M. Huskic
Kemijski institut
1115 Ljubljana, Hajdrihova 19
Kemijski institut Ljubljana
A. Sebenik, Fakulteta za kemijo in kem. tehnologijo, Ljubljana
Nukleofilna substitucija klora v PVC s ksantatnimi skupinami
poteka po stereospecificnem S N 2 mehanizmu, predvsem na mezomernih
delih verige. Poleg substitucije potekata se zamrezevanje in
razpad ksantata. Substitucija poteka hitreje s kalijevim n-propil
kot kalijevim etil ksantatom. Dobljenim produktom se spremenijo
polarnost, topnost in temperatura steklastega prehoda, kar
omogoca uporabo produktov za cepljenje ali mesanje z drugimi
polimeri.
Kljucne besede: PVC, nukleofilna substitucija, ksantati,
temperatura steklastega prehoda, NMR
Nucleophilic substitution of chlorine in PVC with potassium
xanthate proceeds by stereospecific S N 2 mechanism mostly on the
m-position of PVC chain. Beside the substitution, also the
crosslinking and decomposition of xanthate groups are going on.
The reaction proceeds faster with potassium n-propyl than with
potassium ethylxanthate. The formed products have different
solubility, polarity and glass transition temperature. The
products are suitable for grafting and compounding with other
polymers.
Key words: PVC, nucleophilic substitution, xanthates, glass
transition, NMR