Abstract: The present invention provides a nematic liquid crystal composition using a 4,6-difluoroindane-based compound that has a low lower limit temperature (T?N) of the liquid crystal phase, high upper limit temperature (TN-I) of the liquid crystal phase, and wide liquid crystal phase temperature range without impairing response speed, threshold voltage and other liquid crystal characteristics within a the range of the optimal ?n as a nematic liquid crystal, and a 4,6-difluoroindane-based compound that is used in said liquid crystal composition. The nematic liquid crystal composition contains at least one type of compound having a 4,6-difluoroindan-2,5-diyl group, and the refractive index anisotropy is within the range of 0.08 to 0.15, the liquid crystal phase upper limit temperature is 70° C. or higher, the liquid crystal phase lower limit temperature is ?20° C. or lower, and the difference between the liquid crystal phase upper limit temperature and liquid crystal phase lower limit temperature is 90° C. or more.

Abstract: A tetrahydronaphthalene derivative represented by the general formula (I) and a liquid crystal composition containing the same. A compound represented by the general formula (I) shows superior liquid crystallinity and co-solubility with conventional liquid crystal compounds and compositions. Furthermore, addition of such a compound enables the threshold voltage to be significantly reduced with almost no deleterious effect on the responsiveness. In addition, a compound of the present invention can also be easily produced industrially, is colorless, and is chemically stable. Consequently, liquid crystal compositions containing such a compound are extremely useful as liquid crystals, and are particularly suitable for liquid crystal displays requiring a wide operating temperature range, low voltage driving and a high response speed.

Abstract: An optically active lactone derivative represented by the following general formula (I): ##STR1## wherein R.sup.1 represents a straight-chain or branched alkyl, alkoxyl, alkanoyloxy, alkoxycarbonyl, alkoxyalkyl, alkoxyalkanoyloxy, or alkoxyalkoxyl group having 1 to 20 carbon atoms or an optically active group of each of the above kinds, R.sup.2 represents a straight-chain or branched alkyl group having 1 to 20 carbon atoms, ##STR2## or trans-1,4-cyclohexylene group of the formula and the asymmetric carbon atoms at the 2- and 4-positions in the lactone ring each independently is of the (S) or (R) configuration, an intermediate therefor, a process for producing the intermediate, a liquid-crystal composition, and a liquid-crystal display device.