Alkene Reactions R&C

Question 1

R&C for Electrophilic addition of halogen

Answer 1

(Test for C=C)
R: Br²/Cl² in CCl⁴
C: rtp in the dark

Observation (c=c) Rapid decolourisation of orange red bromine
(Pale yellow chlorine)

Question 2

R&C for Electrophilic addition of hydrogen halide

Answer 2

R: Dry HCl (g)/HBr (g)
C: rtp

Question 3

R&²C for Electrophilic addition of steam

Answer 3

R: Steam
C(1): cold conc. H²SO⁴ heated with H²O
C(2): Heat + high pressure with conc. H³PO⁴ catalyst

Question 4

R&³C for reduction of alkenes

Answer 4

R: H² (g)
C(1): Ni catalyst, high temp & pressure
C(2): Pd (palladium)catalyst RTP
C(3): Pt (platinum) catalyst rtp

Question 5

R&C for mild oxidation of alkenes

Answer 5

R&C: cold alkaline KMnO⁴ (can be acidic)
Observation: Purple KMnO⁴ decolourises to brown MnO²

Question 6

R&²C for strong oxidation of alkenes

Answer 6

R&C: HOT acidified KMnO⁴
R&C²: HOT KMnO⁴ + dilute H²SO⁴

Observation: Decolourisation if KMnO⁴ (+ effervescence if CO²)

Carbonic acid O=C(OH)² & Ethanedioic acid HOC(O)C(O)OH
decomposes to CO² & H²O