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Give rection which shows hydro-halogenation and hydration of alkyne. |
Answer» Solution :(a) Hydro-halogenation of alkyne or addition of hydrogen halide in alkyne : The electrophilic addition reaction of alkyne compounds occurs while it reacts with hydrogen halide (HCl, HBr, HI). In this reaction two molecule of hydrogen halide added in alkyne compound and form gem-dihalide. In gem-dihalide two halogen atoms arc attached on same carbon atoms.   NOTE : Addition of HX molecule in alkene or alkyne follows Markovnikov.s rule, and `H^(+)` (electrophilic) attach with those carbon having more hydrogen and more double bonds. (b) Hydration of alkynes or addition of water into alkyne : Hydration of alkyne means addition of water `(H_(2)O)`, which follows electrophilic addition reaction. In which, FIRSTLY it follows addition of electrophilic `H^(+)` of `H_(2)O (H^(+)OH^(-))` according to Markovnikov rule in first step andform more stable carbocation. In second step, they form `alpha`-akenal by addition. In second step, they form `alpha`-akenal by addition of `OH^(-)` ions  In above reaction only one ATOM of water is added and gives aldehyde or ketone as a product, which possesses  group. In this reaction, addition of `H^(+)` ion of dilute sulphuric acid and water molecule is talking place at 333K temperature and in presences of `Hg^(2+)` ions of mercuric sulphate CATALYST and gives a product. (i) Ethanol is formed by the reaction of ethyne. 
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