Organic Analysis Flashcards
as chem
Describe how to test for alcohols?
Using acidified potassium dichromate which oxidises primary and secondary alcohol but not tertiary alcohols.
Turns from orange to green.
To further test to see if its either primary or secondary you test through fractional distillation to see if ketone or aldehyde is produced.
When testing for aldehydes and ketones what must be done?
You need to add the chosen solution warm (fehlings/tollens)- using a warm waterbath.
How is tollens reagent made?
Using silver nitrate solution add a few drops of NAOH and add a few drops of dilute ammonia until precipitate dissolves.
How to test for alkenes?
React alkene with bromine water .
results:
orange to colourless solution
How to test for carboxylic acids.
Add carbonate to potential carboxylic acid fizzing should occur as co2 produced.
How do you determine the MR of a compound?
Identify the M+1 peak or molecular ion peak. This is the same as the MR of molecule
Why is high resolution mass spectrometry used?
To identify different molecules with the same molecular mass rounded to the nearest whole number.
It can measure the MR to a several decimal places.
What does the frequency of infrared radiation absorbed by a covalent bond depend on?
1) The atoms that are either side of the bond
2) The position of the bond in the molecule
Describe the fingerprint region of infrared spectroscopy..
The fingerprint region lies between 500cm-‘ and 1500cm-1.
Like a real fingerprint, the size and position of the peaks are unique to a particular molecule.
This can be used to compare to a known library of spectra to identify the molecule.
What’s the link between infrared and global warming.
Electromagnetic radiation from the sun reaches the Earth and is absorbed by land and sea. Some of this radiation is re-emitted as infrared.
These greenhouse gases absorb this radiation and re-emit this back towards the Earth. We call this the GREENHOUSE EFFECT It is actually the covalent bonds that absorb this radiation.
The gradual warming of the earth is called global warming.
