Episulphidation

TABLE 9. Orbital energies and population analysis (from PP MO calculations) and assumed geometries20 for ethylene episulphide, sulphone and sulphoxide0... 

FIGURE 16. (a) The HOMO of ethylene episulphoxide and episul-phone. (b) The energy spectrum at the top of the band for ethylene episulphide I, PP II, AE calculations (Reference 10) III, experimental values. 

Enantiomers, preferential crystallization of 59 Endo selectivity 798 Ene reactions 808, 809 Enones, synthesis of 732 Enthalpies of formation 102, 103 Enynes, synthesis of 956 Enzymatic kinetic resolution 829 Epimerization 399 Episulphides, oxidation of 237 Episulphones 650, 775 Episulphoxides, photolysis of 742 a,/J-Epoxysulphones reactions of 811, 812 rearrangement of 685 synthesis of 612 / ,y-Epoxysulphones 781 y,<5-Epoxysulphones 627, 628 Epoxysulphoxides reactions of 613 rearrangement of 744 synthesis of 327, 612 Erythronolides 831... 

The reaction of tetrafluorobenzyne with iV-methylpyrrole leads to a good yield of the adduct (106), and with thiophen to tetrafluoro-naphtha-ene 56>. That this latter reaction was the first example of a Diels-Alder reaction of thiophen was shown by following the reaction by XH n.m.r. spectroscopy. Evidence for the intermediacy of the episulphide (107) was obtained. 

Some of the more important monomers whose ring opening polymerisations have been induced by stable cation salts include, 1,4-epoxides, notably tetra-hydrofuran (20,112,113), 1,2-epoxides (114), 1,3-episulphides (thietans) (33,53), 1,2-episulphides (thiiranes) (53), azetidines (115,116), aziridines (117), the cyclic formals, 1,3-dioxolan (23,54, 118-120), and 1,3-dioxepan (118,119), trioxane (121,122) and more recently lactones (123). Aldehydes (124) may also be included since these molecules can be regarded as the smallest possible oxygen hetero-... 

A number of 1,3-episulphides (thietans) have been shown to polymerise readily by cationic means using stable salts as initiators (53). The most studied monomer is 3,3 -dimethylthietan (33,52,53) which gives reasonable rates of... 

The foregoing adduct (9.4 g, 0.034 mol) is dry tetrahydrofuran (25 ml) is added dropwise to a stirred suspension of lithium aluminium hydride (1.1 g) in tetrahydrofuran (10 ml) at — 78 °C under nitrogen. After stirring for 10 minutes, the mixture is allowed to warm to room temperature and then quenched with water. The episulphide is extracted with ether and, after drying over magnesium sulphate, the solvent is removed and the residue distilled under reduced pressure to afford cyclooctene sulphide (4.7 g, 97.35%), b.p. 50 °C/2 mmHg. 

Coordination polymerisation of heterocyclic monomers comprises polymerisation and copolymerisation processes of such monomers as oxacyclic monomers, especially epoxides [2,61-71], thiacyclic monomers like episulphides [72-76], azacyclic monomers [77,78] and phosphacyclic monomers [79]. Monomers with an exocyclic oxygen atom, such as cyclic esters like lactones [80-90] and lactide [90-92], cyclic acid anhydrides [93-98], cyclic carbonates [99,100] and related monomers, belong to oxacyclic monomers undergoing coordination polymerisation or copolymerisation. 

The ruthenium(II) - ethylene episulphide complex [152] may serve as a model for the coordination of tiiranes at the catalyst active site. 

SYNS AETHYLENSULFID (GERMAN) 2,3-DIHYDROTHIIRENE ETHYLENE EPISULHDE ETHYLENE EPISULPHIDE ETHYLENE SULPHIDE THIACY CLOPROPANE THIIRANE... 

A convenient, general and stereoselective synthesis of trisubstituted and tetra-substituted alkenes (144), which may contain a cyanide function, as well as trisubstituted episulphides (145) have been elaborated. The method makes use of readily available thiophosphates and selenophosphates (146) (Scheme 43). ... 

A truly vast literature has accumulated on the polymerization of the epoxides and episulphides. This is probably the result of their far reaching commercial importance and of their high reactivity and the multiplicity of possible reaction pathways. The investigation of their polymerization appears to continue at an almost frantic pace still today. New catalyst... 

These sulphur analogs of the 1,2-epoxides are variously known by the names thiiranes, thiacyclopropanes, alkylene sulphides, and episulphides. They are known to polymerize by the three catalytic mechanisms discussed for the oxygen compounds. Thus the same divisions are possible. For a discussion of some of the mechanistic aspects of these polymerizations as compared to epoxides, the reader is referred to a recent paper by Vandenberg [35]. 

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