1. Halogenation of alcohols 2. free radical substitution of alkanes. 3. Electrophillic addition to alkenes
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Halogenation of alcohols requires
ACTIVATION. STEP 1 IS ALWAYS ACTIVATION
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Why is activation required
OH is a poor leaving group- activation makes a better leaving group ie h20
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Reactivity to halide carbon bonds
MOST C-I C-Br C-Cl C-F LEAST
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Leaving groups best to worst
best I- Br- H2o Cl- OH-
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other ways of producing halogenalkanes from alcohols
1. alcohol plus phosphorous trihalide 2. alcohol plus trionyl chloride
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what do both of these reactions involve
activation step to make OH better leaving group
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what does the reaction between alcohol and trionyl chloride have that differs
a 3rd step
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SN2 reaction
Nuc sub reactions 2nd order - rate SN2 = k[HA][Nuc]. NO INTERMEDIATE FORMED
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effects of R group on rate of SN2
increasing alkyl groups, decreases rate of SN2 reactions- since more alkyl groups harder for nuc to attack. Halogens are good leaving groups which is why an intermediate is not required
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SN1 reactions
Nuc sub reactions 1st order with rate = k[HA] . INVOLVES INTERMEDIATE
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effect of R groups on rate of SN1 reactions
increased alkyl groups increases the rate of SN1 reactions
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