Nomenclatura de Alquinos

Prévia do material em texto

282 CHAPTER 9 
 
lowest possible locant (“3” indicates that the triple bond 
is located between C3 and C4). 
 
 
(d) We begin by identifying the parent. The longest 
chain is four carbon atoms, so the parent is butyne. 
There are two substituents – both methyl groups 
(highlighted). We number the parent so that the triple 
bond receives the lowest possible locant (C1). 
According to this numbering scheme, the methyl groups 
are both located at C3: 
 
 
 
(e) We begin by identifying the parent. The longest 
chain containing the triple bond has nine carbon atoms, 
so the parent is nonyne. There are two substituents 
(highlighted) – a methyl group and a propyl group. We 
number the parent so that the triple bond receives the 
lowest possible locant (C1). According to this 
numbering scheme, the propyl group is located at C5 and 
the methyl group is located at C7. These substituents are 
arranged alphabetically in the name: 
 
 
 
(f) We begin by identifying the parent. The longest 
chain containing the triple bond has ten carbon atoms, so 
the parent is decyne. There are three substituents 
(highlighted) – two methyl groups and an ethyl group. 
We number the parent so that the triple bond receives the 
lowest possible locant (C3). According to this 
numbering scheme, the ethyl group is located at C5 and 
the methyl groups are both located at C7. These 
substituents are arranged alphabetically in the name 
(ethyl before methyl): 
 
 
(g) We begin by identifying the parent. The longest 
chain containing the triple bond has ten carbon atoms, so 
the parent is decyne. There are many substituents 
(highlighted). We number the parent so that the triple 
bond receives the lowest possible locant (C2), and the 
substituents are arranged alphabetically in the name 
(chloro, then ethyl, and then methyl): 
 
1
2
3
4
5
6
7
8
9
1,1,1-trichloro-8-ethyl-4,4-dimethyl-2-decyne
10
Cl
Cl Cl
 
 
9.2. 
(a) The parent (pentyne) indicates a chain of five carbon 
atoms. The triple bond is between C2 and C3, and there 
are two methyl groups (highlighted), both located at C4. 
 
 
 
(b) The parent (heptyne) indicates a chain of seven 
carbon atoms. The triple bond is between C3 and C4, 
and there are three substituents (highlighted) – two 
methyl groups (at C2 and C5), as well as an ethyl group 
at C5. 
 
 
9.3. The parent is cyclononyne, so we draw a nine-
membered ring that incorporates a triple bond. The triple 
bond is (by definition) between C1 and C2, and a methyl 
group is located at C3. This position (C3) is a chiral 
center, with the R configuration, shown here: 
 
 
 
9.4. The parent chain contains eight carbon atoms with 
two methyl substituents. Numbering so that the triple 
bond receives the lowest possible locant, the two methyl 
groups are located at C3 and C7: 
 
 
www.MyEbookNiche.eCrater.com