CHEM 210 REACTIONS EXAM NEWEST QUESTIONS AND ANSWERS (2023 / 2024) (VERIFIED ANSWERS)

Describe the mechanism for the electrophilic addition of a weak acid. <>>Pre-step: acid
catalyst will generally be used to protonate the weak acid reagent (but will technically protonate the
strongest base)
Step 1) strongest acid available protonates the alkene
Step 2) the conjugate base of that acid bonds to the carbocation intermediate
Step 3) deprotonation to reform acid and to give neutral product
What is the stereochemistry of an electrophilic addition product? <>>Can be syn or anti
because the product is formed through a carbocation intermediate
What are the reagents for electrophilic addition of a strong acid? <>>Alkene and a
strong acid (pKa < 5)
What are the reagents for electrophilic addition of a weak acid? <>>Alkene, a weak acid
(pKa > 5), and a strong acid catalyst
What is the degree of substitution? <>>The number of alkyl groups a specific carbon is
bonded to (more alkyl groups means more stable)
What reagents are required in a dissolving metal reduction? <>>Na or Li, ammonia
(NH3) as solvent
Provide a summary of dissolving metal reduction <>>2 hydrogens (one equivalent) are
added to an alkyne to form the E alkene (anti addition)
What is the stereochemistry of the dissolving metal product? <>>E alkene (anti addition)
What reagents are used for a hydrogenation with a poisoned catalyst? <>>- H2
- Metal (usually Pd)
- Solid Support (BaSO4 or CaCO3)
- Additive (PbO or quinoline)
FACT CHECK THIS IN BOOK
What is the stereochem for hydrogenation with poisoned catalyst? <>>Syn addition;
forms Z alkene
Provide a summary for what happens in a hydrogenation of an alkyne <>>H2 will
continue to be added until the molecule is fully saturated (one equivalent is added at a time, syn
addition)
What are the reagents for catalyzed hydrogenation? <>>H2 and a catalyst (like Pd/C)
Provide a summary for what happens in an epoxidation <>>Oxygen is added to an
alkene to form an epoxide
What reagents are necessary for an epoxidation? <>>Peroxy acid and an alkene
What is the stereochem for an epoxidation? <>>Syn addition (top or bottom)
What is the regioselectivity for an epoxidation? <>>None
Describe the mechanism for an epoxidation <>>The oxygen that becomes the epoxide is
the one in the alcohol, double bond captures hydrogen, remaining bond closes the circle, forms
other double bond
Provide a summary for what happens in a halogenation <>>Alkene adds a halogen group
and nucleophile group (through a halonium ion intermediate)
What reagents are required for a halogenation? <>>Halogen source (diatomic halogens,
mixed halogen diatomics, NBS, NCS) and nucleophile (monoatomic halogen anions, H20, NaOH,
CH3OH, NaOCH3)
What is the stereochem for halogenations? <>>Overall anti addition (the first step is syn
addition to form the halonium ion, and the second step adds the nucleophile from the opposite side,
like in Sn2)
Describe the mechanism for a halogenation <>>Step 1) Form halonium ion
Step 2) add nucleophile (analagous to Sn2)
What is the regioselectivity for halogenations? <>>The nucleophile follows th