Palladium‐Catalyzed Insertion of Ethylene and 1,1‐Disubstituted Difunctional Olefins: An Experimental and Computational Study

• Published in: ChemPlusChem (Weinheim, Germany) Germany), 2020-06, Vol.85 (6), p.1200-1209
• Main Authors: Gaikwad, Shahaji R., Patel, Ketan, Deshmukh, Satej S., Mote, Nilesh R., Birajdar, Rajkumar S., Pandole, Satish P., Chugh, Jeetender, Chikkali, Samir H.
• Format: Article
• Language: English
• Subjects: homogeneous catalysis; insertion copolymerization; olefins; palladium; polyethylene
• ISSN: 2192-6506; 2192-6506
• DOI: 10.1002/cplu.202000309

Insertion or coordination copolymerization of ethylene with di‐substituted olefins is challenging and the choice of di‐substituted mono‐functional olefin versus di‐substituted di‐functional olefin (DDO) appears to be decisive. Here we show that DDO‐inserted species are amenable to ethylene insertion and polymerization. DDOs such as 2‐acetamidoacrylic acid (AAA), methyl 2‐acetamidoacrylate (MAAA), and ethyl 2‐cyanoacrylate (ECA) were treated with palladium complex [{P∧O}PdMe(L)] (P∧O=κ2‐P,O−Ar2PC6H4SO2O with Ar=2‐MeOC6H4; L=C2H6OS) and the existence of respective insertion intermediates in moderate yield (up to 37 %) was established. These intermediates were exposed to ethylene and corresponding ethylene‐inserted products were isolated and characterized. A careful comparison with three model compounds confirmed ethylene insertion and polymerization. Thus, the combined experimental and computational investigations show that DDO‐inserted species can undergo ethylene insertion and polymerization. Two in one: Insertion of di‐substituted di‐functional olefins (DDO) in a Pd−Me bond is reported. Three DDO's, 2‐acetamidoacrylic acid, methyl 2‐acetamidoacrylate, and ethyl 2‐cyanoacrylate were treated with the palladium complex [{P∧O}PdMe(L)] (P∧O=κ2‐P,O−Ar2PC6H4SO2O with Ar=2‐MeOC6H4; L=C2H6OS) and the presence of insertion intermediates was investigated. The DDO‐inserted species were found to be amenable to ethylene insertion, suggesting facile insertion copolymerization of ethylene with DDO's.