We have found that 4-[trans-4-alkylcyclohexyl]benzoni-triles ( 4 ) form nematic phases with higher clearing points and wider temperature intervals than those of the industrially important 4-alkylbiphenyl-4-carbonitrilesrt1. This means that the effect of a short-range orderr2] of steric origin on the stability of nematic phases must be much greater than hitherto assumed. H -1 J. R Compounds ( 4 a ) to ( 4 e ) (Table 1) are obtained as follows:The cisltrans isomeric 4-alkyl-1 -phenylcyclohexanols (2) and (2') formed in approximately equal amounts on reaction of 4-alkylcyclohexanone (I) with phenylmagnesium bromide in diethyl ether are separated on a column packed with silica gel (Kieselgel 60, Merck). Light petroleum (boiling range 50 to 70°C) containing an amount of diethyl ether increasing up to 15 vol-"/;:, was used as solvent. (2) is hydrogenated with retention over Raney nickel in ethanol, and (2') with inversion over palladium/activated charcoal (10 % Pd) in ethanol. The nitrile group is introduced into the common product (3) in known manner (Friedel-Crafts acetylation, haloform reaction to give the carboxylic acid, conversion into the amide, and dehydration with P0Cl3).The structures of the products ( 4 a ) to ( 4 e ) are in accord with the results ofelemental analysis and the IR and I3C-NMR spectra. Since the formation of a nematic phase requires an elongated molecular shapeL31, compound ( 4 ) probably exists in the equatorial trans form. Table I . Properties of compounds (4). R Yield [a] M.p. Clearing ["/.I YC] point I"CJ[a] Based on amount of ( 1 ) weighed in.[b] (4e) has a smectic-nematic transition at 17°CCompounds ( 4 ) have viscosities of about 20 CP at 20°C. These low values are advantageous for their application in electro-optical devices. The absorption maxima at 235 nm suggest use of eutectic mixtures as solvents in the study of anisotropic molecular properties. The optical anisotropy lies between 0.12 and 0.13, and the D C anisotropy is around + 10. We report here on a new method, extensively tested by us['', for the assignment of the configuration of di-and trialkyl-substituted olefins, diols, and epoxides, as well as for
Approximately 5 % of all organic compounds are transformed at their melting point into liquid crystals-thermodynamically stable, anisotropic liquids which in contrast to isotropic melts appear turbid and are also known as mesophases. Such melts are classed as smectic, nematic, and cholesteric liquid crystalline phases, depending upon the arrangement of the constituent molecules. The discovery of numerous potential applications during the past ten years has awakened the study of liquid crystals from its former slumber as a physical curiosity and placed it in the limelight of the scientific stage. Uses in display systems for measured values and for computer and process data, as well as for remote controlled timetables, for windows of variable light-transmission, etc., appear particularly promising. Not only black-and-white contrasts are now possible but also color production.
Intramolecularly stabilized four‐coordinated organoaluminium, ‐gallium, and‐indium compounds R2MC6H4CH2NR'2‐(2) (1–7), Me2MCH2C6H4NMe2‐(2) (8, 9), Me2MCH2C6H4CH2‐NMe2‐(2) (10, 11), and Me2GaC6H4NMe2 (12) have been synthesized from O ‐[(dialkylamino)methyl]phenyllithium, [O ‐(dimethylamino)phenyl]methyllithium, {O ‐[(dimethylamino)methyl]phenyl}methyllithium and O ‐(dimethylamino)phenyllithium, respectively. The 1H‐, 13CNMR, and mass spectra of the new compounds and the X‐ray crystal structures of 2 and 7 are reported and discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.