ORG CHEM TESTS ONLY

Question 1

[ALKENES] Test for C=C/unsaturation?

Answer 1

Test for unsaturation/ presence of C=C
Halogen in CCl4 (inert) or H2O (nucleophilic)
Reddish brown Br/ Orange Br water
decolourises

Mild oxidation/cleavage of C=C pi bond
KMnO4, H2SO4 , cold
Purple KMnO4 is decolourised

Question 2

Add X-X in CCl4

Answer 2

Test for unsaturation/ presence of C=C
Reddish brown Br decolourises

Question 3

Add X-X in H2O nucleophillic

Answer 3

Test for unsaturation/ presence of C=C
Reddish brown Br water decolourises

Question 4

[ALKENES] DIFFERENCE between mild and vigorous oxidation of alkenes?

Answer 4

Mild: cleavage of pi bond NOT C=C bond
-diol is produced (2 OHs)
-test PRESENCE of C=C
-COLD
-Different products in acidic vs alkaline medium

Vigorous: cleavage of C=C bond
-produce ketone, carboxylic acid or CO2
-test for POSITION of C=C
-HEATED
-Different products in acidic vs alkaline medium

Question 5

[ALKENES] Testing for position of C=C

Answer 5

Vigourous oxidation; cleavage of C=C
Reagent: KMnO4, H2SO4/NaOH , heat
Products; Ketone, R-COOH or CO2 gas
Depends on the position so CO2 means its terminal C=C

Alkaline gives MnO4- brown ppt
Acidic does not

Question 6

[ALKENES] Mild oxidation of alkene tests for?

Answer 6

C=C is present
Mild oxidation of alkene to alcohol
when KMnO4 decolourised
Brown ppt formed in alkaline
No ppt for acidic

Question 7

[COOH] Test for carboxylic acids

Answer 7

Add Na2CO3 (metal carb)
Products: H2O, CO2, salt
CO2 in limewater

Question 8

[ALKANE] Test for halogenoalkanes

Answer 8

Add NaOH (aq) and small amt of ethanol (to dissolve), heat
Products: Alcohol and X-

Detect X- using HNO3 and AgNO3
White, cream, yellow ppt
Cl-, Br-, I-