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Explain with example oxidation of alkene in different situations ? |
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Answer» SOLUTION :(a) Bayer.s test of alkene of unsaturation test : Preparation : Colour of POTTASIUM permanganate `(KMnO_(4))` is purple in colour. Cold and diluted pottasium permanaganate does the colution colurless when their conformation of unsaturation, Bayer.s test is well known. Alkene is unsaturated hydrocarbon. Treating alkene with potassium permanganate, vicinal diol is formed. Formation of di-ol, known as hydroxylation. There is a oxidation of alkenes. colour of pottasium permangnate disappears. e.g.-1 : Bayer.s test of ethene YIELDS ethelene glycol. `2KMnO_(4) + H_(2)O rarr 2KOH + 2MnO_(2) + 3(O)` `underset("(Ethelene)")underset("Ethene")(CH_(2)=CH_(2))+ubrace((H_(2)O+O))_("From " KMnO_(4)) underset(273 K)overset(dil. KMnO_(4))rarr underset("(Ethelen glycol)")underset("Ethane-2-diol")(underset(OH)underset(|)(CH_(2))-underset(OH)underset(|)(CH_(2)))` e.g.-2 : Bayer.s test of propene yields propane-1, 2-diol. `underset("Propene")(CH_(3)CH)=CH_(2)+H_(2)O+O underset(273 K, (O))overset(Dil. KMnO_(4))rarr underset("Propene-1,2-diol")(CH_(3)-underset(OH)underset(|)(CH)-underset(OH)underset(|)(CH_(2)))` Common reaction in Bayer.s test is :  (b) Oxidation of alkene in presence of strong oxidizing agent : Reactant : Acidic or alkyl pottasium permanganate or potassium dichromate. Reaction : Oxidation of alkene results into acid or ketone. Product depends upto the nature of alkene. reaction examples : (i) Oxidation of 2-methylpropene with `KMnO_(4)` gives propane.  (ii) On oxidation of But-2-ene, ethanoic acid is formed. `underset("But-2-ene")(CH_(3)CH=CHCH_(3))underset(Delta, (O))overset(KMnO_(4), H^(+))rarr underset("Ethanoic acid")(2CH_(3)COOH)` Note : In carboxylation, only main product is, carbonic reaction should be balanced. (iii) `underset("Ethene")(CH_(2)=CH_(2)) underset((O), Delta)overset(KMnO_(4), H^(+))rarr underset("Ethanoic acid")(HCOOH)overset((O))rarr CO_(2)+H_(2)O` |
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