Skip to content

Chemistry · Ch 13 — Hydrocarbons

Nomenclature and Isomerism of Aromatic Hydrocarbons

13.5.1

Nomenclature and Isomerism of Aromatic Hydrocarbons

Benzene (C6H6), the first aromatic hydrocarbon, is represented as a regular hexagon with a circle inscribed in it. Since all six hydrogens of benzene are equivalent, only ONE monosubstituted product is possible for any given substituent -- e.g. methylbenzene (C6H5-CH3), named toluene; ethylbenzene (C6H5-CH2CH3); and isopropylbenzene (C6H5-CH(CH3)2), named cumene. When TWO substituents are introduced -- whether identical or different -- three distinct position isomers become possible, distinguished as ortho (1,2-), meta (1,3-) and para (1,4-); for example, dimethylbenzene (xylene) exi …

Misc 13.5.1-ey1Evaluate Yourself: isomers of C8H10

Worked out. Asks the student to write all possible isomers for an aromatic benzenoid compound of molecular formula C8H10 -- ethylbenzene plus the three xylene (dimethylbenzene) isomers, ortho/meta/para. …

Misc 13.5.1-ey2Evaluate Yourself: monosubstituted isomers of C9H12

Worked out. Asks the student to write all possible isomers for a MONOSUBSTITUTED aromatic benzenoid compound of molecular formula C9H12 -- i.e. the various single C3H7-type substituents (n-propylbenzene, isopropyl/cumene arrangement re-checked at this formula, and related branched analogues) consistent with one substituent and no ring di-substitution. …