new derivatives of phenic acid, method of obtaining them, liquid crystal material with a negative dielectric anisotropy, method of obtaining that liquid crystal material, liquid crystal material with low frequency inversion of sign of dielectric anisotropy and method of obtaining that liquid crystal mate rial

摘要

New derivatives of phenic acid of general formula (1) where R and R1 are identical or different and are each an alkyl containing 1 to 9 carbon atoms; O is an atom of oxygen; m and n have the same or different values and are equal to 0 or 1; X is a simple bond (FORMULA) where y is NO2 or a CN group, or X is (FORMULA) where Y is hydrogen; it being excluded that R=R1=CH3 C4H9. Are described as well a method of obtaining said derivatives of phenic acid, a liquid crystal material with negative dielectric anisotropy containing said new derivatives of phenic acid of the general formula (1) and a method of obtaining that liquid crystal material; a liquid crystal material with low-frequency inversion of the sign of its dielectric anisotropy containing said new derivatives of phenic acid of the general formula (1) and a method of obtaining that liquid crystal material. The general formula (1) is: