20139-92-8Relevant academic research and scientific papers
Electrostatic Control of Regioselectivity in Competing Biomolecular Eliminations
Grubbs, Edward J.,Schmidt, Stephen P.,Wang, Charles T.,Chen, Zhangping,Hamed, Ashraf A.,et al.
, p. 2886 - 2892 (1985)
The isomeric trans-11,12-dichloro-9,10-dihydro-9,10-ethano-1-anthroic acids (1 and 2) have been prepared and characterized.Base-induced dehydrochlorinations of these and the corresponding cis-dichloroethano derivatives 3 and 4 were conducted under several sets of base/solvent conditions.Preparations and dehydrochlorinations of 2-ethanoic acid (15) and the corresponding cis-dichloro isomer 16 are also reported.Regioselectivities in vinyl halide formations are highest with K+O--t-Bu/t-BuOH/18 crown-6, conditions under which ion aggregation is minimized.The results of these studies indicate that both the syn and quasi-anti eliminations possess some carbanionic character but with most of the charge remaining on the attacking base in the transition states.
Factors influencing orientations of covalently-attached and doped aromatic groups in stretched polyethylene films
Wang, Caihua,Xu, Jinqi,Weiss, Richard G.
, p. 7015 - 7025 (2007/10/03)
Linear polarizations have been measured for covalently attached and doped 9-anthryl and 1-pyrenyl groups residing in interior sites of stretched polyolefinic films. The influences of polymer crystallinity, the concentration of aromatic groups and the length of the substituents attached to doped molecules or of the tethers to polymer chains of covalently attached species on the degree of polarization have been explored. The results demonstrate the utility of comparing orientational parameters from doped and covalently attached groups in analyzing the factors responsible for stretch-induced orientation. The anthryl and pyrenyl groups prefer to reside in interfacial regions more than amorphous regions even before film stretching, and the specificity of their orientations is determined by the nature of interactions with surrounding polymer chains. The magnitudes of orientation factors are dependent on polymer crystallinity and substituent or tether length, but are independent of aromatic group concentrations as long as they are low. There are significant differences between the orientations of doped and covalently attached groups of the same type due to the inability of the latter to translocate between site types during film stretching. The results, as interpreted in the context of current theories, demonstrate the necessity of crystallite surfaces (i.e., interfacial sites), but not stretching-induced translocation, for selective orientation of aromatic groups along the axis of stretching.
