13C NMR chemical shifts of polyisobutylene end groups and related model compounds

Thermally induced polymerization of isobutylene in the presence of SnCl4: Kinetic study of the polymerization and NMR structural investigation of low molecular weight products

“…13 C NMR spectra of samples 1 and 2 are in Figure 8. Here, the pairs of lines at 114.45 ppm (CH 2 ) and 143.8 ppm (quaternary carbon), and at 128.0 ppm (quaternary carbon) and 135.55 ppm (CH) correspond to the terminal structures A and B, respectively 33, 38, 39–41. As was shown in our previous study,33 the pair of weak lines observed in sample 1 at 122.8 ppm (CH) and 133.8 ppm (quaternary carbon) corresponds to terminal structure C. This conclusion was confirmed by other studies 39, 40.…”

Addition Reaction of Living Polyisobutylene to “Double” Diphenylethylenes. Synthesis of 1,1-Diphenylethylene-Functionalized Polyisobutylene Macromonomers

“…As shown in Figure , resonance signals corresponding to PIB-Cl are not observed from both 1 H and 13 C NMR spectra of the PIB-DPE macromonomer. For example, the 13 C NMR spectrum of PIB-Cl exhibits characteristic resonance signals at δ = 71.9 and 35.6 ppm for the quaternary carbon attached to the terminal chloro group (−CH 2 C (CH 3 ) 2 Cl) and geminal methyl carbons of this quaternary carbon (−CH 2 C( C H 3 ) 2 Cl), respectively .…”

Synthesis and characterization of carboxylic acid‐terminated polyisobutylenes

“…Thus difunctional tert-chloride-terminated PIB (Sample 1, M n ¼ 6700 g/mol) was nonregiospecifically dehydrochlorinated by passing through a packed bed of basic alumina. 13 C NMR confirmed the formation of a mixture of endo (1) and exo (2) olefins at the chain ends 30 (Fig. 1).…”

“…6, inset). 30,34 It has been shown that a small amount of endo olefin is always produced when dehydrochlorination is carried out by the tert-butoxide method. 35 Both the 1 H and 13 C spectra of Sample 2 showed additional resonances in the olefinic region indicating a significant fraction of anomalous chain-end structures, primarily chain ends resulting from a cumyl initiating site that added only one IB unit (single-unit chain).…”