WM - Organic Analysis Flashcards
what does a mass spectrometer detect?
the mass:charge ratio of molecular ion
this gives the molecular mass off compound
how are molecular ions formed in mass spec?
electron is lost to form a positive ion
what does the m+ represent on mass spec?
the molecular mass of ion
(molecular peak)
what causes the M+1 peak?
carbon is represented as the carbon- 13 isotope
what is fragmentation?
the molecular peak breaks down into smaller pieces = fragmentation
what causes the other peaks in the mass spectrum?
fragmented ions
how can a mass spec differentiate between structural isomers?
they will break apart differently = having different mass spectra
what is IR spectroscopy?
analysis that shows how different groups in a molecule absorb IR
what is unique about each bond when absorbing IR radiation?
they can only absorb radiation that has the same frequency at the natural frequency of the bond
how does infrared spectroscopy work?
sample placed inside an IR spectrometer,
beam of IR radiation in range 200/cm to 4000/cm passed through the sample
molecule absorbs some of the IR frequencies and the emerging beam is analysed to find the absorbed frequencies.
what is the term given to the dips in the graph?
peaks
what do the peaks represent?
the bond types in the molecule
What is below 1500/cm known as on the IR spectrum and why?
Fingerprint region
the peaks in this region are unique for every compound
what are ‘rouge’ absorptions an indication of?
impurities
