Orgo 2 Reagents

Mg, ether

Turns R-Br into a Grignard reagent (R-MgBr)

1) CO2 (cold) 2) H3O+

Grignard (R-MgBr) → carboxylic acid (R-COOH); adds one carbon

CrO3, H3O+ (Jones)

Strong oxidant: 1° alcohol → COOH, aldehyde → COOH, 2° alcohol → ketone

K2Cr2O7, H3O+

Same as Jones: 1° alcohol or aldehyde → COOH, 2° alcohol → ketone

KMnO4, H+ or OH-, heat

Strong oxidant: 1° alcohol or aldehyde → COOH; alkylbenzene → benzoic acid (benzylic oxidation)

Ag2O, NH4OH (Tollens)

Mild oxidant: aldehyde → carboxylate (silver mirror); ketones don't react

DMP

Mild oxidant: 1° alcohol → aldehyde, 2° alcohol → ketone; stops at the aldehyde

Acetone (with CrO3)

Solvent used in the Jones oxidation

NaCN

R-X → R-CN by SN2; hydrolysis then gives R-COOH (adds one carbon)

H3O+, heat (on a nitrile)

R-C≡N → R-COOH (nitrile hydrolysis)

NaOH, H2O, heat then H3O+ (on a nitrile)

R-C≡N → R-COOH (basic nitrile hydrolysis)

NaOH, H2O

R-COOH → R-COO- Na+ (carboxylate salt, water soluble)

KOH

Same as NaOH for deprotonating an acid; also the base in Wolff-Kishner

H3O+ (on a carboxylate)

R-COO- → R-COOH (reprotonates)

LiAlH4, then H3O+

Strong reducing agent: COOH → 1° alcohol (also reduces esters, aldehydes, ketones)

BH3, THF, then H3O+

COOH → 1° alcohol; reduces an acid faster than a ketone

NaBH4

Reduces only aldehydes and ketones; does NOT reduce COOH

N2H4, KOH, heat

Wolff-Kishner: C=O → CH2

HOCH2CH2OH, cat. H3O+

Protects an aldehyde or ketone as a cyclic acetal

H3O+, H2O (on an acetal)

Removes the acetal protecting group, giving back the C=O

PPh3, then n-BuLi

Makes the Wittig ylide from R-X (C=O → C=C)

NaNH2

Deprotonates a terminal alkyne to give an acetylide

RNH2, cat. H3O+

Aldehyde or ketone → imine (C=N-R)

R2NH, cat. H3O+

Aldehyde or ketone → enamine

HNO3, H2SO4

Aromatic nitration (Ar-H → Ar-NO2)

Which reagent reduces a ketone but not a COOH?

NaBH4

Which reagent reduces a COOH but is selective over a ketone?

BH3, THF

How do you reduce a COOH with LiAlH4 without touching a ketone?

Protect the ketone as an acetal first (ethylene glycol, cat. H3O+), reduce, then deprotect with H3O+

Which oxidants stop at the aldehyde?

DMP (from a 1° alcohol)

Which oxidants take a 1° alcohol all the way to COOH?

Jones (CrO3, H3O+), K2Cr2O7, KMnO4

Which reagent only oxidizes aldehydes?

Tollens (Ag2O, NH4OH)