Unsaturated Alcohols Hydroxyl group takes precedence.Assign that carbon the lowest number. Use alkene or alkyne name. OH CH2-CHCH2CHCH3 4-penten-2-ol (old) pent-4-ene-2-ol (1997 revision of IUPAC rules) => Chapter 10 7Chapter 10 7 Unsaturated Alcohols • Hydroxyl group takes precedence. Assign that carbon the lowest number. • Use alkene or alkyne name. 4-penten-2-ol (old) pent-4-ene-2-ol (1997 revision of IUPAC rules) => CH2 CHCH2 CHCH3 OH