Basic
Organic Nomenclature
Alkynes - Multiple Triple Bonds
Family name: suffix: -yne
There are of course compounds which contain two or more triple bonds. The
general formula for these alkynes are: CnH2n-8,
CnH2n-12, CnH2n-16, ..., for
two, three, four, ... triple bonds. Again, the loss of two pairs of hydrogen
atoms indicates the presence of an additional triple bond between two carbon
atoms.
The naming of the poly-alkynes is similar to that of a simple alkyne.
-
Locate the longest chain (or ring) which contains all
of the carbon atoms of all triple bonds.
-
The chain is then numbered from the end which has a triple bond closet
to that end of the chain. Substituents are then located according to this
numbering scheme.
-
If there is no preferred numbering scheme due to the triple bonds (i.e.
the triple bonds are the same distance from the ends of the chain), pick
the one that will give the substituent closet to one end of the chain the
lowest number possible.
-
Rings are treated the same way, but note, one of the triple bonds will
always start at carbon 1, then number around the ring, the shortest distance,
to the other triple bond(s). (Note: it requires a large ring to contain
multiple triple bonds as they are linear.)
The presence of the multiple bonds are indicated in the name by: first,
the number locating each triple bond present; second, by adding the di,
tri, tetra, ... prefixes before the -yne ending. NOTE: you need to add
an "a" before the di, tri, etc, i.e. 1,3-butadiyne, 1,3,5-hexatriyne.
Examples of naming poly-alkenes are:
Next Page: Alkynes - III
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