The Foundations of Chemistry

Some types of natural condensation polymers play crucial roles in living systems.

Proteins(Section 28-9) are polymeric chains of L-amino acidslinked by peptide bonds. A

peptide bondis formed by the elimination of a molecule of water between the amino

group of one amino acid and the carboxylic acid group of another.

Nylon is formed at the interface
where hexamethylenediamine (in the
lower water layer) and adipyl
chloride (a derivative of adipic acid,
in the upper hexane layer) react.
The nylon can be drawn out and
wound on a stirring rod. In industry,
adipic acid is used in place of adipyl
chloride.

1096 CHAPTER 27: Organic Chemistry I: Formulas, Names, and Properties

Figure 27-22 Fibers of synthetic polymers are made by extrusion of the molten material

through tiny holes, called spinnerets.After cooling, nylon fibers are stretched to about four

times their original length to orient the polymer molecules.

H

H

H

O

NNC C OHHNCCNCCC C OH H OHH 2 O

R H R

HO

H R

HO

H R

HO

peptide

bond

When this process is carried out repeatedly, a large molecule called a polypeptideis

formed.

H

H

H

O

NNNCC CC CCNCC

R H R

HO

H R

HO

H R

HO

NCCNCC

H R

HO

H R

HO

NCCOH

H R

HO

peptide bonds

Spinneret

Nylon fibers

Pump

Pressure

N 2

285 C

Nylon chips

Proteins are discussed in greater detail in Section 28-9.