When additional functional groups are present,the suffixes are combined. H,C-C-C=C-CH, CH,一CH-C=C-H CH,=CH一CH2一C=CH CH, OH old IUPAC name: 2-methyl-I-penten-3-yne 3-butyn-2-ol 1-penten-4-yne new IUPAC name: 2-methylpent-1-en-3-yne but-3-yn-2-ol pent-1-en-4-yne 2013 Pearson Education,Inc Terminal and Internal Alkynes The position of the triple bond can alter the reactivity of the alkyne. Compounds with triple bonds at the end of a molecule are called terminal alkynes.(Terminal C-H groups are called acetylenic hydrogens). acetylenic hydrogen (no acetylenic hydrogen) HC=C一CH,CH CH3一C=C一CH3 but-1-yne,a terminal alkyne but-2-yne,an internal alkyne If the triple bond is flanked by alkyl groups on both sides it is an internal alkyne. Ch09 Alkynes (landscape) Page 2 Ch09 Alkynes (landscape) Page 2 When additional functional groups are present, the suffixes are combined. Terminal and Internal Alkynes The position of the triple bond can alter the reactivity of the alkyne. Compounds with triple bonds at the end of a molecule are called terminal alkynes. (Terminal C-H groups are called acetylenic hydrogens). If the triple bond is flanked by alkyl groups on both sides it is an internal alkyne