Organic Chemistry 12: Separations and Purifications

A/an [...] combines two immiscible liquids, one of which easily dissolves the compound of interest

extraction

In an extraction, the [polar or nonpolar] layer is the organic layer and dissolves nonpolar compounds

nonpolar

In an extraction, the [polar or nonpolar] layer is the aqueous (water) layer and dissolves compounds with hydrogen bonding or polarity

polar

A/an [...] is the reverse of an extraction. A small amount of solute that dissolves impurities is run over the compound of interest

wash

During a filtration, a solid, also known as the [...], is isolated from a liquid, also known as the [...]

residue

filtrate

[... filtration] can be used to collect solid product, although generally [... filtration] is used for this purpose because it is faster

gravity filtration

vacuum filtration

[...], also known as [...], is a procedure for purifying an impure compound in a solvent

recrystallization

fractional crystallization

• - an impure compound is dissolved to prepare a highly concentrated solution at a high temperature

• the solution is cooled

• decreasing the temperature cause the solubility of the impurities in the solution and the substance being purified to creaceas

• the impure substance then crystallized before the impurfires -assuming that there was impure substance there were imprttutes

Chromatography is a laboratory technique for the separation of a mixture based on [...]

how fast each component travels through a structure

• the mixture is dissolved in a fluid called the mobile phase which carries it through a structure another material called the stationary phase

• the various constituents of the mixture travel at different speeds causing them to separate

In chromatography, the stationary phase is typically [...] and this causes [...] molecules to elute slower

polar and polar

In chromatography, the mobile phase is typically [...] and this causes [...] molecules to elute faster

nonpolar

In a typical thin-layer chromatography setup, the spot that moves farthest is the [...] substance and the spot that moves the shortest distance is the [...] substance

nonpolar and polar

the stationary phase is typically silica gel which is polar

In liquid chromatography, [...] is a common stationary phase while [...] or another nonpolar liquid is used as the mobile phase

silica

tuluence

[... chromatography] relies on pumps to pass a pressurized liquid solvent containing the sample mixture through a column filled with a solid adsorbent material

high-performance liquid chromatography

• this gives HPLC higher resolving power

In gas chromatography, the liquid sample is vaporized before separation. Molecules are separated based on their [...] and [...]

polarity and boiling point

• the stationary phase is a thin layer of material applied to the inside of the column

• typically the polarity if the stationary phase matches that of the solute

• the mobile phase is an entry gase

Gel-filtration chromatography separates molecules based on their [...]

size

also known as size-exclusion chromatography

smaller molecules enter the porous gel beads causing them to elute slower

larger molecules do. not fit in the pores so they elute faster

In size-exclusion chromatography, large molecules will elute [first or last]

first

• larger molecules do not fit in the pores so they elute faster

• smaller molecules enter the porous gel beads causing them to elute later

Ion exchange chromatography separates proteins by their [...]

net charge

• the column is filled with charged beads: either positivity or negativity charged

• cation exchange; negatively charged beads: negatively charged proteins elute first

• anion exchange: positively charged beads positively charged proteins elute first

In anion exchange chromatography, the beads are [positively or negatively] charged and this causes [positively or negatively] charged proteins to elute first

postivitely, positivity

In cation exchange chromatography, the beads are [positively or negatively] charged and this causes [positively or negatively] charged proteins to elute first

negativity

Affinity chromatography separates proteins based on [...]

their affinity for a specific ligand

• beads are bound to a specific ligand and proteins with a high affinity for that ligand will bond to the breads

• proteins with a low affinity for the ligand will elute first

In a typical thin-layer chromatography setup, the stationary phase is made up of [substance] which is [polar or nonpolar]

silica gel which is polar

• polar molecules are slowed by the stationary phase, nonpolar molecules are repelled by the stationary phase and elute first

The retention factor in thin-layer chromatography is:

R_f = [...]

A distillation separates liquids according to differences in their [...]

boiling points

• the liquid with the lowest BP vaporizes first and its collected as the distillate

Simple distillation can be used if the boiling points are under 150°C and are at least [#°C] apart

25 °C

Vacuum distillation should be used if the boiling points are over 150°C to prevent degradation of the product. The vacuum [...], which decreases the BP of the liquid

lowers the air pressure

Fractional distillation is a process by which components in a mixture are separated into different parts (called fractions) according to their different [...]

boiling points.