Organic Analysis Flashcards
What is the test and observation for an Alkene?
Bromine water
obs> orange to colourless
What is the test and observation for a 1°/2° Alcohol?
acidified potassium dichromate (K2Cr2O7)
obs> orange to green
What are the tests and observations for an Aldehyde?
Tollens reagent
obs> silver mirror
Fehlings reagent
obs> brick red ppt
What are the tests and observations for a carboxylic acid?
Sodium Carbonate (Na2CO3)
obs> effervescence
Sodium Bicarbonate
obs> effervescence
What is the Mr of the sample in electron impact?
the peak with the greatest m/z value
What is the Mr of the sample in electrospray?
the peak with the greatest m/z value minus 1
What is a high resolution mass?
masses to 4/5 decimal places
e.g O= 15.99491
What is the function of Infra-red spectroscopy?
used to identify the type of bonds in a compound
How does infrared spectroscopy work?
- each bond vibrates at the same frequency as IR
- frequency depends on ; mass of atoms in the bond; bond strength; type of vibration
- observing which frequencies of radiation are absorbed allows bonds to be identified
What happenes in a IR spectrometer
- beam of IR radiation containing a spread of frequencies is passed thru sample
- bonds in a molecule absorb IR at wave numbers
- the radiation that emerges is missing the frequencies that were absorbed by bonds
- graph is plotted of the transmittance against frequency of radiation
- frequency is expressed as a wave number(cm-1)
What is the fingerprint region?
area of an IR spectrum below 1500cm-1
shape is unique for a particular substance
How can IR be used to find impurities?
by revealing absorptions that shouldnt be in the pure compound
What are the greenhouse gases?
water vapour
carbon dioxide
methane
What do greenhouse gases do?
absorb radiation from the sun and eventually re-emit this as long wavelength radiation that increases the earths temperature
What do the best greenhouse gases do?
absorb the most infrared radiation
and trap heat in the earths atmosphere
