P Thioxane

NHs and H2S also undergo addition to ethylene oxide in the presence of NaX, but the initial addition products rapidly condense to produce heterocyclic molecules. At 340°, ethylene oxide and NHs produced piperazine, morpholine, and p-dioxane. Byproducts included ethylene and acetaldehyde, the latter arising from an isomerization reaction. HsS reacts with ethylene oxide at 200° to produce p-dithiane, p-thioxane, and p-dioxane, along with byproduct acetaldehyde. These transformations are summarized in the accompanying diagram. 

The high-spin pseudo-tetrahedral complexes [Fe(S2PX2)2] (X = CF3, Me, or Ph) have been reported, as have the pseudo-octahedral complexes [FeL2X2] [X = Cl, Br, or I L = (63)].p-Thioxan (TX) forms the complex [Fe(TX)2-... 

Similar ring-closure procedures have been applied for the preparation of (12a, X = S) from 1,2-dichloro-1,2-dimethoxyethane [124] and (12c) from 2,3-dichlor-odioxane (see [68-70,81,124] and refs, cited therein). Also, the preparation of (20) from 2,3-dichloro-p-thioxane by a similar method has been reported veiy recently [265]. Scheme 3.4 outlines the preparation procedure of (12c) and (20) [68,265]. Compound (20) has also been prepared by a ring-closure procedure [111] starting from mercaptoethanol and methyl bromoacetate [235]. The derivative with X = O has limited shelf-life, even in the freezer, and it is used immediately after preparation [235]. 

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