| 摘要 |
NEW MATERIAL:A compound shown by formula I (R is 1-20 C straight-chain alkyl; R' is 1-5C straight-chain alkyl; m and n are 0 or 1; * is asymmetric carbon atom). EXAMPLE:A compound shown by formula V. USE:Since addition of a small amount of the titled compound to an ordinary nematic liquid crystal composition prepares a chiral nematic liquid crystal composition having a short spiral pitch, the compound is useful as an electro- optical display material effective for producing SBE element having especially improved high time sharing properties. PREPARATION:A compound shown by formula II is reacted with a halogenating agent such as thionyl chloride, etc., at normal pressure at reflux temperature of the reaction mixture to give a compound shown by formula III (X is halogen, preferably Cl) and then this compound is reacted with a compound shown by formula IV in an inert organic solvent such as toluene, etc., in the presence of a basic substance such as preferably pyridine, etc., at normal pressure, and normal temperature - the reflux temperature of the reaction mixture to give a compound shown by formula I.
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