1 (616)

Prévia do material em texto

608 CHAPTER 17 
 
17.5. 
(a) Eugenol contains three substituents: an allyl group, a hydroxy group, and a methoxy group. 
 
 
 
All benzene derivatives can be named with benzene as the parent. In this case, the parent could also be either phenol 
(hydroxybenzene) or anisole (methoxybenzene). So there are three choices for the parent. For each possibility, the 
assignment of locants is shown by numbering to give the lowest possible number to each consecutive substituent: 
 
 
 
The last step is to arrange the substituents alphabetically so the three names for eugenol are as follows: 
As a benzene derivative: 4-allyl-1-hydroxy-2-methoxybenzene 
As a phenol derivative: 4-allyl-2-methoxyphenol 
As an anisole derivative: 5-allyl-2-hydroxyanisole 
 
Thymol contains three substituents as well: a methyl group, a hydroxy group, and an isopropyl group. Each can be 
named based on benzene, phenol, or toluene as the parent. These possibilities are shown below, with the corresponding 
locants shown: 
 
HO
1
2
3
4 HO 1
2
3
4
5
HO 1
2
3
4
parent = benzene parent = phenol parent = toluene 
 
Arranging the substituents we obtain the following three possible IUPAC names: 
As a benzene derivative: 2-hydroxy-1-isopropyl-4-methylbenzene 
As a phenol derivative: 2-isopropyl-5-hydroxyphenol 
As a toluene derivative: 3-hydroxy-4-isopropyltoluene 
 
(b) This name violates two of the rules for naming polysubstituted aromatic compounds. First, the substituents are not 
listed alphabetically. Second, if named with benzene as the parent, the methyl group needs to have the first locant in 
order to minimize the number of the third locant. Thus, a correct name would be 2-hydroxy-4-isopropyl-1-
methylbenzene. 
 
 
 
17.6. The molecular formula (C8H8) indicates five 
degrees of unsaturation (see Section 14.16), four of 
which are accounted for by the aromatic ring, so the 
structure must also contain either a ring or a double bond 
(in addition to the aromatic ring). If compound A 
undergoes bromination to produce a dibromide, then it 
must contain a C=C double bond (outside of the aromatic 
ring, which does not react with Br2). This C=C double 
bond accounts for the last degree of unsaturation, 
described above. The structure of compound A, as well 
as the structure of the resulting dibromide (compound B) 
are shown here: 
 
www.MyEbookNiche.eCrater.com