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(GLC) using a 4 ft X 6 mm (all glass) 4% silicone gum rubber UCCW-982 (methyl vinyl) on 80-100 mesh H P Chromosorb W (AW, DMCS) column; and by gas-liquid partition chromatographymass spectrometry (GLC-MS). All products gave satisfactory spectral and analytical data; mixtures were compared by GLC and GLC-MS with authentic samples. Lithium-Ammonia-Ammonium Chloride. To a pear-shaped metal-ammonia reaction vessel containing a stirred mixture of 105 mg of Li (15 mg-atoms, six pieces) in 20 ml of NH3 and 10 ml of T H F was added (10 min) a solution of 741 mg (4.99 mmol) of l - t e tralol in 10 ml of T H F . After 10 min, ca. 1.2 g of NH&1 was cautiously added (ca. 2 min) to discharge the blue color, and the NH3 was allowed to evaporate. After the residue had been partitioned between brine and EtZO, the organic phase was dried, filtered, concentrated, and analyzed by GLC and GLC-MS. Following column chromatography, 646 mg (98%) of tetralin was obtained as a colorless oil. Sodium-Ammonia-Ethanol. T o a stirred mixture of 741 mg (4.99 mmol) of 1-tetra101 and 500 mg (10.96 mmol) of EtOH in 20 ml of NH3 was added six pieces of Na (253 mg, 11 mg-atoms) over a 14-min period t o maintain a dark blue solution. Approximately 1 2 min later the mixture turned white and then the NH3 was allowed to evaporate. Work-up as described above yielded a mixture of tetralin (75%) and 5,8-dihydrotetralin (25%).
Registry No.-Toluene, 108-88-3; 1-methylethylbenzene, 9882-8; l-methoxy-4-methylbenzene, 104-93-8; 1,2,3,4-tetrahydronaphthalene, 119-64-2; 2,3-dihydrom1,4-indene,496-11-7; 1,l'methylenebis(benzene), 101-81-5; l,l',l"-methylidynetris(benzene), 519-73-3.
References and Notes (1) A. J. Birch, J. Chern. Soc., 809 (1945). (2) A. J. Birch, J. Chem. Soc., 430 (1944). (3) (a) S. S. Hall, S. D. Lipsky, and G. H. Small, Tetrahedron Lett., 1853 (1971); (b) S. S. Hall, S. D. Lipsky, F. J. McEnroe, and A. P. Bartels. J. Org. Chern., 36, 2588 (1971); (c) S . S. Hall, A. P. Bartels, and A. M. Engman, /bid., 37, 760 (1972).
Transfer of Oxygen to Organic Sulfides with Dimethyl Sulfoxide Catalyzed by Hydrogen Chloride. Preparation of Disulfoxides C. Max Hull*' and Thomas W. Bargar*
Department of Chemzstry, State University of Ne& York, Binghamton, N e & York 13901 Received J u n e 11, 1975
The transfer of oxygen from a sulfoxide to a sulfide has been reported,3 but with limited success as a preparative method. Thus, Bordwell and Pitt3a isolated dibenzyl sulfoxide in 17% yield from a tarry mixture obtained by refluxing an acetic acid solution of dibenzyl sulfide and fourfold excess 1-thiacyclopentane 1-oxide in the presence of sulfuric acid. Barnard3b observed oxygen exchange up to ca. 7% equilibration between 35S-labeled cyclohexyl methyl sulfoxide and a large excess of inactive cyclohexyl methyl sulfide by heating the mixture with acetic acid containing a trace of perchloric acid. Searles and HaysZCprepared di-npropyl, di-n-butyl, and tetramethylene sulfoxides by heating the respective sulfides with Me2SO for several hours at 160-175°, The reaction was accompanied by considerable pyrolysis. They were unsuccessful in catalyzing the reaction with acids. In connection with an investigation of metal ion complexes of 2,5-dithiahexane 2,5-dioxide (1): one of us attempted to prepare the ligand by transferring oxygen from MezSO t o 2,5-dithiahexane. In the absence of catalysts no
Notes reaction occurred, even on boiling the mixture for many hours a t approximately 180'. However, the addition of small amounts of hydrogen chloride to the mixture catalyzed the reaction a t about 100' and afforded the desired disulfoxide in good yield.5 Since the method has advantages over the procedures with conventional oxidizing agents, we report here the preparation of disulfoxides from sulfides of the type RS(CH2),SR ( n 2 2, R alkyl or benzyl). We were unable t o isolate sulfoxides from formals ( n = I), or from other mercaptals and mercaptoles. Instead we obtained oxidative cleavage, generating formaldehyde (or the analogous carbonyl compounds), the disulfide RSSR, and dimethyl sulfide-a consequence of the rapid acid-catalyzed decomposition of monosulfoxides RS(0)CR'2SR,6 which would form initially by 0-transfer from Me2SO. In recer*i years, the effects of halogen halides, and particularly HC1, on sulfoxide behavior, including racemization? and 0-exchange8 reactions, have been investigated inten~ i v e l yA . ~common intermediate appears to be the halosulfonium ion, e.g., Me2SC1, whose formation, via protonated sulfoxide, is kinetically dependent on both H+ and halide ion, and usually rate determining. The completion of the process would involve relatively fast reactions with nucleophilic agents, e.g., H20 regenerates the sulfoxide, halide ion effects racemization (specifically by C1- or Rr-), or reduction to sulfide (especially by I-). Modenag includes sulfides among the nucleophiles which would react with halosulfonium ions. Accordingly, 0-transfer with MezSO would proceed as follows. Me,SO
ZHCI
several
R,SO
2HC1
steps
This course would appear to be more reasonable than direct involvement of protonated sulfoxide by nucleophilic attack of sulfide on o ~ y g e n , ~ ~and J Owould explain catalysis by halogen acid specifically as opposed to acids in general. The advantages of the HC1-catalyzed Me2SO method include cheapness of reagent, the absence of overoxidation which inevitably occurs with conventional oxidizing agents," and the relatively simple isolation and purification of the product. The reaction is unfortunately limited to nonaromatic sulfides. The disulfoxide preparations are summarized in Table I. The crude products usually have a wide melting range, expected of a mixture of diastereoisomers ( d l pair and meso). Recrystallization was used to isolate a t least one isomer, both in the case of 3 and 4. Infrared Spectra. All products absorb most intensely a t ca. u 1000--1050cm-', typical of the sulfoxide SO stretching frequency (see Table I). As a test of oxidation methodsMe2SO vs. commonly used oxidizing agents-we prepared l a and 2 with H202 in acetic acid,12a,band la also with sodium metaperiodate,13 and determined their ir spectra. In the sulfoxide region the analogous spectra are indistinguishable. Thus, whether produced by Me2SO or the other methods, la shows a broad band with a maximum a t ca. 1018 cm-l and 2, distinct bands a t 1019 (more intense) and 1044 cm-I.l4 However, elsewhere in the spectrum, as shown in Table 11, there are significant differences. We offer the following explanations for extra bands in the spectra of products of peroxide and periodate oxidation. Compound la. Shoulders a t 1307, 1318, and 1324 cm-' and the band at 1139 cm-l suggest the sulfone group.16a,b The bands a t 508 and 520 cm-l (peroxide method) and a t 538 and 551 cm-I (periodate method) may also be associated with su1f0ne.l~~ A band a t 1267 cm-' appears in the
J. Org. Chem., Vol. 40, No. 21, 1975
Notes
3153
Table I Disulfoxides R S O ( C H Z ) ~ S O R Anal
MP, Compd n
1
R
Crude
73
125-164
1,2-Bis(methylsulf iny1)ethane 1,2-Bis(ethylsulf iny1)ethane 1,2-Bis (pr opylsulf iny1)ethane
Ir max,
OC
Recryst (SoIvent)
cm-'
H, %
C, %
v (KW,
Calcd
Found
Calcd
Found
169-170" 1018 31.15 31.33b 6.54 6.58* (ethanol) 2 2 Et 62 146-148 149-149.5c 1019 (ethanol) 3 2 Pr 63 140-147 (Y 161-162.5d 1012 45.68 45.84 8.70 8.70 (benzenehexane, 3:2 v/v) p 111-112d 1013 45.68 45.68 8.70 8.61 (benzenehexane, 1:2 v/v) 4 2 PhCH, 1,2-Bis(benzyl82 140-191 CY 228-22ge 1020 62.71 62.96 5.92 5.92 sulfiny1)ethane (ethanol) /3 196-19Y 1020 62.71 62.79 5.92 5.89 (p-xylene) 5 3 Me 1,3-Bis(methyl65 114-116 117-1 18 1050 35.69 35.09 7.19 6.85 sulfiny1)propanef (tetrahydrofuran) 6 4 Me 1,4- Bis (methyl71 117-121 120-122h 1035 39.53 39.76 7.74 7.95 sulfinyl)butaneg (ethyl acetate) 7 4 Pr 1,4-Bis(propyl2 5 125-127 126-1 2 7.5 1015 50.38 50.54 7.30 9.22 sulf iny1)butane (tetrahydrofuran) 8 5 Me 1,5-Bis(methyl52 113-114 1019 42.83 42.49 8.22 8.65 sulf iny1)pentanefsg (ethanol) 9 6 Me 1,g-Bis(methyl59 94-104 106-108 1021 45.68 45.20 8.63 8.92 sulfinyl)hexanef' (benzene) a Reference 12a reports mp 163-164". Analysis courtesy of GAF Corp.; also found S, 41.44, 41.12 (calcd: S,41.57). Reference 12b reports 2
Me
Name
Yield, %
(Y
that oxidation with either HzOz or "03 gives only one disulfoxide with mp 150". Percent ratio a:P, 60:40. e Percent ratio a:@,84:16. r Very hygroscopic. g We thank C. W. Muhlhausen for preparing compounds 6 and 8. D. Jerchel, L.Dippelhofer, and D. Renner, Chem Ber., 87, 947 (1954), report compound 6,m p 110-111", compound 9,mp 113-114". Purification was not very satisfactory. There appeared to be two very hygroscopic compounds present.
spectrum of the unoxidized 1,2-bis(methylthio)ethane,16 suggesting the presence of some unoxidized sulfide in both the peroxide and periodate oxidation products. Compound 2. Bands a t 1318 and 1137 cm-l (peroxide method) may arise from the sulfone group.16a,cAlso the band a t 528 cm-l compares with the 533-cm-l band of the d i s ~ l f o n eand , ~ ~contrasts ~ with the absence of bands in the region 450-600 cm-l for the disulfoxide prepared with Me2SO. No explanation is offered for the band at 743 cm-l, which is absent in the spectrum of the MezSO product. In conclusion, it appears that disulfoxides produced by the MezSO 0-transfer method are purer than the respective products of conventional oxidants, and probably free of sulfone contamination. Experimental Section The sulfides were prepared by standard methodsi7 or purchased from commercial sources and used as received. Other chemicals were reagent grade. Melting points were determined in the FisherJohns or the Gallenkamp apparatus and were corrected. Carbon and hydrogen analysis were carried out in the F. B. Strauss Microanalytical Laboratory, Oxford, England. Infrared analyses were run in the Perkin-Elmer 457 grating infrared spectrophotometer. General Procedure. I n a well-ventilated hood, a mixture of 10-100 mmol of bis sulfide with 50-100% excess MeZSO and 2-6 mol % HCll* was heated in a steam bath or oil bath a t 80-looo until the evolution of dimethyl sulfide (MeZS) subsided. The MezS was trapped in an ice bath or allowed to escape. After cooling t o room temperature, the disulfoxide mixture was filtered, washed with ether or benzene to remove excess MezSO and unreacted sulfide, and recrystallized from alcohol or other solvent (see Table I). Except for evaporation losses, the HCl appeared in the filtrates.
Sample Preparation. 1,2-Bis(methylsulfinyl)ethane (1). A mixture of 10.4 g (85 mmol) of 1,2-bis(methylthio)ethane,1620 ml
Table I1 Comparison of I r Spectra of Disulfoxides Prepared with MezSO and Analogous Products Prepared with H202 or NaI04, Y (KBr), cm-' 1,2 -Bis(methylsulfinyl)ethane (lor) -1 v , cm
MeZSO
HZOZ
NaIO4
1298a
1298b 1267 1122 1139
1298b 1267 1122 1139
C
1122 d
3
508 528
Single narrow band.
538 552
1 ,Z-Bis(ethylsulfiny1)ethane (2) -1 v , cm MeZSO
HZOZ
e
1318f
1125 g It
1125 1137 743'
3
528
Shoulders a t 1307. 1318, and 1324 c m - 1
No band a t 1267 c m - l No hand a t 1139 cm-1 (cf. twin bands 1122 and 1139 c m - l in case of HZOZand NaI04 products). No band a t 1318 cm-1 Single narrow hand. p No band a t 1137 cm 1 (cf. twin bands a t 1125 and 1137 c m - l in case of HzOz product) ti No band a t 743 c m - l Single narrow band 1 No hands a t 450600 cm (21.3 g, 273 mmol) of MeZSO, 0.18 g ( 2 mmol) of 12 M HC1, and a few boiling chips in an erlenmeyer flask was heated overnight on the steam bath. After cooling, the mixture was filtered with suction, and the solid was washed three times with a few milliliters of benzene and dried, giving 9.6 g of mixed disulfoxides. Heating the filtrate for an additional 3 hrI9 gave 0.5g, total 10.1 g (77%), mp 125-164'. Three crystallizations from ethanol gave mp 169-170° (lit.*2aa,163-164'; p, 128-130').
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J . Org. Chem., Vol. 40, No. 21, 1975
T h e disulfoxides 2-9 listed in Table I were prepared similarly. Except for the bis(benzylsulfiny1) compounds ( 4 ) ,the disulfoxides are substantially water soluble and several were sufficiently hygroscopic to present difficulties in handling and analysis. Compounds 1 and 2 (Method of Bell and Bennett).12 T h e procedure with hydrogen peroxide in glacial acetic acid gave essentially the results previously reported: la, m p 164-165'; 18,m p 129-130.5' (lit.'2a a , 163-164'; B, 128-130'); 2, m p 146-147' (lit.lZb150'). The ir spectrum of l p is essentially the same as that of l a . Compound l a (Method of Leonard and Johnson).13The procedure with NaI04 was essentially as described, except that the water solution of the product was deionized by passing successively through Dowex 1-X4 and Dowex 50W-X8 resins, followed by evaporation and three crystallizations from ethyl acetate, m p 165-167' (lit.12a163-164').
Registry No.-1, 10349-04-9; 2, 10483-95-1; dl-3, 56391-04-9; meso-3, 56348-32-4; dC-4, 56348-33-5; meso-4, 56348-34-6; 5, 56348-35-7; 6, 56348-36-8; 7, 56348-37-9; 8, 56348-38-0; 9, 5051241-9; MeZSO, 67-68-5; 1,2-bis(methylthio)ethane,6628-18-8; 1,2bis(ethylthio)ethane, 5395-75-5; 1,2-bis(propylthio)ethane,2203797-4; 1,2-bis(benzylthio)ethane, 24794-19-2; 1,3-bis(methylthio)propane, 24949-35-7; 1,4-bis(methylthio)butane,15394-33-9; 1,4-bis(propylthio)butane, 56348-39-1; 1,5-bis(methylthio)pentane, 54410-63-8; 1,6-bis(methylthio)hexane, 56348-40-4.
References and Notes Supported in part by Faculty Fellowships and Grants-in-Aid through the Research Foundation of the State University of New York. NSF Undergraduate Research Participant, summers 1970, 1971. (a) F. G. Bordwell and B. M. Pitt, J. Am. Chem. SOC.,77, 572 (1955);(b) D. Barnard, Chem. lnd. (London), 565 (1955);(c) S.Searles, Jr., and H. R. Hays, J. Org. Chem., 23, 2028 (1958). S. K . Madan, C. M. Hull, andL. J. Herman, lnorg. Chem., 7, 491 (1968). Previously unpublished work. Other substances found to be catalysts include bromine, HBr, and bromosuccinimide. Substances having ilttle or no catalytic effect include iodine, HI, HF, "01, HpSOI, and BFs. Aliphatic sulfides such as Bu, LBu, and PhCH2 and cyclohexylmethylafford the respective sulfoxides in good yield; t-Bu, Ph, and other aromatic SUIfides (including pnitrophenyl and pmethoxyphenyi)do not. (a) R. Kuhn et al., Justus Liebigs Ann. Chem., 641, 160 (1961); Chem. Ber., 94, 2629 (1961); (b) K. Ozura and G. Tsuchihasha, Tetrahedron Lett., 3151 (1971); (c) H. Nieuwenhuyse and R. Louw, ibid., 4141 (1 97 1). See review by K. Mislow, Rec. Chem. Prog., 28,217 (1967).and references citedtherein. I. Ookuni and A. Fry, J. Org. Chem., 36, 4097 (1971), and references cited to extensive work of Oae and collaborators. See review by G. Modena, ht. J. Sulfur Chem., Pari C, 7,95 (1972),and references cited therein. J. 0. Edwards in "Peroxide Reaction Mechanisms", J. 0. Edwards, Ed., Intersicence, New York, N.Y., 1962, p 67. See, for example, C. R. Johnson and J. C. Sharp, 0. Rep. Sulfur Chem., 4, 1 (1969);G. Barbieri et ai., J, Chem. SOC.C, 659 (1968). (a)E. V. Beii and G. M. Bennett, J. Chem. Soc., 1798 (1927);a designation was assigned to the less soluble isomer, later shown to be the dl [R. Louw and H. Nleuwenhuyse, Cbem. Commun.. 1561 (1968)J.(b) G. M. Bennett and F. S. Statham,'J, Chem. Soc., 1684 (1931)]. N . J. Leonard and C. R. Johnson, J. Org. Chem., 27,282 (1962). T. Cairns, G. Eglinton, and D. T. Gibson, Spectrochim. Acta, 20, 159 (1964),investigating samples furnished by G. M. Bennett (ref 12), report u (KCI): compound la, 1017 and 1037 (former more intense); compound 2, 1017 and 1040 cm-' (latter more intense). (a) C. C. Price and S. Oae, "Sulfur Bonding", Ronald Press, New York, N.Y., 1962, p 73 f f , assign sulfone group frequencies in the regions 1100-1200 and 1300-1400 cm-'. (b) We prepared the disulfone 1,2bis(methylsulfony1)ethaneby the method of A. E. Wood and E. G. Travis, J. Am. Chem. Soc., 50, 1226 (1928), mp 192-193' [P. Allen, Jr., J. Org. Chem.. 7, 23 (1942) reports m p 190'1: ir (KBr) 492, 528, 1118, 1150 (shoulder at 1140),and 1331 cm-'. (c)We prepared 1,2-bls(ethylsulfony1)ethane as in ref 15b, mp 136' (P. Allen. Jr., reports m p 136137'): ir (KBr) 533, 568, 1142, and 1275 cm-' (broad band). Product of Aldrich Chemical Go.: ir (neat, NaCi disks). Three bis(methylthi0)compounds ( n = 3, 4, and 5) were prepared from methyl mercaptan and the appropriate dichlorides by the procedure of S. T. Morgan and W. Ledburg, J. Chem. SOC., 121, 2882 (1922): bpo 83-86.5 (13 mm), 87-89 (6 mm), and 84 (2 mm) [M. Protiva et al., Chem. Listy, 47, 580 (1953); Chem. Abstr., 49, 155 (1955), report 92 (15 mm). 121-123 (28 mm), and 112-114 (8 mm), respectively]. 1.2Bis(benzy1thio)ethanewas prepared from S-benzylthiouronium chloride and ethylene dibromide by the method of R. H. Baker, R. M. Dodson, and E. Riegel, J. Am. Chem. SOC.,68, 2636 (1946),m p 36-39' [S.Mathias, Bo/.Fac. Filos. Cienc. Let., Univ. Sao Paulo, Quimica, 14, 75 (1942);Chem. Abstr., 40, 2792 (1946),reports mp 39.4-40.4'1. 12 M HCI was added to the mixture or premixed with MepSO to concentration of 0.2-0.5 M HCI. Premixed solutions, stored on the shelf for months, retained their titer and reactivity. Caution. Benzene should be trapped to avoid noxious vapors.
Notes
A Convenient New Procedure for Synthetic Reactions of Gaseous Alkenes via Automatic Gasimetry Charles Allan Brown
Baker Chemistry Laboratory, Cornell University, Ithaca, N e w York 14853 Received October 17, 1974
Syntheses involving gaseous alkenes often prove problematic, especially where stoichiometric control of reagents is desired. Where justified by continual need, a variety of systems have been developed, e.g., the use of constantpressure controllers coupled with wet test flow meters. In most cases, however, the occasional user resorts to one of three methods. Either the gas is passed through the reaction mixture in considerable excess (resulting in loss and disposal requirements for considerable quantities of flammable gas) or contained in gas burets (cumbersome for all but very small scale), or else the reaction is run in a pressurized autoclave (with complications for subambient ternperature operation). Of these three, only the gas buret is readily amenable to stoichiometric control. In connection with other work, we have had occasion to carry out such reactions and find a marked convenience in quantitative automatic gasimetry. Quantitative automatic gasimetryl has proven valuable both in synthesis and in reaction studies. With this technique-first employed in hydrogenation-the gaseous reagent is generated as needed to supply the reaction at a constant pressure, the gas being generated by automatically controlled mixing of two solutions. In addition to hydrogen,l,* HCl,3 C0,4 02,5and CO$ have been utilized. In many cases considerably higher yields are obtained through ready optimization of reaction timesa3s5 Gaseous alkenes are readily prepared by addition of the corresponding 1,2-dibromoalkane to a hot suspension of zinc powder in ethylene glycol. Of the numerous methods envisioned which have been tested, this alone met the requirements: rapid and quantitative alkene generation; lack of gel or precipitate formation; and available, inexpensive reagents. Reactions were carried out in an apparatus (Figure 1) modified from the hydrogenator previously describedl by addition of heating for the generator and insertion of a U-tube packed with porous CaCl2 as a trap between the generator and reactor. The concentration of neat
Figure 1. Automatic gasimeter adapted from Brownn hydrogenator (Delmar Scientific Glass Division of Coleman Instruments Co., Maywood, Ill.): ////, mercury; B, buret containing dibromide; V, mercury valve for regulating addition of dibromide t o maintain constant gas pressure; G, generator flask; H, heating mantle; M, poly-TFE covered magnetic stirring bar; T, trap packed with CaC12; R, reactor flask; S, mercury safety bubbler with anti-back-, up check valve.
