26567-11-3

Upstream product

• 108-68-9 3,5-Dimethylphenol 
• 4746-77-4 2,2',6,6'-tetramethyl-[1,1'-biphenyl]-4,4'-diamine 

Relevant academic research and scientific papers

Ferroelectric liquid crystals induced by atropisomeric dopants: Dependence of the polarization power on the core structure of the smectic C host

A series of 11 chiral dopants with an atropisomeric core derived from 4,4′-dihydroxy-2,2′,6,6′-tetramethyl-3,3′- dinitrobiphenyl were synthesized in optically pure form. These compounds were doped into five different smectic C (SC) liquid crystal hosts to induce a ferroelectric SC* liquid crystal phase, and the reduced polarization Po was measured as a function of the dopant mole fraction xd over the range 0.005 d ≤ 0.05. The polarization power δp was found to strongly depend on the core structure of the SC host. For example, the dopant (+)-2,2′,6,6′-tetramethyl-3,3′-dinitro-4,4′-bis[(4- octyloxybenzoyl)oxy]biphenyl gave δp values of 2 in a phenyl benzoate SC host and 1738 nC/cm2 in a phenylpyrimidine SC host; the latter is one of the highest polarization power values reported thus far in the literature. In the phenylpyrimidine SC host, the polarization power was found to depend on the length of the dopant side chains and on the position of the atropisomeric core with respect to those of the surrounding SC host molecules, on the time average. The polarization power followed a trend opposite to that followed by the SC* helical pitch. Analysis of these results suggests that chirality transfer from the atropisomeric core of the dopant to those of the Sc host molecules plays a key role in amplifying the polarization induced in the phenylpyrimidine host. It is likely that such intercore chirality transfer results in an asymmetric distortion of the SC* lattice, which in turn, further increases the conformational asymmetry of the chiral dopant by virtue of increased diastereomeric bias between the SC* lattice and the chiral conformations of the dopant.

Enhanced polar ordering in ferroelectric liquid crystals induced by atropisomeric dopants

The spontaneous polarization of a SC* liquid crystal phase induced by atropisomeric dopants with large transverse molecular dipoles exhibits a very strong dependence on the nature of the Sc liquid crystal host.

Oxidativ Coupling of Phenols. Part 6. A Study of the Role of Spin Density Factors on the Product Composition in the Oxidations of 3,5-Dimethylphenol and Phenol

Oxidations of both 3,5-dimethyphenol and phenol with di-t-butyl peroxide at 140 degC gave as the major product the ortho-ortho-C-C coupled dimer, while oxidations with di-t-butyl peroxyoxalate at room temperature give much more of the ortho-para-C-C dimer.The results are not consistent either with the spin density distribution in the phenoxyl radical intermediates or with steric effects being the major factor which determines the product composition.It is proposed that the two phenoxyl radicals involved in coupling preferentially approach each other in a 'sandwich like' manner with the oxigens in a 1,3-relationship.

THE ROLE OF STEREOELECTRONIC FACTORS IN THE OXIDATION OF PHENOLS

The oxidative coupling of both 3,5-dimethylphenol and phenol leads to the ortho-ortho and ortho-para coupled products as the predominant C-C dimers: stereoelectronic factors determine the preferred mode of approach of the phenoxyl radicals.