Page 30 - Carrahers_Polymer_Chemistry,_Eighth_Edition

Polymer Nomenclature xxix

and
8-Membered ring >7-Membered ring >6-Membered ring >5-Membered ring

and

>

C. For hetero-atomed linear chains or cyclic rings, the order of seniority is O> S> Se> Te>
N> P> As> Sb> Bi> Si> Ge> Sn> Pb> B> Hg
Thus, because –O–CH – is senior to –S–CH –, it would be named first in a polymer that contained

2
2
both –O–CH – and –S–CH – segments. Further, a polymer containing these alternating units would
2
2
not be poly(thiomethyleneoxymethylene) but would be named poly(oxymethylenethiomethylene).
Another example,
O
−(−O−C−CH −) −
—
—
2 n
is named poly[oxy(1-oxy-1,2-ethanediyl)] or less preferred poly[oxy(1-oxoethylene)] but not poly[(2-
oxo-1,2-ethanediyl)oxy] or poly[(2-oxoethylene)oxy].
D. Unsaturation is senior to saturation. The more it is unsaturated the more senior it is with
all other items being equal. Thus 1,4-phenylene is senior to 2,5-cyclohexadiene-1,4diyl,
which in turn is senior to 2-cyclohexene-1,4-diyl, which is senior to cyclohexane-1,4diyl.
For linear chains –CH=CH–CH=CH– is senior to –CH=CH–CH –CH –, which is in turn
2 2
senior to the totally saturated chain segment.

ROUTE

A. From the senior subunit determined from “Seniority” take the shortest path (smallest num-
ber of atoms) to another like or identical unit or to the next most preferred subunit. Thus,
for the homo polymer poly(oxymethylene) it is simply going from one oxygen to the next
oxygen and recognizing that this is the repeat unit. For a more complex ether this means
going until the chain begins to repeat itself going in the shortest direction from the senior
unit or atom to the next most senior unit or atom.
Thus, –O–C–C–O–C–C–C– is named “oxy-1,2-ethanediyloxy-1,3propanedily” rather
than “oxy-1,3-propanediyloxy-1,2-ethanediyl.”

B. Where the paths are equal, such as in some nylons, the repeat unit is named so that the

heteroatom “N” is first named and then more highly substituted (carbonyl) unit appears
next. Thus, nylon 3,3, with the structure

9/14/2010 3:35:47 PM
K10478.indb xxix
K10478.indb xxix 9/14/2010 3:35:47 PM