arylalkyne

An arylalkyne is an alkyne compound in which one or more of the alkyne carbons bears an aryl substituent. The simplest example is phenylacetylene (phenyl–C≡C–H), a terminal arylalkyne. Internal arylalkynes include diaryl acetylenes such as diphenylacetylene (Ph–C≡C–Ph) and aryl–alkyl variants (Ar–C≡C–R). The presence of an aryl group commonly extends the π-conjugation of the system and influences reactivity and physical properties.

Classification among arylalkynes can be by substitution pattern. Terminal arylalkynes have a hydrogen on one alkyne carbon and an aryl group on the other (Ar–C≡C–H). Internal arylalkynes substitute both alkyne carbons with aryl or other carbon groups (Ar–C≡C–Ar′ or R–C≡C–Ar). The aryl substituents often stabilize negative charge developed during reactions and can direct regioselectivity in metal-catalyzed processes.

Synthesis of arylalkynes is dominated by transition-metal-catalyzed coupling methods. The Sonogashira reaction—coupling a terminal alkyne with an aryl or vinyl halide under Pd/Cu catalysis—is widely used to form Ar–C≡C–R linkages. Other approaches include direct C–H alkynylation of arenes and cross-coupling of alkynyl derivatives with aryl partners. Dehydrohalogenation of haloalkynes and coupling of diaryl chlorides are also employed in some contexts.

Applications of arylalkynes span materials science and synthesis. They serve as building blocks for conjugated polymers and organic electronic materials, including dyes and light-emitting technologies. Their persistent π-system makes them versatile intermediates in further cross-coupling and cyclization reactions.