carbonyls and carboxylic acids Flashcards
carbonyls
C = O bond
eg aldehydes at end
ketones middle of chain
-carboxylic acid NOT classified as carbonyls
oxidation of aldehydes
aldehyde + [O] –> carboxylic acid
acidified dichromate
reducing an aldehyde
aldehyde + 2[H] (NaBH4)/(H2O) primary alcohol
reducing a ketone
ketone + 2[H] (NaBH4)/(H2O) –> secondary alcohol
aldehyde reacting with HCN
propanal + HCN (H2SO4/NaCN) –> hydroxynitrile
detecting aldehydes
tollens reagent
+sodium nitrate +sodium hydroxide = brown brecipitate
+ NH3 goes colourles
-in water bath 50-60
silver mirror should form if aldehyde present
Ag + e- –> Ag(s)
detecting alcohols
acidified potassium dichromate + alcohol
orange–>green
negative remains orange
detecting carbonyls (C=O)
2,4 DNP +sulfuric acid + methanol (bradys solution)
add bradys solution
-orange yellow precipitate if present
add more sulfuric acid if no crystals present
esterification of carboxylic acids
alcohol + carboxylic acid –> ester + water
conc sulfuric acid (heat under reflux)
-then distil as backwards is favourable
OH comes off carboxylic acid
H comes off alcohol
acid anhydrides
made with 2 carboxylic acids ( condensation)
alkyl chain(oic) anhydride
if unsymetrical (alphabetical)
(ethanoic anhydride)
esterification with acid anhydride
acid anhydride + alcohol –> ester + carboxylic acid
(warm gently)
making acyl chloride
-OH of COOH is replaced with Cl
carboxylic acid + thionyl sulphate –> acyl chloride + SO2 + HCl
carbon chain + oyl chloride
synthesis of carboxylic acids from acyl chlorides
acyl chloride + water –> carboxylic acid + HCl
esterification of acyl chloride
acyl chloride + alcohol –> ester + HCl
synthesis of primary amides
acyl chloride + ammonia –> acetamide + ammonium chloride
