عنوان البحث(Papers / Research Title)
Multimetallic Lithium Complexes Derived from the Acids Ph2C(X)CO2H (X=OH, NH2): Synthesis, Structure and Ring Opening Polymerization of Lactides and Lactones
الناشر \ المحرر \ الكاتب (Author / Editor / Publisher)
يحيى فاهم عبيد محمد الخفاجي
Citation Information
يحيى,فاهم,عبيد,محمد,الخفاجي ,Multimetallic Lithium Complexes Derived from the Acids Ph2C(X)CO2H (X=OH, NH2): Synthesis, Structure and Ring Opening Polymerization of Lactides and Lactones , Time 26/01/2018 04:08:17 : كلية العلوم
وصف الابستركت (Abstract)
lithium complexes as catalysts for polymerization of lactide and lactone
الوصف الكامل (Full Abstract)
Reaction of LiOR (R=t-Bu, Ph) with the acids 2,2/-Ph2C(X)(CO2 H), X=OH (benzH), NH2 (pdgH) was investigated. For benzH, one equivalent LiOt-Bu in THF afforded [Li(benz)(THF)]2·2THF (1·2THF), which adopts a 1D chain structure. If acetonitrile is used (mild conditions), another solvate of 1 is isolated; LiOPh also led to 1. Robust work-up afforded [Li7(benz)7(MeCN)](2·2MeCN·THF). Use of LiOt-Bu (2 equivalents) led to {Li8(Ot-Bu)2[(benz)](OCPh2CO2CPh2CO2t-Bu)2(THF)4} (3), the core of which comprises two open cubes linked by benz ligands. For dpgH, two equivalents of LiOt-Bu in THF afforded [Li6(Ot-Bu)2 (dpg)2(THF)2] (4), which contains an Li2O2 6-step ladder. Similar reaction of LiOPh afforded [Li8(PhO)4(dpg)4(MeCN)4] (5). Complexes 1–5 were screened for their potential as catalysts for ring opening polymerization (ROP) of e-caprolactone (e-CL), rac-lactide (rac-LA) and d-valerolactone (d-VL). For ROP of e-CL, conversions > 70% were achievable at 1108C with good control. For rac-LA and d-VL, temperatures of at least 1108C over 12 h were necessary for activity (conversions > 60%). Systems employing 2 were inactive.
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