4′-octyl-4- biphenylcarbonitrile (8CB) is a low molar mass liquid crystal (LCs), which shows different liquid crystalline phases depending on temperature conditions. Under normal temperature conditions 8CB exists only as bulk smectic-A phase. LCs are responsive to minor changes in temperature, shear, electric (or magnetic) fields, and the structure of solid surfaces with which they are in contact.
GENERAL STEPS: 4'-hydroxybiphenyl-4-carbonitrile (20.0 g, 0.1 mol), potassium carbonate (28.0 g, 0.2 mol) and N,N-dimethylformamide (600 mL) were added sequentially in a 1000 mL three-necked flask with magnetic stirring turned on. Subsequently, 1-bromooctane (23.0 g, 0.12 mol) was slowly added dropwise, and the reaction system was warmed to 120 °C and kept for 48 hours. Upon completion of the reaction, the mixture was cooled to room temperature, slowly poured into ice water (1000 mL) and allowed to stand overnight. The precipitated solid product was collected by filtration and purified by recrystallization with ethanol to afford the target compound 4'-octyloxy-[1,1'-biphenyl]-4-carbonitrile.
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