Butanol is a higher alcohol with a 4 carbon atoms and a general formula of C₄H₁₀O. There are 4 different isomeric structures for butanol:

butan-1-ol         CH3-CH2-CH2-CH2-OH

butan-2-ol         CH3-CH2-CH(OH)-CH3

sec-butanol        CH3-CH-CH3
                       |
                       CH2OH

                      OH
                      |
tert-butanol      CH3-C-CH3
                      |
                      CH3

These butanol isomers, due to their different structures, have somewhat different melting and boiling points. All are moderately miscible in water and used as a base for perfumes. Like most alcohols, they are poisonous.