Chemoselective Polymerization of Polar Divinyl Monomers with Rare-Earth/Phosphine Lewis Pairs

Pengfei Xu; Lei Wu; Liqiu Dong; Xin Xu

doi:10.3390/molecules23020360

Chemoselective Polymerization of Polar Divinyl Monomers with Rare-Earth/Phosphine Lewis Pairs

Molecules. 2018 Feb 8;23(2):360. doi: 10.3390/molecules23020360.

Authors

Pengfei Xu¹, Lei Wu², Liqiu Dong^{3

4}, Xin Xu⁵

Affiliations

¹ Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China. 20164009015@stu.suda.edu.cn.
² Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China. 1509401010@stu.suda.edu.cn.
³ Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China. dongliqiufrank@gmail.com.
⁴ Suzhou International Academy, BFSU, Suzhou 215200, China. dongliqiufrank@gmail.com.
⁵ Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China. xinxu@suda.edu.cn.

Abstract

This work reports the chemoselective polymerization of polar divinyl monomers, including allyl methacrylate (AMA), vinyl methacrylate (VMA), and 4-vinylbenzyl methacrylate (VBMA), by using simple Lewis pairs comprised of homoleptic rare-earth (RE) aryloxide complexes RE(OAr)₃ (RE = Sc (1), Y (2), Sm (3), La (4), Ar = 2,6-tBu₂C₆H₃) and phosphines PR₃ (R = Ph, Cy, Et, Me). Catalytic activities of polymerizations relied heavily upon the cooperation of Lewis acid and Lewis base components. The produced polymers were soluble in common organic solvents and often had a narrow molecular weight distribution. A highly syndiotactic poly(allyl methacrylate) (PAMA) with rr ~88% could be obtained by the scandium complex 1/PEt₃ pair at -30 °C. In the case of poly(4-vinylbenzyl methacrylate) (PVBMA), it could be post-functionalized with PhCH₂SH. Mechanistic study, including the isolation of the zwitterionic active species and the end-group analysis, revealed that the frustrated Lewis pair (FLP)-type addition was the initiating step in the polymerization.

Keywords: Lewis pairs; chemoselective polymerization; phosphines; rare-earth.

MeSH terms

Butadienes / chemistry*
Lewis Acids / chemistry*
Lewis Bases / chemistry*
Metals, Rare Earth / chemistry*
Models, Molecular
Molecular Structure
Phosphines / chemistry*
Polymerization*

Substances

Butadienes
Lewis Acids
Lewis Bases
Metals, Rare Earth
Phosphines
phosphine
1,3-butadiene