Chemistry Class 11 Chapter 13. Hydrocarbons | Page 12

4 . Addition of water ( Hydration ): - Acid catalyzed addition of water
CH3 CH CH + H O
2 2
65-70 % H2SO4
CH3 CH CH3 OH
CH3
C
CH2
H2O / H
CH 3
CH3
C CH
3 OH
CH3
Oxidation : - Combustion : - CO2 + H2O
Hydroboration – oxidation : - Alkanes react with diborane to form trialkyl boranes which on oxidation with alkaline H2O2 give alcohols .
3CH2 = CH2
BH3 CH
3
CH
2 3 B
Triethylborane
H2O2 / OH -
3CH3CH2OH Ethyl alcohol
Oxymercuration – demercuration : -
Hg ( OAC ) 2
Hg OAC NaBH4
H2C CH2
CH 2 CH 2
CH3CH2OH + Hg THF , H2O OH
OH
Oxidation with potassium permanganate : - 2KMnO 4 + H 2 O 2KOH + 2MnO 2 + 3 [ O ]
3 C C + H2O + O Cold 3 C C
From KMnO4
OH OH
( pink Colour ) ( Colourless ) This reaction is also called Hydroxylation Cis product I . e . cis-diol is obtained .
Noted : - The alkaline potassium permanganate solution is known as Baeyer ’ s reagent . It has bright pink colour . It oxidizes alkenes to glycols which is colourless . This reaction is used as a test for the presence of double bond in a molecule . This is also known as Baeyer test .
( i ) Alk . KMnO 4 CH 3 CH CH 2 CH COOH + CO
2
+ H O
3 2
( ii ) H +