CH221 Substitution, Elimination, Alkene, and Alkyne Reaction Flashcards

Hydrogenation reagent (H2).

Metal catalyst (Pd/C, Pt, Ni).

Hydrogenation of Alkenes:

Reduce C=C to C-C

+ -H + -H

Syn addition.

Hydrogen halide reagent (e.g., HI, HBr, HCl)

Electrophilic Addition of Hydrogen Halides to Alkenes:

Reduce C=C to C-C

+ -X ← halogen (X)

Markovnikov addition, Rearrangements.

Acid catalyst (e.g., dilute H2SO4, H3O(+) / H(+)).

Acid-Catalyzed Hydration of Alkenes:

Reduce C=C to C-C

+ -OH to more-substituted carbon

Markovnikov addition, Rearrangements.

Hydroboration reagent (BH3 or B2H6 + THF or diglyme).

Oxidizing agent (H2O2 + NaOH, KOH, or HO(-)).

Hydroboration-Oxidation of Alkenes:

Reduce C=C to C-C

+ -OH to less-substituted carbon.

+ -H to other carbon.

Anti-Markovnikov, Syn addition.

X2 (molecular halogen).

Hydrohalogenation / Addition of Halogens:

Reduce C=C to C-C

+ -X + -X ← halogen (X)

Anti-addition, Vicinal dihalide.

X2 (molecular halogen).

Solvent (H2O or ROH).

Halohydrin Formation:

Reduce C=C to C-C

+ -OH (from H2O) or -OR (from ROH) to more-substituted carbon

+ -X to other carbon

Markovnikov, Anti-addition.

Peroxyacid reagent (ROH or peroxyacetic acid (mCPBA)).

Epoxidation of Alkenes:

Reduce C=C to C-C

- 2 H

+ C-O-C ring across bond carbons

Syn addition

Sodium hydride (NaH).

Conversion of Vicinal Halohydrins to Epoxides:

Reduce C=C to C-C

- X

+ C-O-C ring (with X's ɑ-carbon)

HBr reagent.

Peroxides (ROOR).

Free-Radical Addition of Hydrogen Bromide to Alkenes:

Reduce C=C to C-C

+ -Br to less-substituted carbon

Anti-Markovnikov.

O3 as a 1. reagent.

Either (1) Zn and H2O or acetic acid (CH3C(O)OH) or (2) CH3SCH3 or (CH3)2S as a 2. reagent.

Reductive Ozonolysis of Alkenes:

Cleave C=C

+ =O (on one carbon)

+ =O (on other carbon)

O3 as a 1. reagent.

H2O2 as a 2. reagent.

Cleave C=C

+ -OH + =O (one one carbon)

+ -OH + =O (on other carbon)

Ethoxide anion (NaOR) and alcohol (CH3OH) reagent.

or

NaCN and water (H2O).

Anionic / Nucleophilic "Ring-Opening":

Cleave C-O-C ring

+ -OR or -C≡N (on less-substituted carbon)

-OH (on other carbon)

Acid (H(+)) reagent.

Alcohol (ROH) reagent.

Acid-Catalyzed "Ring-Opening":

Cleave C-O-C ring

+ -OR (on more-substituted carbon)

-OH (on other carbon)

NaNH2 + NH3 or Na as 1. reagent.

R-X as 2. reagent.

Alkylation of Acetylene and Terminal Alkynes:

Reduce C≡C to C=C

+ -R (at terminal position)

2 NaNH2 (for internal alkyne product) or 3 NaNH2 (for terminal alkyne product) as reagent.

Double Dehydrohalogenation of a Geminal Dihalide:

- 2 H-X (from same carbon).

Formation of C≡C bond from C-C.

2 NaNH2 (for internal alkyne) or 3 NaNH2 (for terminal alkyne) as reagent.

NH3 as solvent.

Double Dehydrohalogenation of a Vicinal Dihalide:

- 2 H-X (from neighboring carbons).

Formation of C≡C bond from C-C.

2 H2 or excess H2 as reagent.

Metal catalyst (Pd/C, Pt, Ni)

Hydrogenation of Alkynes:

Reduce C≡C to C-C.

+ 4 H (+ 2 H to each neighboring carbon) (on same side).

Syn addition

H2 as reagent.

Lindlar Pd as catalyst.

Cis Partial Hydrogenation of Alkynes:

Reduce C≡C to C=C.

+ 2 H (on neighboring carbons) (on same side)

→ cis alkene.

Na or Li.

NH3 (or other amine: RNH2).

Trans Partial Hydrogenation of Alkynes / Dissolving Metal Reduction:

Reduce C≡C to C=C.

+ 2 H (on neighboring carbons) (on opposite sides)

→ trans alkene.

2 HX as reagent.

Addition of Hydrogen Halides to Alkynes:

Reduce C≡C to C-C.

+ 2 -X (on more-substituted carbon of bond) (on same carbon)

Markovnikov, Geminal dihalyde

2 X2 as reagent.

Addition of Halogens to Alkynes:

Reduce C≡C to C-C.

+ -X + -X (one on each carbon of bond)

+ -X + -X (one on each carbon of bond)

Markovnikov, Anti-addition, Geminal dihalydes

H2O as reagent

H2SO4 and HgSO4 or Hg(2+) as solvents.

Hydration of Alkyne / Tautomerization in Acidic Conditions:

Reduce C≡C to C=C.

+ -OH on internal carbon of bond ← >1 internal carbons → >1 products.

Reduce C=C to C-C.

-OH → Ketone: =O group

O3 as 1. reagent.

H2O or H3O(+) as 2. reagent.

Ozonolysis of Alkynes:

Cleavage of C≡C bond

+ -OH and =O (on one carbon)

+ -OH and =O (on other carbon) or + -OH + -OH + =O (for terminal carbon)

NaSR or KSR as reagent.

Preparation of Sulfides / Thiols (SN2):

+ SR

Inversion of stereochemistry.

R-O(-) as reagent.

William Ether Synthesis (SN2):

- -X

+ -O-R (attacks X carbon)

Inversion of stereochemistry.

HX as reagent.

Acid-Catalyzed Cleavage of Ethers (SN1 or SN2):

- -CH3

+ -H

2- or 3-prime substrate with H2O, CH3OH, KHSO4, H3PO4, HCl, etc. reagent

or

3-prime alpha carbon with N3(-), CN(-), I(-), Br(-), etc. reagent.

SN1:

- -X

+ -R

Rearrangements, Retention of stereochemistry.

E1:

- -X

Form C=C bond from C-C

Zaitsev's rule (most-substituted alkene), Rearrangements.

2- or 3-prime substrate with CH3O(-), NaO-, SH-, etc. reagent.

or

1-, 2-, or 3-prime alpha carbon with t-BuO(-), KOtBu, etc. reagent.

E2:

- -X

Form C=C bond from C-C

Unhindered base —> Zaitsev's product (most-substituted)

Hidnered base —> Hoffman product (least-substituted)

Anti-Coplanar Requirement, Rearrangements.

Methyl, 1- or 2-prime substrate with N3(-), CN(-), I(-), Br(-), etc. reagent.

or

Methyl or 1-prime substrate with CH3O(-), NaO-, SH-, etc. reagent.

or

Methyl substrate with t-BuO(-), KOtBu, etc. reagent.

SN2:

Cl2 as reagent

Heat or light (Δ or hv)

Chlorination:

+ Cl (on less- or more-substituted carbon)

Br2 as reagent

Heat or light (Δ or hv)

Bromination:

+ Br (on most-substituted carbon)