Organic Chemistry : Organic Chemistry
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Example Questions
Example Question #1 : Reactions Types
Classify the type of reaction given.
Rearrangement
Elimination
Addition
Substitution
Addition
An addition reaction is a reaction in which the reactants react to combine and form one product. It is the opposite of an elimination reaction. In the reaction given, the reactants hydrochloric acid and ethylene combine to form the product 1-chloropropane.
Example Question #1 : Reactions Types
Classify the type of reaction given.
Substitution
Rearrangement
Addition
Elimination
Addition
An addition reaction is a reaction in which the reactants react to combine and form one product. It is the opposite of an elimination reaction. In the reaction given, the reactants 2-butene and molecular hydrogen combine to form the product butane.
Example Question #1 : Help With Addition Reactions
Classify the type of reaction given.
Rearrangement
Elimination
Substitution
Addition
Addition
An addition reaction is a reaction in which the reactants react to combine and form one product. It is the opposite of an elimination reaction. In the reaction given, the reactants hydrochloric acid and propyne combine to form the product 2-chloropropene.
Example Question #1 : Reactions Types
Classify the type of reaction given above.
Addition
Rearrangement
Elimination
Substitution
Addition
An addition reaction is a reaction in which the reactants react to combine and form one product. It is the opposite of an elimination reaction. In the reaction given, the reactants hydrobromic acid and propene combine to form the product 2-bromopropane.
Example Question #11 : Help With Addition Reactions
What is the major product of the following reaction?
None of these
The reaction shown is a Markovnikov addition of a hydracid (HX) across a double bond. According to Markovnikov's rule, the hydrogen gets added to the lesser-substituted carbon in the double bond, and the halide (in this case, 
Example Question #1 : Help With Substitution Reactions
Which of the following reaction conditions favors an SN1 mechanism?
Weak base
Strong nucleophile
Weak electrophile
Strong base
Protic solvent
Protic solvent
SN1 reactions occur in two steps. First, the leaving group leaves, forming a carbocation. Next, the weak nucleophile attacks the carbocation (beware of rearrangements during this step). The protic solvent stabilizes the carbocation intermediate.
Example Question #2 : Help With Substitution Reactions
Which of the following reaction conditions favors an SN2 mechanism?
Weak base
Strong base
Tertiary alkyl halide substrate
Protic solvent
Strong nucleophile
Strong nucleophile
SN2 reactions undergo substitution via a concerted mechanism. Thus, no carbocation is formed, and an aprotic solvent is favored. Furthermore, tertiary substituted substrates have lowest reactivity for SN2 reaction mechanisms due to steric hindrance.
Example Question #3 : Help With Substitution Reactions
Which of the following characteristics does not reflect an SN2 reaction mechanism?
Aprotic solvent
Concerted mechanism
Strong nucleophile
Tertiary substrate
Stereochemical inversion of the carbon attacked (backside attack)
Tertiary substrate
SN2 reaction mechanisms are favored by methyl/primary substrates because of reduced steric hindrance. No carbocation is formed via an SN2 mechanism since the mechanism is concerted; thus a strong nuclephile is used.
Example Question #4 : Help With Substitution Reactions
Which of the following characteristics does not reflect an SN1 reaction mechanism?
Unimolecular reaction rate
Use of a strong nucleophile
Use of a protic solvent
Formation of a carbocation intermediate
Formation of a racemic mixture of products
Use of a strong nucleophile
All of the given answers reflect SN1 reactions, except the claim that SN1 reactions are favored by weak nucleophiles.
SN1 reactions occur in two steps and involve a carbocation intermediate. The product demonstrates inverted stereochemistry (no racemic mixture). Tertiary substrates are preferred in this mechanism because they provide stabilization of the carbocation.
Example Question #4 : Help With Substitution Reactions
In a substitution reaction __________.
one sigma bond is broken and one sigma bond is formed
two sigma bonds are broken and one pi bond is formed
one sigma and one pi bond are broken, and two sigma bonds are formed
one pi bond is broken and one pi bond is formed
one pi bond is broken and two sigma bonds are formed
one sigma bond is broken and one sigma bond is formed
Substitution reactions—regardless of the mechanism—involve breaking one sigma bond, and forming another sigma bond (to another group).
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