Zur Taktizität von Poly(α-methylstyrol), 4. Das 1H- und 13C-NMR-Spektrum des 1,3,3-Trimethyl-1-phenylbutyllithium

✍ Scribed by Wicke, Reinhard ;Elgert, Karl-Friedrich

• Publisher: Wiley (John Wiley & Sons)
• Year: 1977
• Weight: 461 KB
• Volume: 178
• Category: Article
• ISSN: 0025-116X
• DOI: 10.1002/macp.1977.021781110

✦ Synopsis

Abstract

The structure of 1,3,3‐trimethyl‐1‐phenylbutyllithium (1b), which is a model compound for the active chain end in the polymerisation of α‐methylstyrene with butyllithium, was investigated with ^1^H and ^13^C NMR spectroscopy. The carbon‐13 chemical shift of the αC‐atom in benzene and tetrahydrofuran as solvent suggests a substantial sp^2^ hybridisation. The rotation of the aromatic ring around the bond (C~6~H~5~)αC is hindered at room temperature. In benzene as solvent the carbon‐13 resonances of the αC‐atom and the aromatic C‐atoms are strongly broadened. This broadening, caused by exchange reactions or ^13^C‐^7^Li‐coupling, can be interpreted by an interaction of the lithium atom with the aromatic ring. This interpretation of the ^13^C NMR spectra leads to a structure, in which the lithium is not located at the αC‐atom but in the space over the bond (C~6~H~5~)αC.