Organic Chemistry 1 Reactions Exam Questions And CORRECT Answer

Organic Chemistry 1 Reactions Exam
Questions And CORRECT Answer
SN1 - Answer -✔✔-2 steps
-Rate limiting step, so reaction rate is dependent on concentration of R-X
-Weak nuc/weak base (typically solvolysis) for secondary and tertiary carbons; also
competes with E1 reactions

SN2 - Answer -✔✔-1 step (concerted)
-Reaction rate is dependent on concentration of R-X and Nuc
-Prefers methyl, primary, or secondary carbons
-Strong nuc/strong base (OH-) or strong nuc/weak base (I-, CH3CO2-) required for
methyl, primary, and secondary

E1 - Answer -✔✔-2 steps
-Rate limiting step, so reaction rate is dependent on concentration of R-X
-Weak nuc/weak base (typically solvolysis) for secondary and tertiary carbons;
competes with SN1 (without heat)

E2 - Answer -✔✔-1 step
-Reaction rate is dependent on concentration of R-X and Nuc
-Weak nuc/strong base (potassium tert butoxide or LDA) for primary carbon
-Strong nuc/strong base or weak nuc/strong base for secondary and tertiary carbon
-Beta hydrogen must be anti to leaving halide

Hydrohalogenation of alkenes - Answer -✔✔-Reagents: HCl, HBr, or KI + H3PO4
-Addition
-Carbocation intermediates, rearrangements possible
-Markovnikov addition
-No stereochemical preference

Radical hydrohalogenation of alkenes - Answer -✔✔-Reagents: Peroxides, heat/light
-Chain reaction
-Radical intermediates
-Anti-Markovnikov addition
-No stereochemical preference

Halogenation of alkenes (anti addition) - Answer -✔✔-Reagents: Br2, Cl2, or I2 in
CH2CL2 or CCl4
-Addition
-Bromonium or chloronium intermediates
-Anti addition stereochemical preference

, Halohydrin - Answer -✔✔-Addition of X2
-Reagents: Br2 or Cl2 in H2O
-Bromonium or chloronium ion intercepted by H2O
-Markovnikov addition of H2O
-Anti addition stereochemical preference

Acid-catalyzed hydration of alkenes - Answer -✔✔-Reagents: H2SO4, HClO4, H3PO4;
high temperature
-Can be reveresed to form alkenes from alcohols
-Addition
-Carbocation intermediates
-Markovnikov addition
-No stereochemical preference

Oxymercuration-demercuration of alkenes - Answer -✔✔-Reagents: 1) Hg(OAc)2 in
H2O or THF/H2O, 2) NaBH4
-Addition of mercury compound
-Mercurinium ion intermediate intercepted by H2O
-Markovnikov addition of H2O
-Addition of H2O is anti, but reduction (NaBH4) scrambles stereochemistry, no
preference

Hydroboration of alkenes - Answer -✔✔-Reagents: 1) BH3-THF (Forms
trialkylboranes/R3B), 2) H2O2/-OH; room temperature or heat
-Addition of BH3
-Cyclic transition state puts boron on least substituted carbon of the double bond
-Syn addition stereochemical preference
-Anti-Markovnikov addition of -OH

Hydrogenation of alkenes - Answer -✔✔-Reagents: H2 over metal catalyst (Pd/C, Pt,
PtO2)
-Surface reaction
-Syn addition from the less crowded/sterically hindered face

Hydroxylation of alkenes (syn addition) - Answer -✔✔-Reagents: KMnO4/-OH (lower
yield) or OsO4/pyridine (higher yield, but dangerous and expensive) or catalytic OsO4
with NaHSO3
-Cyclic transition state and intermediate
-Syn addition of -OH groups

Ozonolysis of alkenes - Answer -✔✔-Reagents: 1) Ozone (O3) at low temperature, 2)
Zn/AcOH

Oxidation of diols - Answer -✔✔-Reagents: 1,2-dioltreated by HIO4 in H2O/THF
-Cyclic intermediate with HIO4