Energy & Fuels 1991,5,823-834 neous surrounding of a fluidized bed. Also, the low concentrations of HCN measured indicate that its importance may be limited. Measurement errors and strong concentration variations in the horizontal plane have to be further checked, however. The char appears to be more important than HCN for the successive formation of NzO seen in Figure 11. It was mentioned above that a conversion of 1&30% of the NO converted by char would be sufficient to explain the N20 formation. This should be considered in relation to a possible contribution from char combustion (step 15). de Soete12has found that up to 5% of the char nitrogen was converted to NzO in his experiments. This value corresponds to 50 ppm of N20assuming a complete combustion of the char. The figure of 5 % is too small to explain the increase of the N20 concentration with height as an effect of char combustion only.
823
The general conclusion of this discussion is that there are several factors which indicate that the principal contribution to the NzO emission originates from the reduction of NO on char surfaces. Contributions from char combustion and HCN appear to be only of minor importance. This conclusion has to be further verified, of course, since the basic knowledge of NzO formation and reduction still has to be improved. Acknowledgment. This work was financially supported by the Swedish National Energy Administration. The contribution to the experimental work by the operating staff of the boiler together with personnel from the Department of Energy Conversion is gratefully acknowledged. Registry No. N20, 10024-97-2; COP, 124-38-9; CO,630-08-0; NO, 10102-43-9; HCN, 74-90-8; NH2, 7664-41-7.
Aqueous High-Temperature Chemistry of Carbo- and Heterocycles. 16.' Model Sulfur Compounds: A Study of Hydrogen Sulfide Generation Alan R. Katritzky,* Ramiah Murugan, Marudai Balasubramanian, and John V. Greenhill Department of Chemistry, University of Florida, Gainesville, Florida 3261 1-2046
Michael Siskin* and Glen Brons Corporate Research Science Laboratory, Exxon Research and Engineering Company, Annandale, New Jersey 08801 -0998 Received December 1 I, 1990. Revised Manuscript Received August 13, 1991
The aquathermolysis reactivity of nine organic sulfur compounds was investigated to determine their potential to generate hydrogen sulfide during the cyclic steam stimulation process to recover Cold Lake bitumen. Dioctyl sulfide, 1-decanethiol, didecyl disulfide, 1-naphthalenethiol, 1,l'-dinaphthyl sulfide, 1,l'-dinaphthyl disulfide, 1-naphthyl 1-octyl sulfide, tetrahydrothiophene, and thiophene were selected as model compounds and subjected to neutral, basic, and acidic aquathermolysis conditions at 250 and 300 "C. Thiols,and thiols formed by cleavage of sulfides and disulfides, were found to be the source of HzS evolution. Aliphatic sulfides, in addition to their usual C-S bond cleavage, showed a,/3C-C bond cleavage. Nontronite clay was found to catalyze all cleavages at 300 "C and to catalyze aromatic sulfide isomerization. Tetrahydrothiophene and thiophene were inert under all the reaction conditions investigated. It is shown that there is a significant increase in HzS production as the temperature is raised from 250 to 300 "C for all substrates and conditions. To minimize the escape of HzS to the atmosphere, the steam stimulation processes should be run at as low a temperature as possible.
Introduction Organic sulfur levels in Cold Lake bitumen (CLB) are high (4-7 w t %), This sulfur is distributed largely as thiophenes (75%), sulfides (25%)) and as thiols and disulfides (99.5% pure). Water and cyclohexane used in the reactions were deoxygenated. The sodium phosphate solution (pH 10.5) was prepared by dissolving 0.02 g of Na3P04in 100 mL of water (0.05 M, pH 12). This solution was diluted with water approximately 15 times until the desired pH was reached. It was then deoxygenated before use. The reaction vessels for the cyclohexane and water runs at 250 "C were Parr 22-mL cup bombs with screw caps, glass liners, and (2) Clark, P. D.; Hyne, J. B.; Tyrer, J. D. Fuel 1983,62,959. (3) Clark, P. D.; Hyne, J. B.; Tyrer, J. D. Fuel 1984, 63, 125. (4) Clark, P. D.; Hyne, J. B. Fuel 1984, 63, 1649. (5) Clark, P. D.; Dowling, N. I.; Hyne, J. B.; Lesage, K. L. Fuel 1987, 66, 1353. (6) Chorbadjiev, S. Reo. Roum. Chim. 1981, 26, 1447. (7) Francisco, M. A.; Kurs, A.; Katritzky, A. R.; Rasala, D. J. Org. Chem. 1988,53, 596. (8) Kubota, S.;Akita, T. Yakugaku Zasshi 1961,81,507 [Chem.Abstr. 1967, 55, 19925el. (9) Kuliev, M. A.; Arabova, A. S.; Mamedova, 2.A. Ser. Khim. Nauk. 1965, 3, 59 [Chem. Abstr. 1967, 66, 28563x1.
Teflon gaskets.1° New procedures were developed to overcome experimental difficulties encountered during runs with water at pH 10.5 and runs at 300 "C and because of the reactivity of the sulfur compounds with the Teflon gaskets. This finally led us to use smaller tubing bombs (4.0 mL, 1/4in. tubing with Swagelok caps at both ends) and T bombs (1.5 mL) (316 SS T joints with screw caps). The later bombs (T bombs) were found to be more useful both for higher temperature runs (300 "C) and with expensive starting materials. General Procedure. For the Parr bombs, 1 g of starting material was reacted in 7 mL of the reagent (C6H12,water, or water at pH 10.5) with, where appropriate, 0.5 g of nontronite. Nontronite is an iron-rich smectite, Ca,,5Fe(II)2Si3A1010(OH)2~H20 representative of the type of clays present in the formation. After the reaction had cooled, ether (10 mL) was used to rinse the contents of the bombs into a small glass container. The mixture was stirred for 2 h, and the aqueous and organic portions were separated. The organic layer was used for GC and GC-MS analysis. [For the 1/4-in. tubing bomb, 0.1 g of starting material, and 1 mL of the reagent were used and the product rinsed with 2 mL of ether. For T bombs, 0.05 g of starting material and 0.3 mL of the reagnet were used, and the product was rinsed with 1mL of ether. Where necessary, an amount of nontronite equal to half the weight of starting material was added.] All the GC analysea were carried out on a Hewlett Packard 5890 instrument with a capillary column (SPB-1). A temperature program from 50 to 250 "C a t 10 "C/min was used. The gas chromatographic behavior of all the compounds encountered in this work (starting materials and products) is summarized in Table I. Table 11records the source and mass spectral fragmentation patterns of the authentic compounds used, either as starting materials or for the identification of products. Tables I11 and IV record the mass spectral fragmentation patterns of products for which authentic samples were not available and which were identified by comparison with literature MS data (Table 111), or by deduction (Table IV). The results for each compound are recorded in a separate table (Tables V-XII). Tables 11,111, and IV have been deposited as supplementary material. Calculations of the amounts of H2S generated from the model compounds were made from a consideration of the products formed and the proportion of each product. A molecule of hydrogen sulfide should be formed from either two molecules of a thiol or one molecule of a sulfide:
:. H2S (mol %) = RSR (mol %)
(1)
Elimination of H2S or RSH from a sulfide gives an olefin and a thiol or a hydrocarbon. The thiol can lose H2S to give a second molecule of the olefin or can be reduced to H2S and RH: H2S (mol %) = [olefin (mol %) + RH (mol %)I - RSH (mol 5%) (2)
:.
2
When the starting material is a sulfide, then following the hydrocarbon and olefin formed together with that of thiol should give the amount of hydrogen sulfide generated in that reaction. That is, the difference in mole percent of the olefin and the hydrocarbon and that of the thiol should give the amount (mol %) of the hydrogen sulfide formed in that reaction. The details of the mass spectral assignments of the structures have been deposited as supplementary material along with Tables 11, 111, and IV.
Results and Discussion The results are collected in Tables V-XII, one table for each compound investigated. The observed transformations are illustrated in Schemes I-XI. Compounds with numbers 2100 are postulated intermediates not detected in the products by the GC-MSsystem. 1-Decanethiol(41) (Table V). At 250 OC over 5 days, 1-decanethiol (41) underwent comparable thermal chemistry in cyclohexane (49% conversion) and in neutral water (10) Katritzky, A. R.; Lapucha, A. R.; Murugan, R.; Luxem, F. J.; Siskin, M.; Brons, G . Energy Fuels 1990, 4, 493.
Energy & Fuels, Vol. 5, No. 6,1991 825
Aquathermolysis of Carbo- and Heterocycles. 16 Scheme I
40
101
102
p-
CIH,,CH=CH2
0
.. .
.................................
IS
12
0
ClOHtl
5
I7 66 IHIS
CIHI7$HCH] SH
C~COCIH,
40
1
HIS
C7HlrCH=CHCH3 -%15
29
i-
39
1109
I8
- - -38
16
37
19
(48% Conversion),but the rate of reaction was significantly lower in water at pH 10.5 (13% conversion). The presence of nontronite in unbuffered water had little effect on conversion (44%) whereas nontronite in water at pH 10.5 increased conversion to 40%. The products were isomer mixtures of decenes, decanethiols, and didecyl sulfides with some didecyl disulfides and didecyl trisulfide. At 300 " C over 3 days, l-decanethiol (41) again reacted faster with neutral water (69% conversion) than with water at pH 10.5 (58% conversion). With the addition of nontronite, the conversion in water goes up to 78'31,and in the buffer solution to 69%. Each run gave large amounts of nonane (12) and l-decene (17), along with mixtures of decenes, oxygenated decanes, and didecyl sulfides. The production of the products from l-decanethiol is rationalized as follows (see Scheme I): (i) l-Decanethiol (41) was the source for the formation of 2-(40), 3-(39), 4-(38), and 5-decanethiol (37) via successive elimination and addition reactions. 1-(17), 2-05), 3-(18), 44 16), and 5-decene (19) were the intermediate olefins in this sequence. The first two cycles of this sequence, which is reminiscent of the Willgerodt reaction mechanism," are illustrated in Scheme I. (ii) Addition of l-decanethiol (41) to the carbocation 101 gave 1,l-didecyl sulfide (81) which underwent a-6 cleavage to a nonane radical 102 and the stabilized radical 103. 102 abstracted an active hydrogen to yield nonane (12). In one reaction, intermediate 103 abstracted a hydrogen atom to give l-decyl methyl sulfide (44) but most of this intermediate reacts with water to give methanol (undetected) and the decanethiol radical 104 (Scheme I). (iii) A [ 1-51sigmatropic rearrangement of radical 104 gives the carbon radical 107 which collapses to the tetrahydrothiophene 42. (iv) Addition of a cyclohexyl radical from the solvent to the olefine 17 accounts for the low yield of l-cyclohexyldecane (66). (v) Addition of the decanethiols 37-41 to olefin 17 could give the dialkyl sulfides 76 and 78-81 (e.g. Schemes I and 11). Alternatively the decanethiol 41 could add to the (11) Carmack, M.;Spielman, M.A. Org. React. 1964, 3, 83.
10
intermediate olefins 15-19 to give the same products. (vi) Decanethiol 41 hydrolyzed to l-decanol (31). 2Decanethiol (40) underwent oxidation to the corresponding thioketone 113 which hydrolyzed to 2-decanone (28) (Scheme 11). 3-Decanone (29) formed similarly from 3decanethiol (39). (vii) The radical 104 attacked the various decanethiols e.g., 40, 41, 38, and 37 to provide 1,2'-(89), 1,1'-(90), 1,4'-(87), and 1,5'-(86) didecyl disulfides, respectively. Didecyl trisulfide (94) was formed by reaction between the disulfide 90 and elemental sulfur. Examples are shown in Scheme 11. Dioctyl Sulfide (65) (Table VI). At 250 " C , dioctyl sulfide (65) reacted faster in cyclohexane (73% conversion) than in water (9% conversion) or water at pH 10.5 (19% conversion) all over 5 days. The major products under all three sets of conditions were octane (4), l-octene (7), and l-octanethiol(24). With the addition of nontronite to the aqueous solutions, these products were formed in lower amounts and the major products were octanal (14) and dioctyl disulfide (77). At 300 "C, the reactivity of 65 was similar in neutral water (41% conversion) and in water at pH 10.5 (33% conversion). At this temperature nontronite brought about a increase in reactivity in both systems (85% and 86% conversion, respectively) and also gave higher levels of H2S production. The major products were heptane (2), octane (4), 1-octene (7), 2-octene (9), l-octanethiol (241, and dioctyl disulfide (77). The proposed mechanistic pathways for the formation of the products from dioctyl sulfide are shown in Scheme 111.
826 Energy & Fuels, Vol. 5, No. 6, 1991
tR,
no. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76
min 0.40 0.47 0.57 0.68 0.71 0.72 0.75 0.77 0.79 0.92 1.07 1.22 1.76 1.86 1.92 1.95 2.05 2.13 2.15 2.41 2.43 2.53 2.64 3.24 3.45 3.51 3.69 3.80 3.98 4.05 4.19 4.84 4.89 4.92 5.27 5.81 5.83 5.85 5.88 5.91 5.95 6.30 6.55 6.64 7.49 7.65 7.82 7.92 8.62 8.88 9.48 10.23 10.61 10.67 10.70 10.79 10.80 11.37 11.58 11.91 12.31 12.37 12.52 12.58 12.62 12.91 13.82 14.13 14.62 14.72 14.77 14.80 14.92 14.97 15.00 15.12
Table I. Structure and Identification of Starting Materials and Products identification stru cture mol wt equiv wt basis 84 84 Table 2 thiophene 100 50 Table 2 heptane 49 Table 2 98 2-heptene 114 57 Table 3 octane 88 88 Table 2 tetrahydrothiophene (thiolane) 112 Table 3 56 4-octene 56 112 Table 3 1-octene 56 112 Table 3 3-octene 56 Table 3 112 2-octene Table 2 53 106 ethylbenzene 53 106 Table 2 1,2-dimethylbenzene 128,” 64b Table 3 128 nonane 128 64 Table 3 2-octanone 64 Table 3 octanal 128 Table 4 140 140,” 70b 2-decene Table 3 140,” 70b 4-decene 140 140 Table 3 140a, 70b 1-decene Table 4 140,” 70b 3-decene 140 Table 3 140 140,” 70b 5-decene 140 Table 3 70 2 4 1-buty1)thiophene 140 Table 3 2-methyl-5-propylthiophene 70 140 Table 3 70 2,5-diethylthiophene 130 Table 2 65 1-octanol 73 Table 3 146 1-octanethiol 144 Table 3 72 2 4 1-buty1)tetrahydrothiophene 132 Table 3 132; 66d tetralin Table 2 128 naphthalene 128; 64d Table 3 156 2-decanone 156,’ 78b 156 Table 3 156,” 78b 3-decanone 158 Table 3 2-decanol 158,” 78b 158 Table 3 1-decanol 158,” 78b 2-(l-hexyl)thiophene Table 3 168 168,” 84b 168 Table 3 2-methyl-5-pentylthiophene 168,” 84b Table 3 168 168,’ 84* 2-butyl-5-ethylthiophene 142 Table 2 142 1-methylnaphthalene 146 I-tetralone 73 Table 2 174 Table 4 5-decanethiol 174,” 87b 174 4-decanethiol 174,” 87b Table 4 Table 3 174 3-decanethiol 174,” 87b 174 174,”87b Table 4 2-decanethiol 174 1-decanethiol 174,’ 87b Table 2 172 172 2-(l-hexyl)tetrahydrothiophene Table 4 156 156 Table 2 1-ethylnaphthalene 1-decyl methyl sulfide 188 188 Table 4 170 170 1-propylnaphthalene Table 3 1-naphthalenethiol 160 160,” 80b Table 2 160 160,” 80b 2-naphthalenethiol Table 2 1-(1-buty1)naphthalene 184 184 Table 4 1-(1-propy1)naphthalene 168 168 Table 3 bicyclohexyl 166 83 Table 3 1-cyclohexylnaphthalene 210 105 Table 4 1-hexyl 1-octyl sulfide 230 230 Table 4 4-cyclohexyloctane 196 98 Table 4 196 3-cyclohexyloctane 98 Table 4 2-cyclohexyloctane 196 98 Table 3 1-(1-hexy1)naphthalene 212 212 Table 4 1-cyclohexyloctane Table 3 196 98 diheptyl sulfide 230 230 Table 3 1-heptyl 1-octyl sulfide 244 244 Table 4 1-(1-hepty1)naphthalene 226 226 Table 4 3,3’-dioctyl sulfide 258 258 Table 4 1,2’-dioctyl sulfide 258 Table 4 258,’ 129’ 1,3’-dioctyl sulfide 258 258 Table 4 2,2’-dioctyl sulfide 258 Table 4 258 dioctyl sulfide 258 258,’ 129’ Table 2 1-cyclohexyldecane 224 224 Table 3 cyclohexyl 1-octyl sulfide 228 114 Table 4 cyclohexyl 1-naphthyl sulfide 242 242, 121f Table 4 1-(4-octy1)naphthalene 240 240 Table 4 143-octy1)naphthalene 240 240 Table 4 1-(2-octyl)naphthalene 240 240 Table 4 1-(1-octy1)naphthalene 240 240 Table 4 4,4’-didecyl sulfide 314 314,” 157b Table 4 3,3’-didecyl sulfide 314 314,” 157b Table 4 2,2’-didecyl sulfide 314 314,” 157* Table 4 1,5’-didecyl sulfide 314 314,” 157b Table 4
Katritzky et al. response factor 0.72 0.96 0.96 0.96 0.72 0.96 0.96 0.96 0.96 0.96 0.96 0.95 0.83 0.63 0.95 0.95 0.95 0.95 0.95 0.70 0.70 0.70 0.78 0.71 0.70 0.95 0.95 0.78 0.78 0.76 0.76 0.85 0.85 0.85 0.94 0.77 0.70 0.70 0.70 0.70 0.70 0.69 0.94 0.68 0.93 0.70 0.70 0.93 0.93 0.94 0.92 0.67 0.93 0.93 0.93 0.92 0.93 0.67 0.67 0.91 0.66 0.66
0.66 0.66 0.66 0.92 0.67 0.66 0.91 0.91 0.91 0.91 0.64 0.64 0.64 0.64
Energy & Fuels, Vol. 5, No. 6, 1991 827
Aquathermolysis of Carbo- and Heterocycles. 16 Table I (Continued) no. 77 78 79 80 81 82 83 84 85 86’ 87 88 89 90 91 92 93 94 95 96 97 98
tp mln 15.25 15.30 15.37 15.49 15.53 15.88 15.92 15.96 16.00 17.95 18.00 18.10 18.15 18.20 18.91 19.10 19.54 19.73 20.05 20.26 20.78 21.31
structure dioctyl disulfide 1,4’-didecyl sulfide 1,3’-didecyl sulfide 1,2’-didecyl sulfide didecyl sulfide 4-octyl 1-naphthyl sulfide 3-octyl 1-naphthyl sulfide 2-octyl 1-naphthyl sulfide 1-octyl 1-naphthyl sulfide 1,5’-didecyl disulfide 1,4’-didecyl disulfide 1,3’-didecyl disulfide 1,2’-didecyl disulfide didecyl disulfide 1,2’-dinaphthyl sulfide 1,l’-dinaphthyl sulfide 2,2‘-dinaphthyl sulfide didecyl trisulfide 1,2’-dinaphthyl disulfide dioctyl trisulfide 1,l’-dinaphthyl disulfide 2,2’-dinaphthyl disulfide
equiv wt 290 314,’ 157b 314,’ 157b 314,’ 157b 314,’ 157b 272 272 272 272 346,’ 173b 346,’ 173b 346,’ 173* 346,’ 173b 346,’ 173b 286,’ 143d 286,’ 143d 286,’ 143d 378 318,’ 15gd 322 318,’ 15gd 318,’ 15gd
mol wt 290 314 314 314 314 272 272 272 272 346 346 346 346 346 286 286 286 378 318 322 318 318
identification basis Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4 Table 4
response factor 0.40 0.64 0.64 0.64 0.64 0.65 0.65 0.65 0.65 0.38 0.38 0.38 0.38 0.38 0.64 0.64 0.64 0.13 0.39 0.15 0.39 0.39
a Obtained from 1-decanethiol. Obtained from didecyl disulfide. Obtained from 1-naphthalenethiol. dObtained from 1,l’-dinaphthyl sulfide and 1,l’-dinaphthyl disulfide. Obtained from dioctyl sulfide. ’Obtained from 1-octyl 1-naphthyl sulfide.
Table V. Products Obtained from 1-Decanethiol (41) Reactions
no. 12 15 16 17 18 19 28 29 31
39 40 41 42 44 66 76 78 79 80 81 86 87 89 90 94
structure nonane 2-decene 4-decene 1-decene 3-decene 5-decene 2-decanone 3-decanone 1-decanol 3-decanethiol 2-decanethiol 1-decanethiol 2 4 1-hexy1)tetrahydrothiophene 1-decyl methyl sulfide 1-cyclohexyldecane 1,5’-didecyl sulfide 1,4’-didecyl sulfide 1,3’-didecyl sulfide 1,2’-didecyl sulfide didecyl sulfide 1,5’-didecyl sulfide 1,4’-didecyl disulfide 1,2’-didecyl disulfide didecyl disulfide didecyl trisulfide loss of s as % of converted material
HZO HZ0 (PH 10.5) (PH 10.5) nontronite nontronite nontronite 250 300 300 300 300 5 3 3 3 3
C&lZ
H20
additive (see text) temD. OC time,’days
250 5
250 5
0.2
3.5 0.7 0.5 6.6 0.4 0.3
7.6
0.1
3.0
4.3 0.3 0.1
0.3 0.1
2.0 0.4
0.4
0.3
0.1
0.6
1.0 86.7
0.6 60.1 0.4
1.2 5.4 1.7 0.8
0.3 3.4 50.7 0.6
H20
H20
HzO
solvent
(pH 10.5) (pH 10.5)
nontronite 250 250 5 5
1.5 0.7 52.0 55.8 0.3 0.9
HzO
HzO
16.0 9.8 3.3 25.7 2.6 2.1 0.3 2.0 0.3 0.2 2.0 31.3 1.0
14.2 12.7 30.7 1.5 2.1 0.3 0.3 1.6 0.2 0.6 21.9 0.8
0.3 1.1 2.0
0.1 0.2 0.3 1.2 7.5
4.3 3.5 1.3 21.2 0.2 0.8
0.8 42.0 0.6
14.0 7.0 2.4 26.2 0.8 1.6 0.3 0.3 1.5 0.2 1.2 31.1 0.9
0.6 0.6 1.4 6.0 16.0
0.3 0.3 0.6 2.7 7.1
0.4
0.5 0.5 87.5
0.4
0.9 0.3 0.6 1.0 2.8 7.2 9.9
0.8 1.2 2.4 12.9 13.8
0.4 1.0 8.8 9.0
0.2
0.1 12.7 0.9 33.9
0.7 1.6
0.9 8.7
1.4 0.9 59.8 50.9
(i) Dioctyl sulfide (65) can undergo C-S bond cleavage to give the radicals 115 and 116. Intermediate 115 would abstract a hydrogen radical H’ from a solvent or other molcule to form octane (4). Compound 65 could also undergo a-@ cleavage to provide the radicals 117 and 118. Intermediate 118 would abstract a hydrogen radical H’to yield heptane (2). These abstraction reactions would give a small yield of cyclohexyl radicals (109) which produce several of the minor products, e.g., 67. Intermediate 115
8.7 0.5 15.0
2.0 4.3 0.5 0.2 1.1 25.0 23.8
1.5 2.0 92.7 88.5
75.7
was the source for ethylcyclohexane (120) which underwent oxidation, probably with elemental sulfur in the reaction medium to form ethylbenzene (10). (ii) An elimination of 1-octanethiol (24) from dioctyl sulfide (65) gave 1-octene (7). Addition and elimination of H2S, as discussd above, would give 2-octanethiol (121), 3-octanethiol, and 4-octanethiol. These compounds each lost H2S to yield 2-(9), 3-(8), and 446) octene. (iii) 1-(24) and 2-octanethiol(121) underwent oxidation
Katritzky et al.
828 Energy & Fuels, Vol. 5, No. 6, 1991
Table VI. Products Obtained from Dioctyl Sulfide (65) Reactions solvent CsHY2 HZo HZo HZO HZ0 RO H2O RO (pH 10.5) (pH 10.5) nontronite nontronite additive (see text) nontronite 300 300 300 250 250 temp, OC 250 250 250 3 3 3 5 5 time, days 5 5 5 no. 2 4 6 7 8 9 10 13 14 22 23 24 25
53 54 55 57 58 59
61 62 63 64 65 67 77
96
structure heptane octane 4-octene l-octene 3-octene 2-octene ethylbenzene 2-octanone octanal 2,5-diethylthiophene l-octanol l-octanethiol 2- (I-butyl)tetrahydrothiophene 4-cyclohexyloctane 3-cyclohexyloctane 2-cyclohexyloctane l-cyclohexyloctane diheptyl sulfide l-heptyl l-octyl sulfide 3,3'-dioctyl sulfide 1,2'-dioctyl sulfide 1,3'-dioctyl sulfide 2,2'-dioctyl sulfide dioctyl sulfide cyclohexyl 1-octyl sulfide dioctyl disulfide dioctyl trisulfide loss of s as % of converted material
0.6 6.4
0.3 2.0
2.5 5.5
1.9 4.6
1.7 3.5
27.5
0.6
1.1
7.8
4.9
0.6
4.6 0.2 0.4
6.0
0.1 17.8 4.0 0.4
0.9
1.2
0.2
0.2
4.1
0.4
0.3 0.3 0.3 0.2 0.5 1.3 0.1 0.1 0.1 0.1 26.4 1.0
0.7
90.8 81.7
11.3 0.7 39.7
0.2
2.0
32.6 72.1
to form the thioaldehyde (119) and the thioketone 122, which were hydrolyzed to octanal(14) and 2-octanone (13), respectively. Octanal (14) could be reduced to l-octanol (23), but this would more likely result from direct hydrolysis of 24 or 65. (iv) The cyclohexyl radical 109 was the source for the formation of l-cyclohexyloctane (57), 2-cyclohexyloctane (55), 3-cyclohexyloctane (541, and 4-cyclohexyloctane (53) by reaction with the various olefines produced in the Willgerodt sequence. These products were formed only in the cyclohexane run. (v) 1,2'-Dioctyl sulfide (62) could be obtained through octanethiol radical (116) attack on 2-octene. Similarly, 1,3'-dioctyl sulfide (63) would arise from reaction between 116 and either 8 or 9. Radicals from the other thiols would add to the appropriate octenes to give the sulfides 61 and 64.
(vi) Intermediate 116 dimerized to yield dioctyl disulfide (771, which with elemental sulfur gave dioctyl trisulfide (90). (vii) As shown in Scheme 111, intermediate 118 reacted with 24 or 65 to give l-octyl l-heptyl sulfide (59). (viii) 2-( l-Buty1)tetrahydrothiophene (25) would form from the radical 116 in a manner analogous to the formation of 2-(l-hexyl)tetrahydrothiophene(42) (Scheme
I).
1.9
Didecyl Disulfide (90) (Table VII). At 250 "C, didecyl disulfide (901, like l-decanethiol, reacted faster in cyclohexane (99% conversion over 5 days) and water (100% conversion) than in water at pH 10.5 (74% conversion). In this case, however, l-decanethiol (41) and l-decene (17) were the major products from all three re-
2.1
4.6
12.0 7.2 0.1 0.2 21.5 39.2 0.3 1.8 3.7 2.4 0.4 0.2 0.2 11.0 17.3 0.6
0.2 0.3
0.2
0.1 0.1
80.9
78.9
59.0 14.4
0.5
2.0 2.7 32.7
1.2
87.4
33
4.1 8.1 0.1 9.5 0.2 1.0
1.7
66.8 76.4
125
9.5
HIO nontronite 300 3 13.9 8.8 0.2
38.8 0.3 4.0 0.1 3.0 0.2 0.2 0.2 14.8 0.6
0.1
0.2
0.1
66.6
13.3
0.6
1.2
67.4
79.0
124
actions. With nontronite the reactivity was greatly reduced in both neutral water (43% conversion) and water at pH 10.5 (9% conversion). Both runs produced l-decanethiol (41) in highest yield and were characterized by the presence of a number of different didecyl sulfide and disflide isomers. At 300 "C over 3 days, all four aqueous reactions gave complete conversion of the didecyl disulfide. The product slates showed mainly lower molecular weight products, principally l-decene, 2-decene, and l-decanethiol. Disulfides readily undergo homolysis to give radicals of the general structure R-S'. Didecyl disulfide does so in all the reactions studied and abstraction of hydrogen a t o m from solvent or other molecules gives l-decanethiol (41). Further reactions of 41 are as discussed above and illustrated in Schemes I and 11. In addition, traces of several thiophene derivatives were detected. The higher concentration of decyl sulfide radicals (104) in these reactions would allow the formation of the hexyltetrahydrothiophene 42 (Scheme I) and its oxidation to 2-(l-hexyl)thiophene (32). Rearrangement of the primary radical 104 through intermediates 123-125 would lead through a similar
Energy & Fuels, Vol. 5, No. 6, 1991 829
Aquathermolysis of Carbo- and Heterocycles. 16
Table VII. Products Obtained from Didecyl Disulfide (90) Reactions solvent H20 HIO H,O HzO H,O (PHio.5) (pH 10.5) (PH io.5) nontronite nontronite additive (see text) nontronite 250 temo. O C 250 250 250 250 300 300 300 5 5 3 3 3 timl,’days 5 5 5 no. structure 12 n-nonane 15 2-decene 16 4-decene 17 1-decene 18 3-decene 19 5-decene 20 2- (1-butyl)thiophene 21 2-methyl-5-propylthiophene 22 2,bdiethylthiophene 28 2-decanone 29 3-decanone 30 2-decanol 31 1-decanol 32 2-(1-hexy1)thiophene 33 2-methyl-5-pentylthiophene 34 2-butyl-5-ethylthiophene 37 5-decanethiol 38 4-decanethiol 39 3-decanethiol 40 2-decanethiol 41 1-decanethiol 44 1-decyl methyl sulfide 66 1-cyclohexyldecane 73 4,4’-didecyl sulfide 74 3,3’-didecyl sulfide 75 2,2’-didecyl sulfide 76 1,5’-didecyl sulfide 79 1,3’-didecyl sulfide 80 1,2’-didecyl sulfide 81 didecyl sulfide 86 1,5’-didecyl disulfide 87 1,4’-didecyl disulfide 88 1,3’-didecyl disulfide 89 1,2’-didecyl disulfide 90 didecyl disulfide loss of s as % of converted material
2.4 11.0
4.9 1.1
2.9 2.1
15.3 35.0 4.4 6.3
3.0
5.2
1.1 15.5 1.0 55.6 13.0
0.5
1.1
nontronite 300 3
10.2 0.2 46.5 7.0
25.7 2.0 22.6 9.4 3.5 0.5
0.5
0.6 1.0
1.2 5.2 2.4
6.2
0.7 5.0
2.0 2.2
1.0
0.7 1.4 1.9 3.7 13.0 23.9
0.1 0.3 0.9 0.7 48.2 21.3 1.2
53.1
3.2
0.3 0.3 0.5 2.1 1.7 0.5
0.3 0.2 0.2 2.3 1.5
0.1 0.3 0.3 1.3 3.1 1.7 0.5
0.3
0.2
0.2
0.8
0.4 2.0 29.1 2.1
1.2 2.2 0.1 0.6 15.0 2.1
0.1
0.3 0.2 2.5
0.8 0.2
3.6 0.1
0.7
72.5
67.5
0.7 1.8 2.8 0.9
0.7 0.8 3.0
3.3
0.4 0.5 40.9
0.3 2.8
0.2
2.7
1.1
0.4 0.2 0.4 1.7
1.0 56.7 48.7 40.4
1.0 2.1
0.4 0.9 1.6
0.2 0.7
14 1.0 26.0 21.1
0.3 0.9 1.6 90.2 24.5
90.3 62.8
16
126
0.4 0.4 0.2 2.7 1.5
0.7 1.7 1.2 26.5
0.2
Scheme VI
Scheme
u
21.6 3.3 24.3 8.2 1.4 0.5
hi0
p
&
&s
46
131
46
+
1
bii 109
133
& y H
68
mechanism to 2-methyl-5-pentylthiophene (33) (Scheme IV). A further cycle of the radical rearrangement would give 2-butyl-5-ethylthiophene(34). Following the mechanism which gave nonane (12) by CY-@ cleavage of decanethiol4l,l-octanethiol(24)was formed after a second CY-@
134
- HIS
-SH-
p WS 91
cleavage. This and ita isomeric 2- and 3-octanethiols give rise to the thiophenes 20, 21, and 22. 1-Naphthalenethiol (46) (Table VIII). A t 250 O C conversion is 74.2% in cyclohexane, 87.5% in water and complete in the other aqueous systems. In this aromatic system the nontronite clay acta as a catalyst and high pH also gives a higher conversion than neutral water. This contrast with the aliphatic compounds attesta to the ability of the aromatic system to stabilize both radical and ionic
Katritzky et al.
830 Energy & Fuels, Vol. 5, No. 6,1991
Table VIII. Products Obtained from 1-Naphthalenethiol(46) Reactions solvent C&lZ HZO H20 HZO HzO HzO HzO H2O (pH 10.5) (pH 10.5) (pH 10.5) additive (see text) nontronite nontronite nontronite 300 300 300 250 250 250 250 250 temp, "C 5 5 5 5 5 3 3 time, days 3 no. 26 27 46 47 50 68 91
92 93 95
97 98
structure tetralin naphthalene 1-naphthalenethiol 2-naphthalenethiol bicyclohexyl cyclohexyl 1-naphthyl sulfide 1,2'-dinaphthyl sulfide 1,l'-dinaphthyl sulfide 2,2'-dinaphthyl sulfide 1,2'-dinaphthyl disulfide 1,l'-dinaphthyl disulfide 2,2'-dinaphthyl disulfide l o s s o f S a s a % of material converted
0.1 0.3 0.3 0.3 1.4 1.8 25.8 12.5
0.3 2.3 0.4
0.3 1.4
63.8 62.5 13.0 6.3 7.7 2.0
40.2 14.6 2.6
63.8 5.2
0.1 1.0 2.4
17.7 14.5
10.6
17.7
7.5
13.0
25.8
14.2
67.4
67.9 73.0
83.5
71.5
1.4
2.5
5.1
2.7
6.7
13.7
11.7
14.2
82.2 82.3
72.0
83.6
0.2
2.8
0.3
4.6
1.2
3.9
3.5
1.8
3.6 1.6
2.2
47.8
50.9 45.8
49.8
46.3
Table IX. Products Obtained from 1,l'-Dinaphthyl Sulfide (92) Reactions solvent CBHl2 H2O HzO HZO H2O HzO HzO H20 (pH 10.5) (pH 10.5) (pH 10.5) additive (see text) nontronite nontronite nontronite temp, OC 250 250 250 250 250 300 300 300 time, days 5 5 5 5 5 3 3 3 no. 27 46 47 51
structure naphthalene 1-naphthalenethiol 2-naphthalenethiol cyclohexyl-lnaphthalene 91 1,2'-dinaphthyl sulfide 92 1,l'-dinaphthyl sulfide 93 2,2'-dinaphthyl sulfide loss of s as % of material converted
HZ0 (pH 10.5) nontronite 300 3
0.6
8.0
HZO (pH 10.5) nontronite 300 3
60.7 21.9 2.0 6.4 1.3
41.8 4.5
56.5 5.9
10.1
5.0
9.1
22.1
89.9
31.0 55.7
44.6
10.7
0.6 0.3 98.5
9.3 92.0 90.7
100.0
15.4
0.7 80.0
100
intermediates. The major product in all runs is 1,l'-dinaphthyl sulfide (92,67-84%), Scheme V. It is notable that much less 1,2'-dinaphthyl sulfide (91) is formed in cyclohexane (2.4%) than in the aqueous reactions (11-18%) where, presumably, the ionic mechanism of Scheme VI takes over. The intermediacy of radicals such as 126 and HS' in Scheme V is demonstrated by the formation of cyclohexyl radicals 109 to give cyclohexyl naphthyl sulfide (68,1%) and even a trace of bicyclohexyl (50,0.1%). The disulfides observed (e.g., 97) would arise from reaction between primary radicals such as 126 and sulfides, particularly the starting material 46. When the aquathermolyses are run at 300 "C the product slates are noticeably different. Conversion rates are slightly lower (85-95%) and high yields of naphthalene are obtained (40-64%). Also significant amounts of 2,2'-dinaphtliyl sulfide (93) are seen with much lower yields of the expected 1,l'-(92) isomer. Scheme V gives mechanisms for these reactions. (i) The radical 126 attacks a further molecule of starting material 46 at the 2-position to give the intermediate 128.
88.0 49.4
4.8 75.5
63.3
This can acquire a hydrogen atom to give 129 which would split out either the disulfide 130 and leave naphthalene (271, or hydrogen sulfide to give 1,2'-dinaphthyl sulfide 91. The unstable disulfide 130 would collapse back to starting material via radical 126. (ii) Alternatively, the radical 126 could attack the starting material at the 1-position to give intermediate 127 which would lose HS' to give 1,l'-dinaphthyl sulfide (92). (iii) Scheme VI11 includes a route for the conversion of the 1-naphthalenethiol radical 126 to the 2-naphthalenethiol radical 145. Attack of 145 on 1-naphthalenethiol would follow a similar sequence to Scheme V (i.e., 128-91) to give 2,2'-dinaphthyl sulfide 93. The loss of sulfur as a percentage of converted material is close to 50% for each of the 250 "C runs (Table VIII). This increased to 72-84% at 300 "C, largely due to the high proportion of naphthalene produced. 1,l'-Dinaphthyl Sulfide (92) (Table IX). This sulfide shows very low levels of conversion at 250 "C in both cyclohexane (1.5%) and aqueous (+lo%) systems. In water, the only product is naphthalene (8%)and at pH
Energy & Fuels, Vol. 5, No. 6, 1991 831
Aquathermolysis of Carbo- and Heterocycles. 16
Table X. Products Obtained from 1,l’-DinaphthylDisulfide (97) Reactions
250 5
H20 Hz0 HzO HZ0 HZO (pH 10.5) (pH 10.5) (pH 10.5) nontronite nontronite nontronite 250 250 250 250 300 300 300 5 5 5 5 3 3 3
14.2 26.5
39.2 3.7
17.8 18.5
66.5
34.3 32.3 43.3 2.3
10.0 69.4 12.9
830 1.4
5.9
10.5
24.9
10.0 11.0
2.9
1.0
40.1
5.6
1.3
5.1
2.0
1.5
11.4
11.2
3.4
3.2
2.8
4.5
9.8
7.8
1.6
2.1
CBHlZ HzO
solvent additive (see text) temp, O C time, days no. structure 26 tetralin 27 naphthalene 46 1-naphthalenethiol 68 cyclohexyl 1-naphthyl su1fide 91 1,2’-dinaphthyl sulfide 92 1,l’-dinaphthyl sulfide 93 2,2’-dinaphthyl sulfide 95 1,2’-dinaphthyl disulfide 97 l,l’-dinaphthyl disulfide loes of s as % of material converted
HZ0
HZ0
(pH 10.5) nontronite 300 3
11.1
22.4
28.3
16.5 6.2
9.6 11.2 45.5 61.2
Scheme VI1
H’
‘OH
136 I35
axs 91
10.5 no conversion occurs. However, both systems containing nontronite clay give only the rearranged 1,2’-dinaphthyl sulfide (91) in 9.3 and 10.1% yields. At 300 “C conversion rates were higher (44-90%). As before, most of the product at this temperature is naphthalene. For example, in water from a 69% conversion, 60.7% is this hydrocarbon. The second product in each case is 1,2’-dinaphthyl sulfide and each run gave a small yield of the direct fission product 1-naphthalenethiol(46). The small naphthalene production in cyclohexane (0.6%) compared to water (8.0%) suggests the ionic mechanism shown in Scheme VII. Protonation of the diaryl sulfide 92 at the 4-position gives 135 which would be attacked by water or hydroxide ion to give 136. Loss of 1-naphthalenethiol (46) gives 1-naphthol (139) which in its keto tautomer (138) is vulnerable to reduction through 137 to naphthalene (27). The charged intermediate 135 could also be attacked at the 3-position by 1naphthalenethiol to give the dihydrodisulfide 141. This would lose hydrogen either directly or via 140 to give the 1,2’-dinaphthyl sulfide (91). Other products in Table IX are derivatives of 1naphthalenethiol (46) as discussed above. The sulfur loss figures are not reliable for the low conversion rates of the 250 “C reactions, but at the higher
8.0
7.8
43.4
65.1
88.0 88.2
2.5
83.2
89.6
temperature similar rates of loss are seen to those in Table VIII. 1,l’-Dinaphthyl Disulfide (97) (Table X). This disulfide shows over 90% conversion in all reactions. In cyclohexane at 250 “C conversion is complete within 5 days to give 66.5% of 1-naphthalenethiol which results from simple homolysis of the weak S-S bond. There is 22.4% of 1,l’-dinaphthyl sulfide (92), formed as shown in Scheme V. The high density of 1-naphthalenethiol radicals which must form early in the reaction cause significant cyclohexyl radical formation from the solvent resulting in no less than 11.1% of cyclohexyl 1-naphthyl sulfide (68). In water, the major product is also 1-naphthalenethiol (43.3%), but in addition there is a high yield of naphthalene (27,34.3%). 1,l’-Dinaphthyl sulfide (16.5%) and 1,2’-dinaphthylsulfide (5.9%) account for the rest of the starting material, Schemes V-VII. With nontronite clay present the lowest conversion is obtained (90.4%). There is a high yield of naphthalene (32.3 % ), but little 1-naphthalenethiol(2.3% ). Instead, the clay catalyzes diaryl sulfide formation and there is more of the rearranged products 1,2’ (92, 28.3%) and 2,2’ (93, 11.4%) dinaphthyl sulfides than the 1,l’-dinaphthyl sulfide (92, 6.2%). There is also 9.8% of the rearranged 1,2’-dinaphthyl disulfide (95). At high pH (92% conversion) there is less naphthalene (14.2%) and more 1-naphthalenethiol(26.5%), presumably fully ionized in this solution. The highest yield is of 1,l’-dinaphthyl sulfide (92,40.7%) and there is 10.5% of the rearranged diaryl sulfide 91 (Scheme VII). With nontronite clay added to the pH 10.5 solution conversion is 92.2% and the slate of products is closely similar to that for the clay/water run. The rearranged 1,2’-dinaphthyl disulfide (95) only forms in the nontronite clay catalyzed runs,where &lo% is seen. It is possible that a radical mechanism operates, as suggested in Scheme VIII. The intermediate 2naphthalenethiol radical (145) provides an explanation for the presence of the two rearranged dinaphthyl sulfides. Some of the intermediate would capture a hydrogen atom to give the thiol 47 which could react with further 145 to give, via 149,2,2’-dinaphthyl sulfide (93). Similarly, attack by radical 145 on 1-naphthalenethiol (46) (or 126 on 47) would go via 144 to 1,2’-dinaphthyl sulfide (91). For the aquathermolyses run at 300 “C over 3 days conversions are 100% in every case and, as with 1,l’-di-
Katritzky et al.
832 Energy 13Fuels, Vol. 5, No. 6,1991 Scheme VI11
Scheme X
04
1 +
46
149
CrH,,CH=CHMc
126
83
I
Scheme IX 82
naphthyl sulfide all four reactions give high yields of naphthalene (7&83%). The second product in all instances is the rearranged 1,2'-dinaphthyl sulfide (91). The other dinaphthyl sulfides and usually a trace of the rearranged 1,2'-dinaphthyl disulfide make up the remainder of the product slate. There is only 11% loss of sulfur in the cyclohexane reaction, but in the low-temperature aqueous runs there is 43-6590 loss and, as usual, in the 300 "C runs the loss is higher at 83-90%. l-Naphthyl 1'-Octyl Sulfide (85) (Table XI). In cyclohexane at 250 "C (43.5% conversion) the main products are l-octene (7, 9%), 2-octene (9, 1.5%), l-octanethiol (24, 10.9%), l-naphthalenethiol (46,7.7%), dioctyl sulfide (65, 5.3%), and 1,l'-dinaphthyl sulfide (92, 4.3%). Most of these and the minor products are accounted for by the radical reactions of Scheme IX. The l-octanethiol would result from an elimination reaction of dioctyl sulfide as discussed above. The dinaphthyl sulfides 91 and 92 would arise from the naphthalenethiol radical 126 by the routes of Scheme V. In water at 250 "C over 5 days this sulfide gives a 33.6% conversion of which 10% is l-octene (7) and 1.1% 2-octene (9). Although the l-octene probably arises from an elimination reaction, there is only 0.5% of l-naphthalenethiol (46) in the product mix. Most of this material is converted to naphthalene (27, 3.9%) and the dinaphthyl sulfides 91 and 92, presumably by the radical mechanisms of Scheme V. There is also l-octanethiol(24, 3.2%) which would be
produced by radical attack of hydrogen sulfide on l-&ne. Finally, there is a significant yield of heptane (2, 3.8%). This must result from a homolysis to the stabilized radical 151 and heptyl radical 118 (Scheme IX). The addition of nontronite clay to this reaction slightly increases the conversion to 44% and in a product slate similar to that from water appears to favor radical reactions. There is an increase in the yield of heptane to 5.7% and some octane (4, 2.6%) is produced from a C-S bond homolysis. The routes of Schemes VI-VI11 give increased amounts of the dinaphthyl sulfides 91 (5.9%), 92 (6.5%), and 93 (1.6%) and 1,l'-dinaphthyl disulfide (97) (1.5%). At pH 10.5 the reaction gives a similar conversion (31.7%) and product slate as obtained in neutral water. With nontronite clay added to the alkaline reaction the conversion is 46.3% and the list of products resembles that from the run with the clay in neutral conditions. At 300 "C over 3 days' conversions vary between 96% in water and 98.5% in alkaline solution. Notably, the highest yield in each reaction is l-octene (34-4290) accompanied by naphthalene (26.3% in water and 11.5-13% in the other three systems). Other important products in water are heptane (7.4%) and 2-heptene (1.2%). Heptane would arise as discussed above and shown in Scheme IX while 2-heptene presumably comes from the loss of a hydrogen from the intermediate 118. There is 3% of 2octene, but no other octenes, indicating that the Willgerodt mechanism is not as important in these reactions as previously. 2-Octanone (13,0.4% in water and ca. 1% in the other runs) would result from hydrolysis of 2-octanethiol (121) or 1,2'-dioctyl sulfide (62) followed by oxidation. l-Octanethiol (24) is present in comparatively low yield (3.5%), the acid-catalyzed elimination of l-octene from the starting material would be faster than the radical reaction to produce this thiol, and the thiol once formed would be depleted by elimination. Neither is l-naphthalenethiol(46, 1.5%) a prominent product. Reductions, at the water/steel interface, may contribute to the formation of trace amounts of tetralin (26, 0.7%) and l-tetralone (36,0.2% through reduction/hydrolysis). Dioctyl sulfide (65,7.4% ) and 1,2'-dioctyl sulfide (62, 0.4%) are present, probably formed by radical routes, Scheme VII, as are the dinaphthyl sulfides 91 (1.3%), 92 (2.1%), and 93 (0.3%) (Schemes V and VIII). The other three sets of conditions all produce very similar product slates at 300 "C as water at 300 "C. The most
Aquathermolysis of Carbo- and Heterocycles. 16
Energy & Fuels, Vol. 5, No. 6, 1991 833
Table XI. Products Obtained from 1-Naphthyl 1’-Octyl Sulfide (85) Reactions solvent additive (see text) temp, O C time, days no. structure 2 heptane 3 2-heptene 4 octane 7 I-octene 8 3-octene 9 2-octene 10 ethylbenzene 11 1,2-dimethylbenzene 13 2-octanone 22 2,5-diethylthiophene 24 I-octanethiol 26 tetralin 27 naphthalene 35 1-methylnaphthalene 36 I-tetralone 43 I-ethylnaphthalene 45 1-(2-propyl)naphthalene 46 1-naphthalenethiol 48 l-(l-butyl)naphthalene 49 1-(1-propyl)naphthalene 56 1-(1-hexyl)naphthalene 60 1-(1-hepty1)naphthalene 62 1,2’-dioctyl sulfide 65 dioctyl sulfide 69 1 - ( 4 - ~ t y l ) naphthalene 70 l-(3-octyl)naphthalene 71 l-(2-octyl)naphthalene 72 1-(1-0ctyl)naphthalene 82 4-octyl I-naphthyl sulfide 83 3-octyl I-naphthyl sulfide 84 2-octyl I-naphthyl sulfide 85 I-octyl 1-naphthyl sulfide 91 1,2’-dinaphthyl sulfide 92 1,l’-dinaphthyl sulfide 93 2,2’-dinaphthyl sulfide 97 1,l’-dinaphthyl sulfide loss of s 88 % of material converted
CBHlZ H20 250 5
H20
HsO
nontronite 250 250 250 5 5 5
HzO H20 (pH 10.5) (pH 10.5) nontronite nontronite nontronite 250 300 300 300 300 3 3 5 3 3
3.8
5.7
1.8
4.6
1.7 9.0
2.6 10.0 8.0
2.5 5.5
2.3 10.0
1.5 1.3
1.1
1.1
1.5
1.1
0.3 0.3
0.5 0.3
10.9 3.2
0.6 2.7
6.9
3.9
2.0
1.2
6.4
HzO
7.4 1.2
HZO
8.0 0.4
38.2 34.0 0.5 3.0 3.0 0.3 0.3 0.4 1.0 0.3 3.5 2.7 0.7 0.4 26.3 13.2 0.2 0.3 0.2 0.2 0.2
6.8
6.9 0.4
42.1
33.9 0.6 2.8 0.3 0.3 1.0 0.3 2.1 0.7 11.5 0.4 0.3 0.5 0.2
4.5 1.1
3.9 0.8 12.3 0.3 0.4
0.1
7.7
0.5
0.5
1.6
2.5
1.5
6.3
0.1
0.4
0.6 5.3
0.2
0.7 2.3
0.4
0.5
3.0
0.3
0.7 1.8
0.6
0.8 3.0
0.3 0.5
0.1
0.7
0.8
0.2
0.2
0.4
0.4
0.5
0.2
0.3
0.3
0.3
0.4 7.4
0.7 12.0 0.1
0.4 9.2
0.1
0.2
0.1
0.1
0.1
0.2
0.5
0.1
0.3
13.3 0.1
0.3
0.1 0.1
0.1
0.8
1.0
0.5
0.7
0.5
56.5
66.4 56.0
68.3
53.7
4.0
3.2
1.5
1.7
0.4
3.5
5.9
1.6
1.4
1.3
3.0
2.6
4.0
4.3
3.9
6.5
5.2
8.8
2.1
5.7
2.7
4.6
1.6
0.7
0.6
0.3
1.1
0.4
0.6
0.8
0.4
0.8
69.8
62.1
1.5 32.9
58.0 45.9
1.7 41.6
41.9
81.8 64.4
Table XII. Products Obtained from Tetrahydrothiophene(5) Reactions solvent C6HK? H2° H’2° H20 H20 HZO H20 H20 (pH 10.5) (pH 10.5) (pH 10.5) nontronite nontronite additive (see text) nontronite 300 250 250 300 300 temp, O C 250 250 250 3 3 3 5 5 5 5 5 time, days no. structure 1 thiophene 5 tetrahydrothiophene
9.3
0.1
0.1 1.0
9.2 0.1
0.6 1.0 100.0 99.4 99.0
noticeable change is the fall in naphthalene production mentioned above, but this is partially compensated by an
0.4 99.6
0.7 99.3
1.0 1.7 99.0 98.3
0.4 99.6
HzO (pH 10.5) nontronite 300 3 1.5 98.5
increase in 1-naphthalenethiol to 6-9%. The presence of nontronite clay in two of the runs gives some increase in
Katritzky et al.
834 Energy & Fuels, Vol. 5, No. 6,1991
under all nine sets of reaction conditions. Conversion is 0-1.5% and the only identifiable product is thiophene. Thiophene (1) itself is unaffected by treatment in any of the standard systems.
Scheme XI
82
. 85
155
154
156
69 70 71 72
R=R. R=Bu R-Et. R = C f i w , , R=Mc.R=GHli R = H . R=C,Hls
f 158
the dialkyl sulfide and diary1 sulfide radical products. The secondary octyl sulfides 82-84 are interesting minor products from the high-temperature runs. Their formation through a Willgerodt sequence in which l-naphthalenethiol (46) takes the place of the hydrogen sulfide used above is summarized in Scheme X. The l-alkylnaphthalenes provide a set of minor products which form from the alkyl naphthyl sulfides 82-85. Both octyl isomers 69-72 and lower alkylnaphthalenes 35,43,48,56, and 60 result from radical rearrangements and sulfur extrusions as shown in Scheme XI. As before the loss of sulfur is greater at the higher temperature (62-82%) than at 250 "C (33-58%). The sulfur loss is mainly from l-naphthalenethiol (46) and dioctyl sulfide (65) as discussed above. Tetrahydrothiophene (5) (Table XII) and Thiophene (1). Tetrahydrothiophene proves to be very stable
Conclusions Model compound studies using conditions that simulate the CSS process at Cold Lake for bitumen recovery show that hydrogen sulfide can be generated directly from thiols (RSH, ArSH) or indirectly by thermal and aquathermal cleavage of organic disulfides and sulfides (see Scheme I). At 250 "C alkanethiols undergo thermal conversion with or without clay catalysis, but reaction is inhibited by the presence of base. Arenethiols are also reactive toward hydrogen sulfide generation and this is independent of pH. Sulfides and alkyl disulfides react thermally with low r a t a of hydrogen sulfide formation under all conditions studied. Aryl disulfides are completely converted, and the levels of hydrogen sulfide generated are as high as with the arenethiols. Thiophenes are essentially unreactive under the conditions studied. High overall conversions are observed at 300 "C along with high hydrogen sulfide generation. There is evidence for some clay catalysis. Again, thiophenes are essentially inert under all conditions studied. It is clear from the results presented that hydrogen sulfide generation is significantly increased from all substrates under all sets of aquathermolysis conditions when the temperature is raised from 250 to 300 "C. Clearly the steam stimulation process at Cold Lake should be run at the lowest temperature possible in order to minimize atmospheric pollution. Registry No. 1,110-02-1; 2,142-82-5; 4,111-65-9; 5,110-01-0; 7,111-66-0;9,111-67-1; 12,111-84-2; 17,872-05-9; !27,91-20-3; 41, 143-10-2; 46,529-36-2; 65,2690-08-6;77,822-27-5; 85,13234-64-5; 90, 10496-18-1; 91, 62393-34-4;92, 607-53-4;93, 613-81-0;95, 128803-05-4; 97, 39178-11-5;VII, 12174-06-0;SHI, 7783-06-4; cyclohexane, 110-82-7; 1-octanethiol, 111-88-6. Supplementary Material Available: Mass spectral assignments of the structures and Tables 11,111, and I V listing mass spectral fragmentation pattems (14pages). Ordering information is given on any current masthead page.
