terphenyl

Terphenyl is the common name for three isomeric polycyclic aromatic hydrocarbons that consist of three benzene rings connected in a linear arrangement by carbon–carbon single bonds. The three isomers—ortho-terphenyl, meta-terphenyl, and para-terphenyl—differ in the orientation of the outer rings relative to the central ring. All three share the molecular formula C18H14.

Terphenyls are generally colorless solids at room temperature with high melting points. They are nonpolar, sparingly soluble in water, and more soluble in organic solvents such as benzene, toluene, and chlorinated solvents. The planar, highly conjugated structure promotes strong pi–pi interactions in the solid state.

Terphenyls are produced mainly by synthetic routes, including cross-coupling of aryl fragments. They are not common natural products; occurrences are primarily as synthetic intermediates or impurities in related hydrocarbon streams.

Terphenyls and their derivatives are used as building blocks in organic synthesis and as model compounds for studying pi-conjugated systems. They find use in liquid-crystal materials, organic electronics, and as components in various luminescent materials; derivatives are investigated for optoelectronic properties.

Terphenyls should be handled with standard laboratory practices for aromatic hydrocarbons, including proper ventilation and personal protective equipment. They are generally of low acute toxicity but may cause irritation; consult material safety data sheets for specific derivatives.