By selective chemical reactions we mean reactions of a compound or polymer containing two different functional groups with a reagent which reacts only or predominantly with one of the said functional groups, leaving the other functional group free to take {HEAD ~ part} in {TAIL ~ a subsequent chemical reaction} 
By selective chemical reactions we mean reactions of a compound or polymer containing two different functional groups with a reagent which reacts only or predominantly with one of the said functional groups , leaving the other functional group free to take { HEAD ~ part } in { TAIL ~ a subsequent chemical reaction }
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