Reagent
18-Crown-6
Phase transfer catalyst, cation complexation
CatalystC₁₂H₂₄O₆
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83Reactions
63Reagents
25Groups
109Reference rows
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Study tip
¹H NMR Integration
Integration tells you relative number of hydrogens. A 3:2:2 ratio with peaks at 1, 3.5, 4 ppm suggests CH₃-CH₂-O-CH₂ pattern.
spectroscopy
Protecting group
Acetal
Stable to base, nucleophiles, reducing agents. Removed by acid.
Protecting group
Reaction
Acetal Formation
Remove water
Carbonyl
pKa
Acetic acid (CH₃COOH)
4.76
pKa4.76
Reaction
Acetoacetic Ester Synthesis
Makes substituted ketones (methyl ketones), Decarboxylation of β-keto acid, Can alkylate twice, Partner: malonic ester synthesis (makes acids)
Substitution
pKa
Acetone (α-H)
Enolizable
pKa20
pKa
Acetonitrile (α-H)
25
pKa25
Protecting group
Acetyl
Forms ester (for OH) or amide (for NH₂). Removed by base hydrolysis.
Protecting group
pKa
Acetylene (≡C-H)
Terminal alkyne
pKa25
Reaction
Acid-Catalyzed Ester Hydrolysis
Aqueous acid, reflux
Carbonyl
Reaction
Acyl Chloride Formation
SOCl₂ most common - gaseous byproducts escape, Acyl chlorides very reactive - use quickly, React with alcohols → esters, amines → amides
Carbonyl
Functional group
Acyl Halide (Acid Chloride)
Carbonyl with halide. Most reactive carboxylic acid derivative. Reacts violently with water.
HalidesR-COX
IR
Acyl halide C=O
1795-1815
IR1795-1815
Functional group
Alcohol
Hydroxyl group attached to sp³ carbon. Versatile, can be oxidized or act as nucleophile.
OxygenR-OH
Reaction
Alcohol Dehydration
Concentrated acid, heat
EliminationE1Zaitsev product (more substituted alkene)
IR
Alcohol O-H
3200-3600
IR3200-3600
Reaction
Alcohol to Alkyl Bromide (PBr₃)
OH is poor leaving group - PBr₃ activates it, Works for 1° and 2° alcohols, Alternative: SOCl₂ for chlorides
SubstitutionInversion (SN2 mechanism)
Reaction
Alcohol to Alkyl Chloride (SOCl₂)
Byproducts are gases - easy purification, Pyridine added to neutralize HCl, Works well for 1° and 2° alcohols
Substitution
Functional group
Aldehyde
Carbonyl at end of chain. Electrophilic carbon, easily oxidized to carboxylic acid.
OxygenR-CHO
H NMR
Aldehyde (R-CHO)
9.5-10.0
H NMR9.5-10.0
IR
Aldehyde C-H
2700-2850
IR2700-2850
IR
Aldehyde C=O
1720-1740
IR1720-1740
Study tip
Aldehyde NMR Signature
Aldehyde proton appears 9.5-10 ppm (very deshielded). IR shows two peaks around 2700-2850 cm⁻¹ (Fermi doublet).
spectroscopy
Reaction
Aldol Addition
Low temperature for addition (warm for condensation)
Carbonyl
Reaction
Aldol Condensation
Condensation = addition + elimination of water, Heat favors elimination (entropy), Product is α,β-unsaturated carbonyl
Carbonyl
Functional group
Alkane
Saturated hydrocarbons with only C-C single bonds. Least reactive functional group.
HydrocarbonsCₙH₂ₙ₊₂
pKa
Alkane (C-H)
Essentially non-acidic
pKa~50
IR
Alkane C-H (sp³)
2850-3000
IR2850-3000
Functional group
Alkene
Unsaturated hydrocarbons with C=C double bond. Nucleophilic, undergo addition reactions.
HydrocarbonsCₙH₂ₙ
pKa
Alkene (=CH)
~44
pKa~44
IR
Alkene =C-H (sp²)
3000-3100
IR3000-3100
IR
Alkene C=C
1620-1680
IR1620-1680
Functional group
Alkyl Halide
Halogen on sp³ carbon. Undergo substitution (SN1/SN2) and elimination (E1/E2).
HalidesR-X (X = F, Cl, Br, I)
Functional group
Alkyne
Unsaturated hydrocarbons with C≡C triple bond. Terminal alkynes are weakly acidic.
HydrocarbonsCₙH₂ₙ₋₂
IR
Alkyne ≡C-H (sp)
3300
IR3300
IR
Alkyne C≡C
2100-2260
IR2100-2260
H NMR
Allylic (C=C-CH)
1.6-2.0
H NMR1.6-2.0
Reagent
Aluminum Chloride
Lewis acid catalyst
CatalystAlCl₃
Functional group
Amide
Carbonyl + nitrogen. Very stable, found in proteins (peptide bonds).
NitrogenR-CONH₂
IR
Amide C=O
1630-1690
IR1630-1690
Reaction
Amide Formation from Acyl Chloride
Use 2 eq amine (one acts as base) or add Et₃N, Most stable carboxylic acid derivative, Peptide bonds are amide bonds
Carbonyl
IR
Amide N-H
3150-3400
IR3150-3400
H NMR
Amide N-H
5-8
H NMR5-8
IR
Anhydride C=O
1740-1840
IR1740-1840
Reaction
Anti Dihydroxylation (Epoxide Opening)
Acid-catalyzed: opens at more substituted carbon, Base-catalyzed: opens at less substituted carbon
AdditionAnti addition (OHs on opposite faces)
Study tip
Anti-Markovnikov Addition
HBr + peroxides (ROOR) = anti-Markovnikov via radical mechanism. Only works with HBr (not HCl or HI). Hydroboration-oxidation also gives anti-Markovnikov alcohols.
mechanism
Reaction
Anti-Markovnikov HBr Addition (Radical)
Peroxide initiator (light or heat)
AdditionAnti-Markovnikov: Br on less substituted carbon
Reaction
Appel Reaction
ROH → RX conversion, CBr₄ for bromides, CCl₄ for chlorides, CI₄ for iodides, Mild conditions, Alternative to PBr₃, SOCl₂
Substitution
H NMR
Ar-OH (phenol)
4-8
H NMR4-8
C NMR
Aromatic C (general)
110-160
C NMR110-160
C NMR
Aromatic C-C (ipso)
125-150
C NMR125-150
IR
Aromatic C-H
3000-3100
IR3000-3100
C NMR
Aromatic C-H
110-130
C NMR110-130
C NMR
Aromatic C-O
150-165
C NMR150-165
IR
Aromatic C=C
1450-1600
IR1450-1600
Study tip
Arrow Pushing
Arrows flow from electron-rich (nucleophile) to electron-poor (electrophile). Show all electron pairs. Formal charges must balance across each step.
general
Functional group
Aryl Halide
Halogen on aromatic ring. Less reactive than alkyl halides. Undergo SNAr or metal-catalyzed coupling.
HalidesAr-X
Reagent
Arylboronic Acids
Coupling partner for Suzuki reactions
NucleophileArB(OH)₂
Study tip
Axial vs Equatorial
Bulky groups prefer equatorial position to avoid 1,3-diaxial interactions. A-value = energy difference between axial and equatorial conformations.
stereochemistry
Reaction
Baeyer-Villiger Oxidation
Ketone → Ester (oxygen inserted), Migratory aptitude: H > 3° > 2° ≈ aryl > 1° > methyl, Aldehydes give formate esters, Cyclic ketones → Lactones
Oxidation
Reaction
Beckmann Rearrangement
Acidic conditions, heat
Rearrangement
H NMR
Benzene ring
6.5-8.5
H NMR6.5-8.5
Functional group
Benzene Ring
Six-membered aromatic ring. Undergoes electrophilic aromatic substitution.
AromaticsC₆H₆
pKa
Benzoic acid
4.2
pKa4.2
Protecting group
Benzyl
Stable to base and mild acid. Removed under hydrogenation.
Protecting group
H NMR
Benzylic (Ar-CH)
2.2-2.5
H NMR2.2-2.5
Reaction
Birch Reduction
-33°C (liquid ammonia)
Reduction
Reagent
Borane-THF
Hydroboration reagent
OtherBH₃·THF
Reagent
Boron Trifluoride
Lewis acid
CatalystBF₃ (as BF₃·Et₂O)
C NMR
C-N (amine)
30-65
C NMR30-65
C NMR
C-O (alcohol, ether)
50-90
C NMR50-90
IR
C-O (alcohols, ethers)
1050-1150
IR1050-1150
IR
C-O (esters)
1000-1300
IR1000-1300
C NMR
C-X (halide)
10-75
C NMR10-75
C NMR
C=C (alkene)
100-150
C NMR100-150
C NMR
C=O (aldehyde)
190-205
C NMR190-205
C NMR
C=O (amide)
160-180
C NMR160-180
C NMR
C=O (carboxylic acid)
170-185
C NMR170-185
C NMR
C=O (ester)
160-175
C NMR160-175
C NMR
C=O (ketone)
195-220
C NMR195-220
C NMR
C≡C (alkyne)
65-90
C NMR65-90
C NMR
C≡N (nitrile)
115-125
C NMR115-125
Reaction
Cannizzaro Reaction
Strong base, no α-hydrogens
Oxidation
Study tip
Carbocation Stability
More substituted carbocations are more stable due to hyperconjugation and inductive effects. Watch for rearrangements (hydride and methyl shifts) to form more stable carbocations!
mechanism
Functional group
Carboxylic Acid
Carbonyl + hydroxyl. Acidic (pKa ~5), forms carboxylate anion.
OxygenR-COOH
H NMR
Carboxylic acid (R-COOH)
10-12
H NMR10-12
IR
Carboxylic acid C=O
1700-1725
IR1700-1725
IR
Carboxylic acid O-H
2500-3300
IR2500-3300
Reaction
Catalytic Hydrogenation
H₂ gas, metal catalyst
AdditionReductionSyn addition
Reaction
Claisen Condensation
Ester equivalent of aldol, Product is β-keto ester, Requires at least 2 α-hydrogens (for irreversible step)
Carbonyl
Reaction
Claisen Rearrangement
Thermal (150-200°C)
Pericyclic
Reagent
Clemmensen Reduction
Complete reduction of C=O to CH₂
ReducingZn(Hg) + HCl
Reaction
Clemmensen Reduction (C=O → CH₂)
Heat
Reduction
Study tip
Common Exam Traps
Watch for: carbocation rearrangements, stereochemistry changes, protecting groups needed, acid/base incompatibility with other functional groups.
general
IR
Conjugated C=O
1665-1685
IR1665-1685
Reaction
Cope Rearrangement
Thermal (150-200°C)
PericyclicChair-like transition state preferred
Study tip
Cross-Coupling Reagents
Suzuki: boronic acid + Pd. Sonogashira: terminal alkyne + Pd/Cu. Heck: alkene + Pd. All require aryl/vinyl halide or triflate.
reagents
Reaction
Curtius Rearrangement
Heat or UV light
Rearrangement
Reagent
DBU
Strong, non-nucleophilic organic base
BaseC₉H₁₆N₂
Reagent
DCC (Dicyclohexylcarbodiimide)
Coupling reagent for amide/ester formation
OtherC₁₃H₂₂N₂
Reagent
DEAD (Diethyl Azodicarboxylate)
Activator for Mitsunobu reaction
OtherEtO₂CN=NCO₂Et
Reaction
Dess-Martin Oxidation
Very mild oxidation - many functional groups tolerated, Stops at aldehyde (no over-oxidation), Room temperature, neutral conditions, Expensive but selective
Oxidation
Reagent
Dess-Martin Periodinane (DMP)
Very mild oxidation of alcohols
OxidizingC₁₃H₁₃IO₈
Reaction
DIBAL Reduction (Ester → Aldehyde)
-78°C, 1 equivalent
Reduction
Reagent
DIBAL-H
Partial reduction of esters to aldehydes
Reducing(i-Bu)₂AlH
Reaction
Diels-Alder Reaction
Heat or pressure
PericyclicSyn addition on both components. Endo product kinetically favored.
Reagent
Diethyl Tartrate (DET)
Chiral ligand for asymmetric synthesis
CatalystC₈H₁₄O₆
Reagent
Dissolving Metal (Na/NH₃)
Reduction of alkynes to trans-alkenes
ReducingNa + NH₃(l)
Reaction
Dissolving Metal Reduction (Alkyne → trans-Alkene)
-33°C (liquid ammonia)
AdditionReductionAnti addition → trans-alkene
Functional group
Disulfide
Two sulfurs bonded. Important in protein structure (cysteine bridges). Reducible to thiols.
SulfurR-S-S-R'
Reagent
DMAP (4-Dimethylaminopyridine)
Nucleophilic catalyst for acylations
CatalystC₇H₁₀N₂
Study tip
E/Z Configuration
Use CIP priorities on each alkene carbon. If higher priority groups are on same side = Z. Opposite sides = E. Not the same as cis/trans!
stereochemistry
Reaction
E1 Elimination
Polar protic solvent, heat
EliminationE1No stereospecificity (unlike E2)Zaitsev: more substituted alkene favored
Study tip
E1 vs E2
E2 requires anti-periplanar geometry (H and leaving group 180° apart). E1 makes the more stable carbocation first. Bulky bases favor elimination over substitution.
mechanism
Reaction
E2 Elimination
Strong base, heat
EliminationE2Anti-periplanar geometry required. E/Z depends on which H is removed.Zaitsev: more substituted alkene favored (with most bases)
H NMR
Electron-poor aromatic
7.5-8.5
H NMR7.5-8.5
H NMR
Electron-rich aromatic
6.5-7.5
H NMR6.5-7.5
Reaction
Enamine Formation
Remove water (Dean-Stark)
Carbonyl
Reaction
Epoxidation (with mCPBA)
mCPBA = meta-chloroperoxybenzoic acid, Concerted mechanism, stereospecific, cis-alkene → cis-epoxide; trans-alkene → trans-epoxide
AdditionSyn addition (stereochemistry of alkene preserved)
Functional group
Epoxide
Strained 3-membered ring with oxygen. Highly reactive, opens with nucleophiles.
OxygenCyclic ether (3-membered)
Functional group
Ester
Carboxylic acid derivative. Pleasant odors, undergo hydrolysis and transesterification.
OxygenR-COO-R'
IR
Ester C=O
1735-1750
IR1735-1750
pKa
Ethanol
16
pKa16
Functional group
Ether
Oxygen between two carbons. Relatively unreactive, common solvents.
OxygenR-O-R'
pKa
Ethyl acetate (α-H)
Ester enolate
pKa25
Reaction
Fischer Esterification
Reflux, remove water
Carbonyl
Protecting group
Fluorenylmethyloxycarbonyl
Removed by base (not acid). Orthogonal to Boc. Standard in solid-phase peptide synthesis.
Protecting group
Reaction
Friedel-Crafts Acylation
Acylium ion resonance-stabilized → NO rearrangement, Product is deactivated → only monosubstitution, Better control than alkylation, Clemmensen/Wolff-Kishner removes C=O if needed
AromaticElectrophilic Aromatic Substitution
Reaction
Friedel-Crafts Alkylation
Carbocation can rearrange!, Product more reactive than starting material → polyalkylation, Does NOT work on deactivated rings (nitrobenzene), AlCl₃ catalyst
AromaticElectrophilic Aromatic Substitution
Study tip
Functional Group Interconversions
Master the "roadmap": Alkenes ↔ Alcohols ↔ Aldehydes/Ketones ↔ Carboxylic acids ↔ Esters/Amides. Know multiple routes to each functional group.
general
Reaction
Gabriel Synthesis
Makes pure PRIMARY amines (no over-alkylation), Only works with 1° (and some 2°) halides (SN2), Alternative to direct alkylation of ammonia, Hydrazine releases amine, forms phthalhydrazide
Substitution
Reagent
Gilman Reagent (Cuprate)
Conjugate addition and coupling
NucleophileR₂CuLi
Reaction
Grignard Addition to Carbonyl
Anhydrous ether, then acid workup
Carbonyl
Study tip
Grignard Reaction Setup
Grignard reagents react violently with any protic source (water, alcohols, amines). Use anhydrous ether or THF. Add acid workup AFTER the reaction.
reagents
Reagent
Grignard Reagent
Carbon nucleophile for C-C bond formation
NucleophileRMgBr (or RMgCl)
Reagent
Grubbs Catalyst
Olefin metathesis catalyst
CatalystCl₂(PCy₃)₂Ru=CHPh
pKa
H₂ (dihydrogen)
35
pKa35
Reagent
H₂/Pd (Catalytic Hydrogenation)
Reduction of C=C, C≡C, and some functional groups
ReducingH₂ + Pd/C
pKa
H₂CO₃
Carbonic acid
pKa6.4
pKa
H₂O
OH⁻
pKa15.7
pKa
H₂S
7
pKa7
pKa
H₂SO₄
First proton
pKa-3
pKa
H₃O⁺
Hydronium ion
pKa-1.7
Reaction
Halogenation of Alkene
Bromonium ion intermediate explains anti stereochemistry, In water: halohydrin forms instead, Test for unsaturation: Br₂/CCl₄ decolorizes, Mechanism shown for Br₂; Cl₂ works analogously via chloronium ion
AdditionElectrophilic AdditionAnti addition (trans-dihalide from cis-alkene)
Reaction
Halogenation of Benzene
Lewis acid catalyst required for benzene, Phenol and aniline react without catalyst (activated), Halogens are ortho/para directors but deactivating
AromaticElectrophilic Aromatic Substitution
Reaction
Halohydrin Formation
Water is nucleophile, not halide, Product can be converted to epoxide with base, Mechanism shown for Br₂; Cl₂ works analogously
AdditionAnti additionOH on more substituted carbon (Markovnikov-like)
pKa
HBr
-9
pKa-9
pKa
HCl
-7
pKa-7
pKa
HCN
Hydrogen cyanide
pKa9.2
Reaction
Heck Reaction
Aryl halide + Alkene → Substituted alkene, Generally gives trans (E) product, Nobel Prize 2010 (Heck), No organometallic partner needed (unlike Suzuki)
Coupling
Reaction
Hell-Volhard-Zelinsky Reaction
α-Bromination of carboxylic acids, Goes through acid bromide intermediate, Br₂/P or Br₂/PBr₃, Product useful for further substitution
Substitution
Reaction
Henry Reaction (Nitroaldol)
Like aldol but with nitroalkane, Product: β-nitro alcohol, Can dehydrate to nitroalkene, NO₂ can be converted to many groups (amine, carbonyl, etc.)
Addition
pKa
HF
Weak due to strong H-F bond
pKa3.2
pKa
HI
Strongest common acid
pKa-10
pKa
HNO₃
-1.4
pKa-1.4
Reaction
Hofmann Elimination
Heat
EliminationE2Hofmann: less substituted alkene (opposite of Zaitsev)
Reaction
Hofmann Rearrangement
Aqueous base
Rearrangement
pKa
HSO₄⁻
Second proton of H₂SO₄
pKa2
Reagent
Hydrazine
Reducing agent and nucleophile
NucleophileN₂H₄
Reaction
Hydroboration-Oxidation
THF solvent, 0°C for BH₃, then oxidation
AdditionSyn AdditionSyn addition (H and OH end up on same face)Anti-Markovnikov: OH ends up on less substituted carbon
Reagent
Hydrobromic Acid
Acid for hydrohalogenation
AcidHBr
Reagent
Hydrochloric Acid
Strong acid for protonation and hydrohalogenation
AcidHCl
Reaction
Hydrohalogenation (HX Addition)
Carbocation stability determines regiochemistry, Rearrangements possible with carbocation intermediate, Follows Markovnikov's rule, Mechanism shown for HBr; HCl and HI work analogously
AdditionElectrophilic AdditionMarkovnikov: H adds to carbon with more H's, X to more substituted carbon
Reagent
Hydroxylamine
Forms oximes from carbonyls
NucleophileNH₂OH
Reagent
IBX (2-Iodoxybenzoic Acid)
Oxidation of alcohols
OxidizingC₇H₅IO₄
Functional group
Imine (Schiff Base)
C=N double bond. Formed from aldehyde/ketone + amine. Hydrolyzable.
NitrogenR-CH=N-R'
IR
Imine C=N
1640-1690
IR1640-1690
H NMR
Internal alkene (=CHR)
5.2-5.7
H NMR5.2-5.7
Study tip
Inversion vs Retention
SN2 = inversion (Walden inversion). SN1 = racemization (both faces attacked). Mitsunobu = inversion. Curtius/Hofmann rearrangements = retention.
stereochemistry
Study tip
IR Key Peaks
Broad peaks usually mean H-bonding (O-H, N-H). Sharp peaks are more characteristic. Carbonyl (1700 cm⁻¹) is the strongest, most diagnostic peak.
spectroscopy
Reagent
Iron(III) Bromide
Lewis acid catalyst for halogenation
CatalystFeBr₃
Reaction
Jones Oxidation (Alcohol → Carboxylic Acid)
Strong oxidizing agent, 1° alcohol → carboxylic acid (through aldehyde), 2° alcohol → ketone, 3° alcohol → no reaction
Oxidation
Reagent
Jones Reagent
Strong oxidation to carboxylic acid
OxidizingCrO₃/H₂SO₄/H₂O
Functional group
Ketone
Carbonyl between two carbons. Electrophilic, undergoes nucleophilic addition.
OxygenR-CO-R'
IR
Ketone C=O
1705-1725
IR1705-1725
Reaction
KMnO₄ Oxidative Cleavage
Heat, aqueous
Oxidation
Reagent
L-Selectride
Stereoselective reduction of ketones
ReducingLi[sec-Bu₃BH]
Reagent
LDA (Lithium Diisopropylamide)
Very strong, non-nucleophilic base for enolate formation
BaseLiN(i-Pr)₂
Reaction
LiAlH₄ Reduction
Very strong reducing agent, Reduces: aldehydes, ketones, esters, acids, amides, nitriles, Ester → 2 alcohols; Amide → amine, Violently reacts with water - use anhydrous!
Reduction