Dinitrobenzenesulfenyl Chloride

Submitted by Nobman Khaeasch and Roeebt B. Langfohd t Checked by D. C. Dittmee and B. C. McKusick 

Caution Both steps skotdd be carried out in a good hood. 

4-Dinitrophenyl benzyl sulfide. The apparatus consists of a 1-1., three-necked, round-bottomed flask equipped with a sealed 

4-Dinitrobenzenesulfenyl chloride. Dry 2,4-dinitrophenyl benzyl sulfide (232 g., 0.80 mole) and 400 ml. of dry ethylene chloride are placed in a 2-1., one-necked, round-bottomed flask equipped with a stirrer (Note 3). Sulfuiyl chloride (119 g., 0.88 mole) (Note 4) is added to the resulting suspension at room temperature. A mildly exothermic reaction causes the solid to dissolve quickly, usually within 1 to 2 minutes, with a temperature rise of 10-15° (Note 5). The resulting clear yellow solution is concentrated to an oil by heating under aspirator vacuum on a steam bath (Note 6). (Caution Do not heat with gas or electricity because the product, like many nitro compounds, can explode if overheated.) The residual oil is cooled to 50-60°, and 3-4 volumes of dry petroleum ether (b.p. 30-60°) are added with vigorous handswirling. The oil quickly crystallizes. The mixture is cooled to room temperature and filtered to separate 2,4-dinitrobenzene-sulfenyl chloride as a yellow crystalline solid. The sulfenyl chloride is washed well with dry petroleum ether and dried at 60-80° (Note 7) weight 150-170 g. (80-90%) m.p. 95-96° (Notes 8, 9). 

After 2 or 3 hours, solid product usually appears in the reaction mixture. 

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Thiophenethiols are prepared by reduction of the sulfonyl chlorides or, more conveniently, by the reaction of Grignard rea-gents or thienyllithium compounds with sulfur. They have also been obtained by cleavage or thienyl alkyl sulfides with sodium in liquid ammonia. 3-Thiophenethiol is a by-product in the commercial thiophene synthesis. Thiophenethiols have recently also been prepared by a synthesis involving Friedel-Crafts reaction of 2,4-dinitrobenzenesulfenyl chloride with thiophenes, followed by basic cleavage of the resulting sulfide. ... 

Subsequently, these authors have also studied the effect of polar factors on the sulfenate-sulfoxide equilibrium and obtained similar results to those reported by Braverman and coworkers . For example, reaction of 2,4-dinitrobenzenesulfenyl chloride with lithium allyl-a-dj alcoholate gives only (or perhaps mainly ) allyl-a-d2 2,4-dinitrobenzenesulfenate, whereas the corresponding reaction with 4-nitrobenzenesul-fenyl chloride results in complete ( > 99%) rearrangement to the sulfoxide. However, when a single nitro group is located in the ortho position, the ratio (K) of sulfenate to sulfoxide approaches unity. This ratio is also affected by the polarity of the solvent and changes from 1.43 in CCI4 to 0.39 in chloroform, consistent with the results described above for the equilibrium shown in equation 9. 

Dinitrobenzenesulfenyl chloride has been obtained by the chlorinolysis of 2,4-dinitrophenyl thiolbenzoate,6 2,4-dinitrothiophenol,4 or bis-(2,4-dinitrophenyl) disulfide,7> 11 and by the present procedure.8... 

Dinitrobenzenesulfenyl chloride is a versatile analytical reagent for the characterization of a wide variety of organic compounds, including alcohols, mercaptans, ketones, olefins, amines, aromatic compounds, olefin oxides, and hydroxysteroids. Review articles summarize these applications.9 10... 

Compound 62 on treatment with 2,4-dinitrobenzenesulfenyl chloride in acetic acid gave a mixture of compounds 105, 106a, 106b and 107, but in the presence of LiC104 only compounds 106a and 106b were isolated. On the other hand, the addition of ArSCl in an apolar solvent (CCI4) yielded exclusively the anti addition product 105 (equation 109). 

Wagner-Meerwein rearrangements occur also when arylsulfenyl chlorides or the mixtures R2NCI + SO3 (R = piperidino, morpholino) add to norbomadiene 393196,197. An addition of 2-nitro- (NBSC) or 2,4-dinitrobenzenesulfenyl chloride to the polyenes 395-397 in AcOH and under doping conditions (AcOH, with LiClO/f) is accompanied by Wagner-Meerwein rearrangements (equations 145-147)198. Thus, new types of struc-... 

Treatment of arylsulfenyl chlorides with KO2 in THF or CH3CN at low temperature (—30 °C) gave the corresponding disulfides and arylsulfonates as the major products . In the case of 2,4-dinitrobenzenesulfenyl chloride, the corresponding disulfide was the major product. The reaction is probably initiated by a nucleophilic attack of 02" on the sulfenyl sulfur atom to form a peroxysulfenate radical 46, which may be readily converted to the peroxysulfenate anion 47 in the presence of excess 02" (equation 74). 

With 2,4-Dinitrobenzenesulf enyl Chloride. Photochemical conversion of 2,4-dinitrobenzenesulfenyl chloride (LXVII) to 2-amino-4-nitrobenzenesulfonic acid (LXVIII) occurs in the presence of water. The intermediate 2-acetoxyamino derivative (LXIX) of LXVIII was shown to hydrolyze to acetic acid and hydroxyamino (LXX) derivative of LXVII, and to give LXVIII on irradiation. The reaction involved an intramolecular transfer of oxygen from 2,4-dinitrobenzenesulfonic acid to the sulfonamide. Compound LXX is photochemically reduced to LXVIII.146... 

Reaction of the optically active allene (205) with bromine leads to the inactive 3-bromodihydropyran (208 X = Br), whereas activity is retained in the reaction with 2,4-dinitrobenzenesulfenyl chloride, giving (208 X = SC6H3(N02)2 Scheme 39) (67JA7001). The different behaviour has been attributed to the varying stabilities of the cyclic intermediates (206 X = Br or SC6H3(N02)2), the latter showing less tendency to rearrange to the achiral allylic cation (207). 

Dinitrobenzenesulfenyl chloride is an explosion hazard both in its preparation and its use. Because of its explosive nature, temperatures above 90°-100cC should be avoided in its preparation. Care should be exercised in its storage. The reagent may be destroyed by addition to several volumes of 20% NaOH and washing away with water (Refs 47 67). See also under Benzenesulfenic Acid and Derivatives, Vol 2,... 

Reaction of thiophenes and benzo[6]thiophenes with 2,4-dinitrobenzenesulfenyl chloride, trifluoromethanesulfenyl chloride or chloroformylsulfenyl chloride, under SnCl4 catalysis, results in efficient sulfenylation (Scheme 22) (62JOC1301, 76CB2475). The reaction with CF3SCI has also been carried out in the presence of pyridine (75JHC845). 

Piperidinium 2-methoxybenzoyltellurolate and 2,4-dinitrobenzenesulfenyl chloride in df chloromethane produced arylsulfenyl 2-methoxybenzoyl tellurium2. 

Piperidinium 2-methoxy(tellurolobenzoate) condensed with 2,4-dinitrobenzenesulfenyl chloride in dichloromethane at — 30°. The product was 2-methoxybenzoyl2,4-dinitrobenzenesulfenyl tellurium isolated in 32% yield as a yellow, crystalline solid that melted at 108-110° with decomposition3. 

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