Studied by 1 personWhat is the general equation for a nucleophilic reaction?
CH3CH2X + Nu- → CH3CH2Nu + X-
What is a nucleophile?
An electron pair donor that is attracted to areas of electron deficiency. Has a lone pair.
Which three nucleophiles can halogenoalkanes react with?
OH, CN, NH3
What conditions are required for nucleophilic substitution with an OH nucleophile and what is produced?
Warm, aqueous KOH/NaOH
Reflux
An alcohol and a halogen ion are produced
Draw the mechanism for the reaction between 1-bromopropane and sodium hydroxide (textbook pg. 213)
XXX.
What conditions are required for nucleophilic substitution with a CN nucleophile and what is produced?
Warm, ethanolic KCN (as water could act as a competing nucleophile)
Reflux
Nitrile is produced
Draw the mechanism for the reaction between 1-bromopropane and potassium cyanide (textbook pg. 213).
XXX.
What conditions are required for nucleophilic substitution with an NH3 nucleophile and what is produced?
Warm, excess ethanolic ammonia
Amine is produced
Draw the mechanism for the reaction between 1-bromopropane and ammonia (textbook pg. 214).
XXX.
What are the three points summarising nucleophilic substitution?
Occurs between a halogenoalkane and a nucleophile.
Nu attacks the delta positive C, and breaks the C-X bond.
One new bond (C-Nu) is formed and one is broken (C-X)
How can the conditions of nucleophilic substitution with a hydroxide nucleophile change to cause elimination?
Warm the halogenoalkane with hydroxide ions dissolved in ethanol, instead of water. Under reflux.
What is produced by elimination of halogenoalkanes?
An alkene, water and halogen ion.
Draw the mechanism for the elimination of 2-bromopropane with potassium hydroxide (textbook pg. 213).
XXX.
What happens if a longer, unsymmetrical halogenoalkane is used in elimination?
Two products are formed as the double bond could go on either side of the carbon with the halogen attached, e.g., 2-bromobutane forms but-1-ene and but-2-ene.
Note
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