TLC Flashcards
What is the MP?
a volatile liquid, which is drawn up by capillary action
What are common MP?
chloroform, toluene, acetic acid, methanol and small amount of water
What are the types of detectors used?
UV light, iodine chamber, chemical stain
What are common SP?
silica gel, alumina, polyamides, cellulose
What are the advantages of TLC?
costs, and a good technique for purity check
What are the categories of commercial plates?
Thick layer silica gel - (200-500 um) dp ~ 20um N~2000
Thin layer silica gel -(100 um) dp~20um N~4000
What is RF?
x/y range of {0 - 0.99}
More polar compounds equal _________
smaller RF values
Less polar compounds equals _________
larger RF values
What is Rs?
2(Z2 - Z1)/[w1 + w2]
Rs > 1 much better separation
What is the relationship between polarity and the MP?
more polar solvents displace substrates from stationary phase more easily than less polar solvents
more polar the MP the faster the substrate travels
can increase polarity to point where there is no separation
What must be considered when prediction elution order?
polarity of each compound in the mixture
polarity of the stationary phase
polarity of the mobile phase
What are some other advantages to TLC?
simultaneous analysis and separation
solute movement is always observable
What is the order of polarity for solvents (least to most)?
hexane carbon tetrachloride toluene chloroform diethyl ether ethyl acetate methanol acetic acid water
What is the order of polarity for substrates (least to most)?
alkanes alkenes ethers alkyl halides aromatics aldehydes and ketones alcohols amines organic acids salts
