Liquid crystal compound having lactone ring, liquid crystal composition, and liquid crystal display device

Abstract

A nematic liquid crystal compound represented by any one of formulas (a-1) to (a-6): in formulas (a-1) to (a-6), Ra and Rb are each independently hydrogen or alkyl having 1 to 10 carbons, provided that in the alkyl, —CH2- may be replaced by —O—, —(CH2)2- may be replaced by —CH═CH—, and hydrogen may be replaced by a halogen; ring A1 and ring A2 are each independently trans-1,4-cyclohexylene or 1,4-phenylene, provided that in these rings hydrogen may be replaced by a halogen, and in the case where the ring is trans-1,4-cyclohexylene, —CH2- may be replaced by —O—, and —CH2CH— may be replaced by —CH═C—; and Z1 and Z2 are each independently a single bond, —COO—, —OCO—, —OCH2-, —CH2O— or —CH2CH2-, provided that in formula (a-3), in the case where ring A2 is trans-1,4-cyclohexylene, Z2 is a single bond, —COO—, —OCO—, —OCH2- or —CH2O—, in the case where Ra is —C3H7, Rb is —OC2H5, and Z2 is a single bond, ring A2 is trans-1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 2-fluoro- 1,4-phenylene, 3-fluoro-1,4-phenylene, 2-fluoro-3-chloro-1,4-phenylene, 2-chloro- 3-fluoro-3,4-phenylene or 2,3-dichloro-1,4-phenylene, and in formula (a-4), in the case where ring A1 is trans-1,4-cyclohexylene, Z1 is a single bond, —COO—, —OCO—, —OCH2- or —CH2O—.