Organic sulfur chemistry. 42. Sulfur-sulfur bond cleavage processes. Selective desulfurization of trisulfides

Harpp, David N.; Smith, Roger A.

doi:10.1021/ja00386a034

Cited by 86 publications

(60 citation statements)

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“…The optical purity of the thiols was analyzed by HPLC using Chiralpak AD, and the deprotection was found to proceed without loss of optical purity. The stereochemistry of the chiral thiols 13, [9] 14, [10] and 15 [11] was assigned to be R, R, and S, respectively, by comparison of the values of the specific rotation with the reported values. The stereochemistry of the thiols, in turn, determined the corresponding stereochemistry of the major products of the chiral sulfides 6, 8, and 9.…”

Section: Preparation Of Chiral Thiolsmentioning

confidence: 99%

Highly Enantioselective Reaction of α-Lithio 2-Quinolyl Sulfide Using Chiral Bis(oxazoline)s: A New Synthesis of Enantioenriched Thiols

2002

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Section: Preparation Of Chiral Thiolsmentioning

confidence: 99%

Highly Enantioselective Reaction of α-Lithio 2-Quinolyl Sulfide Using Chiral Bis(oxazoline)s: A New Synthesis of Enantioenriched Thiols

2002

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“…phosphine, [58][59][60][61][62] trisdimethylaminophosphine, 61,[63][64][65] trisdiethylaminophosphine, 61,[64][65][66][67] triethylphosphite, 58 trimorpholinophosphine 61,64 and tributylphosphine 68,69 have been employed to convert trisulfides to the corresponding disulfides or monosulfides, β-keto sulfides to ketones, and sulfenimides to amines in moderate yields. Trialkyl phosphines can be used to remove sulfur from thioethers, In the course of our ongoing investigations on desulfurizations of organosulfur compounds and on new synthetic applications of the exceedingly strong nonionic base and catalyst 1 first reported from our laboratories [75][76][77] and now sold commercially by Aldrich Chemicals, we found that 2 could be formed from 1 in the presence of sulfur.…”

Section: P(mench 2 Ch 2 ) 3 N: An Efficient Desulfurizing Reagentmentioning

confidence: 99%

“…Increasing the steric hindrance of the disulfide obviously decreased the desulfurization rate (entries 7 and 12, Table 13). Although (Me 2 N) 3 P was effective for desulfurizing trisulfides to disulfides and some activated monosulfides to sulfur-free compounds, 61,63 it showed much poorer desulfurizing efficiency than 1 under the same reaction conditions (entries 5, 8, 9 and 11, Table 13). Using excess (Me 2 N) 3 P, benzyl trisulfide was desulfurized to benzyl disulfide (39.6%) and benzyl monosulfide (42.9%) in THF at room temperature within 25.5 h, but under the same conditions it was quantitatively desulfurized to dibenzyl monosulfide by 1 within 3 h (entries 4 and 5, Table 13).…”

Section: P(mench 2 Ch 2 ) 3 N: An Efficient Desulfurizing Reagentmentioning

confidence: 99%

A Novel Approach to Catalytic Desulfurization of Coal

Verkade¹

2001

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Column chromatographic separation of the S=PBu 3 /PBu 3 product mixture followed by weighing the S=PBu 3 , and by vacuum distillation of S=PBu 3 /PBu 3 mixture followed by gas chromatographic analysis are described. Effects of coal mesh size, pre-treatment with methanol Coal (S) + excess PR 3 Coal + S=PR 3 /PBu 3 and sonication on sulfur removal by PBu 3 revealed that particle size was not observed to affect desulfurization efficiency in a consistent manner. Coal pretreatment with methanol to induce swelling or the addition of a filter aid such as Celite reduced desulfurization efficiency of the PBu 3 and sonication was no more effective than heating. A rationale is put forth for the lack of efficacy of methanol pretreatment of the coal in desulfurization runs with PBu 3 . Coal desulfurization with PBu 3 was not improved in the presence of miniscule beads of molten lithium or sodium as a desulfurizing reagent for SPBu 3 in a strategy aimed at regenerating PBu 3 inside coal pores. Although desulfurization of coals did occur in sodium solutions in liquid ammonia, substantial loss of coal mass was also observed.Of particular concern is the mass balance in the above reaction, a problem which is described in some detail. In an effort to solve this difficulty, a specially designed apparatus is described which we believe can solve this problem reasonably effectively.Elemental sodium was found to remove sulfur quantitatively from a variety of polycyclic organosulfur compounds including dibenzothiophene and benzothiophene under relatively mild conditions (150 0 C) in a hydrocarbon solvent without requiring the addition of a hydrogen donor. Lithium facilitates the same reaction at a higher temperature (254 0 C). Mechanistic pathways are proposed for these transformations. Curiously, dibenzothiophene and its corresponding sulfone was virtually quantitatively desulfurized in sodium solutions in liquid ammonia at -33 0 C, although the yield of biphenyl was only about 20 to 30%. On the other hand, benzothiophene gave a high yield of 2-ethylthiophenol under these conditions. Although our superbase P(MeNCH 2 CH 2 ) 3 N, which is now commercially available, is a more effective desulfurizing agent for a variety of organophosphorus compounds than PPh 3 or its acyclic analogue P(NMe) 3 , it does not desulfurize benzothiophene or dibenzothiophene.ii 95208R10

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“…Hence they are promising subjects for the study of the mechanisms of certain reactions and the synthesis of many practically interesting compounds [4]. In the thermolysis reactions of selenadiazoles with elemental sulfur and selenium polysulfur and polyselenium cyclic systems are formed [5][6][7]. Various selanylethylenes can be prepared by treatment of selenadiazoles with nucleophilic agents such as butyl lithium, trialkylphosphites, mercaptans, disulfides etc.…”

mentioning

confidence: 99%