Chemistry Reference
In-Depth Information
The additions take place at room temperature and the reactions take from 7 to 30 days [
252
]to
complete.
Polyacrylonitrile reacts with hydroxylamine and the product can be metalated by elements from
Group IV (Sn, Ge, and Si). This is a convenient route to formation of polymers with such pendant
organometallic groups [
253
]:
+
H
2
NOH
N
HON
NH
2
ClSnR3
N
NH
2
O
SnR
3
The yields are high when the reactions are carried out on dilute solutions of polyacrylonitrile in
dimethylformamide at 75
C. The solutions must contain 1.5 mol each of hydroxylamine hydrochlo-
ride and sodium carbonate per mole of acrylonitrile groups [
253
].
A
-hydroxymethylamides of
acetic, benzoic, and benzene-sulfonic acids [
254
]. When the same reactions are carried out with
Ritter
reaction can be carried out on atactic polyacrylonitrile with
N
N
-
hydroxymethylimides of succinic or phthalic acids in tetramethylene sulfone, there is a stronger
tendency toward cross-linking.
Copolymers of methacroyl chloride will undergo an
Arbuzov rearrangement
in reactions with
triethyl phosphite in dimethylformamide, dioxane or benzene at 75
C[
255
]. The conversions are
high, ranging between 96 and 98%.
The aldehyde groups of polyacrolein can be reduced by the
. There is
a limit, however, to the amount of alcoholate that can be used and to the concentrations of free
aldehyde groups in the starting material [
256
]. Also, ester condensations take place (
Meerwein-Ponndorf reaction
Tischenko
reaction) at the same time as the reductions occur [
256
].
9.4.5 Substitution Reactions of Poly(vinyl alcohol)
There are many practical uses for products from reactions of poly(vinyl alcohol). Among them are
commercial preparations of poly(vinyl acetal)s formed through condensations with aldehydes. Two
materials that are currently being marketed are poly(vinyl formal) and poly(vinyl butyral). The first
one is formed from partially hydrolyzed poly(vinyl acetate) that is dissolved in aqueous acetic acid
and excess formaldehyde. The mixture is heated, sulfuric acid is added, and the reaction is allowed to
proceed at 70-90
C for 6 h. Sulfuric acid is then neutralized and the formal precipitates out.
