Page 791 - Carrahers_Polymer_Chemistry,_Eighth_Edition

754 Carraher’s Polymer Chemistry

Cl H Cl
Cl
H H
R
R
H R R
Cl
2R, 3R-dichloro diad 2R,4S-dichloro diad plus inserted methylene
Racemic Meso

Let us now move to the insertion of another methylene forming the following segments. The fi rst
set contains racemic pairs.

Cl
H H Cl
R
R
R R
Cl
H
Cl H
2R, 5R-dichloro segment 2S,5S-dichloro segment
Racemic pairs

The second pair contain a meso pairing.

Cl
H H Cl
R
R
R R
H
Cl
H Cl
2R,5S-dichloro segment 2S,5R-dichloro segment
Meso pair

Now let us look at triad segments of our poly(vinyl chloride). The first one had meso adjacent

units and is isotactic by definition of the meso, racemic argument but the adjacent chlorides are not
on one side of the plane.

Cl Cl
H H

Isotactic R R
CI
H

Meso
Meso

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