Organic Separation Techniques (5/15) Flashcards
Extraction
Separates liquid mixtures by partitioning compounds between two liquid phases organic and aqueous phase (polar)
Separating solutes
solutes with similar traits will separate based on density
Can also give one of the molecules a charge, if possible, to put it into the aqueous phase
Determining if a molecular will go to organic layer (is nonpolar)
Molecules with one polar group for every 5 carbons is non-polar
Extracting using acid-base properties
adding a strong acid to an organic phase will allow it to go to aqueous
or adding a base to an acid so it becomes negative and goes to aqueous
If we have two acids
can be separated by adding a weak base and it will deprotonate the stronger acid so it can go to aqueous layer
Volatile substances
easily transitions from liquid to the gas phase
Distillation
process to separate liquids by boiling point, volatility, and vapor pressure
Vapor pressure
pressure exerted by molecules entering gas phase
pressure increases as temperature increases
pressure increases if more volatile (lower boiling point, more easily boiled)
Volatility
polar= hydrogen bonding and have a higher boiling point size= larger means higher boiling point
Simple distillation
separates liquids with boiling points 25 C apart or more (very different boiling points)
Fractional distillation
can separate liquids with closer boiling points
How does fractional distillation separate?
increases vertical distance vapor travels
allows liquids to re-condense or re-vaporize
Unsure of being able to reach high boiling point
lower pressure with vacuum distillation so liquids boil at a lower temperature
Polar compounds and vapor pressure
have a lower vapor pressure
TLC
usually has a nonpolar mobile phase so nonpolar travels further than polar
Retention factor
Rf value
Column chromatography
Separates components of a mixture based on size
large goes first
Ion exchange
electrostatic interactions
Cation: negative charge stationary phase (traps positive molecules)
Anion: positive charge stationary phase (traps negative charge molecules)
Affinity
ligands designed to bind specific compound sticks
Gas liquid chromatography
gas: stationary phase
High performance liquid chromatography
uses extremely high pressures
nonpolar moves faster
reverse phase: polar moves faster because mobile phase is polar
Recrystallization
making more pure
soluble at high temperature and insoluble at lower temperatures
Nucleation
a tiny crystal initiates crystallization process. if slow, scratch side of glass
