reagents ochem - part 2 (unit 6)

NaBH4, CH3OH

or

[1] LiAlH4, [2] H2O

ketone/aldehyde → 1° or 2° alcohol

[1] R'MgX or R'Li, [2] H2O

ketone/aldehyde → adds R' and turns C=O to OH

nitrile → ketone

NaCN, HCl or HCN

ketone/aldehyde → cyanohydrin (OH + CN)

wittig

ketone/aldehyde + wittig (Ph3P + substituents) → new alkene bond

synthesis of wittig reagents

RX → (1) PH3P:, (2) Bu-Li → PH3P-R

RNH2, mild acid

ketone/aldehyde → imine (N-R'' replaces O)

R2NH, mild acid

ketone/aldehyde → enamine

H2O, H+ or OH-

ketone/aldehyde → diol

nitrile (OH and C≡N) → alpha-hydroxy carboxylic acid

R-C≡N → carboxylic acid (if acid) or carboxylate (if base)

H+

ketone/aldehyde + R''OH → acetal + H2O

acetal → aldehyde/ketone + R''OH (2 equiv)

OH-

cyanohydrin → ketone/aldehyde + H2O + (-) CN

H2O, H+

imine or enamine → aldehyde or ketone

acid-base rxn

carboxylic acid + base → carboxylate anion + HB+

nitrile synthesis

RX + (-) CN → SN2 → R-C≡N + X-

[1] LiAlH4, [2] H2O

[1] DIBAL-H, [2] H2O

nitrile → 1° amine

nitrile → aldehyde

synthesize acid chlorides

carboxylic acid + SOCl2 → acid chloride + SO2 + HCl

synthesize anhydrides

acid chloride + carboxylate anion → anhydride + Cl-

dicarboxylic acid + heat → cyclic anhydride + H2O

synthesize carboxylic acids

acid chloride + H2O over pyridine → carboxylic acid

acid anhydride + H2O → 2 carboxylic acid

ester + H2O over H+ or OH- → carboxylic acid (if acid) or carboxylate anion (if base) + R'OH

amide + same as ester → same but makes R'2NH2+ if acid and R'2NH if base

synthesize esters

acid chloride + R'OH over pyridine → ester + other

acid anhydride + R'OH → ester + RCOOH

carboxylic acid + R'OH over H2SO4 → ester + H2O

synthesize amides

acid chloride + 2 NH3 → amide + NH4+ Cl-

anhydride + 2 NH3 → amide + RCOO-NH4+

carboxylic acid → [1] NH3, [2] heat → amide (NH2) + H2O

carboxylic acid + R'NH2 over DCC → amide (NHR) + water

ester + NH3 → amide + R'OH

reactivity

acid chloride > anhydride > carboxylic acid > ester > amide

the big 4 mechanisms

know (1) enamine (2) imine (3) acetal and (4) intramolecular fisher esterification forwards and backwards

CH3OH, H+ catalyst

ketone → hemiacetal → dimethyl acetal

*acetal can be a protecting group (use diol to make cyclic acetal, get rid of it with H3O+)

review of preparing RCOOH

alcohol → CrO3, H3O+ → RCOOH

aldehyde → Ag2O, NH4OH → RCOOH

MgBr → (1) CO2, (2) H3O+ X- → RCOOH

ozonolysis of alkyne (1) O3 (2) H2O