CHEM 281 REACTIONS EXAM QUESTIONS WITH CORRECT ANSWERS LATEST UPDATE 2026
Alkene to Alkane - Answers H2, Pd/Pt
Wilkinsons Catalyst (SYN)
Alkyne to Alkane - Answers 2 H2, Pd/C
Alkyne to Cis-Alkene (syn) - Answers H2, Lindlar's catalyst
or NiB (P-2)
Alkyne to Trans-Alkene (anti) - Answers 1. Li, EtNH2
NH4 Cl
metal reduction!
Dihalide to Alkyne - Answers NaNH2 (2 equiv.)
deprotonates alkane, halides leave!
Alkyl Halide to Alkene - Answers requires a base (proton acceptor)
Alcohol to Alkene (acid catalyzed dehydration) - Answers Strong acid, heat
Mark
1° alc - E2 (all at once)
2° or 3° alc - E1 (carb cat)
Oxymercuration-Demercuration - Answers 1) Hg(OAc)2, H2O
2) NaBH4 (Replaces Hg with H)
Mark
Acid-Catalyzed hydration (alkene to alcohol) - Answers H2O, dilute strong acids (H3O+, H2SO4,
H3PO4)
Mark
H-OH over double bond
not stereoselctive
Hydroboration-Oxidation (alkene to alcohol) - Answers 1.BH3 THF
2. H2O2 (OA)
Alkene to Dihaloalkane (Halogenation) - Answers X2 where X is a halogen
- facilitated by halonium ion formation
Alkene to Epoxide (Simmon-Smith reaction) - Answers CH2I2, Zn(Cu) Syn
Alkene to C.A, Ketones, CO2 (oxidative cleavage) - Answers KMnO4 + heat + OH- + H2O (STRONG)
aldehydes -> CO2
Dihydroxylation (Alkene to Vicinal Cis-Diol) - Answers KMnO4 + cold + OH- + H2O
OR
OsO4, pyridine, NaHSO3
SYN!!!!!!
Alkyne to Geminal Dihalide - Answers 2 mol HX (double addition)
Ozonolysis (soft cleavage) of alkenes - Answers O3, Me2S
does NOT continue to oxidize. (R.C) alkene to aldehydes and ketones
Alkyne - Alkyne (carbon extension) - Answers NaNH2 + NH3 (l)
CH3CH2Br
Alkoxymercuration-Demercuration - Answers 1) Hg(OAc)2, ROH
2) NaBH4
Alkene to ether. usually anti.
Hydrohalogenation (Alkene to Alkyl halide) - Answers HX where X = Br, Cl, I - MARK
Alkene to Alkyne via halogenation - Answers 1. Br2
Alkene to Alkane - Answers H2, Pd/Pt
Wilkinsons Catalyst (SYN)
Alkyne to Alkane - Answers 2 H2, Pd/C
Alkyne to Cis-Alkene (syn) - Answers H2, Lindlar's catalyst
or NiB (P-2)
Alkyne to Trans-Alkene (anti) - Answers 1. Li, EtNH2
NH4 Cl
metal reduction!
Dihalide to Alkyne - Answers NaNH2 (2 equiv.)
deprotonates alkane, halides leave!
Alkyl Halide to Alkene - Answers requires a base (proton acceptor)
Alcohol to Alkene (acid catalyzed dehydration) - Answers Strong acid, heat
Mark
1° alc - E2 (all at once)
2° or 3° alc - E1 (carb cat)
Oxymercuration-Demercuration - Answers 1) Hg(OAc)2, H2O
2) NaBH4 (Replaces Hg with H)
Mark
Acid-Catalyzed hydration (alkene to alcohol) - Answers H2O, dilute strong acids (H3O+, H2SO4,
H3PO4)
Mark
H-OH over double bond
not stereoselctive
Hydroboration-Oxidation (alkene to alcohol) - Answers 1.BH3 THF
2. H2O2 (OA)
Alkene to Dihaloalkane (Halogenation) - Answers X2 where X is a halogen
- facilitated by halonium ion formation
Alkene to Epoxide (Simmon-Smith reaction) - Answers CH2I2, Zn(Cu) Syn
Alkene to C.A, Ketones, CO2 (oxidative cleavage) - Answers KMnO4 + heat + OH- + H2O (STRONG)
aldehydes -> CO2
Dihydroxylation (Alkene to Vicinal Cis-Diol) - Answers KMnO4 + cold + OH- + H2O
OR
OsO4, pyridine, NaHSO3
SYN!!!!!!
Alkyne to Geminal Dihalide - Answers 2 mol HX (double addition)
Ozonolysis (soft cleavage) of alkenes - Answers O3, Me2S
does NOT continue to oxidize. (R.C) alkene to aldehydes and ketones
Alkyne - Alkyne (carbon extension) - Answers NaNH2 + NH3 (l)
CH3CH2Br
Alkoxymercuration-Demercuration - Answers 1) Hg(OAc)2, ROH
2) NaBH4
Alkene to ether. usually anti.
Hydrohalogenation (Alkene to Alkyl halide) - Answers HX where X = Br, Cl, I - MARK
Alkene to Alkyne via halogenation - Answers 1. Br2
