Ethylene glycol, glycol (ethane-1,2-diol), the simplest glycol may be

1.	Ethylene glycol, glycol (ethane-1,2-diol), the simplest glycol may be prepared by
Answer» `(i),(ii)` `(i),(iv),(iii)` `(i),, (ii), (iii)(iv)` `(i), (ii), (iv)` Solution :(i) `CH_(2)=CH_(2)+H_(2)O+[O]overset(Cold dilute)underset(KMnO_(4),OH^(-))(rarr) underset(OH)underset(\|)(CH_(2))-underset(OH)underset(\|)(CH_(2))+KOH +MnO_(2)` (ii) `CH_(2)=CH_(2)+HOClrarrClCH_(2)CH_(2)OHoverset(aq.NaHCO_(3))(rarr)HOCH_(2)CH_(2)OH+NaCl+CO_(2)`We can ALSO boil ethlene chlorohydrin with milk of lime: The low yield in this reaction is due to the conversion of some ethylene dibromide into vinyl BROMIDE: `BrCH_(2)CH_(2)Br+Na_(2)CO_(3)rarrCH_(2)=CHBr+NaBr+NaHCO_(3)` If aqueous sodium hydroxide is used instead of sodium carbonate, vinyl bromide is again obtained as a byproduct. the best yield of glycol is obtained by heating ethylene dibromide with potassium acetate in glacial acetic acid and subsequently hydrolysing the glycol diacetate with hydrogen chloride in methanolic solution `BrCH_(2)CH_(2)Br+2CH_(3)COOKrarrCH_(2)(OCOCH_(3))CH_(2)(OCOCH_(3))+2KBroverset(HCl)(rarr)HOCH_(2)CH_(2)OH` (iv) Ethylene oxide is made by passing ethylene andair over a silver catalyst at `300^(@)C`. Notice that glycol is prepared INDUSTRIALLY by this method and also by the CATALYTIC reduction of methyl glycollate: The first three methods are used for the laboratory preparation of glycol

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