Organic Chemistry - Identification of Functional Groups

Alkane, Alkyl Benzene

Br2/CH2CL2 in light

Positive Result: Discoloration

Alkenes, Alkynes

Br2/CH2CL2 in dark // Positive Result: discoloration

Cold, dilute neutral KMnO4 (Baeyer’s test) // Positive Result: loss of purple color, brown ppt

Primary and Secondary Alcohols, Aldehydes and Phenols

hot acidic KMnO4

Positive Result: loss pf purple color, brown ppt

Aldehydes and Phenols

Ag(NH3) or Tollen’s test

Positive Result: Silver mirror

Terminal Alkynes

Ag(NH3) (test for terminal alkynes)

Positive Result: gray ppt

Aldehydes and Ketones

2,4-DNP (test for carbonyl compounds)

Positive Result: yellow to orange ppt

methyl ketones and secondary methyl alcohols

I2/KI, NaOH (Iodoform Test)

positive result: yellow ppt

Carbohydrates

alpha naphthol in ethanol, H2SO4 (Molisch Test)

positive: purple interface

Reducing Sugars

Cu(OH)2 in sodium citrate (Benedict’s test)

positive: brick red ppt

Phenylhydrazine in HCl (Osazone test)

positive: yellow crystals

Proteins, peptide chains with at least 3 amino acids

CuSO4, NaOH (Biuret Test)

Positive: violet complex

alpha amino acids and peptides

ninhydrin (ninhydrin test)

positive result: violet compound

S-containing amino acids and proteins

Pb(CH3COOH)2, NaOH (Lead acetate test)

Positive result: black ppt

Phenols

FeCl3 (test for phenols)

positive result: purple complex