Sulfur Series

Lethal concentrations (I. C sos) for inhalation of these agents are as low as 11 ppm for a 2-minutes exposure. 

Lethal percutaneous exposures (LD50S) to liquid are as low as 1.4 grams per individual. 

Incapacitating concentrations (ICtso) for dermal exposure to these agents at moderate temperatures (i.e., between 65 and 85°F) are as low as 2 ppm for a 30-minutes exposure. Temperatures above 85°F reduce the concentration necessary to produce similar effects. 

Eye irritation from exposure to agent vapors occurs at concentrations as low as 2 ppm after a 2-minutes exposure an incapacitating concentration (ICtso) f°r exposure of the eyes is as low as 5 ppm for a 2-minutes exposure. 

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In the case of the sulfur analogues thioesters and thioacids, this delocalization is much less favourable. In the oxygen series, delocalization involves overlap between the oxygen sp orbital and the n system of the carbonyl, which is composed of 2p orbitals. Delocalization in the sulfur series would require... 

Figure 5 The generic phase diagram of the (TMfjX as a function of pressure or anion substitution. On the left, the normal phase of sulfur compounds can be described as a Luttinger liquid that becomes gapped in the charge sector (LL, ) below Tj, and can develop either a spin-Peierls (SP) or localized antiferromagnetic ordered state. Under pressure, the properties of the sulfur series evolve toward those of the selenides for which the normal state shows a progressive restoration of a Fermi liquid (FL) precursor to antiferromagnetism (AF) and superconductivity (S), after [28].

A similar amination is known in the sulfur series (equation 81). Here, the reactive species is generated in situ from (216). Deprotonation and reprotonation isomerize the vinylsulfimide (216) to an allylsulfimide which gives the amino compound (217). (217) exhibits the expected (c/. Scheme 25) ( )-configuration of the C=C bond. 

The A -methylthioimidazoyl moiety, among the various aromatic and heteroaromatic moieties used in the sulfur series, proved to be the one with the highest propensity to direct the alkylation of the corresponding organometallics (even those bearing an alkyl group in the a-position) to the a-carbon atom (Scheme 19, entry e). - ... 

Wittig (74) and Wittig-Homer (75) reagents of 1,3-dichalcogenoles are useful starting materials, and they have been used extensively for synthesis of extended fulvenes in the sulfur series as well as for their selenium analogues. As expected, the phosphonate esters are more reactive nucleophiles in these reactions as compared to the phosphoranes. 

The relative stabilities of nitrenes and three-membered heterocyclic rings seem to be reversed in the sulfur series Holm and co-workers found 3-phenylthiazirine (117) as a stable intermediate in the photolysis of several... 

In the sulfur series oxidation of the thiol (52) with aqueous iodine produced the sulfur lactam analogue (53) (Scheme 12) <90JOC4156>. 

The development in the sulfur series has gone through roughly four stages... 

The common method involves deprotonation of a thiocarbonyl compound and reaction of the intermediate enethiolate with an allyl halide (Scheme 9.8). This actually relies on two noticeable features of the sulfur series. (1) The proton located a to a thiocarbonyl group is much more acidic, by 7-10 pKa units, than the one of a carbonyl moiety [39, 41]. This may be related to the strong ability of the sulfur atom (polarizability) to stabilize the negative charge of the enethiolate. Presently, the preferred conditions involve LDA as a base for optimum deprotonation [42-45]. (2) The resulting anionic species are soft ambident nucleophiles. The... 

It must be stressed that in the sulfur series, the reaction of crotyl halides takes place regioselectively, leading to S-crotyl derivatives (examples [42, 47]). The oxygen series stand in contrast, with reactions of enolates proceeding on the carbon atom, and not on oxygen. Furthermore, it is not regioselective with crotyl-type halides. 

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