Organic Analysis & Structure Determination Flashcards
What is the test for sulphate ions?
Barium chloride solution acidified with dilute hydrochloric acid.
(BaCl2/HCl)
What is the test for distinguishing between 1°/2° alcohols and 3° alcohols?
Test: acidified postassium dichromate (VI) (K2Cr2O7/H2SO4)
- 1°/2°orange to green
- 3° no visible change
What are the following alcohols oxidised to:
- 1°
- 2°
- 3°
- 1° Aldehyde then carboxylic acid
- 2° Ketone
- 3° Isn’t oxidised
How can aldehydes and ketones be distinguished from one another?
Tollen’s Reagent [diamminesilver (I)]:
- Aldehyde: Silver mirror
- Ketone: No visible change
OR
Fehling’s solution:
- Aldehyde: Brick red precipitate
- Ketone: No visible change
How can halide ions in solution be distinguished?
Test: acidified silver nitrate (AgNO3/HNO3)
- F- - no precipitate
- Cl- - white precipitate
- Br- - cream precipitate
- I- - yellow precipitate
How can isomer X be identified using its infrared spectra?
Compare the fingerprint region
Match with a known sample from a database of spectra
Why does bromine react with the double bond in an alkene?
The double bond is a region of high electron density It induces a dipole in the bromine molecule
(repels electrons in the bromine)
How could liquid X be purified?
Fractional distillation
OR
Column chromatography
What is the test for an alkene?
Add bromine water (Br2(aq))
Decolourises in presence of an alkene (orange to colourless)
What is the test for haloalkanes?
Add NaOH and warm
Acidify with HNO3 and add AgNO3
The relevant coloured precipitate will form (depends on halogen)
What is the test for carboxlic acids?
Add NaHCO3
Effervesces
What is the test for acyl chlorides?
Add AgNO3(aq)
A white precipitate will form
What is represented by the peak of highest abundance on a mass spectra?
The most stable fragment
What is the fragmentation equation of a molecular ion?
M+• → X+ + Y•
Which irons are most stable?
Tertiary carbocations
The acylium ion [R-C=O]+
