Introduction to Organic Chemistry and Purification Methods

Flashcards covering the fundamentals of organic chemistry, including molecular geometry, macromolecules, purity testing, and various purification techniques such as distillation and chromatography.

Organic Chemistry

The scientific study of carbon compounds and the reactions they undergo, excluding exceptions such as $Na_2CO_3$, $KCN$, and $CO_2$.

Catenation

The ability of Group 4 elements (C, Si, Ge, Sn, Pb) to form chains with themselves; this ability decreases down the group.

Tetrahedral geometry

The molecular geometry formed when four atoms or groups are attached to a carbon atom, resulting in a bond angle of $109.5^\circ$.

Trigonal planar geometry

The molecular geometry formed when three atoms or groups are attached to a carbon atom, resulting in a bond angle of $120^\circ$.

Linear geometry

The molecular geometry formed when two atoms or groups are attached to a carbon atom, resulting in a bond angle of $180^\circ$.

Formic acid ($HCOOH$)

The simplest of the organic acids found in the stings of red ants, bees, and some plants.

Ethylene

The gas responsible for ripening fruit; it is emitted by ripe fruit and can act on unripe fruit.

Macromolecule

A combination of many small but similar molecules polymerized into a chain structure.

Proteins

Macromolecules that are polymers of amino acids.

Carbohydrates (Saccharides)

Molecular compounds made from carbon, hydrogen, and oxygen; includes simple sugars like monosaccharides (glucose) and disaccharides (sucrose).

Nucleic acids

Macromolecules, including DNA and RNA, which are made from monomers known as nucleotides.

Metabolism

The process of breaking down macromolecules (to release energy) or building them up (requiring energy).

Melting Point Purity Rule

A pure solid will melt reproducibly over a narrow range (usually less than $1^\circ C$); impurities lower the melting point and widen the range.

Boiling Point

The temperature at which the vapor pressure of a liquid equals the atmospheric pressure; used to characterize organic liquids but is less affected by impurities.

Refractive Index ($n$)

A wave-dependent value representing the ratio of the velocity of light in a vacuum to the velocity in a sample, calculated as $n = \frac{\sin(\phi)}{\sin(\phi_1)}$.

Thin Layer Chromatography (TLC)

A technique using a stationary phase (Silica or Alumina) and a mobile phase (Solvents) to separate mixtures and follow reaction progress.

$R_f$ value

A measure of the distance traveled by a substance relative to the solvent in chromatography, calculated as $R_f = \frac{\text{distance travelled by substance}}{\text{distance travelled by solvent}}$.

Distillation

The process of separating substances from liquid mixtures by selective evaporation and condensation.

Simple Distillation

A method most effective when the boiling points of the samples are widely different, specifically greater than $30^\circ C$ to $40^\circ C$.

Fractional Distillation

A process used when boiling points are close ($< 30^\circ C - 40^\circ C$), using a fractionating column to provide repeated vaporization-condensation cycles.

Vacuum Distillation

Distillation performed under reduced pressure to lower boiling points, used for air-sensitive compounds or those with high boiling points that might decompose upon heating.

Steam Distillation

A technique used for heat-sensitive compounds nearly immiscible with water, where the mixture boils at a temperature lower than either pure component.

Recrystallization

A purification method for solids where a compound is dissolved in a hot solvent and precipitates out as crystals when cooled, while impurities remain in the solvent.

Sublimation

The process of separating molecules that can interconvert between the solid and gaseous states without passing through the liquid phase.

Soxhlet extractor

An instrument used for solid-liquid extraction that recycles small amounts of solvent to extract large amounts of material using a thimble and siphon system.

Partition coefficient ($K$)

A constant defining the relative amounts of a compound in two immiscible phases at equilibrium, expressed as $K = \frac{C_o}{C_w}$.