Carbonyl Compounds Flashcards
Give the notation of aldehydes
RCHO
Give the notation of ketones
RCOR
How do you name aldhydes
Add al onto alkyl
How do you name ketones
Add one onto alkyl
How do you differentiate between aldehydes and ketones via a test
Add acidfied Potassium dichromate
Only aldehydes will oxidise causing colour change from orange to green
By what mechanism do carbonyl react, why
Nucleophillic addition
Negetive oxygen
Double bond= addition
Why do carbonyl react differently to alkenes
The oxygen is more electronegetive
Carbon is partially positive so is attacked by nucleophile
Unlike c=c
How are carbonyls reduced
H- acts as nucleophile form NaBH4
Reduces to original alcohol
What are the dangers of HCN
It’s a poisonous gas
Very volatile
Why might HCN be used?
To increase carbon chain length
Describe the reaction between a nucleophile and a carbonyl
Nucleophile attacks partially positive carbon by donating a pair of electrons forming dative bond
Pi bond in c=o breaks by heterolytic fission so oxygen has a lone pair and is negetive
Lone pair on O2 os donate to a H+ in acid or H2O
Describe the qualitative test for a carbonyl bond
2,4-DNP / 2,4-DNPH/ Brady reagent
Yellow to orange
Preciptitae formed.
How do you determine the carbonyl used once you’ve added 2,4-DNP
Recrystalise and purify precipitate
Test melting point and compare to data base
Why does care need to be taken when using 2,4-DNP
It’s hazardous
Friction or a blow will cause explosion
How do you differentiate between a ketone and aldehyde without reflux
Use tollens reagent
Oxidses aldehydes to carboxylic acid
Silver mirror produced
How is tollens reagent made and why
Short self life
Silver nitrate, aqueous ammonia and sodium hydroxide
What are the results for addition of Fehlings solution
Aldehyde= blue to red
Ketone = not change
How do you name carboxylic acids
Place oic acid at end of alkyl name