Chemistry Reference
In-Depth Information
become considerably more reactive [
150
]. As a result,
ortho
-methylene bridges predominate in
the products:
Zn
+
+
H
HO
OH
O
OH
Zn
Zn
OH
H
O
O
Zn
+
OH
O
OH
OH
H
Zn
O
O
OH
+
H
2
O
+
Zn
Zn
OH
OH
O
OH
OH
OH
H
+
OH
OH
It is possible to form high molecular weight novolacs by carrying out the reactions of alkyl phenyl
ethers with formaldehyde in acetic acid in the presence of perchloric acid [
149
]:
CN
CN
O
OH
O
NaOCH
3
+
HClO
4
O
n
n
Novolacs are cross-linked by additions of more formaldehyde to the soluble, thermoplastic
materials. The additional formaldehyde can be in the form of paraform, an oligomer of formaldehyde
