Metal oxidizing agents L1 Flashcards
Oxidation
Loss of H2
primary alcohol to aldehyde
Reduction
Aldehyde to alcohol
Gain of H2
Examples of readily available oxidizing agents
KMnO4
CrO3
Na2Cr2O7
What are drawbacks of readily available oxidizing agents?
Toxicity
Lack of selectivity - some things may be oxidised when you dont want them to be
What is Jones oxidation?
Oxidation with Na2Cr2O7 and H2SO4 in acetone (Jones reagent)
Why is acetone important in the Jones oxidation?
Modifies the reactivity of the chromium, making it less reactive and therefore less selective
Limitations of the Jones oxidation?
Over oxidation - keep oxidising until the carboxylic acid
Strong acid - cant be used on acid sensitive substrates
Toxicity of chromium
Aqueous based - need to try and eliminate the water
What is PDD?
Pyridinium chlorochromate
Still quite acidic as a chromium reagent
What is PDC?
Pyridinium dichromate
More mild than the jones reagent
What are the issues with chromium reagents?
Hard to separate chromium residues from product
Cr is highly toxic - not suitable for use in pharmaceuticals
Cr-containing waste is produced
Expensive (esp for PDD and PCC) on a large scale and a lot of metal is needed for stoichiometric amounts
What is TPAP?
Tetrapropylammonium perruthenate
What is TPAP?
Tetrapropylammonium perruthenate
Mild oxidising agent which uses catalytic amounts of metal
What is the driving force for oxidations with TPAP?
The reduction of Ru (VII) to Ru (V)
What are the limitations of using TPAP?
Expensive
Limited to small scale use
What is the role of NMO with TPAP?
It is a co-oxidant in the oxidation reaction
N-methylmorpholine N-oxide
