TOP

Summary of Qualitative Analysis of Organic

Must learn these.
 This is qualitative analysis.
 Testing Phenol: Phenols acidic so can be tested using pH indicator paper. However phenols not
as acidic as carboxylic acid and do not react with sodium carbonate.
 Or can add bromine at room temperature (electrophilic addition). Bromine decolourises and
white precipitate formed.
 Testing Alkene: Add bromine water. Bromine water decolourises from orange to colourless.
 Testing Haloalkane: Add silver nitrate and ethanol. Warm to 50C in water bath. Chloroalkaneswhite precipitate. Bromoalkane- cream ppt. Iodoalkanes- yellow ppt.
 Testing Carbonyl: Add 2,4- dinitrophenylhydrazine, 2-4 DNP. Orange precipitate. No ppt = not
carbonyl.
 Testing Aldehyde: Add Tollens’ reagent and warm. Silver mirror formed. Or Fehlings/ Benedict’s
solution used and brick red ppt forms in presence of aldehyde.
 Testing Aldehyde and Primary/ Secondary Alcohol: Add acidified potassium dichromate (VI)
(H2SO4 and K2Cr2O7) and warm in water bath. Colour changes orange to green.
 Testing Carboxylic Acid: Add aqueous sodium carbonate/ Hydrogencarbonate. Observe
effervescence, suggests reaction.
 Testing Transition Metals: Aqueous sodium hydroxide produces precipitates with aqueous
transition metals.
 No change = not the substance testing for.
 ‘Series of chemical test’- must talk about more than one.
 If question says ‘confirm bottle is ketone’ when there are other substances, should test and
observations around ketone mostly.

Comments are closed.