Organic Chemistry Reagents: What They Do

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H2O, heat

hydration (adds OH and H)

conc H2SO4, heat

dehydration (removes H2O), 2+3 alcohol to alkene

HBr (no peroxides)

markovnikov addition of Br

PDC, CH2Cl2

• Primary alcohol → aldehyde

• Secondary alcohol → ketone

• Tertiary alcohol → no reaction

MILD OXIDATOR

1. LiAlH4

2. H2O

strong reduction, 

        Aldehyde → primary alcohol

• Ketone → secondary alcohol

• Carboxylic acid → primary alcohol

• Ester → two alcohols (one from the alkoxy part, one from the carbonyl carbon)

• Amide → amine

• Nitrile → primary amine

Basically, LiAlH₄ reduces almost everything that can be reduced!

Br2, hv or heat

free radical substitution

Substitutes a hydrogen atom on an alkane (or the benzylic/allylic position) with bromine (Br).

• Selectivity: Bromine is highly selective — it favors substitution at the most substituted carbon (tertiary > secondary > primary).

Benzene, AlCl3

friedl-crafts

1. 3 eq NaNH2, NH3

2. H2O

If you start with an aryl halide (like chlorobenzene or bromobenzene), especially with a leaving group ortho or para to another substituent, this reagent will:

• Remove a hydrogen atom and the leaving group (like Cl or Br) from the ring,

• Form a benzyne intermediate (a benzene with a triple bond in the ring),

• Then NH₂⁻ adds to the benzyne,

• Followed by acidic workup (H₂O) to give an aniline (Ar–NH₂).

Na, NH3

alkyne to trans alkene

NH3, H2O

does nucleophilic substitution

KMnO4, OH1-

STRONG oxidator that cleaves, oxidizes any benzylic carbon with hydrogens all the way to carboxylic acid

RLi in diethyl ether

very strong nucleophile/base used for forming C–C bonds (via nucleophilic addition to carbonyls) or deprotonating acidic hydrogens.

SOCl2, heat

SOCl₂, heat → replaces –OH with –Cl

• From alcohol → alkyl chloride

• From acid → acyl chloride

• From amide → nitrile (with heat)

Zn(Hg), HCl

CLEMMENSEN REDUCTION: reduces aldehydes and ketones to CH2 ACIDIC CONDITIONS

HNO3, H2SO4, heat

adds NO2 to a benzene ring

Cl2, H2O or Br2, H2O

halohydrin formation, adds halide and OH, OH is markovnikov

1. O3 2. H2O, Zn

ozonolysis

NaOH

strong nucleophile and base, can deprotonate, do substitution, elimination

H2NNH2, KOH, 175 °C in triethylene glycol

reduces ketones and aldehydes to CH2

NaC≡CH, NH3

acetylide formation

MnO2

SELECTIVE: ONLY ALLYLIC AND BENZYLIC 1 PRIME ALDEHYDE 2 PRIME KETONE

PBr3

its basically SOCl2, replaces OH with Br

H2SO4, HgSO4

oxymercuration of alkynes, mark addition of OH

Ph3P─CR2

convert carbonyl to alkene

1. B2H6 2. H2O2, NaOH

hydroboration, anti mark OH addition