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Polymerization of (3 S , 6 S )‐3‐isopropyl‐6‐methyl‐2,5‐morpholinedione with tin octoate and tin acetylacetonate
Author(s) -
Jörres Volker,
Keul Helmut,
Höcker Hartwig
Publication year - 1998
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19980501)199:5<835::aid-macp835>3.0.co;2-s
Subject(s) - polymerization , tin , polymer chemistry , moiety , polymer , chemistry , racemization , monomer , isopropyl , catalysis , organic chemistry
Polymerization of (3 S ,6 S )‐3‐isopropyl‐6‐methyl‐2,5‐morpholinedione ( 1 ) with tin octoate (Sn(oct) 2 ) and tin acetylacetonate (Sn(acac) 2 ) results in an alternating polymer with lactic acid and valine repeating units, poly[( S )Lac‐ alt ‐( S )Val] ( 2 ). From time dependent analysis of the monomer conversion and the number average molecular weight of the polymer it is concluded that Sn(oct) 2 acts as a catalyst and Sn(acac) 2 as an initiator. From 1 H NMR spectroscopic analysis of the polymer 2 it is concluded that the lactate moiety suffers from racemization during polymerization, while the valine moiety does not. The number ratio of not racemized repeating units ( S , S ) and racemized repeating units ( R , S ) in the polymer was calculated to be 11.5 for the polymer prepared with Sn(oct) 2 as a catalyst and 18.9 for the polymer prepared with Sn(acac) 2 as an initiator.