Reagants for Organic Chemistry

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SN1 Characteristics

1. Polar protic acid

2. Weak nucleophile

3. Forms carbocation —> rearrangement

4. Forms racemic mixture

5. Prefers tertiary and secondary substrates.

Bu₃SnH, AlBn + heat

Replaces halide (Br, Cl, I) with H.

Benzyolperoxide or AlBN + heat

Polymerizes alkenes via free radical mechanism

SN2 Characteristics

1. Polar aprotic solvent

2. Strong nucleophile

3. No carbocation rearrangement

4. Stereochemical inversion (backside attack)

5. Prefers primary and secondary over tertiary substrates

TsCl, NEt₃ or Pyridine

Converts alcohols into OTs, a good leaving group. Does not change configuration.

TfCl, NEt₃ or Pyridine

Converts alcohols into OTf, a better leaving group than OTs. Does not change configuration.

MsCl, NEt₃ or Pyridine

Converts alcohols into OMs, a good leaving group. Does not change configuration.

PBr₃

Converts alcohols into bromides. Inverts configuration. (SN2)

SOCl2

Converts alcohols into chlorides. Inverts configuration. (SN2)

Mitsunobu: PPh₃, DEAD, THF, and and HX (can be RCOOH, PhOH, RSH, HCN, HN3).

Converts alcohols into X (ex: RCOO, OPh, RS, CN, N3). Inverts configuration.

Williamson Ether Synthesis (NaH, NaNH_2, or NaOH + CH₃Br)

Deprotonates alcohol to form alkoxide, which then undergoes nucleophilic substitution with an alkyl halide to form an ether.

• If intramolecular (OH on one end and leaving group on other end) then forms cyclic ether.

Ether + Strong Acid (HBr, HI)

Strong acid attacks least hindered sp³ carbon adjacent to O and cleaves ether.

Ether + (CH₃)₃SiI

(CH₃)₃SiI attacks least hindered sp³ carbon adjacent to O and cleaves ether.

NaOH, H₂O (OH bonded to Carbon adjacent to another Carbon with a halogen)

Synthesizes an epoxide. Stereochemistry may invert.

• If leaving group is solid line, bond is not broken and stereochemistry does not change.

• If leaving group is wedge or dash, bond is broken and stereochemistry inverts.

Epoxide Opening in Acidic Conditions

SN1. Nucleophile attacks more substituted carbon. Acid is usually H₂SO₄ or HX.

Epoxide Opening in Basic Conditions

SN2. Nucleophile reacts with less substituted carbon. Strong nucleophile (basic).

Thiols (RSH) + NEt₃

Forms thioethers (R-S-R). Inverts stereochemistry (SN2)

Thiols (RSH) + OH^-

Forms thioethers (R-S-R). Forms carbocation after leaving group leaves. May undergo rearrangement before adding thiol. (SN1)

Thiols + PPh₃, DEAD, THF

Thiols can act as nucleophile in Mitsunobu. Inverts stereochemistry. SN2.

H₂ + Pd-C/Pd/Pt/Ni

• Syn addition

• Reduces aldehydes and ketones on ring

• Used to add H atoms

• CN → CH₂NH₂

• N₃ → NH₂

• Ph-NO₂ → Ph-NH₂

H₂ + Pd-C (Lindlar’s Catalyst)

Converts alkynes into cis alkenes (Partial reduction)

2H₂ + Pd-C or other catalyst (Pt, Ni, Pd)

Converts alkynes into alkanes (complete reduction)

Na, NH_{3 (l)}, -33 degrees Celsius

Converts alkynes into trans alkenes.

NaCN + DMF

Replaces leaving group (usually Br, I, Cl) with CN and inverts stereochemistry.

NaBH₄ + protic solvent (H₂O or CH₃OH)

Reduces carbonyls (aldehydes and ketones).

• Ketones → secondary alcohols

• Aldehydes → primary alcohols

O₃ + (CH₃)₂S

Converts alkene into aldehyde and ketone

O₃ + H₂O₂

Converts alkene into carboxylic acid and ketone

OsO₄ + t-BuOOH + t-BuOH + OH^-

• Syn addition

• Converts alkene into diol (two OH groups; one at each end of double bond)

• If cis alkene → meso

• If trans alkene → enantiomers (racemic)

HIO₄ or NaIO_4, H₂O

Vicinal diols (two OH adjacent OH) are cleaved and form aldehydes and/or ketones

RCO₃H or MCPBA + CH₂Cl₂

• Converts alkene into epoxide

• Syn addition

• Cis alkene → meso

• Trans alkene → enantiomers (racemic)

1. H₂CrO₄, H₂O, acetone

2. H₂SO₄, acetone (Jones reagant)

3. Na₂Cr₂O₇, H₂SO₄, H₂O

4. CrO₃, H₂SO₄

1. These all oxidize primary and secondary alcohols

2. In primary alcohols, forms aldehyde, then can oxidize again into carboxylic acid

3. In secondary alcohols, forms ketones

CrO₃, Pyr (Collen’s Reagant)

Stops reaction of oxidation of primary alcohols at aldehyde

PCC + CH₂Cl₂ (Corey’s Reagant)

Stops reaction of oxidation of primary alcohols at aldehyde

DMSO, COCl₂, Et₃N

Stops reaction of oxidation of primary alcohols at aldehyde. Less toxic.

IBX in DMSO

Oxidizes alcohol group without affecting other functional groups.

DMP in CH₂Cl₂

Oxidizes alcohol group without affecting other functional groups.

MnO2

Oxidizes benzylic and allylic alcohols to aldehydes and ketones

RCO₃H + H₂O₂

Oxidizes tertiary amine (it just adds O)

H-X (HBr, HI, HCl) added to alkene

• Forms carbocation → can rearrange.

• Markovnikov addition

• Rate = k[alkene][HX]

• Regioselective (tertiary > secondary > primary)

• Adds X (Br, I, Cl) to more substituted carbon in alkene

• SN1 → forms racemic mixture

H-X (HBr, HI, HCl) added to alkene in presence of ROOR

• DOES NOT FORM carbocation

• Anti-Markovnikov addition

• Adds X (Br, I, Cl) to less substituted carbon in alkene

• SN1 → forms racemic mixture

H₂O + H₂SO₄

• Forms carbocation → can rearrange

• Markovnikov addition

• Regioselective (tertiary > secondary > primary)

• Adds OH to more substituted carbon in alkene.

• SN1 → forms racemic mixture

ROH + H₂SO₄

• Forms carbocation → can rearrange

• Markovnikov addition

• Regioselective (tertiary > secondary > primary)

• Adds ROH to more substituted carbon in alkene.

• SN1 → forms racemic mixture

Hg(OAc)₂ + H₂O + THF (Oxymercuration)

1. Does not form carbocation

2. Markovnikov addition

3. Anti addition (HgOAc and OH on different sides)

4. Forms triangle thing. H2O attacks more substituted carbon and then gets deprotonated

   1. HgOAc always on less substituted end and OH always on more substituted end.

NaBH₄ (Demercuration)

Replaces HgOAc with H after oxymercuration

Hg(OAc)₂ + ROH + THF (Oxymercuration)

1. Does not form carbocation

2. Anti addition (HgOAc and ROH on different sides)

3. Forms ether due to ROH

4. Markovnikov addition

5. Forms triangle thing. ROH attacks more substituted carbon and then gets deprotonated

   1. HgOAc always on less substituted end and ROH always on more substituted end.

1. BH₃, THF

2. H₂O₂, OH^-

• Does not form carbocation

• Syn addition

• Anti-markovnikov addition

  • H on more substituted C and OH on less substituted C

• If trans, forms enantiomers

• If cis, forms meso compound.

X₂, CH₂Cl₂ (X₂ = Br₂, Cl₂) in alkenes

• No carbocation

• Anti addition

  • Both X are added and have different configurations

• Markovnikov addition

• Forms triangle thing

  • X attacks more substituted carbon

    • If cis, forms enantiomers

    • If trans, forms meso compound

• If bulky substituent, only one product

X₂, H₂O (X₂ = Br₂, Cl₂) in alkenes

• No carbocation

• Anti addition

• Markovnikov addition.

• Forms triangle thing

  • OH attacks more substituted carbon and gets deprotonated

• Forms enantiomers

H-X + alkyne (X = Br, Cl)

Converts alkynes into alkenes,

IF EXCESS: converts alkene into alkane

X₂ (Br₂, Cl₂) in alkynes

• No carbocation

• Anti addition.

• Forms trans alkene

• Markovnikov addition

• Forms triangle thing

• X attacks more substituted carbon

• IF EXCESS: trans alkene forms alkane

HgSO₄ + H₂SO₄ + H₂O

OR

PtCl₂ + H₂O

• Converts internal alkynes into ketones and terminal alkynes into methyl ketones

• OH attached on more substituted C (enol)

• Both: Alkyne → enol → ketones (resonance)

1. (Sia)₂BH, THF

2. H₂O₂, OH^-

• Does not form carbocation

• Syn addition

• Anti-markovnikov addition

  • H on more substituted C and OH on less substituted C

• If trans, forms enantiomers

• If cis, forms meso compound.

• Stops at alkene (enol), but can become ketone through keto-enol tautomerism

H₂SO₄ or HCOOH + alkene

Forms C-C bonds (Polymerization)

H₂SO₄ or HCOOH + alkene with OH

Forms C-C bonds. Forms ring if possible

Anything with Zn, CH₂I₂ + Alkene

Forms triangle thing

• If cis, stereochemistry is same

• If trans, stereochemistry is different

CHCl₃ + Alkene

Forms triangle thing with two Cl coming out of the point (solid line).

• If cis, stereochemistry of other ends are same

• If trans, stereochemistry if other ends are different

E1 for Alcohol

• H₂SO₄ or H₂PO₄ + Heat

• Acid protonates alcohol, OH₂ leaves, forms carbocation, rearrangement, Beta hydrogen forms alkene.

• Favors tertiary and secondary carbocations. NEVER primary

• Forms carbocation

• More substituted alkene is more stable

E1 for Alkyl Halide

• Leaving group leaves, carbocation forms, rearrangement, beta hydrogen forms alkene

• Favors tertiary and secondary carbocations

• Forms carbocation

• More substituted alkene is more stable

• Weak base

• Polar protic solvent + heat

• Competing with SN1

E2 for Alcohol

• H₂SO₄ or H₂PO₄ + Heat

• MUST BE anti-periplanar

• ONLY Primary alcohol

• HIGH HEAT REQUIRED

E2 for Alkyl Halide

• One step. Base attacks beta hydrogen and forms alkene and leaving group leaves all at once.

• Antiperiplanar

• Strong base (OH, OR, NH3, LDA)

• Polar protic solvent + heat

• Can work with primary, secondary, and tertiary alkyl halides