Organic Chemistry Ch 12. Separations and Purifications Flashcards
Extraction
Combines two immiscible liquids, one of which easily dissolves the compound of interest, carried out in a separators funnel, one phase is collected and the solvent is then evaporated, acid base properties can be used to increase solubility
Aqueous phase
Polar (Water) layer in extraction, dissolves compounds with hydrogen bonding or polarity
Organic phase
Nonpolar that dissolves nonpolar compounds
Wash
Reverse of extraction, in which small amounts of solute that dissolves impurities is run over the compound of interest
Filtration
Isolates a solid from a liquid
Residue
Solid in filtration
Filtrate
Liquid in filtration
Gravity filtration
Used when the product of interest is in the silgrate, hot solvent is used to maintain solubility
Vacuum filtration
Used when the product of interest is the solid, a vacuum is connected to the flask to pull the solvent through more quickly
Recrystallization
The product is dissolved in a minimum amount of hot solvent, if the impurities are more soluble, the crystals will reform while the flask cools, excluding the impurities
Distillation
Separates liquids according to differences in their boiling points, the liquid with the lowest boiling point vaporizes first and is collected as the distillate
Distillate
The liquid with the lowest boiling point that vaporizes first in distillation
Simple distillation
Can be used in the boiling points are under 150C and are at least 25C apart
Vacuum distillation
Should be used if the boiling points are over 150C to prevent degradation of the product
Fractional distillation
Should be used if the boiling points are less than 25C apart because it allows more refined separation of liquids by boiling points
Chromatography
Use two phases to separate compounds based on physical or chemical properties
Stationary phase
aka absorbent, usually a polar solid
Mobile phase
Runs through the stationary phase and is usually in a liquid or a gas, elutes the sample through the stationary fan
Compounds with higher affinity for stationary phase
Have smaller retardation factors and take longer to pass through
Compounds with higher affinity for mobile phase
Elute through more quickly
Partitioning
When compounds with varying affinities for stationary/mobile phases get separated from each other during chromatography
Thin layer and paper chromatography
Used to identify a sample, stationary phase is a polar material such as silica, alumina, or paper, mobile phase is a nonpolar solvent which climbs the card through capillary action, the card is spotted and developed Rf values can be calculated and compared to reference values
Reverse phase chromatography
Uses a nonpolar card with a polar solvent
Column chromatography
Utilizes polarity, size, or affinity to separate compounds based on their physical or chemical properties, stationary phase is a column containing silica or alumina beads, the mobile phase is a nonpolar solvent which travels through the column via gravity
Ion exchange chromatography
Beads are coated with charged substances to bend to compounds with opposite charge
Size-exclusion chromatography
The beads have small pores which trap smaller compounds and allow larger compounds to travel through faster
Affinity chromatography
Column is made to have higher affinity for a compound by coating the beads with a receptor or antibody to the compound
Gas chromatography
Separates vaporizable compounds according to how well they adhere to the absorbent in the column, the stationary phase is a coil of crushed metal or a polymer, the mobile phase is a nonreactive gas, may be combined in sequence with mass sepctrometry
Mass spectrometry
Ionizes and fragments molecules and passes these gradients through a magnetic field to determine molecular weight or structure
High-performance liquid chromatography (HPLC)
Similar to column chromatography but uses sophisticated computed mediated solvent and temperature gradients, used if the sample size is small or if forces such as capillary action will affect results, formerly called high pressure liquid chromatography
