Synthesis of Sulfides

(methylthio)cyclopentene, which is a cyclic pentene molecule with a methylthio group on the third carbon of the ring.

Sulfides are easily oxidized using hydrogen peroxide. In the reaction, the RSR molecule becomes R2SO, which is a sulfoxide. This can be further oxidized to produce a sulfone using a peroxyacid. As you remember, the sulfone molecule is R2SO2. Figure 96 shows the oxidation of a sulfide to make a sulfoxide and a sulfone:

Figure 96.

The sulfoxide you should memorize is DMSO or dimethyl sulfoxide, in which the two R groups are methyl groups. This is considered a polar aprotic solvent.

Other things you should know about a sulfide is that the C-S bonds are longer than the similar C-O bonds, in part because sulfur is larger.

SYNTHESIS OF SULFIDES

Sulfides must be synthesized by the nucleophilic substation reaction using thiols. The reaction starts with the addition of sodium hydroxide or NaOH, which pulls off the hydrogen ion, leading to the thiolate anion. This gets acted on by a primary halide, in particular, methyl halide, which acts similarly to the making of ethers. The methyl group on the methyl halide gets attached to the thiolate anion, giving a sulfide. This reaction is described in figure 97:

Figure 97.