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TMPZnN(SiMe 3 ) 2 , [TMPZn( μ -O i Pr)] 2 and TMPZn[OCMe 2 C(O)OEt]. Their role in the ring-opening of rac -lactide and ε -caprolactone where TMP = 1,5,9-trimesityldipyrromethene
- Source :
- Journal of Organometallic Chemistry. 812:56-65
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- From the reaction between Zn[N(SiMe3)2]2 and TMP-H (1 equiv.) in toluene at room temperature TMPZn[N(SiMe3)2] was prepared and subsequently reacted with PriOH (1 equiv.) and HOCMe2C(O)OEt (1 equiv.) to give [TMPZn(μ-OPri)]2 and TMPZn[OCMe2C(O)OEt], respectively. The three compounds were each crystallized and characterized by single crystal X-ray diffraction. The compound TMPZn[N(SiMe3)2] was a three coordinated N3Zn compound with an anagostic N(SiMe3)2 ligand where one SiMe3 was annexed to the Zn2+ ion. The compound [TMPZn(μ-OPri)]2 has a molecular C2 axis and is dimeric in toluene-d8 solution having a N2ZnO2 core for each Zn2+ ion. In TMPZn[OCMe2C(O)OEt] compound the Zn2 + ion is four-coordinated. This too is present in solution (IR) and also present in toluene-d8 and THF where there is evidence of fluxionality with Tc ∼15 °C and −85 °C, respectively. The compound [TMPZn(μ-OPri)]2 polymerizes both e-caprolactone (e-CL) and rac-lactide (rac-LA) to give polycaprolactone (PCL) and polylactic acid (PLA), respectively. The rate of the reactions are e-CL > LA and are influenced by the nature of solvent, THF > CD2Cl2/CH2Cl2. The nature of PLA derived from rac-LA is heterotactic: Pr = 0.96 in THF and Pr = 0.75 in CD2Cl2/CH2Cl2. In the copolymerization of rac-LA: e-CL by both [TMPZn(μ-OPri)]2 and TMPZn[OCMe2C(O)OEt] only PLA is produced, PCL is not formed.
- Subjects :
- Lactide
Chemistry
Ligand
Organic Chemistry
02 engineering and technology
010402 general chemistry
021001 nanoscience & nanotechnology
01 natural sciences
Ring-opening polymerization
Toluene
Biochemistry
0104 chemical sciences
Solvent
Inorganic Chemistry
chemistry.chemical_compound
Polylactic acid
Polycaprolactone
Polymer chemistry
Materials Chemistry
Physical and Theoretical Chemistry
0210 nano-technology
Caprolactone
Subjects
Details
- ISSN :
- 0022328X
- Volume :
- 812
- Database :
- OpenAIRE
- Journal :
- Journal of Organometallic Chemistry
- Accession number :
- edsair.doi.dedup.....24732ce0d18b625a19459974451fbe8a
- Full Text :
- https://doi.org/10.1016/j.jorganchem.2016.01.001