Organic Chemistry Terms Starting with S
Definitions of 64 organic chemistry terms that start with S, such as S, s-Cis, s-Trans. Plain-language explanations linked to reactions and reagents.
Terms starting with S
- S: One absolute stereochemical configuration: sinister.
- s-Cis: Conjugated diene conformation where the double bonds lie on the same side of the central single bond.
- s-Trans: Conjugated diene conformation where the double bonds lie on opposite sides.
- Sandmeyer Reaction: Replaces an aromatic diazonium group using copper salts, commonly introducing Cl, Br, or CN.
- Saponification: Base-promoted ester hydrolysis, commonly converting fats/esters into carboxylate salts.
- Saturated: Contains no carbon–carbon multiple bonds in the relevant hydrocarbon framework.
- Saturated Hydrocarbon: Hydrocarbon containing only C–C single bonds.
- Schiemann Reaction: Converts an aromatic diazonium salt into an aryl fluoride.
- Second Order: Overall reaction-rate dependence has total exponent two.
- Secondary (2°): Carbon/group connected to two carbon groups, depending on context.
- Secondary Alkyl Halide: Halogen-bearing carbon attached to two other carbons.
- Secondary Structure: Local protein structures such as α-helices and β-sheets.
- Sharpless Asymmetric Epoxidation: Converts certain allylic alcohols into chiral epoxides selectively.
- Shielded: Nucleus surrounded by relatively high electron density; tends to appear more upfield in NMR.
- Sigma (σ) Bond: Bond formed by head-on orbital overlap; the first bond between two atoms.
- Sigma Complex: Non-aromatic carbocation intermediate in electrophilic aromatic substitution; also called an arenium ion.
- Sigmatropic Rearrangement: Pericyclic reaction where a σ bond moves while π bonds reorganize.
- Simple Lipid: Lipid composed mainly of fatty acids and alcohol components.
- Singlet: NMR signal with one peak.
- SN1: Two-step substitution involving a carbocation.
- SN2: One-step substitution involving back-side nucleophilic attack.
- Sodium Cyanoborohydride: Mild reducing reagent, NaBH₃CN, commonly used for reductive amination.
- Soluble: Able to dissolve significantly in a particular solvent.
- Solvent Extraction: Separates compounds based on how they distribute between two immiscible liquids.
- Solvolysis: Reaction where the solvent acts as a reactant/nucleophile.
- sp-Hybridized Orbitals: Hybridization giving linear, ~180° geometry.
- sp²-Hybridized Orbitals: Hybridization giving trigonal planar, ~120° geometry.
- sp³-Hybridized Orbitals: Hybridization giving approximately tetrahedral, 109.5° geometry.
- Specific Rotation: Standardized optical rotation corrected for path length and concentration.
- Spectroscopy: Study of how matter interacts with electromagnetic radiation.
- Spin–Spin Splitting: NMR signal splitting caused by coupling between nearby nuclei.
- Spontaneous: Thermodynamically favorable under the specified conditions; does not necessarily mean fast.
- Staggered Conformation: Bonds are offset when viewed down a bond; lower energy than eclipsed.
- Standard Atomic Weight: Weighted average atomic mass based on natural isotope abundances.
- Step-Growth Polymers: Polymers formed through reactions between functional groups of monomers/oligomers.
- Stereoisomers: Same connectivity but different 3D arrangement.
- Stereoselective: Reaction produces one stereoisomer preferentially.
- Stereospecific: Different stereoisomeric reactants give specifically related stereoisomeric products.
- Steric Number: Number of σ bonds plus lone pairs around a central atom; helps predict hybridization/shape.
- Sterically Hindered: Crowded by bulky groups, making a site harder to approach.
- Steroids: Molecules based on a characteristic fused four-ring framework.
- Stork Enamine Synthesis: Uses an enamine as a carbon nucleophile to functionalize a carbonyl compound.
- Strecker Synthesis: Makes α-amino acids from carbonyl compounds through an α-aminonitrile intermediate.
- Stretching: Vibration where bond lengths increase and decrease.
- Strong Activators: Groups that strongly increase aromatic-ring reactivity toward electrophilic substitution.
- Strong Deactivators: Groups that strongly decrease aromatic-ring reactivity.
- Structural Proteins: Proteins mainly providing physical support, such as collagen.
- Substituents: Atoms/groups attached to the parent structure.
- Substitution Reaction: One atom/group is replaced by another.
- Substrate: Molecule being acted upon in a reaction.
- Sulfide: Organic sulfur functional group R–S–R′.
- Sulfonate Ions: Sulfur-containing anions related to RSO₃⁻ groups.
- Sulfonation: Introduction of a sulfonic-acid-related group, often –SO₃H.
- Sulfone: R–S(=O)₂–R′.
- Sulfoxide: R–S(=O)–R′.
- Superimposable: Two structures can be placed on top of each other and match exactly.
- Symmetric Stretching: Bonds stretch together in a symmetric pattern.
- Symmetrical Ether: Ether with identical groups on both sides of O: R–O–R.
- Symmetry Allowed: Pericyclic reaction pathway allowed by orbital-symmetry rules under specified conditions.
- Symmetry Forbidden: Pathway disfavored/forbidden by orbital-symmetry rules under specified conditions.
- Syn Addition: Two groups add to the same face of a molecule.
- Syn-Coplanar: Groups lie in the same plane and point generally in the same direction.
- Syndiotactic: Polymer with substituent configurations alternating regularly along the chain.
- Systematic Name: Name generated using standardized naming rules such as IUPAC rules.
Open a term starting with S
- S
- s-Cis
- s-Trans
- Sandmeyer Reaction
- Saponification
- Saturated
- Saturated Hydrocarbon
- Schiemann Reaction
- Second Order
- Secondary (2°)
- Secondary Alkyl Halide
- Secondary Structure
- Sharpless Asymmetric Epoxidation
- Shielded
- Sigma (σ) Bond
- Sigma Complex
- Sigmatropic Rearrangement
- Simple Lipid
- Singlet
- SN1
- SN2
- Sodium Cyanoborohydride
- Soluble
- Solvent Extraction
- Solvolysis
- sp-Hybridized Orbitals
- sp²-Hybridized Orbitals
- sp³-Hybridized Orbitals
- Specific Rotation
- Spectroscopy
- Spin–Spin Splitting
- Spontaneous
- Staggered Conformation
- Standard Atomic Weight
- Step-Growth Polymers
- Stereoisomers
- Stereoselective
- Stereospecific
- Steric Number
- Sterically Hindered
- Steroids
- Stork Enamine Synthesis
- Strecker Synthesis
- Stretching
- Strong Activators
- Strong Deactivators
- Structural Proteins
- Substituents
- Substitution Reaction
- Substrate
- Sulfide
- Sulfonate Ions
- Sulfonation
- Sulfone
- Sulfoxide
- Superimposable
- Symmetric Stretching
- Symmetrical Ether
- Symmetry Allowed
- Symmetry Forbidden
- Syn Addition
- Syn-Coplanar
- Syndiotactic
- Systematic Name