39 Sulfides, Sulfoxides, and Sulfones
I
n this chapter, organic sulfur compounds corresponding to the structures RSR', RS(O)R', and R S 0 R ' , where R and R' are the same or different, are discussed. These three functional classes, which are known as sulfides, sulfoxides, and sulfones, respectively, also include cyclic systems in which one or more sulfur atoms are members of a ring. However, compounds of the latter type are usually named as heterocycles (see Chapter 6). Sulfides are the sulfur analogs of ethers and are best named similarly to oxygen compounds of corresponding structure (see Chapter 26). The same kind of nomenclature is applicable to sulfoxides and sulfones. Also considered here are disulfides, which have the structure RSSR, and polysulfides having more than two sulfur atoms arranged in a straight chain. (The term polysulfide also denotes compounds containing more than one monosulfide group.) Thioacetals, a subclass of sulfides derived from aldehydes and ketones, are treated in Chapter 20. Compounds in which a sulfur atom carries a positive charge are discussed in Chapter 24. 2
Recommended Nomenclature Practice Sulfides. Acyclic sulfides containing no more than two —S— linkages within a single straight chain otherwise composed of carbon atoms are preferably named substitutively as derivatives of one of the all-carbon chains present in the molecule. Principles to be followed in selecting the parent chain are given in Chapter 26. Names for SR groups in which R is cyclic are formed by combining the prefix name of the R group with thio.
CH SCH CH CH 3
2
2
l-(Methylthio)propane
3
CH CH SCH CH SCH CH 3
2
2
2
2
l,2-Bis(ethylthio)ethane
3
SC H | CgH5SCH CHCH SCgH5 6
2
5
l,2,3-Tris(phenylthio)propane
2
299
300
NOMENCLATURE OF ORGANIC COMPOUNDS
Cyclic sulfides having one or more —S— linkages connecting two ring systems are preferably named substitutively as derivatives of the senior ring system carrying the most SR groups. Criteria for use in selecting the senior ring system are given in Chapter 26. Names of SR groups are formed as described above for acyclic groups.
(Cyclopentylthio)benzene
_SCH—CHS—/ ^ctf
\ W
2
1,2-Bis(phenylthio)cyclopropane
2-(2-NaphthyIthio)oxacyclopentane
For both acyclic and cyclic symmetrical monosulfides, radicofunctional names ending with the word sulfide are acceptable alternatives to the preferred substitutive names. CH
I
CH
3
I
l-(Isobutylthio)-2-methylpropane Diisobutyl sulfide
3
CH CHCH SCH CHCH 3
2
2
0
