;3 2-substituted quinolines also undergo mainly reduction.4 In 49% aqueous formic acid under liquid conditions, quinoline has been seen to undergo mainly reduction and significant formylation;5 under identical conditions isoquinoline underwent reduction and formylation. Abstract published in Advance ACS Abstracts, November 1, 1996. * Address correspondence to this author at the Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL 32611-7200 [telephone (352) 392-0554; fax (352) 392-9199; e-mail
[email protected]]. (1) Part 29: Katritzky, A. R.; Ignatchenko, E. S.; Allin, S. M.; Barcock, R. A.; Siskin, M.; Hudson, C. W. Energy Fuels 1997, 11, 160173. (2) Katritzky, A. R.; Lapucha, A. R.; Siskin, M. Energy Fuels 1992, 6, 439. (3) Katritzky, A. R.; Barcock, R. A.; Siskin, M.; Olmstead, W. N. Energy Fuels 1994, 8, 990. (4) Siskin, M.; Ferrughelli, D. T.; Katritzky, A. R.; Ra´bai, J. Energy Fuels 1995, 9, 331. X
S0887-0624(96)00081-3 CCC: $14.00
In the current study we have investigated the reaction of various hydroxylated quinoline derivatives under suband supercritical conditions, in the hope that the presence of the oxygen functionality as a substituent would provide a handle for more facile ring opening, denitrogenation, and possible biaryl cleavage. Experimental Section The purities of all starting materials were checked by gas chromatography (GC) prior to use, and they were purified to >99% when necessary before reaction. Solvents were deoxygenated with nitrogen for 1 h just before use. All GC analyses were carried out on a Hewlett-Packard 5890 gas chromatograph operated in the split injection mode (30:1 ratio) and equipped with a flame ionization detector (FID). A 15 m capillary column (SPB-1) was used, and the oven temperature was programmed from 50 to 250 °C with the initial time set at 1 min and a subsequent rate of 20 °C/min. All of the GC/ MS analyses were carried out on a Hewlett-Packard 5890 gas chromatograph equipped with a Hewlett-Packard 5972 mass selective detector. The oven temperature was programmed from 50 to 250 °C with the initial time set at 1 min and a subsequent rate of 10 °C/min. 1H-NMR spectra were recorded on a Varian VXR 300 (300 MHz) spectrometer. 13C-NMR spectra were recorded at 75 MHz on the same spectrometer. Chemical shifts are reported in parts per million (ppm) downfield from tetramethylsilane (TMS) used as an internal standard. Coupling constants (J values) are reported in hertz (Hz). (5) Katritzky, A. R.; Shipkova, P. A.; Balasubramanian, M.; Allin, S. M.; Siskin, M. Unpublished results.
© 1997 American Chemical Society
Aqueous High-Temperature Chemistry. 30 4-Phenyl-2-hydroxyquinoline (58) was prepared in 38% yield by cyclization of N-(2-benzoylacetyl)aniline in a solution of phosphorus pentoxide in 85% phosphoric acid according to the method of Stephenson.6 After two recrystallizations from 96% ethanol and drying over P2O5 and KOH, a pale solid was obtained (mp 266-268 °C; lit.6 mp 259-261 °C): 1H NMR (DMSO-d6, TMS) δ 6.41 (1H, s, CH), 7.12-7.18 (1H, m), 7.387.56 (8H, m), 11.88 (1H, s, OH); 13C NMR (DMSO-d6, TMS) δ 161.3, 151.4, 139.3, 136.7, 130.5, 128.7, 128.6, 126.1, 121.8, 121.2, 118.3, 115.7. 2-Phenyl-3-hydroxyquinoline (52) was prepared in 89% yield according to the procedure of Dilthey7 by refluxing 2-phenyl3-methoxyquinoline-4-carboxylic acid8 with anhydrous aluminum chloride in absolute benzene to form 2-phenyl-3-hydroxyquinoline-4-carboxylic acid followed by thermal decarboxylation of the acid at 250-260 °C and recrystallization from acetonewater (mp 228-232 °C; lit.8 mp 230.5-232 °C): 1H NMR (CDCl3-DMF-d7, TMS) δ 7.47-7.56 (5H, m), 7.72 (1H, s), 7.83-7.86 (1H, m), 7.99-8.01 (1H, m), 8.13-8.16 (2H, m), 10.61 (1H, s, OH); 13C NMR (CDCl3-DMF-d7, TMS) δ 149.9, 149.5, 142.3, 137.9, 129.5, 128.7, 128.5, 127.7, 126.5, 125.9, 116.8. 2-Phenyl-4-quinolone (59) was synthesized by reaction of methyl anthranilate with acetophenone diethyl ketal in refluxing diphenyl ether according to the procedure of Fuson.9 After recrystallization from 96% ethanol, a pure colorless product was obtained in 24% yield (mp 252-254 °C; lit.9 mp 259-260 °C): 1H NMR (DMSO-d6, TMS) δ 7.07 (1H, s, CH), 7.58-7.70 (4H, m), 7.88-8.00 (3H, m), 8.23-8.27 (2H, m); 13CNMR (DMSO-d6, TMS) δ 173.1, 152.6, 140.3, 133.2, 132.9, 131.3, 129.1, 128.2, 125.5, 123.9, 121.9, 119.7, 105.7. 4-Phenyl-3-hydroxy-2-quinolone (56) was prepared in 41% yield by reaction of 2,3-indolinedione with phenyldiazomethane at room temperature according to the literature procedure.10,11 Recrystallization from methanol yielded a colorless solid [mp 252-254 °C (dec); lit.10 mp 267-268 °C): 1H NMR (DMSOd6, TMS) δ 7.09-7.58 (9H, m), 9.26 (1H, br, NH), 12.28 (1H, br, COH). 2-Phenyl-3-hydroxy-4-quinolone (62) was prepared via a literature procedure12 by treating trans-1-benzoyl-2-(o-nitrophenyl)ethylene oxide13 with ethanolic HBr at room temperature for 48 h to give N-hydroxy-2-phenyl-3-hydroxy-4quinolone. Further reduction by sodium dithionite in 75% ethanol gave 62 as a yellow solid (mp 265-270 °C; lit.12 mp 265-270 °C). General Experimental Procedure for Quantitative Product Analysis. All experiments were carried out in small (capacity 4 mL) stainless steel Swagelok (plug and cap) bombs that were not equipped for the collection or analysis of gaseous products. An accurately weighed sample of the model compound (0.16 g) was charged into a nitrogen-blanketed stainless steel bomb with an accurately weighed amount of degassed solvent (1.14 mL). The reaction vessel was then sealed. The reactor was immersed in a Techne fluidized sand bath (Model SBS-4) set at the desired temperature using a Techne temperature controller (TC-8D) for 7 min. The temperature profile was measured by a Barnant 115 thermocouple thermometer (type J) placed in the sand bath adjacent to the reaction vessel. After the reaction time period, the reaction was quenched by cooling the bomb initially with cold air and then in dry ice and the bombs were carefully opened while the contents were still solidified (at -44 °C) to minimize loss of material. The (6) Stephenson, E. F. M. J. Chem. Soc. 1956, 2557. (7) Dilthey, W.; Thelen, Cl. Chem. Ber. 1925, 58, 1588. (8) March, L. C.; Romanchick, W. A.; Bajwa, G. S.; Joullie´, M. M. J. Med. Chem. 1973, 16, 337. (9) Fuson, R. C.; Burness, D. M. J. Am. Chem. Soc. 1946, 68, 1270. (10) Eistert, B.; Selzer, H. Z. Naturforsch. 1962, 17B, 202. (11) Wulfman, D. S.; Yousefian, S.; White, J. M. Synth. Commun. 1988, 18, 2349. (12) Spence, T. W. M.; Tennant, G. J. Chem. Soc. C 1971, 3712. (13) Cromwell, N. H.; Setterquist, R. A. J. Am. Chem. Soc. 1954, 76, 5752.
Energy & Fuels, Vol. 11, No. 1, 1997 175 product mixture was transferred to a glass vial; care was taken to recover the maximum amount of reaction mixture from the reaction vessel. The reaction vessel was then rinsed in diethyl ether, and this organic fraction was combined with the reaction mixture. After warming to room temperature, the reaction mixture was extracted with diethyl ether (2 × 3 mL) and the ether layers were combined in a separate glass vial. An initial GC analysis was performed on the ether solution prior to addition of an internal standard. This procedure helps to determine the choice of standard since it is important that the GC peak for the internal standard does not obscure any of the product peaks. An accurately weighed amount of the internal standard, heptane (ca. 0.050 g), was then added to the ether solution, and the resultant solution was again subjected to GC analysis. From the GC traces obtained, the reaction mixture was analyzed in a quantitative fashion and the mass of a particular product could be obtained and its yield determined.14 By carrying out the analysis in triplicate, the reproducibility of the analysis could be observed. Average values were taken and are highlighted in the tables of results. The GC behaviors of all compounds included in the present paper (starting materials and products) are collected in Table 1. Table 2 records the source and mass spectral fragmentation patterns of the authentic compounds used, either as starting materials or for the identification of products. Table 3 records the mass spectral fragmentation patterns of products for which authentic samples were not available and which were identified by comparison with published MS data. Tables 1-3, along with the details of the mass spectral analyses, have been deposited as Supporting Information (see paragraph at the end of the paper).
Results and Discussion All of the results are collated in Tables 5-9, which have also been deposited as Supporting Information. They are presented in the same manner as was described in detail elsewhere.14 All product yields in Tables 5-10 are calculated in mole percent and are corrected with regard to their response factor.14 In cases where product mixtures contained insoluble residues, these precipitates were isolated, accurately weighed, dissolved in an appropriate solvent, and analyzed using the internal standard technique and the results are incorporated in the tables. The observed transformations described below are illustrated in Schemes 1-5. Compounds with numbers g100 are postulated intermediates not detected by the GC/MS system. Note: Hydroxy-oxo tautomerism occurs for hydroxy-substituted N-heterocycles.15 For pyridine and its benzo-fused analogs, it is well established that the oxo form predominates by large factors for aqueous solutions and under most other conditions.16,17 We have represented the compounds studied in this paper accordingly. 2-Phenyl-4-quinolone (59) (Scheme 1, Table 5) was only slightly reactive at 315 °C for 2 h in water, in 15% aqueous formic acid, and in 15% aqueous sodium formate with over 70% of starting material recovered in all cases. In water, the major products were benzoic acid (24, 5.4%), aniline (8, 2.0%), and indole (20, 1.1%). These results suggest that initially two reaction path(14) Katritzky, A. R.; Lapucha, A. R.; Murugan, R.; Luxem, F. J.; Siskin, M.; Brons, G. Energy Fuels 1990, 4, 493. (15) Uff, B. C. Comprehensive Heterocyclic Chemistry; Katritzky, A. R., Rees, C. W., Eds.; Pergamon Press: Oxford, U.K., 1984; Vol. 2, Chapter 2, p 346. (16) Elguero, J.; Marzin, C.; Katritzky, A. R.; Linda, P. The Tautomerism of Heterocycles; Academic Press: New York, 1976; p 84. (17) Katritzky, A. R. Advances in Heterocyclic Chemistry; Academic Press: New York, 1963; Vol. 1, p 341.
176 Energy & Fuels, Vol. 11, No. 1, 1997
Katritzky et al.
Table 10. Summary of Reactivity of Phenylhydroxyquinolines at 460 °C for 1 h no.
compound
59
2-phenyl-4-quinolone
CyC6b H2O 15%HCO2H 15%HCO2Na
58
4-phenyl-2-quinolone
CyC6b H2O 15%HCO2H 15%HCO2Na
52
2-phenyl-3-hydroxy quinoline
CyC6b H2O 15%HCO2H 15%HCO2Na
62
2-phenyl-3-hydroxy-4quinolone
CyC6b H2O 15%HCO2H 15%HCO2Na
56
4-phenyl-3-hydroxy-2quinolone
major productsa
medium
CyC6b H2O 15%HCO2H 15%HCO2Na
2PhQ (64.6%), PhH (14.8%), PhMe (3.2%), PhEt (1.8%) PhCOMe (33.4%), PhOH (31.8%), PhNH2 (18.5%), 2PhQ (6.0%), 2PhInd (3.6%), PhEt (3.7%), PhH (2.8%) PhNH2 (25.3%), 2PhQ (21.6%), PhCOMe (18.9%), PhOH (16.1%), PhEt (15.0%), PhMe (8.7%), 2PhInd (2.5%), 2Ph3MeQ (2.4%), PhH (2.0%) PhNH2 (54.5%), PhCOMe (40.2%), 2Ph3MeQ (11.1%), 2NH2PhCOMe (11.0%), 2MePhNH2 (8.9%), 2PhInd (6.9%), PhH (5.7%), 2PhQ (3.4%), PhEt (1.7%), PhMe (1.3%) PhH (81.3%) 3PhInd (2.3%), PhCH2Ph (0.7%) PhMe (1.6%), PhNH2 (1.3%), PhH (1.2%), 4PhQ (1.1%) PhMe (15.2%), 3PhInd (13.7%), BenzoQ (13.2%), 2MePhNH2 (12.8%), R-MeBzPhNH2 (9.8%), PhInd (8.0%), PhEtPhNH2 (7.3%), PhNH2 (7.3%), 2NH2Fl (7.2%) PhH (38.9%), PhMe (5.9%), 2PhQ (4.5%) Ind (9.7%), PhH (6.4%), 2PhInd (4.6%), PhNH2 (4.2%), PhMe (3.3%), 3Me2,3Di[H]Ind (2.7%) 2PhQ (25.9%), PhMe (11.2%), Ind (10.1%), 2MePhNH2 (5.1%), 3Me2PhQ (3.8%) Ind (37.6%), PhH (19.5%), 3Me2PhInd (8.6%), PhMe (8.0%), 2PhQ (7.9%), 2MePhNH2 (6.8%) PhH (50.7%), 2PhQ (20.6%), PhMe (6.0%) PhNH2 (25.9%), PhCOMe (15.8%), Ind (14.3%), PhH (10.9%), PhCO2H (3.7%), 2PhInd (3.6%), PhMe (3.6%) PhNH2 (27.1%), 2PhQ (25.6%), PhCOMe (17.2%), Ind (11.9%), PhEt (8.7%), PhMe (7.7%), PhH (6.0%) Ind (18.8%), PhNH2 (15.5%), PhH (10.1%), PhCOMe (9.4%), 2MePhNH2 (8.9%), PhMe (8.7%), 2PhInd (6.9%), 2PhQ (6.6%) PhH (42.3%), PhMe (3.9%), 2CyC6 (2.1%) 4Ph1Me2,3Di[H]Ind (6.0%), 2PhInd (5.8%), PhCH2PhNH2 (4.2%), 3PhInd (3.8%), 4Ph3[OH]Q (3.2%), PhNH2 (1.5%), PhH (1.1%) 2PhInd (9.7%), 3PhInd (4.6%), 3Me2PhInd (3.4%), PhCH2PhNH2 (2.6%), Ind (2.6%), PhH (3.0%), PhMe (1.4%) 2PhInd (23.9%), 3PhInd (19.3%), 2MePhNH2 (5.5%), PhMe (5.1%), PhCH2PhNH2 (3.4%), PhNH2 (2.6%), PhEt (2.0%)
denitrogenation
ring opening
M H
M H
H
H
M
H
H L L M
H M M H
M M
M M
M
M
M
M
H M
M M
M
M
M
H
L L
L L
L
L
L
L
a PhCH Ph, diphenylmethane; PhH, benzene; 2CyC , bicyclohexyl; PhMe, toluene; PhEt, ethylbenzene; PhNH , aniline; PhCOMe, 2 6 2 acetophenone; PhOH, phenol; 2MePhNH2, 2-methylaniline; 2PhQ, 2-phenylquinoline; 2PhInd, 2-phenylindole; 2Ph3MeQ, 2-phenyl-3methylquinoline; 2NH2PhCOMe, 2-aminoacetophenone; R-MeBzPhNH2, R-methylbenzylaniline; 3PhInd, 3-phenylindole; 3Me2,3Di[H]Ind, 3-methyl-2,3-dihydroindole; 3Me2PhQ, 3-methyl-2-phenylquinoline; 3Me2PhInd, 3-methyl-2-phenylindole; PhEtPhNH2, o-phenethylaniline; BenzoQ, benzo[h]quinoline; 4Ph1Me2,3Di[H]Ind, 4-phenyl-1-methyl-2,3-dihydroindole; 4Ph3[OH]Q, 4-phenyl-3-hydroxyquinoline; PhCH2PhNH2, 2-benzylaniline. b Solvent reactivity predominates. H ) high (>50%); M ) medium (
