Energy & Fuels 1991,5, 327-332 Table VIII. Carbon(coa1) as Percent of Carbon of the CoDrocessina Distillate Fractions IBP X 477 X 616 X calcn method 477 K 616 K 797 K >797 K A
12.5 2.0 11.3 8.6 5.7
B
C av of methods
SD
9.2 12.7 9.5 10.5 1.9
18.5 19.6 18.7 18.9 0.6
35.7 38.2 36.6 36.8 1.3
Table IX. Carbon(coa1) as Percent of Product Fraction IBP X 477 x 616 X calcn method 477 K 616 K 797 K >797 K A
B
C
10.8 1.7 9.8
8.2 11.3 8.4
16.4 17.4 16.6
28.8 38.2 29.6
respectively, and the PC(bitumen processing product fraction) and the 613C(coprocessingproduct fraction) are the carbon isotope ratios of the product fractions derived from the bitumen-only and the coprocessing mode of operation. The percent carbon(coa1) as the percent of the fraction is calculated in the same manner as described above. The results of the three methods of calculating the carbon(coal) as the percent of carbon in the coprocessing distillate fractions are given in Table VIII. Comparison of the results calculated from the three methods indicates that the two methods (method A and method C) which attempt to correct the coprocessing 6I3C ratios for the isotopic fractionation caused by the processing result in similar values of coal-carbon incorporation into the distillate fractions. All values calculated by method A and method C agree within 5% and indicate an increasing coal contribution to the distillate fractions as the distillate range increases. In addition, the resulting carbon(coa1) incorporation values calculated with the assumption that no isotopic fractionation occurred during processing (method
327
B)are consistently higher in the calculated carbon(coal) as percent of carbon in the middle, heavy, and resid distillate fractions. From the carbon(coal) as a percent of total carbon and the elemental carbon data, the percent of the carbon(coal) in the product fraction can be calculated. The data derived by using the three methods of calculations are given in Table IX. The same trends are observed for these data as discussed above.
Conclusions The stable carbon isotope technique was utilized to determine the contributions of the coal and the tar sand bitumen to the coprocessing product slate. The experimental design of the operation of the pilot plant indicated that fractionation of the carbon isotopes occurred during processing and must be accounted for in the mass balance calculations. The greatest amount of fractionation occurred in the naphtha fraction and the product gases. The two methods which accounted for fractionation produced the same results, within experimental error, for the coal contribution to the coprocessing product slate. The method which did not take into account the fractionation produced results which consistently indicated larger percentages of the coal contributions to the distillate fractions in which little fractionation was found and smaller coal contributions in the distillate fraction in which the largest fractionation of the carbon isotope was observed. The results of the mass balance calculations which account for the isotopic fraction indicate that the contribution of the coal during coprocessing was greatest in the heavy distillate and resid fraction. Acknowledgment. This work was supported by the Commonwealth of Kentucky and DOE Contract No. DEFC22-88PC8806as part of the Consortium for Fossil Fuel Liquefaction Science (administered by the University of Kentucky).
Ionic Hydrogenation of Organosulfur Compounds Mirjana Eckert-Maksi6* and Davor MargetiE Department of Organic Chemistry and Biochemistry, Rudjer BoBkoviE Institute, Zagreb, Croatia, Yugoslavia Received July 27, 1990. Revised Manuscript Received December 6, 1990
Ionic hydrogenation of the three most abundant types of organosulfur constituents of coal, aromatic sulfides, aromatic disulfides, and benzo[b] thiophene derivatives, in BF3-H20-Et3SiH is studied. Reduction of aromatic sulfides results in partial saturation of the aromatic moiety and cleavage of the corresponding SR group. Aromatic disulfides undergo quantitative sulfur-sulfur bond cleavage, while benzo[ blthiophene derivatives produce 2,3-dihydrobenzo[b] thiophenes in high yields.
Introduction Selective hydrogenation of multiring aromatic sulfur compounb found in the fossil fieh k one of the important steps not only for their upgrading but also in producing useful intermediates for various molecules. Particularly intriguing in this respect is the method of ionic hydrogenation (IH).l This method owes its high selectivity to
the fact that the direction of the hydride ion attack depends exclusively on the structure of the carbonium ion formed through the interaction with the acidic (proton donor) component.2 With the proper choice of a hydro(1) Cheng, J. C.; Maioriello,J.; Lamen, J. W. Energy Fuels 1989, 3,
321-329.
0887-0624/91/2505-0327$02.50/00 1991 American Chemical Society
Eckert-MaksiE and MargetiE
328 Energy & Fuels, Vol. 5,No.2, 1991 genating pair, high reactivity is generally achieved." Most of the ionic hydrogenation studies of interest for fossil fuel processing reported hitherto have been confined to unsubstituted polycondensed aromatics or molecules actiReports on the reactivity vated with oxy s~bstitutents.'~*~ of sulfur- or nitrogen-containing aromatic compounds, although of undeniable importance for understanding basic processes occurring during hydrogenation of fossil fuels, are surprisingly scarce.' The work described here demonstrates the scope and limitations of the ionic hydrogenation of the three most abundant types of organosulfur constituents of coal, namely, aromatic sulfides, aromatic disulfides, and benzo[b]thiophene derivativese6 Hydrogenation experiments were performed by using boron trifluoride monohydrate-triethylsilane as ionic hydrogenating pair. Ita advantages over the vast majority of other ionic hydrogenating pairs were thoroughly discussed by Larsen3 and Kursanov.2 It should be mentioned that ionic hydrogenation of aromatic disulfidess and several benzo[b]thiophene derivatives7t8has been studied previously, but no evidence on their behaviour in BF3*H2&E@iH is available. Hence, their inclusion is not only justified but also of significant importance for evaluation of the hydrogenating capacity of the BF3*H20-E@iH system. For the same reason hydrogenation of several other sulfur-containing heterocycles resembling some common features of organosulfur constituents of coal5 was also attempted.
Results and Discussion The model substrates subjected to ionic hydrogenation are depicted in Scheme I. The sulfides are represented by a variety of alkylthio (1,2,6,9-12)and arylthio (3-5, 7,8)derivatives of naphthalene. The phenyl alkyl sulfides are not considered due to their low basicityg and the preference for the sulfur over the ring protonation,'O while the extension to the derivatives of higher polycyclic arenes will be described in subsequent publication." Among the other classes of compounds, two disulfides (13 and 14), benzo[b]thiophene (15)and two of its methyl derivatives (16and 17), dibenzothiophene (18),phenazine (19),thioxanthen-9-one (20), and di-Cquinolinyl sulfide (21)are included. The hydrogenation experiments were performed at ambient temperature by using 10-20 M excess of boron trifluoride monohydrate, 3-4 M excess of triethylsilane, and methylene chloride as cosolvent. In some instances ESSiD was used instead of Et3SiH. Compounds 6-8, 11,12 and 18-21 were found to be un(2) Cf.: Kursanov, D. N.; Parnes, 2. N.; Kalinkin, M. I.; Loim, N. M. Ionic Hydrogenation and Related Reactions; (English translation by Wiener, L.),Harwood London, 1985. (3) Laraen, J. W.; Chang, L. W. J. Org. Chem. 1979, 44, 1168-1170. (4) Olah, G.A.; Bruce, M. R.; Edelson, E. H.; Husain, A. Fuel 1984, 63, 1130-1137. (5) Attar, A.; Hendrickson, G. G.In Functional Groups in Coal; Adu.
Chem. Ser. 292. Gorbatv. M. L., Ouchi, K., Eds.: American Chemical Society: Washington, DC, 1981. (6) Kalinkin. M. I.: Parnes, 2. N. Dokl. Akad, Nauk SSSR 1968,180,
1370-1371. (7) Yakushina, T. A.; Zvyagintseva, E. N.; Litvinov, V. P.; Oolins, S.; Goldfarb, Ya.L.; Shatenstein, A. I. Zh. Obshch. Khim. 1970, 40, 1622-1626. (8) Bolestova, G. I.; Korepanov, A. N.; Parnes, Z. N.; Kursanov, D. N. Izu. Akad. Nauk SSSR, Ser. Khim. 1974,2547-2549. (9) Brouwer, D. M.; Mackor, E. L.; MacLean, C. Arenium Ions. In
Carbonium Ions; Olah, G. A., Schleyer, P.v.R., Eds.; Wiley: New York, 1970; Vol. 11, pp 837-899. (IO) Eckert-MaksiE, M. J. Org. Chem. 1980, 45, 3355; J . Chem. SOC., Perkin 2 1981,6244. (11) Eckert-MaksiE, M., MargetiE, D. Manuscript in preparation. (12) Compound 11 undergoes partial (40% in 24 h) demethylation within the SCH, group.
Scheme I
WSR
R - S - S - R
12 R-
CH3
13 R14 R-
a
19
NH
X-
20 x-
co
reactive under reaction conditions employed, while the results for the rest of substrates are summarized in Tables I and 11. Reactivity of Alkyl Aryl and Diary1 Sulfides. Perusal of the data presented in Table I reveals that all of the listed sulfides undergo hydrogenation within one ring and subsequent alkyl (aryl)-sulfur bond cleavage producing corresponding tetralin derivative as the single hydrogenating product. The reaction, however, in most cases proceeds sluggishly, presumably due to the limited degree of protonation in BF3.H20 caused by the low basicity of the starting compounds? Furthermore, the efficacy of hydrogenation, as will be illustrated below, depends critically on the homogeneity of the reaction media. It should be noted also that some improvement in the yield can be attained by prolonging reaction time, as exemplified by experiments 5, 8, and 10. The most readily hydrogenated system among the investigated compounds is di-1-naphthyl sulfide. This compound after a reaction period of -6 h affords -20% tetralin accompanied by an equimolar amount of 1naphthalenethiol. Prolongation of the reaction time leads to a considerable improvement in yield, but also to a substantial increase in the proportion of tetralin in reaction products. The latter finding can be rationalized in terms of capability of BF3-H20-Et3SiH to reduce 1naphthalenethi~l.~If, however, one of the 1-naphthyl groups in 4 is replaced by the 2-naphthyl moiety (leading to 51,the extent of hydrogenation in 24 h drops to -30%
Hydrogenation of Organosulfur Compounds
Energy & Fuels, Vol. 5, No.2, 1991 329
Table I. Reduction of Alkyl Aryl and Diary1 Sulfides with Triethylsilane and BFa.H20, at 25 "C expt no.
starting compound
1
hydrogenation products
conversion," 5%
a
reaction time, h
20
24
40
168
30
20
20
1
50
20
25
22
16
22
70
92
90
6
100
24
70
24
1
2
3
2 \
0
8 3 3
4
ad' \
0
/
4
5
\
0
/
a 4
6
& 5
7
@ n, 9
@ HJ
9
(p 10 10
@ HJ
P P P
10
11
@j \
0
12 a
Based on 'H NMR and/ or GC analyses.
Eckert-MaksiC and MargetiC
330 Energy & Fuels, Vol. 5, No. 2, 1991
Table 11. Reduction of Diary1 Disulfides and Benzo[b]thiophenes with Triethylsilane and BF,*H,O, at 25 O C expt no. starting compound hydrogenation product conversion," % reaction time, h
13
13
g
1
27
asH 100
21
30
3
90
24
100
24
100
3
14
14 15
15 15
m
16
16
17
17 a
Based on
'H NMR and/or GC analyses.
(experiment 6). Finally, on going from 4 to di-2-naphthyl sulfide no hydrogenation takes place with appreciable yield. The extremely low reactivity of the latter compound is in full agreement with the results obtained for other sulfides (6 and 7) derived from 2-naphthalenethiol, as well as with the behavior of 2-methyl-' and 2-methoxyna~hthalene.~."It is worth mentioning, however, that all these compounds undergo H/D exchange in BF,.D,O presumably by a protonation deprotonation Hydrogenation of 4 was also attempted in the presence of CC14and CH3N02as well as in the absence of solvent. Unlike the situation in CH2C12,the ring system remained intact in all these reactions. 1-Phenylthionaphthalene (experiment 3) and 1methylthionaphthalene (experiment 1) produce upon treatment with BF,.H20-Et2SiH tetralin in significantly lower yield than 4. It is also noteworthy that substitution of the methylthio group in 1 with the benzylthio moiety slows down the hydrogenation considerably. Thus, while ionic hydrogenation of 1 affords ca. 20% of tetralin in 24 h, compound 2 remains practically inert under the same conditions. However, if the reduction of 2 is allowed to proceed for 164 h (experiment 2) about 40% of tetralin is produced. Experiments 7,8, and 11indicate that introduction of the second methylthio group into wring position (compounds 9 and 12, respectively) considerably increases reactivity toward hydrogenation of only one ring. This produces a 5-methylthiotetralin as the single hydrogenated product. Even stronger activation toward hydrogenation is observed upon introduction of the OCH, into a-ring position, as evidenced by experiment 10. Exclusive formation of the 5-methylthiotetralin in this reaction can be understood in terms of much stronger electron-donating ability of the OCH, group? As a consequence, protonation of the carbon atom in the para position to the OCH,
Table 111. Calculated PA Values for Compound 10
atom no.
2 3 4 6
PA, kJ mol-' 829 791 850 791
atom no. 7 8 11 12
PA, kJ mol-' 812 814 760 773
carrying carbon atom becomes more favorable than the protonation within the ring carrying SCH3group. Hence, hydrogenation occurs in the ring where OCH, group is attached. Additional support to such an explanation is offered by calculation of the proton affinity (PA) values for each of the individual ring positions in 10 by using semiempirical MNDO pr0~edure.l~Full geometry optimizations were performed on the parent compound (B)and all of ita protonated forms (BH+). After determination of the equilibrium geometries of B and BH+, the proton affinity (PA) can be calculated from the negative of the enthalpy change of the reaction B + H+ BH+. The calculations were performed by utilization of the experimental heat of formation of the protonI4 1529 kJ mol.-* Although the PA values derived in this way generally depart from experimental values by ca. h870 ,I4 their relative ordering is ex-
-
(13)Dewar, M.J.S.; Thiel,W. J. Am. Chem. SOC.1977,99,4899,4907. (14) Lias, S. In Kinetics oflon-Molecule Reactions; Ausloos, P.,Ed.; Plenum Press: New York, 1978;p 233.
Hydrogenation of Organosulfur Compounds
Energy & Fuels, Vol. 5, No. 2, 1991 331
Scheme I1
Q
D
48 h
D
&
pected to be reliable.1sJ6 Inspection of the calculated PA values listed in Table I11 shows that MNDO predicts the highest proton affinity for the C-4 atom of the naphthalene ring, indicating that protonation at this position is most favorable. This is in full accordance with the empirical consideration presented above. Finally, in order to shed some light on the reaction pathway occurring in the hydrogenation of aromatic sulfides, some of the reactions were carried out in the presence of Et,SiD instead of Et3SiH. The results of these studies for 1, 3, and 9 as the representative cases are shown in Scheme 11. In each case incorporation of three deuterium atoms in the hydrogenated ring was observed. Two of them enter the position occupied by the departing SR group in the parent molecule, while the third deuterium atom is located meta to it. Such a pattern of deuterium incorporation strongly suggests that the reaction is initiated by protonation of the aromatic ring in the position para to the SR carrying ring carbon atom and subsequent transfer of the hydride ion in the ortho position to the protonated carbon. The second step involves hydrogenation of the intermediately formed 1,2-dihydronaphthalenederivative, followed by the hydrogenolysis of the SR groups. Reactivity of Diary1 Disulfides and Benzo[b]thiophenes. As was mentioned in the Introduction, ionic hydrogenation of several dialkyl and diary1 sulfides has been studied previously by Kalinkin and Parnesa6 These studies were performed by using CF,COOH-E@iH as the hydrogenating system. Most of the disulfides were found to undergo sulfur-sulfur bond cleavage under these conditions, but in none of the experiments was complete conversion of the starting material achieved? In contrast to that, both disulfides (13 and 14) examined in the present study are found to react readily, producing the corresponding mercapto compound as the sole product. In both cases quantitative conversion was achieved at room temperature and thus within 1-2 h. This clearly illustates stronger reducing power of the BF,.H,O-Et,SiH hydrogenating pair. This conclusion is further corroborated by experiments performed with benzo[b]thiophene (15) and its methyl derivatives 16 and 17 (Table 11). For instance, (15) DeKock, R. L.;Jaspeme, C. P. h o r g . Chem. 1983,22,3839-3943. (16) Olivella, S.; Urpi, F.; Vilarrasa, J. J. Comput. Chem. 1984, 5, 230-236.
in CF,COOH-Et,SiH at 50 OC, a 55% conversion of benzo[b]thiophene to 2,3-dihydrobenzo[b]thiopheneis realized in 125 h. Experiment 14 shows that almost the same extent of hydrogenation can be reached in 3 h if BF3*H20 is used instead of CF3COOH.' In addition, the latter reaction proceeds at the room temperature. The same conclusion can be drawn if the reactivity of 16 and 17 in the two ionic hydrogenating media is compared. Concluding Remarks The results presented here indicate that BF3.H20Et3SiH is capable of hydrogenating and desulfurizing certain classes of aromatic and heterocyclic sulfur compounds existing in coal. The least reactive among the compounds shown in Tables I and 11 are alkyl naphthyl sulfides, presumably due to the limited degree of protonation in BF,-H20 caused by the low basicity of the starting compounds. Another point of interest is that dibenzothiophene (18), thioxanthen-9-one(19), and the quinolinoic ring (appearing in 21) are not susceptible to hydrogenation. The inertness of thioxanthene-9-one is not clear because of the known capacity of the BF3-H20-Et3SiHionic hydrogenation pair to reduce cyclic ketonesa2v3The quinolinic ring is also known to be reactive in the presence of some ionic hydrogenating pairs (NaBH,-carboxylic acids).2 Hence, it is conceivable that hydrogenation of these compounds requires more drastic conditions. It should be stressed, however, that the inertness of certain sulfides and sulfur-containing heterocycles in the presence of BF3.H20-Et3SiH does not necessarily imply that this hydrogenating pair is not suitable for hydrogenation of structurally related molecules in coal itself. Namely, due to the complexity of organic matrix in coal, all these species are hardly expected to exist without carrying additional substituents. As indicated by the presented results, an increase in the degree of substitution of an aromatic (particularly with electron-donating groups) or heterocyclic ring might be expected to influence its basicity and consequently its reactivity under ionic hydrogenation conditions. Experimental Section Instrumentation. Infrared (IR) spectra were recorded on a
NMR spectra Perkin-Elmerspectrometer (Model 297). 'H and were obtained with Jeol spectrometer (Model FX-SOFT). The chemical shifts are reported in the 6 scale in parts per million with reference to internal tetramethylsilane. GC analysis were carried out on an Varian chromatograph (Model Aerograph M-180) equipped with 3% SE-30 on Vaporite 30,100/120 mesh. Mass spectra were recorded with Varian CH-7 spectrometer. GC/MS analyses were obtained with a Varian GC spectrometer (Model 3400) equipped with a 30-m narrow bore methylsilica capillary column connected with Finnigan MS spectrometer (Model MAT ITD 800). Calculations were performed on Univac 1100 and Convex CP120 at the University Computing Center in Zagreb. Starting Materials. Solvents were purified according to recommended published procedures."J8 Diphenyl disulfide (13), benzo[b]thiophene (15), dibenzothiophene (18), phenothiazine (19),and thioxanthen-9-one(20) were commercially available and they were used as received. All other model compounds were prepared by using established synthetic procedures. Thus, 1methylthionaphthalene (l), 2-methylthionaphthalene (6), 1,5dimethylthionaphthalene(9), 1-methoxy-5methylthionaphthalene (lo), 1-methylthio-5-dimethylaminonaphthalene(ll),and 1,8dimethylthionaphthtalene (12) were obtained through the action (17) Perrin, D. D.;Armarego, W.L.F.; Perrin, D. R. Purification of Laboratory Chemicals, 2nd ed.; Pergamon Press: Oxford, U.K., 1980. (18) Vogel, E.J.; Furnis, B. S.; Hanaford, A. J.; Rogers, V.; Smith, P. W. G. A Textbook offiactical Organic Chemistry, 4th ed.; Longman: London, 1978.
332 Energy & Fuels, Vol. 5, No. 2, 1991 of dimethyl sulfate on the correspondingmercapto compound^.'^" The synthesis of 1-naphthalenethiol has been recordedz1as have those for 1,5-naphthalenedithiol,=1,8naphthalenedithiol,B and 5-dimethylaminonaphthalene-1-thiol.2' Preparation of benzyl 1-naphthyl sulfide (2), phenyl 1-naphthyl sulfide (3), 1-naphthyl 2-naphthyl sulfide (5), phenyl 2-naphthyl sulfide (7), and di-2naphthyl sulfide (8) was accomplished according to the procedure described by Furman et al.,25while the procedure of Francisco et alaNwas used to prepare di-1-naphthyl sulfide (4) and di-4quinolinyl sulfide (21). Di-2-naphthyl disulfide (14) was prepared by treating 2-naphthalenethiol with iodine.27 Finally, 2methylbenzo[b]thiophene (16) and 3-methylbenzo[b]thiophene (17) were obtained by following the procedures reported by Arnoldi28and Cabiddu.29 The purity of the prepared compounds was assesed by comparing their boiling or melting points and spectroscopicdata (IR, lH and 13C NMR, MS) with the literature values. Boron trifluoride monohydrate and BF3.Dz0 were prepared by bubbling boron trifluoride into ice-cooled water3 and D20,30 respectively, while reduction of Et3SiC1 with LiAlD4 afforded deuteri~triethylsilane.~~ General Procedure for the Reduction with BF3.H20EkSiH. A solution of the appropriate model compound (1.0 equiv, typical scale was 0.31-0.75 mmol) in CHzClzwas added dropwise to a flask containing BF3.H20 (10-15 equiv) at 0 OC. After the addition was completed the mixture was stirred for 10-15 min and allowed to warm up to room temperature, and then triethylsilane (3-5 equiv) was added dropwise. The reaction mixture was stirred at room temperature for a variable amount of time depending on the substrate (see Table I), neutralized by cold saturated aqueous Na2C03solution, and extracted with CH2C12 (19)Bun-Hoi, N.P.; Lavit, D. J. Chem. SOC. 1956,2412. (20)Zweig, A,; Mauerer, A. H.; Roberta, B. G. J. Org. Chem. 1967,32, 1322-1329. (21)Testaferri, L.;Tingoli, M.; Tiecco, M. J. Org. Chem. 1980,45, 4376;Tetrahedron Lett. 1980,3099 Chianelli, D.;Testaferri, L.; Tiecco, M.; Tignoli, M. Synthesis 1982,475-480. (22)Houben-Weyl Methoden der Organischen Chemie, 4th ed.; Thieme, G.: Stuttgart, 1965;Vol. X/1,p 477. C a w , P. D. Org. Synth. 1952,32,88-89. Marvel, C. S.;Caesar, P. D. J. Am. Chem. SOC. 1951,73, 1097-1099. (23)Zweig, A,; Hoffmann, A. K. J. Org. Chem. 1965,30,3997-4001. (24)Averill, B. A.; Bale, J. R.; Orme-Johnson, W. H. J. Am. Chem. SOC. 1978,100,3034-3043. (25)Furman, F. M.; Thelin, J. H.; Hein, D. W.; Hardy, W. B. J. Am. Chem. SOC. 1960,82,1450-1452. (26)Francisco, M. A.; Kurs, A.; Katritzky, A. R.; Rasala, D. J. Org. Chem. 1988,53,596-600. (27)Weinstein, A. H.; Pierson, R. M. J. Org. Chem. 1958,23,554-560. (28)Arnoldi, A.; Carughi, M. Synthesis 1988,2,155-157. (29)Cabiddu, S.;Cancellu, D.; Floris, C.; Gelli, G.; Melis, S. Synthesis 1988,11,888-890. (30)Larsen, J. W.; Chang, L. W. J. Org. Chem. 1978,43,3602. (31)Karahanov, E.A.; Demjanova, E. A,; Skarin, E. G.; Viktorova, E. A. Khim. Geterosykl. Soedin. 1975,11, 1479-1481.
Eckert-Maksic' and Margetic' (3 X 10 mL). The combined organic extract was washed with water (2 x 15 mL), dried (MgSO,), and evaporated on a rotary evaporator to yield the crude product which (as indicated by GC and lH and 13CNMR spectroscopy) apart from the hydrogenated product contained starting material and in the case of diary1 sulfides the appropriate mercapto compounda (see Table 11). No attempt was made to isolate the hydrogenation product from the reaction mixture. Ionic deuteration experiments were carried out under strictly comparable conditions as described above except that ESSiD was substituted for Et3SiH. Following this procedure, reduction of I and 3 led to the formation of tetralin-l,1,3-d3in 80% and 35% yield, respectively (see Scheme 11). The following spectroscopic data of the latter compound were recorded after purification by column chromatography (silica gel, 70-120 mesh; eluent pentane: CH2C1241): IR (KBr) 2920,2860,2160,1490,1450,780,760cm-'; lH NMR (CDC13)b 1.75 (s, 3 H), 2.71-2.73 (m, 2 H), 7.04 (s, 4 H); MS, m / e (relative intensity) 135 (M', 66),134 (21), 106 (loo), 105 (48), 93 (25), 92 (18). Similarly, reduction of 9 by BF3.H20-Et3SiD resulted in the formation of 5-methylthio-tetralin-l,l,3-d3 in 80% yield (see Scheme 111). The following spectroscopic data of the latter compound were recorded after purification by column chromatography (silica gel, 70-120 mesh, eluent pentane:CHzC1241): IR (KBr) 2930, 2860, 2170, 1550, 1450, 760, 725 cm-l; 'H NMR (CDC13)6 1.82 (br s, 3 H), 2.51 (8, 3 H), 2.72 (d, J = 65 Hz, 2 H), 7.06-7.74 (m, 3 H), MS, m / e (relative intensity) 181 (M+, loo), 166 (63), 134 (35), 133 (49), 132 (36), 131 (27).
Acknowledgment. Financial support by Grant PN 740 from the Department of Energy and Self-managing Authority for Scientific Research of SR Croatia is gratefully acknowledged. We are indebted to Bayer AG, Leverkusen, Bayerwerk for a generous gift of 1-amino-5-hydroxynaphthalene, and to L. Romano-Stojanoska for preparation of 9 and 12. We also thank Professor J. W. Larsen for valuable discussions. Registry No. 1, 10075-72-6; 2, 5023-64-3; 3, 7570-98-1; 4, 607-53-4; 5, 62393-34-4; 9, 10075-74-8; 10, 131513-81-0; 12, 7343-31-9; 13,882-33-7;14,5586-15-2; 15,95-15-8; 16,1195-14-8; 119-64-2;mercap17,1455-18-1;1,2,3,4-tetrahydronaphthalene, tomethylbenzene, 100-53-8; mercaptobenzene, 108-98-5; 1mercaptonaphthalene, 529-36-2; 2-mercaptonaphthalene,91-60-1; 1,2,3,4-tetrahydro-5-mercaptonaphthalene, 95391-90-5; 2,3-dihydrobenzo[b]thiophene, 4565-32-6; 2,3-dihydro-2-methylbenzo[blthiophene, 6165-55-5; 2,3-dihydro-3-methylbenzo[b] thiophene, 6383-15-9. (32)Small portion of mercapto compound formed during reaction remains in the form of sodium salt in the aqueous extract, as evidenced by acidification of the latter (with concentrated HCI) and subsequent extraction with CH2C12.
