Halogenoalkanes reactions

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Created by: Zohar
Created on: 15-03-15 20:58

Halogenoalkane reaction with KOH (aq)

SN1/2 reaction forming alcohols - hydrolysis

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halogenoalkane reaction with KOH (ethanol) when boiled under reflux

Elimination reaction forming alkene +Br- + H2O with E2 mechanism (OH- attacks an H on the halogenoalkane)

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Rate of reaction with halogenoalkanes

C-I > C-Br > C-Cl bc decreasing bond length = stronger bond = more E to break

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reaction of haloalkane with NaOH (aq)

forms alcohol + Br-, must be boiled under reflux

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reaction of haloalkane with NH3 (eth) when boiled under reflux

C2H5Br + 2NH3 -> HBr + C2H5NH2 (aminoethane) then NH3 +HBr -> NH4Br

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what are nucleophiles that react with haloalkanes

OH- , CN- and NH3 (lone electron pair)

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test for halogenoalkanes

add to NaOH (aq) & warm -> cool -> add dilute nitric acid -> add silver nitrate solution. Results: RCl is white ppt (soluble in dilute NH3 soln), RBr is cream ppt (insoluble in ", soluble in conc NH3), RI is yellow ppt (insoluble in" &")

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uses of haloalkanes

refrigerants: chemically inert CFCs which break down ozone (become Cl radicals under UV). Fire retardants bc v chemically inert- non-flammable. Herbicides &pesticides which stay in environment for ages

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why use 50% H2SO4 when preparing CH3Br?

to prevent the product HBr being oxidised by the acid to Br2

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What is oxidation?

Addition of oxygen or removal of hydrogen

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Other cards in this set

Card 2

Front

halogenoalkane reaction with KOH (ethanol) when boiled under reflux

Back

Elimination reaction forming alkene +Br- + H2O with E2 mechanism (OH- attacks an H on the halogenoalkane)

Card 3

Front

Rate of reaction with halogenoalkanes

Back

Card 4

Front

reaction of haloalkane with NaOH (aq)

Back

Card 5

Front

reaction of haloalkane with NH3 (eth) when boiled under reflux

Back

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Halogenoalkanes reactions