Organic Chemistry Ch 12. Separations and Purifications

Question 1

Extraction

Answer 1

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

Question 2

Aqueous phase

Answer 2

Polar (Water) layer in extraction, dissolves compounds with hydrogen bonding or polarity

Question 3

Organic phase

Answer 3

Nonpolar that dissolves nonpolar compounds

Question 4

Wash

Answer 4

Reverse of extraction, in which small amounts of solute that dissolves impurities is run over the compound of interest

Question 5

Filtration

Answer 5

Isolates a solid from a liquid

Question 6

Residue

Answer 6

Solid in filtration

Question 7

Filtrate

Answer 7

Liquid in filtration

Question 8

Gravity filtration

Answer 8

Used when the product of interest is in the silgrate, hot solvent is used to maintain solubility

Question 9

Vacuum filtration

Answer 9

Used when the product of interest is the solid, a vacuum is connected to the flask to pull the solvent through more quickly

Question 10

Recrystallization

Answer 10

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

Question 11

Distillation

Answer 11

Separates liquids according to differences in their boiling points, the liquid with the lowest boiling point vaporizes first and is collected as the distillate

Question 12

Distillate

Answer 12

The liquid with the lowest boiling point that vaporizes first in distillation

Question 13

Simple distillation

Answer 13

Can be used in the boiling points are under 150C and are at least 25C apart

Question 14

Vacuum distillation

Answer 14

Should be used if the boiling points are over 150C to prevent degradation of the product

Question 15

Fractional distillation

Answer 15

Should be used if the boiling points are less than 25C apart because it allows more refined separation of liquids by boiling points

Question 16

Chromatography

Answer 16

Use two phases to separate compounds based on physical or chemical properties

Question 17

Stationary phase

Answer 17

aka absorbent, usually a polar solid

Question 18

Mobile phase

Answer 18

Runs through the stationary phase and is usually in a liquid or a gas, elutes the sample through the stationary fan

Question 19

Compounds with higher affinity for stationary phase

Answer 19

Have smaller retardation factors and take longer to pass through

Question 20

Compounds with higher affinity for mobile phase

Answer 20

Elute through more quickly

Question 21

Partitioning

Answer 21

When compounds with varying affinities for stationary/mobile phases get separated from each other during chromatography

Question 22

Thin layer and paper chromatography

Answer 22

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

Question 23

Reverse phase chromatography

Answer 23

Uses a nonpolar card with a polar solvent

Question 24

Column chromatography

Answer 24

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

Question 25

Ion exchange chromatography

Answer 25

Beads are coated with charged substances to bend to compounds with opposite charge

Question 26

Size-exclusion chromatography

Answer 26

The beads have small pores which trap smaller compounds and allow larger compounds to travel through faster

Question 27

Affinity chromatography

Answer 27

Column is made to have higher affinity for a compound by coating the beads with a receptor or antibody to the compound

Question 28

Gas chromatography

Answer 28

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

Question 29

Mass spectrometry

Answer 29

Ionizes and fragments molecules and passes these gradients through a magnetic field to determine molecular weight or structure

Question 30

High-performance liquid chromatography (HPLC)

Answer 30

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