Sulfides, unsaturated

The photoelectron spectroscopy of organic sulfur compounds was reviewed in detail by Gleiter and Spanget-Larsen in 19796. At that time most of the published work in this area involved compounds of divalent sulfur, particularly those in which sulfur is bonded to one or two carbon atoms. Consequently, the review was confined to the cases of saturated sulfides, unsaturated sulfides and thiocarbonyls, though some polyvalent sulfur compounds were included. 

NH, mercaptans, sulfides, unsaturated hydrocarbons, amines, isocyanides, pyrazines, ketones, esters, aldehydes, carboxylic acids, furanones, lactones, ionones, Ru" ... 

Tautomerism of the A-2-thiazoline-5-thiones has not been investigated intensively. A recent report shows that 2-phenylthiazo e-5-thiols exist in the thiol form in both polar and nonpolar solvents (563). This behavior is in contrast with that of corresponding thiazolones. Addition reactions involve only the exocyclic sulfur atom, and thiazole-5-thiols behave as typical heteroaromatic thiols towards unsaturated systems, giving sulfides (1533) (Scheme 80) (563),... 

Various methods can be used to analy2e succinic acid and succinic anhydride, depending on the characteristics of the material. Methods generally used to control specifications of pure products include acidimetric titration for total acidity or purity comparison with Pt—Co standard calibrated solutions for color oxidation with potassium permanganate for unsaturated compounds subtracting from the total acidity the anhydride content measured by titration with morpholine for content of free acid in the anhydride atomic absorption or plasma spectroscopy for metals titration with AgNO or BaCl2 for chlorides and sulfates, respectively and comparison of the color of the sulfide solution of the metals with that of a solution with a known Pb content for heavy metals. 

Generally, unsaturated compounds, eg, alkenes and natural fats and their derivatives, are much more reactive toward sulfur than alkanes. Sulfur reacts with unsaturated compounds at temperatures of 120—215°C, forming products that are usually dark and often viscous cross-linked mixtures of dithiole-3-thiones (eq. 4) (2) and sulfides (Table 1) (3). 

Sulfurization of unsaturated compounds ia the presence of hydrogen sulfide also affords polysulfides (9). It is postulated that this reaction forms the mercaptan in situ which then further reacts to form the polysulfide (see Sulfurcompounds). 

Sulfurization of unsaturated compounds and meicaptans is normally carried out at atmospheric pressure, in a mild or stainless steel, batch-reaction vessel equipped with an overhead condenser, nitrogen atmosphere, an agitator, heating media capable of 120—215°C temperatures and a scmbber (typically caustic bleach or diethanolamine) capable of handling hydrogen sulfide. If the reaction iavolves the use of H2S as a reactant or the olefin or mercaptan is a low boiling material, a stainless steel pressurized vessel is recommended. 

The highly ionic thaHic nitrate, which is soluble in alcohols, ethers, and carboxyhc acids, is also a very useful synthetic reagent. Oxidation of olefins, a,P-unsaturated carbonyl compounds, P-carbonyl sulfides, and a-nitrato ketones can aH be conveniently carried out in good yields (31,34—36). 

Vinyllithium [917-57-7] can be formed direcdy from vinyl chloride by means of a lithium [7439-93-2] dispersion containing 2 wt % sodium [7440-23-5] at 0—10°C. This compound is a reactive intermediate for the formation of vinyl alcohols from aldehydes, vinyl ketones from organic acids, vinyl sulfides from disulfides, and monosubstituted alkenes from organic halides. It can also be converted to vinylcopper [37616-22-1] or divinylcopper lithium [22903-99-7], which can then be used to introduce a vinyl group stereoselectively into a variety of a, P-unsaturated systems (26), or simply add a vinyl group to other a, P-unsaturated compounds to give y, 5-unsaturated compounds. Vinyllithium reagents can also be converted to secondary alcohols with trialkylb o r ane s. 

The kinetics of formation and hydrolysis of /-C H OCl have been investigated (262). The chemistry of alkyl hypochlorites, /-C H OCl in particular, has been extensively explored (247). /-Butyl hypochlorite reacts with a variety of olefins via a photoinduced radical chain process to give good yields of aUyflc chlorides (263). Steroid alcohols can be oxidized and chlorinated with /-C H OCl to give good yields of ketosteroids and chlorosteroids (264) (see Steroids). /-Butyl hypochlorite is a more satisfactory reagent than HOCl for /V-chlorination of amines (265). Sulfides are oxidized in excellent yields to sulfoxides without concomitant formation of sulfones (266). 2-Amino-1, 4-quinones are rapidly chlorinated at room temperature chlorination occurs specifically at the position adjacent to the amino group (267). Anhydropenicillin is converted almost quantitatively to its 6-methoxy derivative by /-C H OCl in methanol (268). Reaction of unsaturated hydroperoxides with /-C H OCl provides monocyclic and bicycHc chloroalkyl 1,2-dioxolanes. 

Various alkylating agents are used for the preparation of pyridazinyl alkyl sulfides. Methyl and ethyl iodides, dimethyl and diethyl sulfate, a-halo acids and esters, /3-halo acids and their derivatives, a-halo ketones, benzyl halides and substituted benzyl halides and other alkyl and heteroarylmethyl halides are most commonly used for this purpose. Another method is the addition of pyridazinethiones and pyridazinethiols to unsaturated compounds, such as 2,3(4//)-dihydropyran or 2,3(4//)-dihydrothiopyran, and to compounds with activated double bonds, such as acrylonitrile, acrylates and quinones. 

Alkenes (Olefins) and Cycloalkenes. Olefins are unsaturated and highly reactive. Because of their propensity to be reduced to paraffins w ilh hydrogen or to merceptans with hydrogen sulfide, alkenes are found in petroleum only in very low concentrations. Single-ring cycloalkenes have the same formula, as olefins and so are difficult... 

When ot, 3-unsaturated aldehydes were employed, vinylepoxides were obtained with excellent transxis ratios but in poor yields. When benzaldehyde was treated with a, 3-unsaturated tosylhydrazone salts, the yields of vinylepoxides were improved but the transxis ratios dropped. When chiral sulfides were utilized, the ees were high with a, 3-unsaturated aldehydes, whereas unsaturated, chiral sulfur ylides gave moderate ees, poor yields, and modest transxis ratios. 

An alternative process for the synthesis of vinylepoxides was clearly needed, so reactions with stoichiometric amounts of chiral sulfide were investigated (Scheme 9.16a) [74]. Indeed, when benzyl sulfonium salt 20 was treated with unsaturated aldehydes, the ees and des were high in all cases, whereas the yields [75] were highly substrate-dependent. The same products could be formed by treatment of an unsaturated sulfonium salt with benzaldehyde, but the yields and se-lectivities were generally slightly lower. 

Depending on the choice of transfer agent, mono- or di-cnd-functional polymers may be produced. Addition-fragmentation transfer agents such as functional allyl sulfides (Scheme 7.16), benzyl ethers and macromonomers have application in this context (Section 6.2.3).212 216 The synthesis of PEG-block copolymers by making use of PEO functional allyl peroxides (and other transfer agents has been described by Businelli et al. Boutevin et al. have described the telomerization of unsaturated alcohols with mercaptoethanol or dithiols to produce telechelic diols in high yield. 

A final, rather different example which fits in appropriately here, in that it involves hydrogen exchange, is the measurement of equilibrium and rate constants for the base-catalyzed isomerization of unsaturated sulfides, sulfoxides and sulfones193 ... 

Abbott and coworkers229 found that nucleophilic addition of amines to a, p-unsaturated sulfoxide gave asymmetrically induced adducts. For example, treatment of (R)-(—)-cis-propenyl p-tolyl sulfoxide 184 with piperidine in methanol gave a quantitative mixture of the diastereomeric adduct 185. Reduction of this mixture gave (Rs)-(Sc)-2-piperidinopropyl p-tolyl sulfide 186 in 74% optical yield, suggesting that the amines attack from the opposite side of the bulky aryl group at the transition state, as shown above (Figure 6). 

Vinylic sulfides containing an a hydrogen can also be alkylated by alkyl halides or epoxides. This is a method for converting an alkyl halide RX to an a,P unsaturated aldehyde, which is the synthetic equivalent of the unknown HC=CH—CHO ion. Even simple alkyl aryl sulfides RCH2SAr and RR CHSAr have been alkylated a to the sulfur. ... 

Superior Environmental Products, Inc. introduced a product based on liquid poly sulfide containing 40% of a surface-modified scrap tire mbber. The product, ER-IOOR, is a coating that can temporarily contain chemical, oil, and gasoline spills. Rodriguez [97] reported that an unsaturated polyester resin containing silane-treated CGR showed better mechanical properties than that containing untreated CGR. 

A more direct access to the unstable and non isolated sulfonium ylides 58a- c is the reaction of diisopropyl diazomethylphosphonate 57 with allylic sulfides, catalyzed by Cu(II), Rh(II) [39], or ruthenium porphyrins.[40] For example, the a-phosphorylated y,d-unsaturated sulfides 59-61 are obtained through the [2,3] -sigmatropic rearrangement of 58a-c. This method allows the use of a greater variety of starting allylic sulfide substrates, such as 2-vinyl tetrahydrothiophene, or propargylic sulfides (Scheme 15). 

Reaction of the cyclic sulfoxide 1176 with trimethylchlorosilane (TCS) 14 in CH2CI2 affords the unsaturated sulfide 1177, in 86% yield, and HCl and HMDSO 7 whereas the ester 1178 gives rise to 72% 1179, 16% isomer 1180, and, via 1181, the chloro compounds 1182 and the ring contracted 1183 in 7% yield [17, 18] (Scheme 8.5). 

When heated in ethylene chloride at 80 °C for 3h the y9-ketosulfide 1203 reacts with the trimethylsilyl ester of polyphosphoric acid (PPSE) 195 (prepared from P2O5 and HMDSO 7) to give 36% 1204 and 8% 1205, whereas the lactone 1206 affords with PPSE 195 the unsaturated sulfide 1207 in 93% yield [27] (Scheme 8.10). 

---