Ethylene → Ethylene methyl 4-pentenoate

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Reaction Steps

A 25-mg (0.029-mmol) sample of {[(2,6-i-PrPh)2DABMe2 ]PdCH2CH2 (O)CH3 }SbF6- was magnetically stirred under 55.2 kPa of ethylene in a 50-mL Schlenk flask with 20 mL of dry methylene chloride and 5 mL (4.5 g; 39 mmol) of methyl 4-pentenoate for 40 hr at room temperature. The yellow solution was rotary evaporated to yield 3.41 g of ethylene/methyl 4-pentenoate copolymer as a yellow oil. The infrared spectrum of the copolymer showed a strong ester carbonyl absorbance at 1750 cm-1. 1H NMR analysis (CDCl3): 84 methyl carbons per 1000 methylene carbons. Comparison of the integrals of the ester methoxy (3.67 ppm and ester methylene (CH2COOMe; 2.30 ppm) peaks with the integrals of the carbon chain methyls (0.8-0.9 ppm) and methylenes (1.2-1.3 ppm) indicated a methyl 4-pentenoate content of 6 mol % (20 wt %). This yield and composition represent about 3400 ethylene turnovers and 200 methyl 4-pentenoate turnovers. 13C NMR quantitative analysis: branching per 1000 CH2 : total Methyls (93.3), Methyl (37.7), Ethyl (18.7), Propyl (2), Butyl (8.6), ≥Am and end of chains (26.6), ≥Bu and end of chains (34.8); ester-bearing branches --CH(CH2)nCO2CH3 as a % of total ester: n≥5 (38.9), n=4 (8.3), n=1,2,3 (46.8), n=0 (6); chemical shifts were referenced to the solvent: chloroform-d1 (77 ppm). Gel permeation chromatography (tetrahydrofuran, 30° C., polymethylmethacrylate reference, results calculated as polymethylmethacrylate using universal calibration theory): M2 =32,400; Mw =52,500; Mw /Mn =1.62.

Provenance & Evidence