Purification and Characterization of Organic Compounds

This flashcard set covers the methods of purification (filtration, solvent extraction, distillation, chromatography, recrystallization) and characterization (melting point, boiling point, TLC) of organic compounds as described in the lecture notes.

Purification of Organic Compounds

The process of isolating desired products in a pure state from reaction mixtures that typically contain unreacted starting materials, side products, and solvents.

Reaction Filtration

Simple filtration accelerated by applying pressure through a water pump using a Büchner funnel inserted into a suction flask.

Solvent Extraction

An indirect isolation technique based on the distribution of a solute between two immiscible solvents based on their relative polarities.

Distribution Coefficient ($K_D$)

The constant ratio of a solute's concentration in two solvents at a given temperature, expressed as $K_D = \frac{C_1}{C_2}$.

Separating Funnel

Apparatus used in solvent extraction where two immiscible layers separate; the lower layer is run out by opening a stop-cock.

Steam Distillation

A technique for separating steam volatile compounds from non-volatile components at a temperature lower than the normal boiling point to prevent decomposition.

Chromatography

A modern separation technique based on the distribution of substances between a stationary phase and a mobile phase.

Stationary Phase

The fixed phase in chromatography, which can be a solid (like alumina or silica gel), a liquid, or a gas.

Mobile Phase

The phase that moves through the stationary phase in chromatography, usually a solvent or gas, carrying components of a mixture.

Adsorption Phenomenon

The basis for separation in chromatography when the stationary phase is a solid material like alumina ($Al_2O_3$) or silica gel ($SiO_2$).

Partition Phenomenon

The basis for separation in chromatography when the stationary phase used is a liquid or a gas.

Elution

The process of a mobile phase solvent running through a column or plate to carry and separate components based on their distribution coefficients.

Sublimation

The phenomenon where a solid (e.g., iodine) changes directly into a gas without passing through a liquid phase upon heating.

Distillation

The conventional method for isolating a liquid product from another liquid based on its definite boiling point at a given pressure.

Boiling Point

The temperature at a given pressure where a liquid and gas are in equilibrium and the free energy of the phase change is zero.

Fractional Distillation

A distillation method involving a fractionating column to separate liquids with different boiling points by collecting fractions at steady temperatures.

Recrystallization

A purification technique for solids based on differences in solubility in a hot versus cold solvent.

Animal Charcoal

A material used at $1 - 2\%$ by weight to remove coloured impurities from a crude product solution during crystallization.

Melting Point

The temperature at which a solid changes into a liquid under one atmosphere of pressure; pure substances usually melt within a sharp $2^\circ\text{C}$ range.

Thin Layer Chromatography (TLC)

A characterization technique where a sample is spotted on an adsorbent glass plate and developed in a mobile phase to identify compounds or monitor reactions.

Retention Factor ($R_f$)

The ratio calculated as the distance traveled by a spot from the origin divided by the distance traveled by the solvent from the origin.

Visualization

Methods to locate colorless compounds on a TLC plate, such as using ultraviolet light, iodine vapor (reversible association), or reagents like concentrated $H_2SO_4$.