Benzothiazoline Converts SO2 to Sulfuric Acid en Route to

Research Article pubs.acs.org/journal/ascecg

Benzothiazoline Converts SO2 to Sulfuric Acid en Route to Benzothiazole Sonam Mehrotra,† Ray J. Butcher,‡ and Raja Angamuthu*,† †

Laboratory of Inorganic Synthesis and Bioinspired Catalysis (LISBIC), Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India ‡ Department of Chemistry, Howard University, Washington, D.C. 20059, United States S Supporting Information *

ABSTRACT: By a new sustainable strategy, sulfur dioxide (SO2) was converted at room temperature into sulfuric acid by taking advantage of the spontaneous aerial oxidation of benzothiazoline into benzothiazole. 2-(4Methoxyphenyl)benzothiazoline (HL) was reacted with SO2 at room temperature, and the adduct upon reaction with aerial oxygen produced 2(4-methoxyphenyl)benzothiazolium bisulfate. The same strategy was applied on [CdL2] and [ZnL2] and found to work better than neat benzothiazoline. Bunte salt, S-(2-((pyridin-1-ium-2-ylmethyl)amino)phenyl) thiosulfate, was obtained upon reacting SO2 with 2-(pyridin-2-yl)-2,3-dihydrobenzothiazole which is an important clue for the intermediates involved in the S-oxygenation of SO2 bound on electron rich centers. This sustainable route offers a new avenue of utilizing the suicidal reaction of benzothiazoline into benzothiazole in the activation of SO2 with the help of aerial oxygen. KEYWORDS: Sulfur dioxide activation, Sulfuric acid, Benzothiazole, Bisulfate, Zinc complex, Cadmium complex

■

INTRODUCTION Sulfur dioxide (SO2) is a major air pollutant and posesses risks to human health and the environment. Prolonged exposure to SO2 contaminated air can cause or worsen respiratory diseases, such as emphysema and bronchitis, and can aggravate existing heart diseases. SO2 in the atmosphere can influence the habitat suitability for plant communities, as well as animal life as SO2 is a precursor to acid rain. Consequently, technologies to sequester SO2 from the point of emission and to convert them into value added products are gaining much attention. Amine based sequestration of SO2 has been achieved exploiting electro n rich amines 1 , 2 such as 1,4diazabicyclo[2.2.2]octane (DABCO)2−4 to form adducts (DABCO·2SO2) which can be used as a convenient source of SO2 for laboratory scale reactions. Absorbing SO2 into ionic liquids has been shown to be effective;5−9 however, volatility, toxicity, and degradability are drawbacks of employing ionic liquids. Insertion of SO2 into M−C bonds has been known for many years now. SO2 can be converted into aryl or alkyl sulfinic acid (RS(O)OH); this method is stoichiometric and needs expensive organometallic complexes which require laborious synthesis.10−28 SO2 binds reversibly on soft acidic metals such as rhodium, ruthenium,29 platinum,30,31 or iridium.32 Recently, Schröder demonstrated that SO2 binds in metal organic frameworks through weak interactions such as −O(H)···SO2 interactions.33 Darensbourg showed that SO2 could bind to thiolate anions of nickel thiolate complexes through S···SO2 interactions.34−36 Multicomponent assembliesof aldehydes and © XXXX American Chemical Society

amines in the presence of transition metals in an atmosphere of SO2have been shown to yield cage molecules comprising sulfite37 and/or sulfate38 dianions originating from SO2. Industry scale formation of H2SO4 from SO2 (SO2 → SO3 → H2S2O7 → H2SO4) necessitates high temperature and transition metal catalyst. Hence sequestration and activation of SO2 utilizing inexpensive materials with less energy consumption needs to be addressed. Nonetheless, Darensbourg’s 2,2′-(1,5-diazocane-1,5-diyl)bis(ethane-1-thiolate)Ni complex (bme-daco-Ni) was able to convert SO2 to sulfate at room temperature and atmospheric pressure, unfortunately, “the interesting reaction consumes an equivalent of a quite expensive ligand”, as quoted by Darensbourg.35 This intrigued us to search for sacrificial electron and proton donors that can transform themselves into value added commodities upon loosing the electrons and protons to activate SO2. In the aforementioned quest, we have stumbled upon benzothiazoline, a versatile hydrogen donor for organocatalytic transfer hydrogenation (Chart 1).48,49 Benzothiazolines are known to undergo spontaneous aerial oxidation to yield benzothiazoles, an important class of organic compounds. Riluzole,39−41 a benzothiazole, is an effective drug for amyotrophic lateral sclerosis (ALS), motor neuron disease (MND), obsessive-compulsive disorder (OCD), and other benzothiazoles such as PMX 610,42,43 5F 203,44 and Phortress45 Received: June 14, 2016 Revised: September 10, 2016

A

DOI: 10.1021/acssuschemeng.6b01330 ACS Sustainable Chem. Eng. XXXX, XXX, XXX−XXX

Research Article

ACS Sustainable Chemistry & Engineering

The 1H NMR of the yellow crystals isolated from the reaction mixture indicated the presence of oxidized form of 2(4-methoxyphenyl)-2,3-dihydrobenzothiazole (Figure 1). Sin-

Chart 1. Structures of Benzothiazoline and Benzothiazole Used in the Present Work and Other Important Benzothiazole Comprised Molecules39−47

Figure 1. 1H NMR of 2-(4-methoxyphenyl)-2,3-dihydrobenzothiazole (bottom) and 2-(4-methoxyphenyl)benzothiazolium bisulfate (top) in CDCl3 at 293 K.

are anticancer agents. Radiolabeled benzothiazole, PiB, is used in the clinical diagnosis of Alzheimer’s disease as an amyloid imaging agent.46 Hence, we have studied the reactions of 2-(4methoxyphenyl)benzothiazoline and its transition metal complexes with SO2 in continuation to our efforts in small molecule activation50 and report herein our maiden effort in activating SO2.

gle crystal X-ray diffraction (SCXRD) of same exposed the presence of 2-(4-methoxyphenyl)benzothiazolium bisulfate indicating the conversion of SO2 into sulfuric acid with concurrent oxidation of dihydrobenzothiazole to benzothiazole (Figure 2).

■

RESULTS AND DISCUSSION 2-(4-Methoxyphenyl)-2,3-dihydrobenzothiazole was chosen to prove our concept of activating SO2 en route to the spontaneous oxidation of 2,3-dihydrobenzothiazole to benzothiazole (Scheme 1). SO2 was purged into a dichloromethane Scheme 1. Formation of 2-(4Methoxyphenyl)benzothiazolium Bisulfate From 2-(4Methoxyphenyl)-2,3-dihydrobenzothiazole upon Interaction with SO2

Figure 2. Solid-state structure of 2-(4-methoxyphenyl)benzothiazolium bisulfate hydrate obtained by the reaction of SO2 with 2(4-methoxyphenyl)-2,3-dihydrobenzothiazole. Please see the Supporting Information for the details on distances, angles, and other information.

solution of 2-(4-methoxyphenyl)-2,3-dihydrobenzothiazole and an aliquot was collected within 5 min, subjected to electrospray ionization mass spectrometry (ESI-MS); an envelope of m/z = 242.0641 (Figure S5) was observed in the positive ion mode indicating the presence of 2-(4-methoxyphenyl)benzothiazolium cation (calculated m/z = 242.0640) whereas the ESI-MS in negative ion mode (Figure S6) denoted the presence of HSO3 (m/z = 80.9646 obs; 80.9646 calc) and HSO4 (m/ z = 96.9599 obs; 96.9596 calc) monoanions in addition to a prominent envelope that may correspond to the anionic adduct of 2-(4-methoxyphenyl)-2,3-dihydrobenzothiazole starting material with HSO3 (m/z = 324.0371 obs; 324.0364 calc). After purging SO2 for 20 min, the solution was left to stand that yielded a yellow crystalline material, which was recrystallized in dichloromethane.

Hence, the observed solid-state structure of 2-(4-methoxyphenyl)benzothiazolium bisulfate is a result of the protonation of oxidized product2-(4-methoxyphenyl)-2,3-dihydrobenzothiazoleon its imine nitrogen by the H2SO4 formed in the reaction solution (Figure 2). We have tried to follow the reaction of 2-(4-methoxyphenyl)-2,3-dihydrobenzothiazole with SO2 in an NMR tube. To our disappointment, we have always observed a small amount of spontaneously oxidized product of 2-(4-methoxyphenyl)-2,3-dihydrobenzothiazole in solutions (Figure S4). The isolated yield of bisulfate salt was only 14%; this low yield is ascribed to the oxidation of dissolved HL prior to the reaction with SO2. Thus, storing benzothiazolines for prolonged periods and using them to activate SO2 have been concluded to be B


Research Article


Figure 3. Zinc(II) and cadmium(II) complexes used for sulfur dioxide activation.

to be bound through electrostatic interaction between the thiolate sulfur of the ligand and the partially cationic sulfur of the SO2 (S−···SO2).34−36,52 Upon leaving this brick red SO2 adduct in open air as a solid, the color changes back to yellow in 2 days. [CdL2] was dissolved in dry dichloromethane and purged with SO2 for 20 min (Scheme 2). A pale yellow precipitate was obtained that exhibited 1H NMR spectrum in CDCl3 similar to 2-(4-methoxyphenyl)benzothiazolium bisulfate; the crystals of the precipitate formed from a dichloromethane solution unequivocally confirmed the composition as bisulfate salt of benzothiazole (Figure 5).

tedious. Therefore, we have decided to store the benzothiazoline as 2-((4-methoxybenzylidene)amino)benzene-thiolates, coordinated to redox-inactive metals such as cadmium and zinc and utilize the [ML2] in SO2 activation (Figure 3).51 Both [ZnL2] and [CdL2] were synthesized following the report of Kawamoto51 by reacting 2 equiv of 2-(4-methoxyphenyl)-2,3-dihydrobenzothiazole with acetate salts of Zn or Cd. Initial characterization of [ZnL2] and [CdL2] were carried out employing NMR spectroscopy. The [CdL2] was formulated as bis-μ-thiolato dimer with two octahedral Cd(II) centers in the literature.51 However, we have unequivocally confirmed that [CdL2] is also monomeric and adapted a tetrahedral geometry in the solid-state similar to its zinc congener (Figure 4).

Figure 4. Solid-state structure of [CdL2]. Selected distances (Å) and angles (deg): Cd(1)−N(2), 2.308(5); Cd(1)−N(1), 2.319(5); Cd(1)−S(1), 2.417(2); Cd(1)−S(2), 2.4299(18); N(2)−Cd(1)− N(1), 108.92(18); N(2)−Cd(1)−S(1), 83.41(13); N(1)−Cd(1)− S(1), 129.22(14); N(2)−Cd(1)−S(2), 130.11(13); N(1)−Cd(1)− S(2), 81.92(14); S(1)−Cd(1)−S(2), 127.87(6). The angle between the mean triangular planes made of Cd1N1S2 and Cd1N2S1 is 77.79°.

Figure 5. Solid-state structure of 2-(4-methoxyphenyl)benzothiazolium bisulfate hydrate obtained by the reaction of SO2 with [CdL2]. Please see the Supporting Information for the details on distances, angles, and other information.

In order to visualize and possibly isolate the SO2 adduct of [CdL2], we have dissolved the [CdL2] in deuterated dimethyl sulfoxide and followed the reaction using 1H NMR spectroscopy (Figure 6). After purging SO2 for 20 min into the DMSOd6 solution of [CdL2], we have observed the presence of both [CdL2] and benzothiazolium bisulfate. The solution was left to

A small batch of solid [CdL2] was placed in a vial and SO2 gas was purged; the color of the solid changed from yellow to brick red within 5 min. This indicated the uptake of SO2 by [CdL2]; parallel observations have been reported for zinc and nickel thiolate complexes in literature where the SO2 was found

Scheme 2. Synthesis of MN2S2 Complex and Formation of 2-(4-Methoxyphenyl)benzothiazolium Bisulfatea

a

(a) Zn(OAc)2·2H2O or Cd(OAc)2·2H2O, ethanol, reflux or RT. (b) SO2 gas (1 atm), CH2Cl2, RT. C


Research Article


Figure 6. 1H NMR spectra of [CdL2] in DMSO-d6 (bottom); after purging SO2 for 20 min (middle); after standing at room temperature for 24 h (top) at 293 K.

stand at room temperature in open air and the 1H NMR recorded after 24 h indicated the complete conversion of [CdL2] to 2-(4-methoxyphenyl)benzothiazolium bisulfate; the same was confirmed by ESI-MS spectrometry (Figure S13, S14). Even though [CdL2] provided 68% yield in the formation of benzothiazolium bisulfate, we wished to study the reactivity of [ZnL2] as zinc is abundant, inexpensive, and ecofriendly in comparison to cadmium. To our satisfaction, [ZnL2] behaved similarly and yielded 66% of bisulfate salt under similar reaction conditions; 1H NMR, ESI-MS, and SCXRD details are provided in the Supporting Information (Figure S19−S22). As the reactions of SO 2 with HL, [CdL 2 ], and [ZnL 2 ] are instantaneous that did not provide any information on the mechanism, the reactivity of 2-(pyridin-2-yl)-2,3-dihydrobenzothiazole was studied in an expectation to gain some understanding on the mechanism and possibly to capture the SO2 adduct which is proposed to be the intermediate which might undergo S-oxygenation to yield sulfite and/or sulfate. A dichloromethane solution of pyridinylbenzothiazoline, prepared under an inert atmosphere, was purged with SO2 for 1 min and the resulting solution was left to stand for 1 h which yielded crystals of Bunte salt (S-(2-((pyridin-1-ium-2-ylmethyl)amino)phenyl) thiosulfate) and the solution contained 2-(pyridin-2yl)benzothiazole (Scheme 3) in addition to a small amount of HSO4− anions. The identities of both benzothiazole (Figure S27) and Bunte salt (Figure S29, S30) were unequivocally confirmed by 1H NMR spectroscopy, ESI-MS. Bunte salt’s structure was further established by SCXRD (Scheme 3). Assistance provided by the pyridinyl nitrogen through the observed weak hydrogen bonding upon protonation with SSO3− anion might be the stabilizing factor for the Bunte salt. This Bunte salt formation confirms the formation of S−···SO2 adduct that undergoes S-oxygenation while the benzothiazoline can provide a pair of electrons and protons to make the sulfuric acid (H2SO4 = SO2 + O2 + 2e + 2H+) which can protonate the formed benzothiazole to yield benzothiazolium bisulfate.

Scheme 3. Formation and Solid-State Structure of Bunte salt, S-(2-((Pyridin-1-ium-2-ylmethyl)amino)phenyl) Thiosulfatea

a

Please see the Supporting Information for details on distances, angles, and other information.

bind on electron rich nitrogen (N···SO2)2 or thiolate sulfur (S··· SO2) to yield adducts; this is due to the cationic nature of S in SO2 (OS+−O− ↔ O−−S+O ↔ O0.5−−S+−O0.5−).34−36,52 DABSO is an infamous example of SO2 adducts comprising N···SO2 interaction. However, the SO2 adducts of metal thiolates, which exhibit S−···SO2 interactions are known to undergo further SSO2-oxygenation to yield sulfite or sulfate dianions where the two electrons are provided by disulfide formation. In the present reaction, we believe that the initially formed SO2 adduct of benzothiazoline has SO2 bound on S atom; this hypothesis is substantiated by the isolation of Bunte salt that resulted from incomplete oxygenation toward sulfate. Isolation of Bunte salt was possible due to the H-bonding assistance provided by the piridinium group in the vicinity. As benzothiazoline is able to provide protons in addition to electrons to activate SO2, this new route is appealing in comparison to any other known routes to activate SO2 at room temperature. Moreover, both productssulfuric acid and benzothiazoleare of great value. The drawback in the storage of unstable benzothiazole has been overcome by parking them as ligands on cheaper metals such as Zn. This sustainable route is being further studied utilizing other benzothiazolines of

■

CONCLUSIONS When oxygen reacts with metal bound thiolates, often Soxygenation occurs.53−55 In the same manner, SO2 is known to D


Research Article


ESI-MS: m/z = 242.0641 (calcd. 242.0640) = 2-(4-methoxyphenyl) benzothiazolium cation. Interaction of [CdL2] with SO2. Yellow crystalline powder of [CdL2] (40 mg) was dissolved in dry dichloromethane (15 mL) and purged SO2 at room temperature. The filtrate was stored at −30 °C and crystals were grown in 3 days (15 mg, 68%). Interaction of [ZnL2] with SO2. Orange crystalline powder of [ZnL2] (50 mg) was dissolved in dry dichloromethane (15 mL) and purged SO2 at room temperature. While purging SO2, color of the solution became yellow followed by yellow color precipitation. The filtrate was stored at −30 °C and crystals were grown in 3 days (20 mg, 66%). Synthesis of 2-(Pyridin-2-yl)-2,3-dihydrobenzothiazole. In 100 mL Schlenk flask 2-pyridinecarboxaldehyde (214 mg, 2 mmol) was dissolved in dry ethanol (5 mL). In this ethanolic solution, 2aminothiophenol (251 mg, 2 mmol) was slowly injected with vigorous stirring. The homogeneous solution was stirred at room temperature for 6 h and left the reaction mixture to stand at 0 °C. Needlelike crystals formed within 1 h and were filtered off and washed with hexane (2 × 10 mL). Yield: 310 mg, (72%). 1H NMR (400 MHz, CDCl3): δ = 8.55 (d, 1H, Ar), 7.72 (t, 1H, Ar), 7.58 (d, 1H, Ar), 7.21 (d, 1H, Ar), 7.20 (d, 1H, Ar), 7.07 (d, 1H, Ar), 6.95 (t, 1H, Ar), 6.78 (t, 1H, Ar), 6.40 (d, 1H, CH), 5.05 (bs, 1H, NH). ESI-MS: m/z = 215.0641 (calcd. 215.0643) = [M + H]+. Interaction of 2-(Pyridin-2-yl)-2,3-dihydrobenzothiazole with SO2. Yellow crystals of 2-(pyridin-2-yl)-2,3-dihydrobenzothiazole (400 mg, 1.9 mmol) were dissolved in dry dichloromethane (5 mL) and purged SO2 at room temperature for 1 min. While purging SO2, color of the solution intensified to orange. The resulting solution was left to stand at room temperature, which yielded beige color crystals within an hour. The crystals were filtered off and found to be 2-(pyridin-2-yl)benzothiazole (190 mg, 0.9 mmol). Orange residue was evaporated to dryness and found to be the Bunte salt, S-(2((pyridin-1-ium-2-ylmethyl)amino)phenyl) thiosulfate (215 mg, 0.72 mmol). Orange color crystals were obtained from a methanolic solution of Bunte salt upon layering ether within a day. 1H NMR of 2(pyridin-2-yl)benzothiazole (400 MHz, CDCl3): δ = 8.70 (d, 1H, Ar), 8.39 (d, 1H, Ar), 8.11 (d, 1H, Ar), 7.98 (d, 1H, Ar), 7.86 (t, 1H, Ar), 7.51 (t, 1H, Ar), 7.42 (t, 1H, Ar), 7.40 (t, 1H, Ar). ESI-MS: m/z = 213.0482 (calcd. 214.0486) = [M + H]+. 1H NMR of Bunte salt, S-(2((pyridin-1-ium-2-ylmethyl)amino)phenyl) thiosulfate (400 MHz, CDCl3): 8.76 (d, 1H, Ar), 8.45 (t, 1H, Ar), 8.07 (d, 1H, Ar), 7.85 (t, 1H, Ar), 7.37 (d, 1H, Ar), 7.06 (t, 1H, Ar), 6.58 (t, 1H, Ar), 7.48 (d, 1H, Ar), 4.84 (s, 2H, CH2). ESI-MS: m/z (cation mode) = 297.0360 (calcd. 297.0368) = [M + H]+; m/z (anion mode) = 295.0213 (calcd. 215.0211) = [M − H]−.

biological and industrial interest and more information on the mechanism will be reported in our future work.

■

EXPERIMENTAL SECTION

Materials. 2-Aminobenzenethiol (SDFCL), 4-methoxybenzaldehyde (SDFCL), pyridine-2-carboxaldehyde (Sigma-Aldrich), Zn(OAc) 2 ·2H2 O (Rankem), Cd(OAc) 2·2H 2O (Merck), and SO2 cylinder (6 Sigma gases) were used as received from commercial sources. Solvents were distilled under dry nitrogen atmosphere using conventional methods. Methods. Elemental analyses were carried out on a PerkinElmer CHNS/O analyzer. NMR spectra were recorded on JEOL 500 MHz and JEOL 400 MHz spectrometers. The temperature was kept constant using a variable-temperature unit within the error limit of ±1 K. The software MestReNova was used for the processing of the NMR spectra. Tetramethylsilane (TMS) or the deuterated solvent residual peaks were used for calibration. Mass spectrometry measurements were performed on a Waters-Q-ToF-Premier-HAB213 system equipped with an electrospray interface. Spectra were collected by constant infusion of the sample dissolved in methanol or acetonitrile with 0.1% formic acid. Crystal Structure Determinations. Single-crystal X-ray data were collected on a Bruker SMART APEX CCD diffractometer using graphite-monochromated MoKα radiation (λ = 0.71069 Å). The linear absorption coefficients, the scattering factors for the atoms, and the anomalous dispersion corrections were taken from the International Tables for X-ray Crystallography. Data integration and reduction were conducted with SAINT. An empirical absorption correction was applied to the collected reflections with SADABS using XPREP. Structures were determined by the direct method using SHELXTL and refined on F2 by a full-matrix least-squares technique using the SHELXL-97 program package. The lattice parameters and structural data are listed at the end of the Supporting Information. Crystallographic data of the structures reported in this paper are deposited with CCDC reference numbers 1457982 (benzothiazolium bisulfate from [ZnL2]), 1484291 [CdL2], 1484292 (benzothiazolium bisulfate from HL), 1484293 (benzothiazolium bisulfate from [CdL2]), and 1484294 (Bunte salt). All the remaining details about the reported crystal structures are provided in the Supporting Information. Synthesis of 2-(4-Methoxyphenyl)-2,3-dihydrobenzothiazole (HL). In a 100 mL Schlenk flask 4-anisaldehyde (245 μL, 2 mmol) was dissolved in dry EtOH (5 mL) under N2 atmosphere. In this ethanolic solution, 2-aminothiophenol (214 μL, 2 mmol) was slowly injected with vigorous stirring. The homogeneous solution was stirred at room temperature for 6 h and left for crystallization under inert atmosphere. The next day, needlelike crystals were formed which were filtered off and washed with hexane (2 × 10 mL) under the same atmosphere to avoid oxidation. Pale yellow crystals were dried under high vacuum. Yield: 300 mg, (61%). 1H NMR (400 MHz, CDCl3): δ = 7.50 (d, 2H, Ar), 7.03 (d, 1H, Ar), 6.92 (t, 1H, Ar), 6.88 (d, 2H, Ar), 6.75 (t, 1H, Ar), 6.66 (d, 1H, Ar), 6.38 (d, 1H, CH), 3.81 (s, 3H, CH3). ESI-MS: m/z = 244.0791 (calcd. 244.0796) = [M + H]+. Synthesis of [CdL2]. In a 100 mL Schlenk flask, HL was dissolved in dry EtOH (5 mL) under N2 atmosphere. Then cadmium acetate dihydrate (266 mg, 1 mmol) was added to ethanolic solution portion wise and stirred at room temperature for 1 h. The resulting yellow precipitate was filtered off and dried under vacuum. Layering of diethyl ether on a dichloromethane solution at room temperature gave crystals of diffraction quality in 1 day (300 mg, 50%). 1H NMR (400 MHz, CDCl3): δ = 8.35 (s, 1H, CH), 7.68 (m, 3H, Ar), 7.13 (t, 1H, Ar), 7.01 (t, 1H, Ar), 6.92 (d, 1H, Ar), 6.55 (d, 1H, Ar), 3.71 (s, 3H, CH3). Interaction of HL with SO2. Pale yellow crystalline powder of HL (300 mg) was dissolved in dry dichloromethane (15 mL) and purged SO2 at room temperature. While purging SO2, the color of the solution intensified followed by yellow color precipitation. The filtrate was stored at −30 °C, and crystals were grown in 3 days (60 mg, 14%). 1H NMR (400 MHz, CDCl3): δ = 8.05 (m, 3H, Ar), 7.89 (d, 1H, Ar), 7.47 (t, 1H, Ar), 7.36 (t, 1H, Ar), 7.01 (d, 2H, Ar), 3.89 (s, 3H, CH3).

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acssuschemeng.6b01330. 1

■

H NMR, electrospray mass ionization spectra, single crystal X-ray diffrcation data, packing diagrams, and crystallographic details (PDF)

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Author Contributions

R.A. designed the work and wrote the paper. S.M. executed the experiments. R.J.B. refined the structure data. Notes

The authors declare no competing financial interest. E


Research Article


■

(18) Graziani, M.; Bibler, J. P.; Montesano, R. M.; Wojcicki, A. Sulfur dioxide insertion. X. Studies on cyclopentadienylmolybdenum and -tungsten sulfinato carbonyl complexes. J. Organomet. Chem. 1969, 16, 507. (19) Pollick, P. J.; Bibler, J. P.; Wojcicki, A. Sulfur dioxide insertion. 9. Sulfinato complexes of divalent mercury. J. Organomet. Chem. 1969, 16, 201. (20) Jacobson, S. E.; Reich-Rohrwig, P.; Wojcicki, A. Intermediacy of o-sulphinates in reaction of transition-metal carbonyl alkyls and aryls with sulphur dioxide. J. Chem. Soc. D 1971, 1526. (21) Jacobson, S. E.; Wojcicki, A. Sulfur-dioxide insertion. 20. reaction of sulfur-dioxide with some alkyl complexes of chromium, manganese, molybdenum, rhenium, and ruthenium, a comparative study of reactivity. J. Organomet. Chem. 1974, 72, 113. (22) Wojcicki, A. Sulfur dioxide insertion reactions of transition metal alkyls and related complexes. Acc. Chem. Res. 1971, 4, 344. (23) Thomasson, J. E.; Robinson, P. W.; Ross, D. A.; Wojcicki, A. Sulfur dioxide insertion. 15. Transition metal-vinyl complexes containing a sultine ring. Inorg. Chem. 1971, 10, 2130. (24) Wojcicki, A.; Jacobson, S. E. Sulfur dioxide insertion. 14. Electronic effects in sulfur dioxide insertion reactions. J. Am. Chem. Soc. 1971, 93, 2535. (25) Reich-Rohrwig, P.; Wojcicki, A. Stereochemical studies at pseudotetrahedral, chiral metal of decarbonylation, carbonylation, and sulfur-dioxide insertion reactions. Inorg. Chem. 1974, 13, 2457. (26) Severson, R. G.; Wojcicki, A. Lewis acid mediated reactions of organotransition metal-complexes - marked promotion of the sulfurdioxide insertion in alkyl(eta-5-cyclopentadienyl)tricarbonyltungsten(II) by boron(III) and antimony(V) fluorides. J. Am. Chem. Soc. 1979, 101, 877. (27) Joseph, M. F.; Baird, M. C. Sulfur-dioxide insertion reactions of alkylruthenium compounds. Inorg. Chim. Acta 1985, 96, 229. (28) Morton, M. S.; Lachicotte, R. J.; Vicic, D. A.; Jones, W. D. Insertion of elemental sulfur and sulfur dioxide into the metal-hydride and metal-carbon bonds of platinum compounds. Organometallics 1999, 18, 227. (29) Zhu, B.; Lang, Z.-L.; Ma, N.-N.; Yan, L.-K.; Su, Z.-M. Bonding interactions between sulfur dioxide and mono-ruthenium(II)-substituted Keggin-type polyoxometalates: electronic structures of ruthenium-sulfur dioxide adducts. Phys. Chem. Chem. Phys. 2014, 16, 18017. (30) Arcís-Castillo, Z.; Muñoz-Lara, F. J.; Muñoz, M. C.; Aravena, D.; Gaspar, A. B.; Sánchez-Royo, J. F.; Ruiz, E.; Ohba, M.; Matsuda, R.; Kitagawa, S.; Real, J. A. Reversible Chemisorption of Sulfur Dioxide in a Spin Crossover Porous Coordination Polymer. Inorg. Chem. 2013, 52, 12777. (31) Albrecht, M.; Gossage, R. A.; Lutz, M.; Spek, A. L.; van Koten, G. Diagnostic Organometallic and Metallodendritic Materials for sulfur dioxide Gas Detection: Reversible Binding of Sulfur Dioxide to Arylplatinum(II) Complexes. Chem. - Eur. J. 2000, 6, 1431. (32) Collman, J. P.; Valentine, J. S.; Valentine, D. Formation of chelated sulfate by reactions between sulfur dioxide and oxygen in the coordination sphere of iridium and ruthenium complexes. Inorg. Chem. 1971, 10, 219. (33) Yang, S.; Sun, J.; Ramirez-Cuesta, A. J.; Callear, S. K.; David, I. F.; Anderson, D. P.; Newby, R.; Blake, A. J.; Parker, J. E.; Tang, C. C.; Schröder, M. Selectivity and direct visualization of carbon dioxide and sulfur dioxide in a decorated porous host. Nat. Chem. 2012, 4, 887. (34) Darkwa, J.; Moutloali, R. M.; Nyokong, T. Reversible sulfur dioxide reactions with cyclopentadienylnickel(II) organochalcogenide complexes. J. Organomet. Chem. 1998, 564, 37. (35) Darensbourg, M. Y.; Reibenspies, J. H.; Tuntulani, T. Sulfur site adducts of sulfur-dioxide in nickel-bound thiolates and their conversion to sulfate. Inorg. Chem. 1994, 33, 611. (36) Bhuvanesh, N. S. P.; Reibenspies, J. H.; Golden, M. L.; Darensbourg, M. Y.; Zhang, Y. G.; Lee, P. L. The vapochromic behavior, desulfoxidation and structural characterization of the sulfur dioxide adducts of Ni(BME-DACH) from powder data. Synth. React. Inorg., Met.-Org., Nano-Met. Chem. 2005, 35, 11.

ACKNOWLEDGMENTS The Ministry of Earth Sciences (MoES, India) and Indian Institute of Technology Kanpur (IITK/CHM/20120078) sponsored this research. S.M. acknowledges the University Grants Commission (UGC, India) for the Senior Research Fellowship. Anant Kumar Jain is acknowledged for valuable discussions while preparing the manuscript.

■

DEDICATION Dedicated to Professor Mallayan Palaniandavar on the occasion of his 65th birthday.

■

REFERENCES

(1) Tailor, R.; Abboud, M.; Sayari, A. Supported Polytertiary Amines: Highly Efficient and Selective sulfur dioxide Adsorbents. Environ. Sci. Technol. 2014, 48, 2025. (2) Woolven, H.; González-Rodríguez, C.; Marco, I.; Thompson, A. L.; Willis, M. C. DABCO-Bis(sulfur dioxide), DABSO, as a Convenient Source of Sulfur Dioxide for Organic Synthesis: Utility in Sulfonamide and Sulfamide Preparation. Org. Lett. 2011, 13, 4876. (3) Zheng, D.; An, Y.; Li, Z.; Wu, J. Metal-free aminosulfonylation of aryldiazonium tetrafluoroborates with DABCO-bis(sulfur dioxide) and hydrazines. Angew. Chem., Int. Ed. 2014, 53, 2451. (4) Nguyen, B.; Emmett, E. J.; Willis, M. C. Palladium-catalyzed aminosulfonylation of aryl halides. J. Am. Chem. Soc. 2010, 132, 16372. (5) Cui, G.; Lin, W.; Ding, F.; Luo, X.; He, X.; Li, H.; Wang, C. Highly efficient sulfur dioxide capture by phenyl-containing azolebased ionic liquids through multiple-site interactions. Green Chem. 2014, 16, 1211. (6) Huang, K.; Chen, Y.-L.; Zhang, X.-M.; Xia, S.; Wu, Y.-T.; Hu, X.B. Sulfur dioxide absorption in acid salt ionic liquids/sulfolane binary mixtures: Experimental study and thermodynamic analysis. Chem. Eng. J. 2014, 237, 478. (7) Tian, S.; Hou, Y.; Wu, W.; Ren, S.; Qian, J. Hydrophobic taskspecific ionic liquids: Synthesis, properties and application for the capture of sulfur dioxide. J. Hazard. Mater. 2014, 278, 409. (8) Zeng, S.; Gao, H.; Zhang, X.; Dong, H.; Zhang, X.; Zhang, S. Efficient and reversible capture of sulfur dioxide by pyridinium-based ionic liquids. Chem. Eng. J. 2014, 251, 248. (9) Yang, D.; Hou, M.; Ning, H.; Ma, J.; Kang, X.; Zhang, J.; Han, B. Reversible Capture of sulfur dioxide through Functionalized Ionic Liquids. ChemSusChem 2013, 6, 1191. (10) Li, K.; Guzei, I. A.; Darkwa, J. Insertion of sulfur dioxide into metal-carbon bonds of chloro(methyl)palladium complexes. Polyhedron 2003, 22, 805. (11) Lefort, L.; Lachicotte, R. J.; Jones, W. D. Insertion of sulfur dioxide into the Metal−Carbon Bonds of Rhodium and Iridium Compounds, and Reactivity of the sulfur dioxide-Inserted Species. Organometallics 1998, 17, 1420. (12) Bibler, J. P.; Wojcicki, A. A Novel Reaction of Transition Metal Alkyls and Aryls. Sulfur Dioxide Insertion. J. Am. Chem. Soc. 1964, 86, 5051. (13) Bibler, J. P.; Wojcicki, A. Sulfur dioxide insertion. 3. Synthesis and characterization of pi-cyclopentadienyliron S-sulfinatodicarbonyl complexes. J. Am. Chem. Soc. 1966, 88, 4862. (14) Hartman, F. A.; Wojcicki, A. Sulfur dioxide insertion. 2. Ssulfinatopentacarbonylmanganese(I) complexes. J. Am. Chem. Soc. 1966, 88, 844. (15) Hartman, F. A.; Pollick, P. J.; Downs, R. L.; Wojcicki, A. Sulfur dioxide insertion. 4. A new allylic rearrangement. J. Am. Chem. Soc. 1967, 89, 2493. (16) Hartman, F. A.; Wojcicki, A. Sulfur dioxide insertion. 6. Ssulfinatopentacarbonyl complexes of group 6 and 7 transition metals. Inorg. Chem. 1968, 7, 1504. (17) Thomasson, J. E.; Wojcicki, A. Sulfur dioxide insertion. V. A new mode of addition of sulfur dioxide to a metal-carbon bond. J. Am. Chem. Soc. 1968, 90, 2709. F


Research Article

ACS Sustainable Chemistry & Engineering (37) Li, X.; Wu, J.; He, C.; Zhang, R.; Duan, C. Multicomponent selfassembly of a pentanuclear Ir-Zn heterometal-organic polyhedron for carbon dioxide fixation and sulfite sequestration. Chem. Commun. 2016, 52, 5104. (38) Browne, C.; Ramsay, W. J.; Ronson, T. K.; Medley-Hallam, J.; Nitschke, J. R. Carbon Dioxide Fixation and Sulfate Sequestration by a Supramolecular Trigonal Bipyramid. Angew. Chem., Int. Ed. 2015, 54, 11122. (39) Salardini, E.; Zeinoddini, A.; Mohammadinejad, P.; KhodaieArdakani, M.-R.; Zahraei, N.; Zeinoddini, A.; Akhondzadeh, S. Riluzole combination therapy for moderate-to-severe major depressive disorder: A randomized, double-blind, placebo-controlled trial. J. Psychiatr. Res. 2016, 75, 24. (40) Whitcomb, D. J.; Molnar, E. Is riluzole a new drug for Alzheimer’s disease? J. Neurochem. 2015, 135, 207. (41) Cetin, H.; Rath, J.; Fuezi, J.; Reichardt, B.; Fueloep, G.; Koppi, S.; Erdler, M.; Ransmayr, G.; Weber, J.; Neumann, K.; Hagmann, M.; Loescher, W. N.; Auff, E.; Zimprich, F. Epidemiology of Amyotrophic Lateral Sclerosis and Effect of Riluzole on Disease Course. Neuroepidemiology 2015, 44, 6. (42) Mondal, J.; Sreejith, S.; Borah, P.; Zhao, Y. One-Pot Synthesis of Antitumor Agent PMX 610 by a Copper(II)-Incorporated Mesoporous Catalyst. ACS Sustainable Chem. Eng. 2014, 2, 934. (43) Aiello, S.; Wells, G.; Stone, E. L.; Kadri, H.; Bazzi, R.; Bell, D. R.; Stevens, M. F. G.; Matthews, C. S.; Bradshaw, T. D.; Westwell, A. D. Synthesis and biological properties of benzothiazole, benzoxazole, and chromen-4-one analogues of the potent antitumor agent 2-(3,4dimethoxyphenyl)-5-fluorobenzothiazole (PMX 610, NSC 721648). J. Med. Chem. 2008, 51, 5135. (44) Bradshaw, T. D.; Stevens, M. F. G.; Westwell, A. D. The discovery of the potent and selective antitumour agent 2-(4-amino-3methylphenyl)benzothiazole (DF 203) and related compounds. Curr. Med. Chem. 2001, 8, 203. (45) Bradshaw, T. D.; Westwell, A. D. The development of the antitumour benzothiazole prodrug, Phortress, as a clinical candidate. Curr. Med. Chem. 2004, 11, 1009. (46) Mathis, C. A.; Wang, Y.; Holt, D. P.; Huang, G.-F.; Debnath, M. L.; Klunk, W. E. Synthesis and Evaluation of 11C-Labeled 6Substituted 2-Arylbenzothiazoles as Amyloid Imaging Agents. J. Med. Chem. 2003, 46, 2740. (47) Ioka, S.; Saitoh, T.; Iwano, S.; Suzuki, K.; Maki, S. A.; Miyawaki, A.; Imoto, M.; Nishiyama, S. Synthesis of Firefly Luciferin Analogues and Evaluation of the Luminescent Properties. Chem. - Eur. J. 2016, 22, 9330. (48) Zhu, C.; Saito, K.; Yamanaka, M.; Akiyama, T. Benzothiazoline: Versatile Hydrogen Donor for Organocatalytic Transfer Hydrogenation. Acc. Chem. Res. 2015, 48, 388. (49) Zhu, C.; Akiyama, T. Benzothiazoline: Highly Efficient Reducing Agent for the Enantioselective Organocatalytic Transfer Hydrogenation of Ketimines. Org. Lett. 2009, 11, 4180. (50) Angamuthu, R.; Byers, P.; Lutz, M.; Spek, A. L.; Bouwman, E. Electrocatalytic carbon dioxide Conversion to Oxalate by a Copper Complex. Science 2010, 327, 313. (51) Kawamoto, T.; Nishiwaki, M.; Tsunekawa, Y.; Nozaki, K.; Konno, T. Synthesis and characterization of luminescent zinc(II) and cadmium(II) complexes with N,S-chelating Schiff base ligands. Inorg. Chem. 2008, 47, 3095. (52) Golden, M. L.; Yarbrough, J. C.; Reibenspies, J. H.; Darensbourg, M. Y. Sensing of sulfur dioxide by base metal thiolates: Structures and properties of molecular NiN2S2/sulfur dioxide adducts. Inorg. Chem. 2004, 43, 4702. (53) Farmer, P. J.; Solouki, T.; Soma, T.; Russell, D. H.; Darensbourg, M. Y. Divergent pathways for the addition of dioxygen to sulfur in nickel cis-dithiolates - an isotopomeric analysis. Inorg. Chem. 1993, 32, 4171. (54) Farmer, P. J.; Reibenspies, J. H.; Lindahl, P. A.; Darensbourg, M. Y. Effects of sulfur site modification on the redox potentials of derivatives of N,N′-bis(2-mercaptoethyl)-1,5-diazacyclooctanato nickel(II). J. Am. Chem. Soc. 1993, 115, 4665.

(55) Farmer, P. J.; Solouki, T.; Mills, D. K.; Soma, T.; Russell, D. H.; Reibenspies, J. H.; Darensbourg, M. Y. Isotopic labeling investigation of the oxygenation of nickel-bound thiolates by molecular-oxygen. J. Am. Chem. Soc. 1992, 114, 4601.

G


Benzothiazoline Converts SO2 to Sulfuric Acid en Route to

Recommend Documents