is generated by the reaction of phenylmagnesium bromide with selenium followed by acidicifation: Another preparative route to selenols involves the alkylation of selenourea, followed by hydrolysis. Selenols are often generated by reduction of diselenides followed by protonation of the resulting selenoate: 2 RSeSeR + 2 LiHB(C2H5)3 → 2 RSeLi + 2 B(C2H5)3 + H2 RSeLi + HCl → RSeH + LiCl Dimethyl diselenide can be easily reduced to methaneselenol within cells. Reactions Selenols are easily oxidized to diselenides, compounds containing an Se-Se bond. For example, treatment of benzeneselenol with bromine gives diphenyl diselenide. 2 C6H5SeH + Br2 → (C6H5Se)2 + 2 HBr In the presence of base, selenols are readily alkylated to give selenides. This relationship is illustrated by the methylation of methaneselenol to give dimethylselenide. Safety Organoselenium compounds (or any selenium compound) are cumulative poisons despite the fact that trace amounts of Se are required for health. See also Alcohol Thiol References Functional groups Selenols