organic tests for functional groups

Question 1

test for alcohol (-OH)

Answer 1

1. PCl5 - misty fumes that form a white smoke with NH3(g) or turns damp blue litmus red
2. Acidified dichromate - turns green with 1o and 2o alcohols
3. Sodium - gentle effervescence & white ppt
4. Warm with carboxylic acid & c.H2SO4 - fruity ester smell

Question 2

test for alkene (C=C)

Answer 2

1. Decolourise bromine water (orange to colourless)
2. Burns with smoky flame
3. KMnO4 - purple to brown

Question 3

test for haloalkanes (-X)

Answer 3

Warm with aqueous NaOH & then add HNO3 & AgNO3
Chloro gives white precipitate
Bromo gives cream/pale yellow precipitate
Iodo gives yellow precipitate

Question 4

test for aldehyde (-C=O -H)

Answer 4

1. Fehlings/Benedicts - red ppt
2. Tollens - silver mirror
   2,4-DNP (Brady’s) - orange ppt & then mpt analysis

Question 5

test for ketone (-C=O -)

Answer 5

2,4-DNP (Brady’s) - orange ppt and then do mpt analysis

Question 6

test for carboxylic acid (-C=O -OH)

Answer 6

1. PCl5 - misty fumes that form a white smoke with NH3(g) or turns damp blue litmus red
2. Sodium - gentle effervescence & white ppte
3. Warm with alcohol & c.H2SO4 - fruity ester smell
4. Add carbonate - effervescence

Question 7

test for ester (-C=O -OH)

Answer 7

fruity smell

Question 8

test for acyl chloride (-C=O -Cl)

Answer 8

Add water - misty fumes that form a white smoke with NH3(g) or turns damp blue litmus red

Question 9

test for amine (-NH2)

Answer 9

1. Soluble in acid
2. Turns red litmus blue
3. Blue ppt/deep blue solution with CuSO4

Question 10

test for amide (-C=O -NH2)

Answer 10

Dilute NaOH will produce NH3 which will turn damp red litmus blue

Question 11

what is the phenyl functional group?

Answer 11

benzene with at least one bond

Question 12

what is a nitrile functional group?

Answer 12

-C=-(triple bond) N

Question 13

what is the functional group of an amino acid?

Answer 13

H2NCHRCOOH