Methyl sulfides

Two efficient syntheses of strained cyclophanes indicate the synthetic potential of allyl or benzyl sulfide intermediates, in which the combined nucleophilicity and redox activity of the sulfur atom can be used. The dibenzylic sulfides from xylylene dihalides and -dithiols can be methylated with dimethoxycarbenium tetrafiuoroborate (H. Meerwein, 1960 R.F. Borch, 1968, 1969 from trimethyl orthoformate and BFj, 3 4). The sulfonium salts are deprotonated and rearrange to methyl sulfides (Stevens rearrangement). Repeated methylation and Hofmann elimination yields double bonds (R.H. Mitchell, 1974). 

Two moles of diphenylacetylene insert into the benzyl methyl sulfide complex 481 to afford the eight-membered heterocycle 482[440j. The cinnolinium Salt 483 is prepared by the insertion of alkynes into the azobenzene com-plex[44l]. 

Methylthio)cyclopentane Thiirane Cyclopentyl methyl sulfide... 

CH3(CH2)ioCH2SCH3 + CH3I Dodecyl methyl sulfide Methyl iodide... 

Substitutive lUPAC name 1 (Methylthio)hexane Functional class name Hexyl methyl sulfide... 

Isoprene [78-79-5] (2-methyl-1,3-butadiene) is a colorless, volatile Hquid that is soluble in most hydrocarbons but is practically insoluble in water. Isoprene forms binary azeotropes with water, methanol, methylamine, acetonitrile, methyl formate, bromoethane, ethyl alcohol, methyl sulfide, acetone, propylene oxide, ethyl formate, isopropyl nitrate, methyla1 (dimethoxymethane), ethyl ether, and / -pentane. Ternary azeotropes form with water—acetone, water—acetonitrile, and methyl formate—ethyl bromide (8). Typical properties of isoprene are Hsted in Table 1. 

Although no consistently effective chemical repellent has been developed for vertebrate pests, some promising materials have been tested as repellents that are based on predator avoidance, specifically compounds from the secretions of predators. In 1995, synthetic sulfur compounds (two thietanes, a thiolane, and a substituted methyl sulfide, which were originally identified from the anal glands of the stoat, ferret, and red fox) suppressed browsing by the introduced AustraUan bmsh-tail opossum in New Zealand about as well as FEP (83). Suggestions were made that these compounds can be made more effective by the use of bitter compounds in a cocktail. 

Dimethyl sultide Methyl sulfide 187 C,H,S 1-Pentene 33 CsHio... 

In a i-l. three-necked flask are mixed 150 g. (r.63 moles) of /3-hydroxyethyl methyl sulfide (p. 54) (Note i) and 200 g. of dry chloroform (Note 2). The flask is placed on a steam bath and is fitted with a dropping funnel, a mechanical stirrer, and a condenser. The condenser is fitted with a trap to remove the vapors of hydrogen chloride and sulfur dioxide (page 2). A solution of 204 g. (1.7 moles) (Note 3) of thionyl chloride in 200 g. (135 cc.) of dry chloroform is added dropwise to the /3-hydroxyethyl methyl sulfide over a period of about two hours (Note 4). The reaction mixture is stirred vigorously during this addition and for about four hours after the addition is complete. The chloroform is distilled on the steam bath and the residue is distilled under reduced pressure. The yield is 135-153 g- (75 5 per cent of the theoretical amount) of a product boiling at 55-s6°/3o mm- (Note 5). 

Chloroethyl methyl sulfide is a vesicant and must be handled with care. It boils at 140° under atmospheric pressure. 

The solution of sodium methyl sulfide in absolute alcohol is transferred to a 3-I. three-necked flask, which is placed on a steam bath and fitted with a dropping funnel, a reflux condenser, and a mechanical stirrer. The solution is heated until the alcohol begins to boil. Heating is then discontinued and 302 g. (3.7s moles) of ethylene chlorohydrin (Note 5) is added dropwise with efficient stirring over a period of about two hours (Note 6). The reaction mixture is concentrated by distilling as much of the alcohol as possible on the steam bath. The mixture is then allowed to cool and the sodium chloride removed by filtration. The flask is rinsed, and the sodium chloride washed with three loo-cc. portions of 95 per cent alcohol. The combined filtrate and washings are concentrated on the steam bath under reduced pressure until no further distillate passes over. The residue is then transferred to a modified Claisen flask (Org. Syn. Coll. Vol. i, 125) and fractionally distilled under reduced pressure. The yield is 238-265 g. (74-82 per cent of the theoretical amount based on the sodium used) of a product boiling at 68-7o°/20 mm. 

The methods for preparing methyl mercaptan and /3-hydroxy-ethyl methyl sulfide are essentially those of Arndt and Kirner, respectively. 

B. Ethyl I -Methyllhiol- -phthalimidopropane-, 3 -dicarboxylate. —A mixture of 85 g. (0.26 mole) of ethyl sodium phthalimidomalonate and 43 g. (0.39 mole) of, fl-chloroethyl methyl sulfide (p. 18) is heated in an oil bath at 160-165° in a i-l. three-necked flask, fitted with a condenser, a thermometer, and a stoppered... 

TRIFLUOROETHANE 83 C2H6S METHYL-SULFIDE -33.596 1.1704E-01 6.2933E-05 6.95... 

C3H8S ETHYL-METHYL- -55.315 2.0160E-01 7.3615E-05 11.42 METHYL-SULFIDE ... 

C10H22 24DIMETHYL- -264.215 1.0048E+00 6.8707E-05 42.26 METHYL-SULFIDE ... 

C18H38S HEPTADECYL- METHYL-SULFIDE -359.398 1.5926E+00 2.2863E-04 136.02... 

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