Organic Chemistry Lecture Notes

This set of vocabulary flashcards covers essential concepts, definitions, and specific chemical reactions from organic chemistry lecture notes, including nomenclature, isomerism, reaction mechanisms, and the chemistry of everyday organic compounds.

Organic Chemistry

The branch of chemistry which deals with hydrocarbons and different derivatives of hydrocarbons, specifically compounds formed by carbon chains and carbo-cyclic structures.

Homologous Series

A group of organic compounds formed by the same elements having similar properties and a common molecular formula with a difference of a methylene ($-CH_{2}-$) group between two adjacent compounds.

Vital Force Theory

A theory proposed by Berzelius in 1815 suggesting that organic compounds are formed in plants and animals by the influence of a mysterious force and could not be prepared in a laboratory.

Friedrich Wöhler

Known as the 'Father of organic chemistry,' he accidentally prepared urea (an organic compound) in 1828 by evaporating a solution of ammonium cyanate, an inorganic compound.

Catenation

The capacity of carbon to form carbon-carbon chains or rings with different numbers of carbon atoms by covalent bonds.

Buckminster Fullerene

A special class of three-dimensional polymeric allotropic structures of carbon, specifically the $C_{60}$ allotrope formed of 12 pentagons and 20 hexagons, often called a 'bucky ball.'

Isomerism

The phenomenon where organic compounds have the same molecular formula but different structural formulae resulting in different physical and chemical properties.

Polymerization

The chemical reaction by which a large number of organic molecules, especially unsaturated ones (monomers), combine to form a big molecule (polymer).

Sigma ($\sigma$) bond

A covalent bond formed by the head-to-head overlapping of two atomic orbitals along their axis, allowing for free rotation.

Pi ($\pi$) bond

A weaker covalent bond formed by the lateral or side-wise partial overlapping of two parallel unpaired p-orbitals after a sigma bond has already formed.

Hybridization

The process of mixing orbitals of different energy to equalize their energy and form an equal number of new orbitals known as hybrid orbitals.

$sp^{3}$-hybridization

Mixing one s-orbital and three p-orbitals to form four equivalent hybrid orbitals directed toward the corners of a tetrahedron with bond angles of $109.5^{\circ}$.

$sp^{2}$-hybridization

Mixing one s-orbital and two p-orbitals to form three hybrid orbitals on a plane with bond angles of $120^{\circ}$, typically found in alkenes like ethene.

$sp$-hybridization

Mixing one s-orbital and one p-orbital to form two new linear hybrid orbitals with bond angles of $180^{\circ}$, found in alkynes like ethyne.

Functional Group

An atom or group of atoms within a molecule that has a characteristic chemical behavior and undergoes the same kind of reactions in every molecule of a homologous series.

Metamerism

A type of structural isomerism that arises due to the difference in alkyl groups attached to the same divalent functional group, commonly seen in ethers and ketones.

Tautomerism

A special functional group isomerism where a compound with a particular functional group spontaneously changes its structure into another in dynamic equilibrium, such as keto-enol tautomerism.

Geometrical Isomerism

Stereoisomerism arising from restricted rotation around a carbon-carbon double bond, resulting in cis (same side) and trans (opposite side) configurations.

Chiral Centre

A carbon atom attached to four different atoms or groups, also called an asymmetric carbon, which allows for optical activity.

Racemic Mixture

An equimolar mixture of two optically active enantiomers (dextrorotatory and levorotatory) that is optically inactive due to mutual nullification of their rotatory power.

Meso Isomer

An optically inactive isomer containing similar chiral centers and an internal plane of symmetry that causes internal compensation of optical activity.

Huckel Rule

The rule stating that for a cyclic, planar compound to be aromatic, it must contain $(4n + 2) \pi$ delocalized electrons, where $n$ is a non-negative integer.

Electrophile

Electron-loving attacking reagents that are short of electrons and accept an electron-pair to form a new bond, such as $H^{+}$, $NO_{2}^{+}$, or $AlCl_{3}$.

Nucleophile

Nucleus-loving reagents that have at least one lone pair of electrons to supply to an electron-deficient substrate, such as $CN^{-}$, $OH^{-}$, or $NH_{3}$.

Markovnikov's Rule

In the addition of an unsymmetrical reagent to an unsymmetrical alkene, the negative part of the reagent adds to the carbon atom of the double bond with fewer hydrogen atoms.

Anti-Markovnikov's Rule

Also known as the Kharasch peroxide effect, it states that in the presence of organic peroxides, the negative part of $HBr$ adds to the double-bonded carbon with more hydrogen atoms.

Ozonolysis

The reaction of ozone with unsaturated hydrocarbons to form an ozonide which is then hydrolyzed to identify the position of double or triple bonds in a carbon chain.

Aldol Condensation

The self-condensation of aldehydes or ketones containing alpha ($\alpha$) hydrogen in the presence of dilute alkali to form $\beta$-hydroxy aldehydes or ketones.

Cannizzaro's Reaction

A disproportionation reaction of aldehydes lacking $\alpha$-hydrogen (e.g., formaldehyde) in the presence of concentrated alkali to produce an alcohol and a carboxylic acid salt.

$S_{N}1$ Reaction

Unimolecular nucleophilic substitution where the reaction rate depends on the concentration of only one reactant (the alkyl halide), typically occurring in two steps through a carbocation intermediate.

$S_{N}2$ Reaction

Bimolecular nucleophilic substitution where the reaction rate depends on both the alkyl halide and the nucleophile, occurring in one step through a transition state.

Saytzeff's Rule

In the elimination of water or $HX$ from secondary alcohols or alkyl halides, the major product is the more substituted (more branched) alkene.

Nitroglycerin

Glyceryl trinitrate, a colourless oily liquid used to make dynamite and as a medicine for heart conditions like angina pectoris.

TNT

2,4,6-Trinitro toluene, a powerful solid explosive used in military applications that explodes with a detonator rather than simple vibration.

Dettol

A commercial antiseptic brand whose active ingredient is 4-Chloro-3, 5-dimethyl phenol (also called chloro-xylenol).

Paracetamol

N-(4-hydroxy phenyl) ethanamide, a phenolic ester drug used as an antipyretic (fever reducer) and analgesic (painkiller).

Thermoplastic Polymer

Polymers with few cross-links that soften and melt upon heating and solidify on cooling, allowing them to be remoulded multiple times (e.g., polythene).

Thermoset Plastic

Cross-linked complex polymers that can be moulded only once and cannot be remelted by heating (e.g., bakelite, melamine).

Glycoside Bond

The divalent $C-O-C$ bond formed between two monosaccharide molecules, such as the $\alpha$-glycoside bond in starch or the $\beta$-glycoside bond in cellulose.

Peptide Bond

The amide bond ($-CONH-$) formed between the carboxyl group of one amino acid and the amino group of another with the elimination of water.

Zwitter ion

A dipolar ion of an amino acid containing both a positive charge ($-NH_{3}^{+}$) and a negative charge ($-COO^{-}$) at its ends, making it soluble in water.