Methyl allyl disulphide

The essential oil, which is present in the fresh bulb in a concentration of 0.1 to 0.3%, contains diallyl sulphide, diallyl trisulphide and allyl methyl disulphide (derivatives of allicin) as main components. Apart from further allyl polysulphides, the steam distilled oil contains limonene as non-sulphurous component [111]. The high pungency of garlic oil makes it necessary to dilute it, commonly in vegetable oil. One gram of oil is equivalent to 900 g of fresh garlic or 200 g of dehydrated garlic powder [112]. 

Recognition of the role of sulphoxides in the inhibition chain has resulted in several studies of the autoxidation of mono- and disulphides (see later). In addition to the work by Hargrave [84], Bateman et al. [88— 90] have studied the oxidation of monosulphides, unsaturated monosulphides and cyclo-hex-2-enyl methyl sulphide. Allylic and vinylic sulphides were found to be much more reactive than saturated sulphides, although the methylene group, rather than the allylic double bond, was suggested to be the primary reaction centre. Reactivities were compared for the percentage yield of sulphoxide (A) and for the yield of hydroperoxide (B), viz. 

Allyl methyl sulphide Allyl methyl disulphide Allyl methyl trisulphide... 

Aldehydes were converted into the corresponding esters by initial dithian formation, metallation, reaction with dimethyl disulphide, and finally hydrolysis of the 2-thiomethyl-l,3-dithians so obtained with HgClj-HgO in aqueous alcohols.The yields of methyl or ethyl esters were high but attempts to prepare t-butyl esters by this route failed and produced only acids in moderate yield. Thiomethylation or deuteriation of the allylic lithio-salt (113) occurred exclusively a to sulphur. Dithianyl carbanions... 

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