1
|
Flores-Romero V, LeBlanc J, Chen Z, Lavoie GG. Ti and Zr complexes bearing guanidine-phenolate ligands: coordination chemistry and polymerization studies. RSC Adv 2024; 14:25889-25899. [PMID: 39156754 PMCID: PMC11328681 DOI: 10.1039/d4ra05146g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2024] [Accepted: 08/05/2024] [Indexed: 08/20/2024] Open
Abstract
A series of group 4 bis(isopropoxide) complexes M[N^O]2(OiPr)2, stabilized by guanidine-phenolate N^O ligands, have been prepared and used as catalysts for the polymerization of unpurified rac-lactide under solvent-free conditions at 130 °C. The resulting polylactic acid (PLA) presented heterotactic bias (P r = 0.56-0.62) with molecular weights similar to those obtained in control experiments with Zr(OiPr)4·iPrOH, Ti(OiPr)4, and Sn(Oct)2. The molecular weights were lower than expected for living polymerization due to chain transfer and/or transesterification. Zr complexes were more active than the Ti homologues, with rate constants ranging from 1.17-3.21 × 10-4 s-1, comparable to that observed with the free guanidine-phenol ligands. The corresponding bis(guanidine-phenolate) titanium dichloride complexes Ti[N^O]2Cl2 were also prepared and tested in ethylene polymerization. The low activity (up to 1.1 kgPE mol-1 h-1) was associated to the strong electron-donating ability of the guanidine moiety and to the trans-N,N-cis-O,O-cis-Cl,Cl coordination mode of the guanidine-phenolate ligand.
Collapse
Affiliation(s)
| | - Jesse LeBlanc
- York University 4700 Keele Street Toronto Ontario M3J 1P3 Canada
| | - Zichuan Chen
- York University 4700 Keele Street Toronto Ontario M3J 1P3 Canada
| | - Gino G Lavoie
- York University 4700 Keele Street Toronto Ontario M3J 1P3 Canada
| |
Collapse
|
2
|
Impemba S, Manca G, Tozio I, Milione S. Ring-Opening Polymerization of rac-β-Butyrolactone Promoted by New Tetradentate Thioether-Amide Ligand-Type Zinc Complexes. Polymers (Basel) 2023; 15:4366. [PMID: 38006091 PMCID: PMC10675234 DOI: 10.3390/polym15224366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 10/27/2023] [Accepted: 11/02/2023] [Indexed: 11/26/2023] Open
Abstract
In this work, thioether-amide ligands featuring a combination of hard amide groups with soft donor groups have been employed to develop new zinc catalysts for the ring-opening polymerization of cyclic esters. All complexes were prepared in high yields through alkane elimination reactions with diethyl zinc and characterized using nuclear magnetic resonance (NMR) spectroscopy. Density functional theory (DFT) characterization provided insight into the parameters that influence catalytic activity, such as steric hindrance at the metal center, Lewis acidity and electronic density of thioether-amide ligands. In the presence of one equivalent of isopropanol, all complexes were active in the ring-opening polymerization of rac-β-butyrolactone. Quantitative conversion of 100 monomer equivalents was achieved within 1 h at 80 °C in a toluene solution. Number-average molecular weights increased linearly with monomer conversion; the values were in optimal agreement with those expected, and polydispersity index values were narrow and relatively constant throughout the course of polymerization. The most active complex was also effective in the ring-opening polymerization of ε-caprolactone and L-lactide. To propose a reliable reaction path, DFT calculations were undertaken. In the first step of the reaction, the acidic proton of the alcohol is transferred to the basic nitrogen atom of the amide ligand coordinated to the zinc ion. This leads to the alcoholysis of the Zn-N bond and the formation of an alcoholate derivative that starts the polymerization. In subsequent steps, the reaction follows the classical coordination-insertion mechanism.
Collapse
Affiliation(s)
- Salvatore Impemba
- Center for Colloid and Surface Science, Department of Chemistry, University of Florence, Via della Lastruccia, 3, 50019 Sesto Fiorentino, Firenze, Italy;
| | - Gabriele Manca
- CNR-ICCOM, Consiglio Nazionale delle Ricerche, Via Madonna del Piano, 10, 50019 Sesto Fiorentino, Firenze, Italy;
| | - Irene Tozio
- Department of Chemistry, University of Salerno, Via Giovanni Paolo II, 84084 Fisciano, Salerno, Italy;
| | - Stefano Milione
- Department of Chemistry, University of Salerno, Via Giovanni Paolo II, 84084 Fisciano, Salerno, Italy;
| |
Collapse
|
3
|
Chellali JE, Alverson AK, Robinson JR. Zinc Aryl/Alkyl β-diketiminates: Balancing Accessibility and Stability for High-Activity Ring-Opening Polymerization of rac-Lactide. ACS Catal 2022. [DOI: 10.1021/acscatal.2c00858] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Jonathan E. Chellali
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Alexander K. Alverson
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Jerome R. Robinson
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| |
Collapse
|
4
|
Yang X, Zhang W, Huang HY, Dai J, Wang MY, Fan HZ, Cai Z, Zhang Q, Zhu JB. Stereoselective Ring-Opening Polymerization of Lactones with a Fused Ring Leading to Semicrystalline Polyesters. Macromolecules 2022. [DOI: 10.1021/acs.macromol.1c02555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xing Yang
- National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
| | - Wei Zhang
- National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
| | - Hao-Yi Huang
- National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
| | - Jiang Dai
- National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
| | - Meng-Yuan Wang
- National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
| | - Hua-Zhong Fan
- National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
| | - Zhongzheng Cai
- National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
| | - Qi Zhang
- Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
| | - Jian-Bo Zhu
- National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu 610064, People’s Republic of China
| |
Collapse
|
5
|
Nie K, Wang C, Cheng X, Li J, Han Y, Yao Y. Unbridged bidentate aluminum complexes supported by diaroylhydrazone ligands: Synthesis, structure and catalysis in polymerization of
ε
‐caprolactone and lactides. Appl Organomet Chem 2020. [DOI: 10.1002/aoc.5627] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Kun Nie
- School of Chemistry and Chemical EngineeringTaishan University Taian 271000 China
| | - Changan Wang
- School of Chemistry and Chemical EngineeringTaishan University Taian 271000 China
| | - Xueli Cheng
- School of Chemistry and Chemical EngineeringTaishan University Taian 271000 China
| | - Jikun Li
- School of Chemistry and Chemical EngineeringTaishan University Taian 271000 China
| | - Yinfeng Han
- School of Chemistry and Chemical EngineeringTaishan University Taian 271000 China
| | - Yingming Yao
- College of Chemistry, Chemical Engineering and Materials ScienceSoochow University Suzhou 215123 China
| |
Collapse
|
6
|
Fang C, Ma H. Ring-opening polymerization of rac-lactide, copolymerization of rac-lactide and ε-caprolactone by zinc complexes bearing pyridyl-based tridentate amino-phenolate ligands. Eur Polym J 2019. [DOI: 10.1016/j.eurpolymj.2019.07.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
|
7
|
Webb D, Fulton JR. Utilising an anilido-imino ligand to stabilise zinc-phosphanide complexes: reactivity and fluorescent properties. Dalton Trans 2019; 48:8094-8105. [PMID: 31011730 DOI: 10.1039/c9dt00681h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A series of zinc complexes bearing the anilido-imino ligand [(o-C6H4{N(C6H3iPr2)}{C(CH3) = NC6H3iPr2})] [(LDipp)ZnX] has been generated. This includes two amide derivatives, [(LDipp)Zn(N{SiMe3}2)] and [(LDipp)Zn(NH{Dipp})] and two phosphanide derivatives, [(LDipp)ZnPCy2] and [(LDipp)ZnPPh2]. The chemistry of the phosphanide complexes towards chalcogens was examined, with sulfur, selenium and tellurium oxidising the phosphorus centre of the dicylohexylphosphanide complex [(LDipp)ZnPCy2] to form [(LDipp)Zn(E)2PCy2] (E = S, Se, Te). Addition of tellurium to the diphenylphosphanide complex [(LDipp)ZnPPh2] results in formation of Ph2PPPh2 and [(LDipp)ZnTeZn(LDipp)]. The absorption and emission properties of these complexes was examined and the quantum yields are highly dependent upon the non-ancillary ligand X.
Collapse
Affiliation(s)
- Dylan Webb
- School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, 6012, New Zealand.
| | | |
Collapse
|
8
|
Kokel A, Schäfer C, Török B. Organic Synthesis Using Environmentally Benign Acid Catalysis. Curr Org Synth 2019; 16:615-649. [PMID: 31984932 PMCID: PMC7432199 DOI: 10.2174/1570179416666190206141028] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 11/28/2018] [Accepted: 01/11/2019] [Indexed: 11/22/2022]
Abstract
Recent advances in the application of environmentally benign acid catalysts in organic synthesis are reviewed. The work includes three main parts; (i) description of environmentally benign acid catalysts, (ii) synthesis with heterogeneous and (iii) homogeneous catalysts. The first part provides a brief overview of acid catalysts, both solid acids (metal oxides, zeolites, clays, ion-exchange resins, metal-organic framework based catalysts) and those that are soluble in green solvents (water, alcohols) and at the same time could be regenerated after reactions (metal triflates, heteropoly acids, acidic organocatalysts etc.). The synthesis sections review a broad array of the most common and practical reactions such as Friedel-Crafts and related reactions (acylation, alkylations, hydroxyalkylations, halogenations, nitrations etc.), multicomponent reactions, rearrangements and ring transformations (cyclizations, ring opening). Both the heterogeneous and homogeneous catalytic synthesis parts include an overview of asymmetric acid catalysis with chiral Lewis and Brønsted acids. Although a broad array of catalytic processes are discussed, emphasis is placed on applications with commercially available catalysts as well as those of sustainable nature; thus individual examples are critically reviewed regarding their contribution to sustainable synthesis.
Collapse
Affiliation(s)
- Anne Kokel
- Department of Chemistry, University of Massachusetts Boston, 100 Morissey Blvd., Boston, MA02125, USA
| | - Christian Schäfer
- Department of Chemistry, University of Massachusetts Boston, 100 Morissey Blvd., Boston, MA02125, USA
| | - Béla Török
- Department of Chemistry, University of Massachusetts Boston, 100 Morissey Blvd., Boston, MA02125, USA
| |
Collapse
|