Sulfenamides salts

Sulfenamides. Sulfenamides (4) are often produced by oxidising an equimolar mixture of MBT and an aliphatic amine. Alternatively, the /V-ch1oroamine can react with the sodium salt of MBT. One sulfenamide, OTOS (S), uses a thiocarbamyl functionaUty in place of the ben2othia2ole group. 

As it has been shown, there are many ways to assemble the 1,4-(oxa/thia)-2-azole ring. Most of them are performed by inter- or intramolecular cyclization of suitable acyclic precursors. Some of them are found to be suitable for the synthesis of various ring systems, by using readily available, and properly modified reactants. Of particular importance are the following (a) the cyclizations of sulfenamides leading to (oxa/thia)azolium salts (Scheme 33) (b) the cyclization of hydroxamic acids (Scheme 39) (c) the dipolar cycloaddition methodology (Scheme 40) (d) the cyclizations of chlorosulfenyl chlorides (Scheme 46) and (e) the cyclizations of chloromethane sulfonamides (Schemes 47 and 48). Other cyclizations reported are preparative ways used mainly for the synthesis of specific compounds and the scope of these reactions has not been widely studied. 

Their synthesis can also be carried out as a two-phase electrolysis, using ammonium salts 326). Sulfenamides can be produced by oxidizing tetraalkylthiuram disulfides in the presence of amines 321 ... 

Many free radical-generating compounds have been disclosed as synergists which may be used in place of peroxides to enhance the selfextinguishing action of bromine compounds. Examples of some of these materials are the disulfides, sulfenamides, a,a -diphenyl-a-methoxybi-benzyl, N-nitroso-N-methylaniline, tetraethyllead, pentaphenylphosphine, 1,2-diphenyltetramethylethane, tetraphenylhydrazine, and heavy metal salts or chelates (7, 9, 40, 41, 42, 55, 59 71, 90, 132). 

The addition of 70% HPF6 led to the production of crystals of this intermediate. Although too unstable to recrystallize, it was possible to obtain crystals for an X-ray investigation of a PF6 salt of an omeprazole analogue, revealing the cyclic sulfenamide structure of the intermediate (Fig. 2.8) [20]. 

Silver salts are also utilized to perform nucleophilic additions to disulfide bonds to yield sulfenamides (146). If alkyl halides are treated with stoichiometric AgBF4 in dimethyl sulfoxide solvent (DMSO, solvent), the corresponding aldehydes/ ketones will form in good yields. This reaction is an alternative to the well-known Swern oxidation (147). In addition, silver can drive the formation of dialkylper-oxonium ions from alkyl halides, which then oxidizes sulfoxides or sulfides (148,149). In the presence of AgN03, sulfides can be oxidized into a-chloro sulfoxides by SO2CI2 (Fig. 36) (150). 

The only known way to synthesize 3-substituted 6-phenyl-l,4,2-oxathiazines 8 is by ring expansion of 1,3-oxathiolinm salts 7 (see Houben-Weyl, Vol. E8a, p lOff) with azide ions (Method A), iodine/ammonia (Method B) or sulfenamides 11,12 (Method C).47 48 As intermediates, sextet structures of the nitrenium ion or nitrene type are under discussion. It is remarkable that the ring expansion obviously only incorporates the nitrogen function into the C—O bond and therefore only produces 8. 1,4,3-Oxathiazine derivatives, which could equally be formed, were not discovered.48 All three methods A C produce 1,4,2-oxathiazines 8 in yields which are moderate at best. The reaction of 2-dialkylamino-5-phenyl-l,3-oxathiolium perchlorates 7b, 7c with N, V-dimethylthiocarbamoylsulfenamide 11 yields, sometimes even as the main product, also bis(4-pheny -2-dialkylamino-5-thiazolyl) sulfides 9.48... 

The formation of the 5-thiazolyl 2-pyridyl sulfides (10, Y = 2-pyridyl) is the dominant reaction pathway when oxathiolium salts 7 are treated with 2-pyridyl sulfenamide 11 48 The mechanisms for the formation of 9 and 10 are not yet clear, however, it is assumed that 8 is an intermediate for 9. 

DIPA Commercial Grade, DIP A Low Freeze Grade 85 DIPA Low Freeze Grade 90 DIPA NF Grade. See Diisopropanolamine DIPA. See Diisopropylamine Diisopropyl adipate Diisopropanolamine DIPAC. See Diisopropyl benzothiazole sulfenamide Di-Pac . See Sucrose DIPA-hydrogenated cocoate Synonyms Fatty acids, coco, hydrogenated, salts with bis (2-hydroxypropyl) amine Definition Diisopropanolamine salt of hydrogenated coconut acid Uses Emulsifier, surfactant in cosmetics DIPA-lanolate... 

Sorrel salt. See Potassium acid oxalate SOS. See Sodium octyl sulfate SOSS. See Starch sodium octenyl succinate Sour gas. See Hydrogen sulfide Southern bentonite. See Bentonite Sovchem MBS (MOR). See N-Oxydiethylene benzothiazole-2-sulfenamide Sovchem MBT. See 2-Mercaptobenzothiazole Sovchem MBTS. See Benzothiazyl disulfide Sovchem TBBS. See Butyl 2-benzothiazole sulfenamide... 

N-Imidoylsulfilimines 1-Imino-l-sulfenamides N-Isothiocyanatoamines Isothiouronium salts Thio acylhydrazines... 

Thiazoles are derivatives of benzothiazole compounded with sulfenamides. The benzothiazoles include 2-MBT, dibenzothiazyl disulfide (MBTS) and the zinc salt of 2-mercaptobenzothiazole (ZMBT). The sulfenamides are principally N-tert-butyl-2-benzothiazyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazyl sul-fenamide (CBS) and morpholinylmercaptobenzo-thiazole (MOR). MBT, MBTS and CBS are the more widely used. Because of their strong capacity to sensitize, thiazoles are less frequently used in gloves than are the thiurams. Nonetheless, they are widely used in the rubber industry, as well as others (Table 7). Indeed, MBT remains the most widely used accelerator for industrial rubber (Feinman 1987). Nonetheless, sensiti-... 

Without additional reagents Reactions of sulfonium salts with sulfenamides... 

Aminosulfenium salts - ylids Sulfenamides Sulfilimines N-Thiols... 

Vulcanization accelerators, in simplest terms, hasten the cleavage of the sulfur ring and formation of thiyl and polysulfenyl radicals. The accelerators react in the form of their more active zinc salts, due to the nearly ubiquitous presence of zinc oxide in sulfim vulcanized compounds. Structures of the more commonly used accelerators - the guanidines, thiazoles, sulfenamides, thiurams, and dithiocarbamates - are shown in Figures 2a and 2b. The choice of accelerator will affect the scorch (premature vulcanization) safety, the erne rate, and the length and number of crosslinks which form. These properties, which are generally related to the speed with which the accelerator is converted to its very active salt form, are compared in Table 1. 

The less polar nature of disulfides and sulfenamides makes the addition of these reagents to alkenes inefficient. Although thiolates can be generated under reducing conditions,the activation of disulfides and sulfenamides is routinely performed by Lewis acids to enable the introduction of new u bonds other than C—S bonds. As a consequence, the stereospecificity and reactivity observed in the Lewis-acid-promoted addition of disulfides and sulfenamides to alkenes is similar to that of sulfenylation by sulfenyl halides and thi-osulfonium salts. Likewise, the accepted reaction mechanism includes the coordination of Lewis acid, resulting in a thio-sulfonium-like species that can further react with alkene either directly or indirectly by way of dithiosuhonium ions. 

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