Chapter 26 key Concepts Flashcards
Uses of Propanone
The simplest ketone it’s aka acetone
Important industrial solvent
Used in nail polish remover
Uses of methanal
The simplest aldehyde
Used to preserve biological specimens (formaldehyde)
Ketones vs Aldehyde
Ketones
-nah undergo oxidation
Aldehyde
-can be oxidised to make Carboxylic Acid
Carbonyls vs Alkenes
Both have double bond
But ALKENE IS C DOUBLE BOND C
-non polar
-reacts with electrophiles in electrophillic addition
CARBONYL IS C DOUBLE BOND O
- polar
- therefore reacts with nucleophiles in nucleophillic addition
Nucleophile
Electron pair donator
Why do carbonyls undergo nucleophillic addiction?
Because carbon in the C DOUBLE BOND O is electron deficient
And the molecule is unsaturated
What is 2,4-DNP/2,4-DNPH and what is it used for?
*usually 24DNP is dissolved in methanol and sulphuric acid as a pale solution called Brady’s reagent
Used to identify the presence of a carbonyl functional group in aldehydes and ketones
In the presence of a carbonyl group the solution goes from 2,4-Dinitrophenylhydrazine to 2,4-Dinitrophenylhydrazone which is a YELLOW or orange PPT
*solid 24DNP can be very hazardous cuz friction or sudden blow can cause explosion
What is tollens reagent and what is it used for?
A solution of silver nitrate in aq ammonia.
- the reagent contains silver ions that act as ox agent in the presence of ammonia
- silver ions reduced to silver as the aldehyde is oxidised to CA
Used to identify aldehyde. If aldehyde present then silver mirror formed.
Differentiate between alcohol ketone and aldehyde.describe any relevant tests and observations
Add 24DNP to each.
-aldehyde and ketone make yellow orange ppt
Then take fresh samples of the compounds that gave the yellow ppt and add Tollens regent to each one at temperature of 50 degrees in a water bath. The aldehyde gives you a silver mirror and the ketone doesn’t react
*alt. Use acidified potassium dichromate and the ketone stays orange but the aldehyde goes from orange to green
Where do I find Carboxylic Acids
Medicines
Fruit juices
Vinegar
Rhubarb leaves
Use CA and it’s derivatives as starting material or intermediates in the formation of more useful compounds eg aspirin formation from salicylic acid
Test for Carboxylic Acids
React with weak base eg sodium carbonate.
CA are the common organic compound sufficiently acidic enough to react with carbonates
Carboxylic Acid vs Phenol
Both weak Acids
Both partially dissociate in water
Both react with solutions of strong bases
CA reacts with weak bases too
