DiSelenide, sodium

The same authors have more recently described the synthesis of dibenzoyl diselenides by reaction of selenium with sodium hydroxide under PTC and MW irradiation conditions to afford sodium diselenides which react further with benzoyl chloride at 0 °C [81]. 

Tetrathionaphthalenes and their corresponding selenium analogues are synthesized by reaction of tetrachloro-naphthalenes 197 with / -generated sodium disulfide or with sodium diselenide (Equation 132). The yields of the sulfur analogues were found to be dependent on the method of disulfide generation (Table 14) <2001HAC287>. 

Telluranthrene was obtained in trace amounts (3%) by the reaction of o-dichlorobenzene with sodium telluride (88M13) and in somewhat higher yield (12%) by the reaction of o-diiodobenzene with sodium ditelluride (91 KGS 1203). It is worth nothing that the analogous reaction of o-dibromobenzene with sodium diselenide leads not to selenanthrene but to poly(o-phenylene)diselenide in 26% yield (87IC1664). 

In aprotic solvents, such as dichloromethane and THF, potassium boro-hydride [10], lithium borohydride [8b], lithium triethylborohydride [8a, 11], and diisobutylaluminum hydride (DIBALH) [11] have been used instead of NaBH4. NaBH4 also reduces elemental selenium in alcohol or water to sodium hydrogen selenide or sodium diselenide (Na2Se2) depending on the stoichiometry of the reactants (Scheme 8) [12]. These anions are useful for the synthesis of selenides or diselenides, respectively, via nucleophilic substitution with various electrophiles. 

Similarly to NaBH4, hydrazine reduces elemental selenium to sodium diselenide (Na2Se2), which is further reduced to sodium selenide (Na2Se) by sodium dithionite (Scheme 10) [131. Under phase-transfer conditions, the method has been successfully applied to the convenient synthesis of diselenides [15]. Phenylhydrazine also reduces elemental selenium in DMF [161. 

Treatment of compound 176 with sodium diselenide unexpectedly gave the diazo compound 177 (Equation 46) <1997CEJ1894>. 

Phenanthro[l,10-rz/ 8,9-fV ]bis-l,2-diselenole 8 and its methyl and methylthio derivatives 34 and 35 were synthesized from 1,8,9,19-tetrachlorophenanthrenes 182a-c and sodium diselenide (Equation 48) <1995JMC1539>. Compounds 6 and 39 were synthesized in a similar way by heating 183a and 183b with sodium diselenide (Equation 49) <2001HAC287>. 

Selenium can be oxidized by lithiumtriethylborohydride in THF to provide high yields of the respective chalcogenide derivatives, which can then be used in situ for further reactions. The presence of a small amount of tBuOH apparently acts to increase the yield of product through an unknown mechanism. Sodium diselenide can be prepared by a related reaction between sodium borohydride (79 mmol) and selenium (38 mmol) in water. After the initial reaction subsides, additional selenium (38 mmol) is added and the mixture heated briefly ". ... 

Dialkylamino-substituted 1,2-diselenolylium cations have been prepared from 1,3-bis(dialkylamino)-l,3-dichloropropenylium chloride by treatment with sodium hydrogen selenide and subsequent oxidation with hydrogen peroxide or w-chloroperbenzoic acid <87BCJ2686>. These salts were also prepared by reaction with sodium diselenide in ethanol <86MCLC333>. 

Preparation. The reagent can be prepared in aqueous or alcoholic solution from selenium (1 eq.) and sodium borohydride (2 eq.). Addition of another equivalent of selenium results in formation of sodium diselenide (NaaSea). 

Reductions. Elemental selenium can be reduced using sodium hydride. The resulting sodium diselenide (Na2Se2) can be used to prepare dialkyl selenides (eq 55). Similarly, elemental sulfur can be reduced to diatomic sulfur by sodium hydride in the presence of a phase transfer catalyst,... 

Poly(methylene diselenide) can also be prepared by the condensation of dibromomethwe and aqueous sodium diselenide [205,211]. This polymer is... 

By condensing dibromopimelic add and sodium diselenide, Fredga and Styrman [221] reported another add group containing polymer. The add hydrolysis of di(selenocyanato)derivatives of both the roc- and meso-dibromo-pimelic acids also yielded in each case the polymeric diselenide Polymers containing both selenium and sulfur in the backbone have been reported by Bergson et al. [222] ... 

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