Question

Draw curved arrow mechanisms for the rin cationic initiator and (b) an anionic initiator You should Then, comment on which method you expect to produce a s for the ring-opening polymerization of E-caprolactone using (a) a monic initiator Vou should show an initiation and a propagation step. od you expect to produce a narrower molar mass distribution and why. -NH E-caprolactone

Answer 1

dnienic polymerization of copuolactam NaH Initiator can be anion of Caprolactam litsell, formed by reaction with a small amount hi of Sodium hydride Thú anion of caprolactam attacks a second! molecule be the lactam, opening the ring Land generating a new & unstabilised anionic nitrogen unta o HN N-acyl lactan o + This anion then abstracts a proton from further moleculd of the lactam preston som further c o I The ring opening Carbonyl carbon in the N-acyl lactam is now strongly activated toward Nucleophillic attack by the prence of N-acyl group, and so is rapidly attacked by the neuly founed caprolactam anion.

IDATE PAGE NO 20 the resulting amide anion deprotonates a there molecule of caprolactan, which can. then attack the Tring - Carbonyl of N-acyl. inctam , thus leading to continued ring opening polymerisation HN 07 o UN & Nylon 6

Cationic Ring opening Polymerization of & tap notactam by a Montmorillonite Clay Catalyst Very strong protonic acid are able to promot Cationic solymerization Montmorri lohes inexpensive, non corrosur solid acid . Reaction catalyzed by montmorillonites ou! carried out in mild condition, with high yield. سلتاميلية بل Gritiator HN - CH₂ - CH2 - CH2 - CH₂ - CH₂ - C - BA J. t n UN Hast order Reaction # Is-415-, -in-one -N-CH₂-CH₂-C₂-04-C4₂-17 un + DIT O N-CH 2 -CH2-CH2-C42-42- High molecular wt & Caprolactam

DATE JPAGE NO 20 Anonic Polymerizalon Cationic Dolymuizalio It proceeds at high rate & high & Temp. Rate of polymerization is usually slow because Election witha ramina substituent on aniont initator stabilize the ve charge through charge delocalisalon Sinsitive to tempo Rate decreases with linc in temp Insensitive to temperature. Can be carried out at both high & low temp Yield regular polymer with less branching more controlled & narrow molecular weight distribution The high reactivity of cationic grourth untus. lead to undesirable side reactions such as chain. tanser & tvemination which in turn lead to high branching lower Me & broader MW distribution