Organic Chemistry - Unit 4 AOS 1 - Edrolo

Organic Substance

Any molecule containing carbon (except CO₂ and carbonates); central to organic chemistry.

Carbon Valence

Carbon has four valence electrons (in group 14), so it typically forms four covalent bonds to complete its octet.

Carbon-Carbon Bond

Strong covalent bond; carbon's tetravalency allows catenation (chain formation) leading to many possible organic molecules.

Tetrahedral Geometry

The 3D arrangement when carbon is single-bonded to four atoms: bond angles ≈109.5°, arranged like a pyramid with triangular base.

Bond Length vs. Strength

Shorter bonds (e.g., C≡C) are stronger; longer bonds (e.g., C-I) are weaker because atomic orbitals overlap less effectively.

Electronegativity Difference

The larger the difference (e.g., C-F), the more polar the bond; can influence bond strength and reactivity.

Atomic Size Effect

Larger atoms (e.g., I) have more diffuse valence orbitals, making their bonds (e.g., C-I) weaker than those with smaller atoms (e.g., C-F).

FONCl Mnemonic

Reminds that among common elements, electronegativity order is F > O > N > Cl, followed by C, H, etc.

Structural Formula

Draws each atom and bond explicitly, showing connectivity in full detail (e.g., H-C-C-O-H).

Condensed (Semi-Structural) Formula

Writes atoms in sequence with implied bonds (e.g., CH₃CH₂OH for ethanol).

Skeletal (Line) Formula

Abbreviates carbon backbone as zigzag lines; carbons are implicit at vertices; H's on C are omitted; heteroatoms shown.

Molecular Formula

Lists total atom counts (e.g., C₂H₆O) but gives no bonding/connectivity information.

Empirical Formula

Simplest integer ratio of atoms in a compound (e.g., CH₂O for C₆H₁₂O₆).

Alkane

Saturated hydrocarbon with only C-C single bonds; general formula CₙH₂ₙ₊₂.

Alkene

Unsaturated hydrocarbon containing at least one C=C double bond; general formula CₙH₂ₙ.

Cycloalkane

Ring hydrocarbon (no double bonds); general formula CₙH₂ₙ (same as alkene formula but cyclic).

Benzene

Aromatic hydrocarbon C₆H₆ with six delocalized π electrons in a planar ring; unusually stable.

Primary Amine

Functional group -NH₂ attached to a carbon; derived from ammonia (NH₃).

Secondary Amine

Functional group R-NH-R′; nitrogen bonded to two carbon groups and one hydrogen.

Tertiary Amine

Functional group R-N-R′-R″; nitrogen bonded to three carbon groups; no N-H bond.

Primary Amide

Functional group -CONH₂; carbonyl (C=O) bonded to nitrogen with two H's (peptide bond in proteins is amide).

Aldehyde

Functional group -CHO; a carbonyl (C=O) at chain end bonded to one hydrogen.

Ketone

Functional group R-C(=O)-R′; carbonyl in the interior of a carbon chain; two alkyl groups attached.

Carboxylic Acid

Functional group -COOH; carbonyl C bonded to -OH; acidic because the proton can dissociate, stabilized by resonance.

Ester

Functional group R-C(=O)-O-R′; formed by condensation of a carboxylic acid and an alcohol.

Alcohol

Functional group -OH attached to a carbon: primary (1°) carbon bonded to one carbon, secondary (2°) to two, tertiary (3°) to three.

Primary Alcohol

R-CH₂-OH; carbon bearing -OH bonded to only one other carbon.

Secondary Alcohol

R-CH(OH)-R′; carbon bearing -OH bonded to two other carbons.

Tertiary Alcohol

R-C(OH)-R′-R″; carbon bearing -OH bonded to three other carbons.

Substitution Reaction

A reaction in which one atom or group in a molecule is replaced by another (e.g., R-Cl + OH⁻ → R-OH + Cl⁻).

Sₙ2 Mechanism

A bimolecular nucleophilic substitution: nucleophile attacks backside of C bearing leaving group; inversion of configuration.

Sₙ1 Mechanism

A unimolecular nucleophilic substitution: leaving group departs first (forming carbocation), then nucleophile attacks.

Alkane Halogenation

Radical chain reaction where an alkane (e.g., CH₄) reacts with Cl₂ (UV light) to yield R-Cl + HCl, then can form RCl₂, RCl₃, RCl₄.

Alcohol to Haloalkane (RX)

Substitution: R-OH + HCl (or PCl₃, SOCl₂) → R-Cl + H₂O. Often requires acid catalyst to convert -OH into a better leaving group.

Haloalkane to Alcohol (R-OH)

Substitution: R-Cl + OH⁻ (aqueous) → R-OH + Cl⁻ (Sₙ2 if primary).

Haloalkane to Amine

R-Cl + NH₃ → R-NH₂ + NH₄Cl. Excess NH₃ ensures primary amine formation.

Alcohol to Amine (Indirect)

First convert R-OH to R-Cl (using SOCl₂ or PCl₃), then R-Cl + NH₃ → R-NH₂.

Alkene Hydrogenation

Addition: R-CH=CH-R′ + H₂ (Pd/Pt/Ni catalyst) → R-CH₂-CH₂-R′ (alkane).

Alkene Halogenation

Addition: R-CH=CH-R′ + Br₂ → R-CHBr-CHBr-R′ (vicinal dihalide).

Alkene Hydrohalogenation

Addition: R-CH=CH₂ + HBr → R-CH₂-CH₂Br (Markovnikov addition: H to carbon with more H's).

Alkene Hydration

Addition: R-CH=CH₂ + H₂O (acid catalyst) → R-CH₂-CH₂OH (alcohol).

Addition Polymerization

Monomers with C=C link to form long chains (e.g., n CH₂=CH₂ → -[CH₂-CH₂]ₙ- polyethylene).

Primary Alcohol Oxidation (to Aldehyde)

R-CH₂-OH + [O] → R-CHO (requires mild oxidizer like PCC).

Primary Alcohol Oxidation (to Acid)

R-CH₂-OH + 2[O] → R-COOH (strong oxidizer like K₂Cr₂O₇/H₂SO₄).

Secondary Alcohol Oxidation (to Ketone)

R-CH(OH)-R′ + [O] → R-C(=O)-R′ (oxidation stops at ketone).

Tertiary Alcohol

No easy oxidation under mild conditions (no H on C-OH to remove); strong conditions may crack it.

Esterification (Acid + Alcohol)

R-COOH + R′-OH ⇌ R-COO-R′ + H₂O (acid-catalyzed; reversible condensation).

Transesterification

R-COO-R′ + R′′-OH → R-COO-R′′ + R′-OH (used in biodiesel: triglyceride + methanol → methyl ester + glycerol).

Ester Hydrolysis (Acidic)

R-COO-R′ + H₂O → R-COOH + R′-OH (acid-catalyzed; reverse of esterification).

Ester Hydrolysis (Basic, Saponification)

R-COO-R′ + OH⁻ → R-COO⁻ + R′-OH (irreversible under basic conditions; makes soap from fats).

Peptide Bond

Amide linkage (-CO-NH-) between amino acids; formed by condensation (-COOH + -NH₂ → -CO-NH- + H₂O).

Peptide Hydrolysis

Rupture of amide bond with water (and acid or enzyme catalyst) → amino acids.

Amino Acid

Contains both -NH₂ (amino) and -COOH (carboxyl) on the same carbon (plus an R side chain).

Protein (Polypeptide)

Long chain of amino acids joined by peptide (amide) bonds; structure determined by primary sequence and folding.

Monosaccharide

A single sugar unit (e.g., glucose C₆H₁₂O₆) with multiple -OH groups and a carbonyl (aldehyde or ketone).

Disaccharide

Two monosaccharides joined by a glycosidic C-O-C bond (e.g., sucrose = glucose + fructose).

Polysaccharide

Long polymer of monosaccharide units (e.g., starch, glycogen); linked via glycosidic bonds.

Glycosidic Bond

Ether linkage (C-O-C) between sugar monomers formed by condensation (-OH + -OH → -O- + H₂O).

Starch

Plant storage polysaccharide made of α-glucose units (amylose + amylopectin); digestible by animals.

Glycogen

Animal storage polysaccharide of α-glucose with more branching than starch; rapidly mobilized.

Triglyceride

Glycerol backbone (three -OH) esterified with three fatty acids; major form of dietary fat.

Fat

Solid triglyceride at room temperature; contains more saturated fatty acids → straight chains pack tightly.

Oil

Liquid triglyceride at room temperature; contains unsaturated fatty acids → kinks prevent tight packing.

Lipid Hydrolysis (Saponification)

Triglyceride + 3OH⁻ → glycerol + 3 fatty acid salts (soap).

Dispersion (London) Forces

Weak attractions arising from instantaneous dipoles; present in all molecules; increase with molecular size.

Dipole-Dipole Interaction

Attraction between permanent molecular dipoles in polar molecules; stronger than dispersion.

Hydrogen Bonding

Special dipole-dipole when H bonded to F/O/N interacts with lone pair on F/O/N; strongest intermolecular force.

Boiling Point

Increases with stronger intermolecular forces; more atoms or more polarity → higher boiling point.

Melting Point

Temperature at which a solid becomes liquid; influenced by intermolecular forces and crystal packing.

Viscosity

A measure of a fluid's resistance to flow; higher when stronger intermolecular forces (e.g., H-bonding) hinder movement.

Structural Isomers

Molecules with the same molecular formula but different connectivity (e.g., ethanol vs. dimethyl ether).

Positional Isomer

Differ only in the location of a functional group on the same carbon skeleton (e.g., 1-propanol vs. 2-propanol).

Functional Isomer

Differ in the type of functional group with the same formula (e.g., C₂H₆O = ethanol or dimethyl ether).

Green Solvent Replacement

Using water, bioethanol, supercritical CO₂, or recyclable ionic liquids to reduce hazardous VOCs.

Biodegradable Packaging

Packaging made from materials that microbes can break down into harmless substances (e.g., PLA from corn starch).

Seaweed-Derived Polymer

Polymers (e.g., agar, alginate, carrageenan) from seaweed; used for biodegradable plastics or edible films.

Solvent Toxicity Reduction

Designing processes to avoid carcinogenic or organ-toxic solvents (e.g., replacing benzene with ethanol).

Biofuel Generation

Classification of biofuel feedstocks by "generations" (1st-4th) based on origin and sustainability.

First-Generation Biofuel

Feedstock: edible crops (e.g., corn, sugar cane); Process: transesterification of crop oil under alkaline conditions; Pro: renewable; Con: competes with food supply.

Transesterification

A reaction in which a triglyceride's glycerol portion is replaced by an alcohol (e.g., methanol) to yield biodiesel (methyl esters) and glycerol.

Second-Generation Biofuel

Feedstock: nonfood biomass (e.g., waste cooking oil, forest residues); Process: pretreat biomass, extract oils or ferment sugars, then transesterify; Pro: avoids food vs. fuel; Con: energy-intensive pretreatment.

Third-Generation Biofuel

Feedstock: algae/microalgae; Process: cultivate algae (using CO₂) → harvest → extract algal lipids → transesterify to biodiesel; Pro: high productivity, CO₂ capture; Con: costly scale-up.

Fourth-Generation Biofuel

Feedstock: genetically engineered cyanobacteria; Process: modify metabolism so cyanobacteria excrete lipids/biofuels while fixing CO₂; Pro: potentially carbon-negative; Con: R&D stage, high cost, biosafety.

Catalyst

A substance that increases reaction rate or selectivity without being consumed; provides an alternative lower‐energy pathway.

Catalyst Selectivity

The ability of a catalyst to direct reactants toward a desired product while minimizing side-products.

Catalyst Energy Reduction

Using catalysts often allows reactions to proceed at lower temperatures/pressures, saving energy and reducing emissions.

Catalyst for Renewable Feedstocks

Catalysts can enable efficient conversion of biomass‐derived materials into target chemicals, making use of renewable raw materials.

Catalyst Safety

Running reactions at milder conditions (lower T, gentler reagents) reduces risk of thermal runaway, toxic by-products, or explosions.

Catalyst Longevity

A good heterogeneous catalyst can be recovered and reused many times, minimizing waste of catalytic material.