Alkynes Alkynes or acetylenes are compounds that contain a carbon-carbon triple bond. E.g. H-C=C-H CHgCH2-C=C-H HgC-C=C-CH3 acetylene The triple bond results in a molecular formula of C H2n2 Ethane CH 0 elements of unsaturation Ethene CH 1 element of unsaturation Ethyne C2H2 2 elements of unsaturation The triple bond contributes two elements of unsaturation. Nomenclature of Alkynes IUPAC nomenclature is similar to that for alkenes,except the-ane ending is replaced with-yne. The chain is numbered from the end closest to the triple bond. CH, Br H-C=C-H CH,-C=C-H CH,-C=C-CH,CH,-CH-C=C-CH,-CH-CH, old IUPAC name: ethyne propyne 2-butyne 6-bromo-2-methyl-3-heptyne new IUPAC name: ethyne propyne but-2-yne 6-bromo-2-methylhept-3-yne Ch09 Alkynes (landscape) Page ICh09 Alkynes (landscape) Page 1 Alkynes Alkynes or acetylenes are compounds that contain a carbon–carbon triple bond. E.g. The triple bond results in a molecular formula of CnH2n-2 Ethane C2H6 0 elements of unsaturation Ethene C2H4 1 element of unsaturation Ethyne C2H2 2 elements of unsaturation The triple bond contributes two elements of unsaturation. Nomenclature of Alkynes IUPAC nomenclature is similar to that for alkenes, except the –ane ending is replaced with –yne. The chain is numbered from the end closest to the triple bond. H C C acetylene H CH3CH2 C C H H3C C C CH3