SnOct2-Catalyzed Syntheses of Cyclic Poly(l-lactide)s with Catechol as Low-Toxic Co-catalyst

  • Hans R. KricheldorfEmail author
  • Steffen M. Weidner
Original paper


Polymerizations of l-lactide in bulk at 160 or 180 °C were performed with 1/1 mixtures of catechol (CA) or 4-tert-butylcatechol (BuCA) and tin(II)-2-ethylhexanoate (SnOct2) as catalysts and a variation of the Lac/Cat ratio. Weight average molar masses (Mw) up to 170,000 g mol−1 were obtained with CA and up to 120,000 g mol−1 with BuCA. The cyclic structure of the resulting poly(l-lactide)s was proven by MALDI-TOF mass spectrometry and by comparison of their hydrodynamic volumes with those of commercial linear poly(l-lactide)s. The predominance of even-numbered cycles increased with lower temperatures and shorter polymerization times. This finding indicates that the cyclic architecture is the results of a ring-expansion polymerization mechanism. Addition of silylated BuCA as co-catalyst was less favorable than addition of free BuCA.


Polylactides Cycles Catechol Ring-expansion polymerization MALDI-TOF mass spectrometry 



We wish to thank Profs G. Luinstra and H.-U. Moritz (TMC, Hamburg) and BAM (Berlin) for technical support. Furthermore, we thank Mrs. Rosemarie Laging (BAM, Berlin) for the SEC measurements.

Compliance with Ethical Standards

Conflict of interest

The authors declare no competing or financial interests.


  1. 1.
    EthiconInc, Offen. G, 2162900. (1973) Chemical Abstracts 76:73051wGoogle Scholar
  2. 2.
    Kanesh GB, Sanchez-Riem F, Svenson DK (1994) Polymers of lactic acid. In: Mobley DP (ed) Plastics from Microbs. Hanser, München, p 1994Google Scholar
  3. 3.
    Kowalski A, Duda A, Penczek S (1998) Polymerization of L, L-lactide initiated by aluminum isopropoxide trimer or tetramer. Macromolecules 31:2114CrossRefGoogle Scholar
  4. 4.
    Kricheldorf HR, Kreiser-Saunders I, Stricker A (2000) Polylactones 48. SnOct(2)-initiated polymerizations of lactide: a mechanistic study. Macromolecules 33:702CrossRefGoogle Scholar
  5. 5.
    Kricheldorf HR, Kreisersaunders I, Boettcher C (1995) Polylactones 31. Sn(Ii)Octoate-initiated polymerization of L-Lactide—a mechanistic study. Polymer 36:1253CrossRefGoogle Scholar
  6. 6.
    Kricheldorf HR, Meierhaack J (1993) Polylactones 22 Aba Triblock copolymers of L-Lactide and poly(ethylene glycol). Macromol Chem Phys 194:715CrossRefGoogle Scholar
  7. 7.
    Penczek S, Duda A, Kowalski A, Libiszowski J, Majerska K, Biela T (2000) On the mechanism of polymerization of cyclic esters induced by Tin(II) octoate. Macromol Symp 157:61CrossRefGoogle Scholar
  8. 8.
    Schmitt EE, Polistina RA, (1967), Cyanamide A, US, 32397033/3463158Google Scholar
  9. 9.
    Witzke DR, Narayan R, Kolstad JJ (1997) Reversible kinetics and thermodynamics of the homopolymerization of L-lactide with 2-ethylhexanoic acid tin(II) salt. Macromolecules 30:7075CrossRefGoogle Scholar
  10. 10.
    Jeong W, Hedrick JL, Waymouth RM (2007) Organic spirocyclic initiators for the ring-expansion polymerization of beta-lactones. J Am Chem Soc 129:8414CrossRefGoogle Scholar
  11. 11.
    Kricheldorf HR, Weidner SM (2018) High molar mass cyclic poly(L-lactide) via ring-expansion polymerization with cyclic dibutyltin bisphenoxides. Eur Polym J 105:158CrossRefGoogle Scholar
  12. 12.
    Kricheldorf HR, Weidner SM, Scheliga F (2018) About formation of cycles in Sn (II) octanoate-catalyzed polymerizations of lactides. J Polym Sci A 56:1915CrossRefGoogle Scholar
  13. 13.
    Zhang XY, Waymouth RM (2014) Zwitterionic ring opening polymerization with isothioureas. ACS Macro Lett 3:1024CrossRefGoogle Scholar
  14. 14.
    Basko M, Kubisa P (2010) Cationic polymerization of L, L-lactide. J Polym Sci A 48:2650CrossRefGoogle Scholar
  15. 15.
    Chisholm MH, Gallucci JC, Yin HF (2006) Cyclic esters and cyclodepsipeptides derived from lactide and 2,5-morpholinediones. Proc Natl Acad Sci USA 103:15315CrossRefGoogle Scholar
  16. 16.
    Culkin DA, Jeong WH, Csihony S, Gomez ED, Balsara NR, Hedrick JL, Waymouth RM (2007) Zwitterionic polymerization of lactide to cyclic poly(lactide) by using N-heterocyclic carbene organocatalysts. Angew Chem-Int Ed 46:2627CrossRefGoogle Scholar
  17. 17.
    Piromjitpong P, Ratanapanee P, Thumrongpatanaraks W, Kongsaeree P, Phomphrai K (2012) Synthesis of cyclic polylactide catalysed by bis(salicylaldiminato)tin(II) complexes. Dalton Trans 41:12704CrossRefGoogle Scholar
  18. 18.
    Prasad AV, Stubbs LP, Zhun M, Zhu YH (2012) Zwitterionic ring opening polymerization of lactide by metal free catalysts: production of cyclic polymers. J Appl Polym Sci 123:1568CrossRefGoogle Scholar
  19. 19.
    Piedra-Arroni E, Ladaviere C, Amgoune A, Bourissou D (2013) Ring-opening polymerization with Zn(C6F5)(2)-based Lewis pairs: original and efficient approach to cyclic polyesters. J Am Chem Soc 135:13306CrossRefGoogle Scholar
  20. 20.
    Kricheldorf HR, Weidner SM (2018) Cyclic poly (L-lactide) s via simultaneous ROP and polycondensation (ROPPOC) catalyzed by dibutyltin phenoxides. Eur Polym J 109:360CrossRefGoogle Scholar
  21. 21.
    Kricheldorf HR, Weidner SM, Scheliga F (2017) Cyclic polylactides via simultaneous ring-opening polymerization and polycondensation catalyzed by dibutyltin mercaptides. J Polym Sci A 55:3767CrossRefGoogle Scholar
  22. 22.
    Kricheldorf HR, Weidner SM, Scheliga F (2017) Cyclic poly (l-lactide) via ring-expansion polymerization by means of Dibutyltin 4-tert-butylcatecholate. Macromol Chem Phys 218:1700274CrossRefGoogle Scholar
  23. 23.
    Kricheldorf HR, Weidner SM, Scheliga F (2017) Cyclic poly(L-lactide)s via ring-expansion polymerizations catalysed by 2,2-dibutyl-2-stanna-1,3-dithiolane. Polym Chem 8:1589CrossRefGoogle Scholar
  24. 24.
    Weidner SM, Kricheldorf HR (2017) The role of transesterification in SnOct2-catalyzed polymerizations of lactides. Macromol Chem Phys 218:1600Google Scholar
  25. 25.
    Kricheldorf HR, Weidner SM (2019) About the influence of salicylic acid on tin(II)octanoate-catalyzed ring-opening polymerization of l-lactide. Eur Polym J 119:37CrossRefGoogle Scholar
  26. 26.
    Charrouf Z, Guillaume DJAJFT (2007) Phenols and polyphenols from Argania spinosa. Am J Food Technol 2:679CrossRefGoogle Scholar
  27. 27.
    Jacobson H, Beckmann CO, Stockmayer WH (1950) Intramolecular reaction in polycondensations 2. Ring-chain equilibrium in polydecamethylene adipate. J Chem Phys 18:1607CrossRefGoogle Scholar
  28. 28.
    Jacobson H, Stockmayer WH (1950) Intramolecular reaction in polycondensations 1 the theory of linear systems. J Chem Phys 18:1600CrossRefGoogle Scholar
  29. 29.
    Bigg DM (1996) Annual Technical Conference—Society of Plastic Engineers 30:2028Google Scholar
  30. 30.
    Dorgan JR, Janzen J, Clayton MP, Hait SB, Knauss DM (2005) Melt rheology of variable L-content poly(lactic acid). J Rheol 49:607CrossRefGoogle Scholar
  31. 31.
    Jamshidi K, Hyon SH, Ikada Y (1988) Thermal characterization of polylactides. Polymer 29:2229CrossRefGoogle Scholar
  32. 32.
    Kalb B, Pennings AJ (1980) General crystallization behavior of poly(L-lactic acid). Polymer 21:607CrossRefGoogle Scholar
  33. 33.
    Kricheldorf H, Weidner SM, Scheliga F (2019) Ring-expansion polymerization (REP) of l-lactide with cyclic tin(II) bisphenoxides. Eur Polymer J 116:256CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Universität Hamburg, Institut für Technische Und Makromolekulare ChemieHamburgGermany
  2. 2.BAM, Federal Institute for Materials Research and Testing BerlinGermany

Personalised recommendations