2 Organic and Physical Chemistry Merged Question Pa
Draw the mechanism for the reaction of a nucleophile (either the cyanide ion or the
hydroxide ion) with bromoethane.
State what type of mechanism this is. - ANSWER Nucleophilic Substitution
How can you tell that the mechanism will be nucleophilic substitution? - ANSWER
1) The halogenoalkane is primary or secondary
and
2) The product is not an alkene.
and
3) If there is a hydroxide ion, it will be cold and in water.
A species (called Y) has a lone pair of electrons and is being reacted with a
halogenoalkane to produce something that is not an alkene. What is Y acting as? -
ANSWER A nucleophile
If sodium (or potassium) hydroxide is dissolved in cold water and mixed with a
halogenoalkane. What is it acting as? - ANSWER A nucleophile
During nucleophilic substitution, where must the arrows be drawn? - ANSWER 1)
From the middle of the lone pair to the partial positive charge
2) From the middle of the C-X bond to the halogen atom
3) For ammonia there is an extra step. The arrow must be drawn from the middle of
the N-H+ bond to the nitrogen atom.
Place the C-X bonds in order of how quickly they can undergo nucleophilic
substitution (start with the fastest) - ANSWER 1) C-I (fastest nucleophilic
substitution reactions)
2) C-Br
3) C-Cl (slowest nucleophilic substitution reactions)
4) C-F (unreactive so cannot undergo nucleophilic substition)
What are the different compounds that can be made from a halogenoalkane using
nucleophilic substitution? - ANSWER 1) Primary amine → Secondary amine →
Tertiary amine
, 2) Alcohol → aldehyde → carboxylic acid
3) Nitrile → Primary amine
4) Nitrile → Carboxylic acid
Draw the mechanism for the reaction of a nucleophile (either with ammonia or water)
with bromoethane.
State what type of mechanism this is. - ANSWER Nucleophilic Substitution
Draw the mechanism for the synthesis of bromoethane from ethene.
State what mechanism this is. - ANSWER Electrophilic Addition
Draw the mechanism for making ethene from bromoethane
State what mechanism this is. - ANSWER Elimination
Draw the mechanism for making ethene from ethanol.
State what mechanism this is. - ANSWER Elimination
Draw the mechanism for making prop-2-ene from propan-2-ol.
State what mechanism this is. - ANSWER Elimination
During an elimination reaction, where must the arrows go? - ANSWER 1) From the
middle of the lone pair to a hydrogen that is attached to the carbon next to the C-X
bond.
2) From the middle of the C-X bond to the halogen atom
What small molecule is always produced from elimination reactions? - ANSWER
Water
How can you tell that the mechanism will be elimination? - ANSWER 1) There is a
halogenoalkane and you are removing a hydrogen atom from it to make an alkene.
2) The halogenoalkane is tertiary or secondary
3) If there is a hydroxide ion, it will be hot and in ethanol.
A species (called Y) has a lone pair of electrons and is being reacted with a
halogenoalkane to produce an alkene. What is Y acting as? - ANSWER A base
If sodium (or potassium) hydroxide is dissolved in hot ethanol and mixed with a
halogenoalkane. What is it acting as? - ANSWER A base