Building Blocks

The grammar of organic chemistry

Every drug, polymer, perfume, and pesticide is assembled from a tiny vocabulary of bonds and functional groups. The C-H bond, the carbonyl, the aromatic ring, the alcohol, the ester — these recur in everything from methane to morphine. This collection covers the small molecules organic chemists call "starting materials" and "building blocks": alkanes, alkenes, aromatics, alcohols, ketones, amines. Not glamorous individually, but understanding them is how you stop seeing molecules as random shapes and start seeing them as sentences. Worth the time even if you'll never run a reaction yourself.

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Urea

Urea

Wöhler's organic synthesis milestone; fertilizer

Polyethylene (repeat)

Polyethylene (repeat)

PE; world's most produced plastic

Acetic acid

Acetic acid

Vinegar; archetypal weak acid

Polystyrene (repeat)

Polystyrene (repeat)

PS; foam + packaging

1-Bromopropane

1-Bromopropane

Primary alkyl halide; SN2 substrate

1-Butanol

1-Butanol

Biofuel candidate; lacquer solvent

1-Butene

1-Butene

Polymer comonomer

1-Butyne

1-Butyne

Terminal alkyne

1-Hexene

1-Hexene

LLDPE comonomer

1-Pentanol

1-Pentanol

Amyl alcohol; flavor solvent

1-Pentene

1-Pentene

Terminal alkene; LDPE comonomer

1-Propanol

1-Propanol

Primary alcohol solvent

1,2,3-Triazole

1,2,3-Triazole

Click chemistry product (CuAAC)

1,3-Butadiene

1,3-Butadiene

Synthetic rubber monomer; conjugated diene

1,3,5-Triazine

1,3,5-Triazine

Melamine + cyanuric acid core

1,4-Dioxane

1,4-Dioxane

Cyclic diether solvent

2-Bromopropane

2-Bromopropane

Secondary alkyl halide; SN1/E1 substrate

2-Butyne

2-Butyne

Internal alkyne

2-Methylpentane

2-Methylpentane

Branched C6 isomer

2,2-Dimethylbutane

2,2-Dimethylbutane

Branched C6; gasoline component

2,3-Pentanedione

2,3-Pentanedione

Buttery flavor; alpha-diketone

3-Methylpentane

3-Methylpentane

Branched C6 isomer

4-Methyl-2-pentanone (MIBK)

4-Methyl-2-pentanone (MIBK)

MIBK solvent

5-Hydroxymethylfurfural (HMF)

5-Hydroxymethylfurfural (HMF)

Biomass platform chemical

Acenaphthylene

Acenaphthylene

PAH with cyclopenta ring

Acetaldehyde

Acetaldehyde

Ethanol metabolite; toxic intermediate

Acetamide

Acetamide

Primary amide; plasticizer

Acetic anhydride

Acetic anhydride

Acetylation reagent; aspirin synthesis

Acetone

Acetone

Simplest ketone; common solvent; nail polish remover

Acetonitrile

Acetonitrile

Polar aprotic solvent; HPLC mobile phase

Acetophenone

Acetophenone

Aryl methyl ketone; Friedel-Crafts product

Acetylacetone

Acetylacetone

1,3-diketone; enol tautomer demo; acac ligand

Acetylene

Acetylene

Welding gas; sp-hybridized; weak acid

Acridine

Acridine

DNA intercalator; dye

Acrolein

Acrolein

Burnt-fat odor; toxic α,β-unsaturated

Acrylic acid

Acrylic acid

Acrylate polymers; super-absorbents

Acrylonitrile

Acrylonitrile

PAN polymer; Michael acceptor

Adamantane

Adamantane

Cage structure; diamond unit cell motif

Adipic acid

Adipic acid

Nylon-6,6 monomer

Adiponitrile

Adiponitrile

Hexamethylenediamine precursor

Aniline

Aniline

Aryl amine; dye industry foundation

Anisole

Anisole

Methoxybenzene; activated aromatic

Anthracene

Anthracene

Linear tricyclic PAH; fluorescent dye

Aziridine

Aziridine

3-ring amine; alkylating warhead

Benzaldehyde

Benzaldehyde

Almond aroma; aldol substrate

Benzimidazole

Benzimidazole

Drug scaffold; PPI precursor

Benzo[a]pyrene

Benzo[a]pyrene

Tobacco-smoke carcinogen; DNA adduct former

Benzofuran

Benzofuran

Fused O-heterocycle

Benzoic acid

Benzoic acid

Preservative E210; melting-point standard

Benzonitrile

Benzonitrile

Aromatic nitrile; coordinative solvent

Benzophenone

Benzophenone

UV blocker; photochemistry sensitizer

Benzothiazole

Benzothiazole

Rubber vulcanization accelerator core

Benzothiophene

Benzothiophene

Fused S-heterocycle; coal-tar

Benzoxazole

Benzoxazole

Fused O+N scaffold

Benzyl alcohol

Benzyl alcohol

Preservative; solvent; fragrance

Benzyl cation

Benzyl cation

Resonance-stabilized benzylic cation

Benzyl chloride

Benzyl chloride

Benzyl-cation stabilized; SN1/SN2 dual

Benzylamine

Benzylamine

Primary benzylic amine

Biphenyl

Biphenyl

PCB scaffold; heat transfer fluid

Bromobenzene

Bromobenzene

Aryl Grignard precursor

Bromomethane

Bromomethane

Methylating agent; fumigant

Butane

Butane

Lighter fluid; LPG component

Butyl acetate

Butyl acetate

Fruity solvent; coatings

Butyraldehyde

Butyraldehyde

Butanal; perfumery

Butyric acid

Butyric acid

Rancid butter odor; gut microbiome

Camphor

Camphor

Bicyclic terpenoid ketone; topical balm

Caproic acid

Caproic acid

Hexanoic acid; goaty odor

Carbazole

Carbazole

OLED hole-transport material

Carbon tetrachloride

Carbon tetrachloride

Banned ozone-depleter; radical initiator solvent

Carvacrol

Carvacrol

Oregano oil; antimicrobial

Carvone

Carvone

Spearmint/caraway enantiomers

Catechol

Catechol

1,2-dihydroxybenzene; redox-active

Chlorobenzene

Chlorobenzene

Aryl halide; SNAr substrate

Chloroethane

Chloroethane

Ethylating agent; topical anesthetic

Chloromethane

Chloromethane

Methylating agent; refrigerant

Chrysene

Chrysene

PAH; coal-tar component

Cinnamaldehyde

Cinnamaldehyde

Cinnamon flavor

cis-2-Butene

cis-2-Butene

cis isomer; geometric isomerism demo

Citric acid

Citric acid

Citrus acid; TCA cycle namesake

Corannulene

Corannulene

Bowl-shaped PAH; buckybowl

Coronene

Coronene

Hexagonal PAH; graphene fragment

Cubane

Cubane

Cubic carbon framework; high strain

Cyanuric acid

Cyanuric acid

Pool sanitizer stabilizer

Cyclobutane

Cyclobutane

Strained 4-ring; puckered conformation

Cyclohexane

Cyclohexane

Chair/boat conformation classic; non-polar solvent

Cyclohexanol

Cyclohexanol

Nylon-6 precursor; ring-puckering demo

Cyclohexanone

Cyclohexanone

Nylon precursor; lab solvent

Cyclohexene

Cyclohexene

Diels-Alder substrate; bromination demo

Cyclopentadiene

Cyclopentadiene

Diels-Alder diene; Cp- ligand precursor

Cyclopentane

Cyclopentane

Envelope conformation; near-strainless

Cyclopropane

Cyclopropane

Highly strained; banana bonds; former anesthetic

DCC

DCC

Peptide-coupling dehydrating agent

Decalin

Decalin

cis/trans-fused bicyclic; conformational analysis

Decane

Decane

Kerosene component

DIBAL-H

DIBAL-H

Partial-reduction of esters to aldehydes

Dichlorodifluoromethane (Freon-12)

Dichlorodifluoromethane (Freon-12)

Banned CFC refrigerant

Dichloromethane

Dichloromethane

DCM; common extraction solvent

Diethyl malonate

Diethyl malonate

Malonic ester synthesis; alpha-anion source

Diethylamine

Diethylamine

Secondary amine; rubber chemicals

Diisopropyl ether

Diisopropyl ether

Peroxide-prone ether solvent

Dimedone

Dimedone

5,5-dimethyl-1,3-cyclohexanedione; aldehyde test

Dimethyl carbonate

Dimethyl carbonate

Green methylating agent

Dimethylamine

Dimethylamine

Secondary amine; rubber accelerator

DIPEA (Hünig's base)

DIPEA (Hünig's base)

Bulky non-nucleophilic base

Diphenylamine

Diphenylamine

Antioxidant; OLED material

DMAc

DMAc

Polar aprotic solvent

DMF

DMF

Common polar aprotic solvent

Dodecane

Dodecane

Diesel surrogate; jet fuel component

EDC·HCl

EDC·HCl

Water-soluble peptide coupling reagent

Erythritol

Erythritol

Sugar alcohol sweetener

Ethane

Ethane

Two-carbon alkane; natural gas component

Ethanol

Ethanol

Beverage alcohol; fuel; solvent

Ethanolamine

Ethanolamine

Phospholipid head group; CO2 scrubber

Ethyl acetate

Ethyl acetate

Fruity solvent; nail polish

Ethyl formate

Ethyl formate

Rum/raspberry flavor

Ethylamine

Ethylamine

Primary amine; drug precursor

Ethylbenzene

Ethylbenzene

Styrene precursor

Ethylene

Ethylene

Plant hormone; polyethylene monomer

Ethylene glycol

Ethylene glycol

Antifreeze; PET precursor

Ethylene oxide

Ethylene oxide

Epoxide reagent; sterilant

Ethylenediamine

Ethylenediamine

Bidentate ligand; EDTA precursor

Fluoranthene

Fluoranthene

PAH; benzopyrene metabolic context

Fluorene

Fluorene

OLED material scaffold; acidic CH

Formamide

Formamide

Simplest amide; polar solvent

Formic acid

Formic acid

Simplest carboxylic acid; ant venom

Fumaric acid

Fumaric acid

trans-butenedioic; TCA cycle

Furan

Furan

5-ring aromatic O-heterocycle

Furfural

Furfural

From pentose dehydration; bio-refinery feedstock

Glutaric acid

Glutaric acid

C5 dicarboxylic; nylon precursor

Glycerol

Glycerol

Triol; humectant; lipid backbone

Glycolic acid

Glycolic acid

Alpha-hydroxy acid; skincare

Glyoxal

Glyoxal

Dialdehyde; crosslinker

Grubbs II

Grubbs II

Olefin metathesis catalyst

Heptane

Heptane

Octane-rating zero reference

Hexadecane (cetane)

Hexadecane (cetane)

Cetane number reference

Hexamethylbenzene

Hexamethylbenzene

Fully substituted benzene; X-ray reference

Hexamethylenediamine

Hexamethylenediamine

Nylon-6,6 monomer

Hexane

Hexane

Common organic solvent; oil extraction

Hydrogen cyanide

Hydrogen cyanide

Highly toxic; gold cyanidation

Hydroquinone

Hydroquinone

1,4-dihydroxybenzene; photo developer; skin lightener

Imidazole

Imidazole

His side chain; histamine; ionic liquid base

Indene

Indene

Indenyl ligand precursor; coal-tar fraction

Indole

Indole

Tryptophan + serotonin + IAA core

Iodobenzene

Iodobenzene

Cross-coupling substrate

Iodomethane

Iodomethane

SN2 substrate textbook; methylating reagent

Isobutane

Isobutane

Branched C4; refrigerant

Isobutanol

Isobutanol

Fermentation byproduct

Isobutylene

Isobutylene

Butyl rubber monomer

Isobutyraldehyde

Isobutyraldehyde

Branched C4 aldehyde

Isooctane (2,2,4-trimethylpentane)

Isooctane (2,2,4-trimethylpentane)

Octane-rating 100 reference

Isopentane

Isopentane

Branched C5; ultra-low-T cryogen

Isophorone

Isophorone

α,β-unsaturated cyclic ketone

Isoprene

Isoprene

Natural rubber monomer; terpene unit

Isopropanol

Isopropanol

Rubbing alcohol; lab solvent

Isoquinoline

Isoquinoline

Alkaloid scaffold (papaverine)

Isoxazole

Isoxazole

1,2-positioned O+N; drug scaffold

Jacobsen catalyst

Jacobsen catalyst

Asymmetric epoxidation

Lactic acid

Lactic acid

Muscle fatigue; fermentation; PLA monomer

LDA

LDA

Hindered non-nucleophilic base

LiAlH4 (LAH)

LiAlH4 (LAH)

Strong hydride reductant

m-Xylene

m-Xylene

meta-dimethylbenzene; isophthalic acid feedstock

Maleic acid

Maleic acid

cis-butenedioic; resin monomer

Maleic anhydride

Maleic anhydride

Diels-Alder dienophile; resin monomer

Malic acid

Malic acid

Sour apples; TCA cycle

Malonic acid

Malonic acid

Malonate ester synthesis backbone

Mannitol

Mannitol

Sugar alcohol; osmotic diuretic

Melamine

Melamine

Plastic resin; protein-adulterant scandal

MeMgBr

MeMgBr

Grignard methyl source

Mesitylene

Mesitylene

1,3,5-trimethylbenzene

Methacrylic acid

Methacrylic acid

PMMA precursor

Methane

Methane

Simplest alkane; natural gas main component

Methanol

Methanol

Simplest alcohol; toxic; antifreeze; fuel

Methyl acetate

Methyl acetate

Pleasant odor solvent

Methyl ethyl ketone (MEK)

Methyl ethyl ketone (MEK)

Industrial solvent; lacquer

Methyl salicylate

Methyl salicylate

Wintergreen oil; topical analgesic

Methyl tert-butyl ether (MTBE)

Methyl tert-butyl ether (MTBE)

Gasoline oxygenate; extraction solvent

Methyl vinyl ketone (MVK)

Methyl vinyl ketone (MVK)

Michael acceptor textbook

Methylamine

Methylamine

Simplest primary amine; fishy odor

Methylcyclohexane

Methylcyclohexane

Axial vs equatorial conformer demo

Methyllithium

Methyllithium

Methyl carbanion source

Morpholine

Morpholine

O+N heterocycle; corrosion inhibitor

n-BuLi

n-BuLi

Strong base + alkyl carbanion source

NaBH4

NaBH4

Mild hydride reductant

Naphthalene

Naphthalene

Bicyclic PAH; mothballs

Neopentane

Neopentane

Highly branched C5; tetrahedrally symmetric

NMP

NMP

Battery slurry + Li-ion solvent

Nonane

Nonane

Mid-distillate hydrocarbon

Norbornane

Norbornane

Bicyclic[2.2.1] scaffold; bridge-bond textbook

o-Cresol

o-Cresol

Disinfectant; resin component

o-Xylene

o-Xylene

ortho-dimethylbenzene; phthalic acid feedstock

Octane

Octane

Gasoline component

Oxalic acid

Oxalic acid

Dicarboxylic; calcium binder; rhubarb

Oxalyl chloride

Oxalyl chloride

Swern oxidation activator + acyl chloride prep

Oxazole

Oxazole

O+N 5-ring; natural product scaffold

Oxetane

Oxetane

Strained 4-ring ether; drug discovery motif

p-Xylene

p-Xylene

para-dimethylbenzene; PET feedstock

Pentaerythritol

Pentaerythritol

PETN explosive precursor; resin polyol

Pentane

Pentane

Low-boiling solvent; foam blowing

Phenanthrene

Phenanthrene

Angular tricyclic PAH

Phenol

Phenol

Weakly acidic OH; antiseptic origin; resin monomer

Phenylacetylene

Phenylacetylene

Sonogashira coupling substrate

Phloroglucinol

Phloroglucinol

1,3,5-triol; antispasmodic; explosives

Phthalic acid

Phthalic acid

Plasticizer feedstock

Phthalic anhydride

Phthalic anhydride

Plasticizer + dye precursor

Piperazine

Piperazine

Saturated 1,4-diazine; pharmacophore

Piperidine

Piperidine

Saturated 6-ring; pharmacophore

Propane

Propane

LPG fuel; bottled gas

Propene

Propene

Polypropylene monomer; Markovnikov demo

Propionaldehyde

Propionaldehyde

C3 aldehyde; plastic precursor

Propionic acid

Propionic acid

Preservative; mold inhibitor

Propylene glycol

Propylene glycol

Food humectant; e-cig vapor base

Propylene oxide

Propylene oxide

Chiral epoxide; polyether monomer

Propyne

Propyne

Methylacetylene; terminal alkyne

Pteridine

Pteridine

Folic acid + butterfly pigment core

Purine

Purine

Adenine/guanine core

Pyrazine

Pyrazine

1,4-diazine; flavor compound (popcorn)

Pyrazole

Pyrazole

1,2-diazole; drug scaffold

Pyridazine

Pyridazine

1,2-diazine

Pyridine

Pyridine

6-ring aromatic N; weak base; common solvent

Pyridine (basic)

Pyridine (basic)

Weakly basic aromatic N; common base solvent

Pyrimidine

Pyrimidine

1,3-diazine; cytosine/thymine/uracil core

Pyrogallol

Pyrogallol

1,2,3-trihydroxybenzene; oxygen absorber

Pyrrole

Pyrrole

5-ring aromatic NH; porphyrin building block

Quinoline

Quinoline

Fused N-heterocycle; quinine scaffold

Quinoxaline

Quinoxaline

Anticancer scaffold

Resorcinol

Resorcinol

1,3-dihydroxybenzene; sunscreen ingredient

Salicylic acid

Salicylic acid

Aspirin precursor; acne treatment

sec-Butanol

sec-Butanol

Secondary alcohol; ketone source

SN2 trigonal bipyramidal transition state

SN2 trigonal bipyramidal transition state

Geometric apex of Walden inversion. 3 H equatorial, Br/I axial along ±z.

Sorbitol

Sorbitol

Sugar alcohol; humectant

Squalane

Squalane

Hydrogenated squalene; cosmetic emollient

Styrene

Styrene

Polystyrene monomer

Succinic acid

Succinic acid

TCA cycle intermediate

Succinic anhydride

Succinic anhydride

Acylation reagent

Sulfuryl chloride

Sulfuryl chloride

Chlorinating agent

Tartaric acid

Tartaric acid

Wine acid; Pasteur's chirality discovery

Terephthalic acid

Terephthalic acid

PET polyester monomer

tert-Butanol

tert-Butanol

Tertiary alcohol; high freezing point

tert-Butyl cation

tert-Butyl cation

Stabilized 3° carbocation; SN1/E1 intermediate

tert-Butyl chloride

tert-Butyl chloride

Tertiary; SN1 textbook substrate

Tetrafluoroethylene

Tetrafluoroethylene

PTFE monomer

Tetrahydrofuran

Tetrahydrofuran

THF; common Grignard solvent

Tetrakis(triphenylphosphine)palladium(0)

Tetrakis(triphenylphosphine)palladium(0)

Cross-coupling Pd(0) catalyst

Tetrazole

Tetrazole

Bioisostere of carboxylic acid

Thiazole

Thiazole

S+N 5-ring; vitamin B1 core

Thiazoline

Thiazoline

Penicillin precursor structural unit

Thionyl chloride

Thionyl chloride

OH→Cl conversion; acyl chloride prep

Thiophene

Thiophene

5-ring aromatic S-heterocycle; conducting polymer backbone

Thymol

Thymol

Thyme essential oil; antiseptic

trans-2-Butene

trans-2-Butene

trans isomer; more stable than cis

trans-Decalin

trans-Decalin

Locked diequatorial chair-chair

Triethylamine

Triethylamine

Non-nucleophilic base; common in coupling

Trifluoromethane (fluoroform)

Trifluoromethane (fluoroform)

Greenhouse gas; refrigerant byproduct

Trimethylamine

Trimethylamine

Tertiary amine; fish odor

Triphenylmethane

Triphenylmethane

Trityl cation precursor; dye scaffold

Triptycene

Triptycene

D3h rigid 3D scaffold

Valeric acid

Valeric acid

Pentanoic acid; valerian root

Vinyl acetate

Vinyl acetate

PVA polymer precursor

Vinyl chloride

Vinyl chloride

PVC monomer; carcinogen

Vinyl fluoride

Vinyl fluoride

Fluoropolymer monomer

Wilkinson's catalyst

Wilkinson's catalyst

Homogeneous alkene hydrogenation

Xylitol

Xylitol

Sugar alcohol; sugar-free sweetener