Tolan derivative and a liquid crystal mixture containing the same

Abstract

A novel tolan derivative compound as a liquid crystal substance having a low viscosity and a good compatibility with existing liquid crystals at low temperatures in addition to a large optical anisotropy value and a high clearing point, and a liquid crystal mixture containing the above compound are provided, which compound is expressed by the formula ##STR1## wherein R 1 represents an alkyl group of 1 to 10 carbon atoms, R 2 represents an alkyl group of 1 to 10 carbon atoms, X represents --CH 2 CH 2 -- and A represents an H atom or an F atom.

What we claim is: 
     
       1. A tolan derivative compound expressed by the formula ##STR14## wherein R 1  represents an alkyl group of 1 to 10 carbon atoms, R 2  represents an alkyl group of 1 to 10 carbon atoms, X represents --CH 2  CH 2  -- and A represents an H atom or an F atom. 
     
     
       2. A tolan derivative compound according to claim 1 wherein A represents H. 
     
     
       3. A tolan derivative compound according to claim 1 wherein said X represents --CH 2  CH 2  -- and said A represents F. 
     
     
       4. A liquid crystal mixture comprising at least two components at least one of which is a tolan derivative compound expressed by the formula ##STR15## wherein R 1  represents an alkyl group of 1 to 10 carbon atoms, R 2  represents an alkyl group of 1 to 10 carbon atoms, X represents --CH 2  CH 2  -- and A represents an H atom or an F atom. .Iadd. 
     
     
       5.  A tolan derivative compound expressed by the formula ##STR16##.Iaddend. wherein each of R 1  and R 2  independently represents an alkyl group of 2 to 5 carbon atoms.  .Iadd. 
     
     
       6.  A tolan derivative compound according to claim 5 wherein R 1  and R 2  are the same. .Iaddend. .Iadd.7. A tolan derivative compound according to claim 5 wherein R 1  and R 2  each comprise an ethyl group. .Iaddend. .Iadd.8. A tolan derivative compound according to claim 5 wherein R 1  and R 2  each comprise a propyl group. .Iaddend. .Iadd.9. A tolan derivative compound according to claim 5 wherein R 1  comprises an ethyl group and R 2  comprises a propyl group. .Iaddend. .Iadd.10. A tolan derivative compound according to claim 5 wherein R 1  comprises an ethyl group and R 2  comprises a butyl group. .Iaddend. .Iadd.11. A tolan derivative compound according to claim 5 wherein R 1  comprises a propyl group and R 2  comprises an ethyl group. .Iaddend. .Iadd.12. A tolan derivative compound according to claim 5 wherein R 1  comprises a propyl group and R 2  comprises a butyl group. .Iaddend. 
     
     
        .Iadd.13.  A liquid crystal mixture comprising at least two components, at least one of which is a tolan derivative compound expressed by the formula ##STR17##.Iaddend. wherein each of R 1  and R 2  independently represents an 
     
     
        alkyl group of 2 to 5 carbon atoms.  .Iadd.14.  A liquid crystal mixture according to claim 13 wherein R 1  and R 2  are the same. .Iaddend. .Iadd.15. A liquid crystal mixture according to claim 13 wherein R 1  and R 2  each comprise an ethyl group. .Iaddend. .Iadd.16. A liquid crystal mixture according to claim 13 wherein R 1  and R 2  each comprise a propyl group. .Iaddend. .Iadd.17. A liquid crystal mixture according to claim 13 wherein R 1  comprises an ethyl group and R 2  comprises a propyl group. .Iaddend. .Iadd.18. A liquid crystal mixture according to claim 13 wherein R 1  comprises an ethyl group and R 2  comprises a butyl group. .Iaddend. .Iadd.19. A liquid crystal mixture according to claim 13 wherein R 1  comprises a propyl group and R 2  comprises an ethyl group. .Iaddend. .Iadd.20. A liquid crystal mixture according to claim 13 wherein R 1  comprises a propyl group and R 2  comprises a butyl group. .Iaddend.