6.3 Flashcards
order ketones+aldehydes, COOHs, alcohols, and esters most to least polar.
COOHs, alcohols, ketones+aldehydes, esters
how does TLC work?
adsorption
what state is the stationary phase in TLC?
solid
in tlc what do you end up with?
spots that have moved up the plate
in gas chromatography what state is the stationary phase?
liquid
how does gas chromatography work?
relative solubility
what does area of peak show in gas chromatography?
amount of compound
which elements have the shortest retention time in gas chromatography?
ones which bind best to the mobile phase.
what are the problems with chromatography?
similar compounds have similar rf values/retention times
if new compounds are discovered they can’t be identified by comparing value to database.
what do you do to be able to know the concentrations of compounds in a sample of gas chromatography?
run calibration curves to find area of known concentrations.
WHAT IS THE MAIN PEAK ON A MASS SPECTRUM THAT SHOWS THE MR PEAK CALLED
THE MOLECULAR ION PEAK
WHAT IS THE PEAK THATS ONE AFTER THE MR PEAK CALLED
THE M+1 PEAK
INSTEAD OF SAYING THE ‘POSITION’ OF NMR PEAKS SAY THE…
CHEMICAL SHIFT VALUE
WHAT IS THE BASE PEAK IN MASS SPECTROMETRY
peak with the greatest (relative) intensity /
peak representing most stable/abundant fragment.
NOT the tallest / biggest / most common peak!!
WHY MIGHT THE MOLECULAR ION PEAK NOT BE SEEN ON A MASS SPECTRUM
The molecular ion is too unstable / will have been
completely fragmented / may not carry a positive charge. cant say theres too little of it!!
