Iodoform can be prepared from all except:

Iodoform test is given by compounds having a methyl keto group (${\text{CH}}_3\text{CO-}$) or a methyl carbinol group (${\text{CH}}_3\text{CH(OH)-}$).Ethyl methyl ketone: ${\text{CH}}_3{\text{COCH}}_2{\text{CH}}_3$ (Has ${\text{CH}}_3\text{CO-}$) - Positive.Isopropyl alcohol: ${\text{CH}}_3{\text{CH(OH)CH}}_3$ (Has ${\text{CH}}_3\text{CH(OH)-}$) - Positive.3-Methyl-2-butanone: ${\text{CH}}_3{\text{COCH(CH}}_3{\text{)}}_2$ (Has ${\text{CH}}_3\text{CO-}$) - Positive.Isobutyl alcohol: $({\text{CH}}_3{\text{)}}_2{\text{CHCH}}_2\text{OH}$ (Primary alcohol, lacks ${\text{CH}}_3\text{CH(OH)-}$) - Negative.