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Kristallstruktur und Gasphasenuntersuchungen von lithiiertem Acetessigsäure‐ tert ‐butylester
Author(s) -
Waldmüller Delia,
Mayer Bernhard,
Braun Manfred,
Hanuschik Andreas,
Krüger Carl,
Guenot Pierre
Publication year - 1992
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19921251225
Subject(s) - chemistry , ethyl acetoacetate , lithium (medication) , moiety , deprotonation , medicinal chemistry , toluene , thermal stability , mass spectrum , crystal structure , crystallography , stereochemistry , organic chemistry , ion , catalysis , medicine , endocrinology
Crystal Structure and Gas–Phase Investigations of Lithiated tert ‐Butyl Acetoacetate The lithium enolate 2 , generated either by deprotonation of tert ‐butyl acetoacetate ( 1 ) or by pyrolysis of lithiated tert ‐butyl acetate ( 3 ) is crystallized from toluene. The X–ray diffraction analysis of unsolvatized 2 reveals a hexameric structure. Thereby, the central skeleton is formed by two Li–O six–membered rings, and the carbonyl group of the ester moiety serves to complete the fourfold coordination of the lithium atom. The thermal stability of 2 enables the very first mass spectrometric and photoelectron spectroscopic investigation of a lithium enolate. The lithium compound 2 forms aggregates even in the gas phase. The first vertical ionization energy of 2 is found to be significantly lower than those observed in the photoelectron spectra of both the enol ether 5 and the ester 1 .