Reaction with methyl mercaptan

Reactions with Alcohols, Mercaptans, and Phenols. Alcohols add readily to acetaldehyde in the presence of trace quantities of mineral acid to form acetals eg, ethanol and acetaldehyde form diethyl acetal [105-57-7] (65). Similarly, cycHc acetals are formed by reactions with glycols and other polyhydroxy compounds eg, ethylene glycol [107-21-1] and acetaldehyde give 2-methyl-1,3-dioxolane [497-26-7] (66) ... 

The significance of industrial acrolein production may be clearer if one considers the two major uses of acrolein—direct oxidation to acryUc acid and reaction to produce methionine via 3-methyhnercaptopropionaldehyde. In acryUc acid production, acrolein is not isolated from the intermediate production stream. The 1990 acryUc acid production demand in the United States alone accounted for more than 450,000 t/yr (28), with worldwide capacity approaching 1,470,000 t/yr (29). Approximately 0.75 kg of acrolein is required to produce one kilogram of acryUc acid. The methionine production process involves the reaction of acrolein with methyl mercaptan. Worldwide methionine production was estimated at about 170,000 t/yr in 1990 (30). (See Acrylic ACID AND DERIVATIVES AmINO ACIDS, SURVEY.)... 

Hydroxy-4-methylthiobutyric acid [583-91 -5] the hydroxy analogue of the amino acid methionine, is manufactured by acid hydrolysis of 3-methylthiopropionaldehyde cyanohydrin [17773-41-0] which is produced by the reaction of methyl mercaptan with acrolein (qv). 

Reaction of the side chain hydroxyacetone in flumethasone (27-4) with periodic acid leads to cleavage of that function to give carboxylic acid (29-1) with the loss of the carbon atom at C-21. Further reaction of the very hindered acid group requires prior activation. Thus, acylation with diphenyl chlorophosphate leads to the mixed anhydride (29-2) this is not isolated, but treated immediately with methyl mercaptan. The product, tibecasone (29-3), is a quite effective topical anti-inflammatory agent [24]. Cleavage of the ester side chain would lead back to the inactive starting acid (29-1). 

Figure 5. Visible emission spectrum from the chemiluminescent reaction of ozone with methyl mercaptan at room temperature (uncorrected for spectral sensitivity). Total pressure 0.2 torr flow rate of 0 /02 is 20 cc/min flow rate of methyl mercaptan 7 cc/min spectral slit width 1.31 nm.

The chemiluminescence spectrum obtained from the reaction of ozone with methyl mercaptan at a pressure of 0.2 torr is shown in Figure 5. Reaction of hydrogen sulfide with dimethylsulfide with ozone give identical spectra consisting of a broad structureless band centered at approximately 370 nm (uncorrected for spectral sensitivity of the detection system). We have recently shown that this emission is identical to the fluorescence spectrum of sulfur dioxide (16). Since ozone oxidizes hydrogen sulfide to sulfur dioxide and water in the gas phase 17, 18), this result is not surprising. 

Gem-dibromocyclopropanes can be converted into synthetically useful cyclopropanone equivalents by a process consisting of lithium-halogen exchange followed by reaction of lithiocyclopropane (113) with dimethyl disulfide (Scheme 43) . The resulting bromo-methylthio derivative (114) undergoes a variety of substitution reactions. Methanolysis gives S,0-dimethylketal (115) which can be converted into l,l bis(methyl-thio)cyclopropane (116) with methyl mercaptan in trifluoroacetic acid. Reaction of 114 with other nucleophiles provides the derivatives shown in Scheme 44 . The sulfur-... 

Lithium methyl mercaptide, CHsSLi. Mol. wt. 54.04, stable off-white solid. The material is prepared by the reaction of methyllithium with methyl mercaptan in anhydrous ether at 0°(N2). A slurry of CHuSLi is formed, from which ether and... 

Since the jS-ketoaldhydes that result from acidification exist with the formyl group extensively enolized, the compounds are often referred to as hydroxymethylene derivatives. The formation of the product is governed by thermodynamic control therefore, the dominant product expected from unsymmetrical ketones can be predicted on the basis of considerations of relative stability. Once formed, hydroxymethylene compounds have several synthetic uses. A hydroxymethylene group can be converted to methyl via reaction with a mercaptan followed by reduction. ... 

Fortunately, men >tans do not tyipear to react with any of the amines to form nonregener-able compounds. Rahman et al. (1989) looked for possible reactions between methyl mercaptan and MEA, DEA, DGA, DIPA, and MDEA and found none. 

Mercaptans add to olefins in good yields according to Markovnikoff s rule in the presence of sulfuric acid, boron trifluoride, or sulfur and also in an anti-Markovnikoff fashion in the presence of peroxides or via photochemical means. Vinyl chloride and allyl alcohol give lower yields than conjugated olehnic ketones, aldehydes, esters, and cyanides. Cupric acetate or triethylamine can be used as a catalyst for the reaction of methyl mercaptan with acrolein to give p-mercaptopropionaldehyde in 84% yield. Allene reacts homolytically with methanethiol to give allyl sulfide and the 1,3- and 1,2-dimethyl-thiopropanes. 

Methyl mercaptan adds to acrolein in neatly quantitative yields in the presence of a variety of basic catalysts (72,73). Other aLkylmercaptopropionaldehydes produced by the reaction of acrolein with a mercaptan are known. Table 8 Hsts a variety of these and their boiling points (74). 

Through reaction with sulfide or elemental sulfur at 215°C, lignosulfonates can also be used in the commercial production of dimethyl sulfide and methyl mercaptan (77). Dimethyl sulfide produced in the reaction is further oxidized to dimethyl sulfoxide (DMSO), a useful industrial solvent (see Sulfoxides). 

Nitroethane. The principal use of nitroethane is as a raw material for synthesis in two appHcations. It is used to manufacture a-methyl dopa, a hypertensive agent. Also, the insecticide 3 -methyl-A/-[(methylcarbamoyl)oxy]thioacetimidate [16752-77-5] can be produced by a synthesis route using nitroethane as a raw material. The first step of this process involves the reaction of the potassium salt of nitroethane, methyl mercaptan, and methanol to form methyl methylacetohydroxamate. Solvent use of nitroethane is limited but significant. Generally, it is used in a blend with 1-nitropropane. 

A 3-necked flesk fitted with e stirrer, thermometer, ges inlet, dropping funnel, and brine-cooled reflux condenser was charged with 53 g (1.1 mol) methyl mercaptan and 0.35 g mercuric methyl mercaptide. After admitting 56 g (1.0 mol) of acrolein during the course of 15 minutes with an inside temperature of about 10°C, the temperature was allowed to rise spontaneously to 75°C, at which point an ice bath was applied. There was no indication of further reaction one hour after the addition of the acrolein. Distillation of the product gave 71 g (yield 68%) of )3-methylmercaptopropionaldehyde, as described in U.S. Patent 2,584,496. 

In an initial step of reactions, methyl mercaptan Is reacted with epiohlorohydrin to give 1 ohloro-3-methylthio-2-propanol. That is reacted with hydrazine hydrate to give 3-methyl-meroapto-2-hydroxypropyl hydrazine. 

DMSO or other sulfoxides react with trimethylchlorosilanes (TCS) 14 or trimefhylsilyl bromide 16, via 789, to give the Sila-Pummerer product 1275. Rearrangement of 789 and further reaction with TCS 14 affords, with elimination of HMDSO 7 and via 1276 and 1277, methanesulfenyl chloride 1278, which is also accessible by chlorination of dimethyldisulfide, by treatment of DMSO with Me2SiCl2 48, with formation of silicon oil 56, or by reaction of DMSO with oxalyl chloride, whereupon CO and CO2 is evolved (cf also Section 8.2.2). On heating equimolar amounts of primary or secondary alcohols with DMSO and TCS 14 in benzene, formaldehyde acetals are formed in 76-96% yield [67]. Thus reaction of -butanol with DMSO and TCS 14 gives, via intermediate 1275 and the mixed acetal 1279, formaldehyde di-n-butyl acetal 1280 in 81% yield and methyl mercaptan (Scheme 8.26). Most importantly, use of DMSO-Dg furnishes acetals in which the 0,0 -methylene group is deuter-ated. Benzyl alcohol, however, affords, under these reaction conditions, 93% diben-zyl ether 1817 and no acetal [67]. 

All reactions of benzotriazole derivatives of the type Bt-CR RbS discussed above are based on electrophilic or nucleophilic substitutions at the ot-carbon, but radical reactions are also possible. Thus, the first report on unsubstituted carbon-centered (benzotriazol-l-yl)methyl radical 841 involves derivatives of (benzotriazol-l-yl)methyl mercaptan. 3 -(Benzotriazol-l-yl)methyl-0-ethyl xanthate 840 is readily prepared in a reaction of l-(chloromethyl)-benzotriazole with commercially available potassium 0-ethyl xanthate. Upon treatment with radical initiators (lauroyl peroxide), the C-S bond is cleaved to generate radical 841 that can be trapped by alkenes to generate new radicals 842. By taking the xanthate moiety from the starting material, radicals 842 are converted to final products 843 with regeneration of radicals 841 allowing repetition of the process (Scheme 134). Maleinimides are also satisfactorily used as radical traps in these reactions <2001H(54)301>. 

Chemical/Physical. In the presence of nitric oxide, gaseous methyl mercaptan reacted with OH radicals forming methyl sulfenic acid and methyl thionitrite. The rate constant for this reaction is 2.1 X 10 cmVmolecule-sec at 20 °C (MacLeod et al., 1984). 

Further routes of cyclizations have been studied in parallel in the case of cis- and rra/J5-2-hydroxymethyl-l-cyclohexylamine (106) (880PP73). The preparation of thiourea or urea adducts 107 and 108 with phenyl isothiocyanate or phenyl isocyanate proceeds smoothly. The reaction of 107 with methyl iodide and subsequent alkali treatment, by elimination of methyl mercaptan, resulted in the iminooxazine 109 in high yields. The ring closures of both cis and trans thiourea adducts to 1,3-oxazines proceed with retention. Cyclodesulfuration of the adduct 107 by mercury(II) oxide or N,N -dicyclohexylcarbodiimide resulted in the iminooxazine 109, but the yield was low and the purification of the product was cumbersome. The ring closure of 108 with thionyl chloride led to the iminooxazine 109 in only moderate yield. 

Mercaptoacetone reacts with methyl propiolate to give a 1 1 adduct, which then cyclizes to a substituted thiophene. Similar addition reactions of mercaptans with acetylenic acids have also been reported by Owen and Sultanbawa. ... 

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