Organic analysis Flashcards
How to test for primary, secondary or tertiary alcohol
Add 10 drops of the alcohol to 2cm cubed of potassium dichromate and warm the mixture ina. water bath and wait for a color change
Primary- orange to green - aldehyde forms
secondary- orange to green - ketone
forms
tertiary- nothing happens
How to distinguish between primary and secondary (collecting product)
Add excess alcohol to 2cm cubed potassium dichromate in a flask
Heat the flask and collect the oxidised and distilled alcohol and test to see if it an aldehyde or ketone
How to test for aldehyde or ketone
Fehlings/ Benedict’s
Add 2cm cubes of F/B to a test tube and 5 drops of the aldehyde or ketone and put it in a hot water bath for a few minutes
Aldehyde should give a red precipitate and ketones should not change the colour
How to use tollens reagent for aldehyde or ketone
Put 2cm cubes of 0.10 mol dm cubed silver nitrate solution in a test tube
Add a few drops of dilute sodium hydroxide and a light brown color should form
Add a few drops of dilute ammonia solution untill the brown precipitate dissolves
Place in a hot water bath and add 10 drops of the aldehyde or ketone and wait a few minutes
Aldehyde should give a silver mirror on the walls of the test tube and with a ketone nothing happens
Test for carboxylic acids
Add 2cm cubes of the solution to a tube
Add one small spatula of solid sodium carbonate and if the solution fizzes bubble tthe gas through limewater
If a carboxylic acids is present the solution will fizz and the carbon dioxide gas produces will turn the limewater cloudy
What can high resolution mass spectrometry be used for
To measure atomic and molecular masses extremely accurately for identifying compounds that have the same Mr when rounded to the nearest whole number
What happens in infared spectroscopy
A beam of IR radiation is passed through a sample of a chemical and is absorbed by covanlent bonds increasing vibrational energy
What is another use of infared spectroscopy
To find out how pure a compound is and see any impurities as impurities produce extra peaks in fingerprint region( 500-1500)
