Organic thermotropic nematic compounds

Abstract

A new family of organic thermotropic nematic compounds comprising N-(para-substituted alkoxy-benzylidene)-anilines having also a para-n-butyl substituent on the aniline ring. These compounds have the following structural formula: ##STR1## wherein R is a straight chain alkyl group containing 1 to 4 carbon atoms and R' is n-butyl. Synthesis involves combining the desired p-substituted benzaldehyde and p-n-butyl aniline in equimolar proportions in anhydrous ethyl alcohol with glacial acetic acid as catalyst. The resulting homologous series of compounds are useful as materials which undergo a change in optical properties under the influence of externally applied energy, preferred members of which, either individually or in binary mixtures, have melting points near room temperature, a broad nematic mesomorphic temperature range within an overall range of about 0° to about 70° C., low viscosity in the nematic phase, good stability, and substantially no color.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. N-(p-methoxybenzylidene)-p-n-butyl aniline. 
     
     
       2. N-(p-ethoxybenzylidene)-p-n-butyl aniline. 
     
     
       3. N-(p-n-propoxybenzylidene)-p-butyl aniline. 
     
     
       4. N-(p-n-butoxybenzylidene)-p-n-butyl aniline. .Iadd. 5. In a visual display device which incorporates a thermotropic nematic compound for converting energy input into visual form, the improvement which comprises using N-(p-methoxybenzylidene)-p-n-butyl aniline as the nematic compound, whereby the display is effective throughout a wide temperature range. .Iaddend..Iadd. 6. In a visual display device which incorporates a thermotropic nematic compound for converting energy input into visual form, the improvement which comprises using N-(p-ethoxybenzylidene)-p-n-butyl aniline as the nematic compound, whereby the display is effective through a wide temperature range. .Iaddend..Iadd. 7. In a visual display device which incorporates a thermotropic nematic compound for converting energy input into visual form, the improvement which comprises using N-(p-n-propoxybenzylidene)-p-n-butyl aniline as the nematic compound, whereby the display is effective throughout a wide temperature range. .Iaddend..Iadd. 8. In a visual display device which incorporates a thermotropic nematic compound for converting energy input into visual form, the improvement which comprises using N-(p-n-butoxybenzylidene)-p-n-butyl aniline as the nematic compound, whereby the display is effective throughout a wide temperature range.