Organic Chemistry Terms Starting with A
Definitions of 69 organic chemistry terms that start with A, such as Absorbance, Absorption Spectrum, Acetal. Plain-language explanations linked to…
Terms starting with A
- Absorbance: How much light a sample absorbs. Higher absorbance = more light absorbed.
- Absorption Spectrum: A graph showing which wavelengths of light a substance absorbs.
- Acetal: A carbon bonded to two –OR groups. Often used to protect carbonyl groups.
- Acetoacetic Ester Synthesis: A method for making substituted ketones using an acetoacetic ester.
- Acetylide Ion: A negatively charged carbon from a terminal alkyne. It is a strong nucleophile.
- Acid-Catalyzed Hydration: Adds H and OH across a double bond using acid and water.
- Acidic Cleavage: Breaking a bond using acidic conditions.
- Activate: Make a molecule or position more reactive.
- Acyl Group: The group R–C(=O)–. Found in many carbonyl compounds.
- Acyl Peroxide: A peroxide containing acyl groups. It can generate radicals.
- Acylium Ion: A resonance-stabilized electrophile, R–C≡O⁺ ↔ R–C⁺=O, important in Friedel–Crafts acylation.
- Addition Polymers: Polymers formed by repeatedly adding monomers, usually containing C=C bonds.
- Addition Reaction: A reaction where atoms/groups are added across a multiple bond.
- Addition to π Bond: Breaking a π bond and adding new groups to its two atoms.
- Adrenocortical Hormones: Steroid hormones produced by the adrenal cortex.
- Alcohol: An organic molecule containing an –OH group.
- Aldaric Acid: A sugar derivative where both ends have been oxidized to carboxylic acids.
- Alditol: A sugar whose carbonyl group has been reduced to an alcohol.
- Aldol Addition Reaction: Two carbonyl compounds join to make a β-hydroxy carbonyl.
- Aldol Condensation: Aldol reaction followed by loss of water, usually forming an α,β-unsaturated carbonyl.
- Aldonic Acid: An aldose where the aldehyde has been oxidized to a carboxylic acid.
- Aldose: A sugar containing an aldehyde in its open-chain form.
- Alkaloids: Naturally occurring nitrogen-containing organic compounds, often biologically active.
- Alkanamine: The IUPAC-style name for an amine attached to an alkane.
- Alkane: Hydrocarbon containing only C–C single bonds.
- Alkene: Molecule containing a C=C double bond.
- Alkoxide: RO⁻, the negatively charged form of an alcohol. Usually a strong base/nucleophile.
- Alkoxy Substituent: An –OR group attached to a molecule.
- Alkoxymercuration–Demercuration: Adds an alcohol across an alkene, usually with Markovnikov orientation.
- Alkyl Amines: Amines where nitrogen is attached to one or more alkyl groups.
- Alkyl Group: A piece of an alkane used as a substituent, such as CH₃–.
- Alkyl Halide: An alkyl group bonded to F, Cl, Br, or I.
- Alkylation: Adding an alkyl group to a molecule.
- Alkylthio Group: A sulfur-containing substituent of the form –SR.
- Alkyne: Molecule containing a C≡C triple bond.
- Alkynide Ion: A negatively charged carbon derived from an alkyne; essentially an acetylide-type ion.
- Allylic: A position directly next to a C=C bond.
- Allylic Bromination: Replaces an allylic hydrogen with bromine, often using NBS.
- Allylic Carbocation: A carbocation next to a C=C bond. It is stabilized by resonance.
- α-Amino Acid: An amino acid where NH₂ and COOH are attached around the same α-carbon.
- Amidomalonate Synthesis: A method for preparing α-amino acids from a malonate derivative.
- Amine: Nitrogen-containing compound such as RNH₂, R₂NH, or R₃N.
- Angle Strain: Instability caused when bond angles are forced away from their preferred values.
- Annulenes: Ring-shaped molecules containing alternating single and double bonds.
- Anti Conformation: Two important groups are about 180° apart when viewed down a bond. Usually stable.
- Anti-Addition: Two groups add to opposite faces of a molecule.
- Anti-Coplanar: Groups lie in the same plane but point in opposite directions.
- Anti-Markovnikov Addition: Addition opposite to the usual Markovnikov orientation.
- Anti-Periplanar: Two bonds are in the same plane and point opposite ways; especially important for E2.
- Antiaromatic: Cyclic, planar, conjugated system with 4n π electrons, making it unusually unstable.
- Antibonding MO: A molecular orbital that weakens bonding when electrons occupy it.
- Antioxidants: Substances that slow oxidation, often by reacting with radicals.
- Arenium Ion: Resonance-stabilized carbocation intermediate in electrophilic aromatic substitution.
- Aromatic: Cyclic, planar, conjugated system with 4n+2 π electrons. Benzene is the classic example.
- Aryl Amine: An amine attached directly to an aromatic ring, such as aniline.
- Asymmetric Hydrogenation: Addition of H₂ that preferentially creates one stereoisomer.
- Asymmetric Stretching: A vibration where bonds stretch differently rather than together.
- Atomic Mass Unit (amu): Unit used for atomic/molecular masses. Approximately the mass of a proton or neutron.
- Atomic Orbital: A region described by a wavefunction where an electron can be found around an atom.
- Aufbau Principle: Electrons generally fill the lowest-energy orbitals first.
- Auto-Oxidation: Oxidation that occurs spontaneously with oxygen, often through radicals.
- Autocatalytic: A reaction where one of the products helps catalyze the reaction itself.
- Auxochrome: A group that changes the light absorption of a chromophore.
- Axial Position: A substituent pointing roughly up or down on a cyclohexane chair.
- Axis of Symmetry: An imaginary axis around which rotation can reproduce an equivalent structure.
- Azide Synthesis: A reaction used to introduce the –N₃ azide group.
- Azo Coupling: Reaction forming an –N=N– linkage, commonly used to make dyes.
- Azo Dyes: Colored compounds containing an –N=N– azo group.
- β-Anomer: A cyclic sugar configuration defined by the orientation of its anomeric substituent relative to the reference group.
Open a term starting with A
- Absorbance
- Absorption Spectrum
- Acetal
- Acetoacetic Ester Synthesis
- Acetylide Ion
- Acid-Catalyzed Hydration
- Acidic Cleavage
- Activate
- Acyl Group
- Acyl Peroxide
- Acylium Ion
- Addition Polymers
- Addition Reaction
- Addition to π Bond
- Adrenocortical Hormones
- Alcohol
- Aldaric Acid
- Alditol
- Aldol Addition Reaction
- Aldol Condensation
- Aldonic Acid
- Aldose
- Alkaloids
- Alkanamine
- Alkane
- Alkene
- Alkoxide
- Alkoxy Substituent
- Alkoxymercuration–Demercuration
- Alkyl Amines
- Alkyl Group
- Alkyl Halide
- Alkylation
- Alkylthio Group
- Alkyne
- Alkynide Ion
- Allylic
- Allylic Bromination
- Allylic Carbocation
- α-Amino Acid
- Amidomalonate Synthesis
- Amine
- Angle Strain
- Annulenes
- Anti Conformation
- Anti-Addition
- Anti-Coplanar
- Anti-Markovnikov Addition
- Anti-Periplanar
- Antiaromatic
- Antibonding MO
- Antioxidants
- Arenium Ion
- Aromatic
- Aryl Amine
- Asymmetric Hydrogenation
- Asymmetric Stretching
- Atomic Mass Unit (amu)
- Atomic Orbital
- Aufbau Principle
- Auto-Oxidation
- Autocatalytic
- Auxochrome
- Axial Position
- Axis of Symmetry
- Azide Synthesis
- Azo Coupling
- Azo Dyes
- β-Anomer