ALDEYHYDES + KETONES Flashcards
WHAT OXIDISES TO FORM ALDEHYDES
PRIMARY ALCOHOLS
WHAT OXIDISES TO FORM KETONES
SECONDARY ALCOHOLS
WHAT FURTHER OXIDISES TO FORM CARBOXYLIC ACIDS
ALDEHYDES
WHY CANT KETONES FURTHER OXIDISE LIKE ALDEHYDES?
BECAUSE KETONES DONT HAVE A READILY AVAILABLE HYDROGEN ATOM LIKE IN ALDEHYDES.
WHAT REAGENTS CAN BE USED TO OXIDISE ALDEHYDES AND KETONES
POTASSIUM DICHROMATE AND H2S04
TO OXIDISE PRIMARY ALCOHOLS STRAIGHT INTO CARBOXYLIC ACIDS WHAT DO U DO?
HEAT REACTION MIXTURE UNDER REFLUX AS THE ALDEHYDE IS STILL FORMED, BUT WHEN IT EVAPORATES IT CONDENSES BACK INTO THE REACTION MIXTURE.
HOW CAN U DISTINGUISH BETWEEN ALDEHYDES AND KETONES.
ADD TOLLENS REAGENT AND WARM, SILVER MIRROR FORMS WHEN AN ALDEHYDE IS PRESENT. IF THERE IS NO VISIBLE CHANGE THIS MEANS THAT A KETONE IS PRESENT.
OR YOU CAN ADD FEHLINGS SOLUTION, AND IF BRICK RED PPT FORMS, ALDEHYDE IS PRESENT. IF THERE IS NO VISIBLE CHANGE ONCE AGAIN KETONE IS PRESENT.
IF YOU HEAT ACIDIFIED POTASSSIUM DICHROMATE WITH AN ALDEHYDE, WHATS OBSERVED?
SOLUTION GOES FROM ORANGE TO GREEN. (IF U HEAT WITH KETONE NO VISIBLE CHANGE)
WHATS THE COMMON REDUCING AGENT USED FOR THE REDUCTION OF ALDEHYDES AND KETONES?
NABH4 ( IN THE FORM :h-)
:h- is strong enough to reduce a c=o bond in a ketone or aldehyde but not strong enough to reduce a c=c bond. why?
cuz its attracted the c in c=om whereas its repelled/not attracted to the c=c since there is a high electron density.
what type of reaction mechanism is the reduction of aldehydes and ketones?
nucleohphilic additon reaction
KETONES CAN BE REDUCED INTO _____?
SECONDARY ALCOHOLS
ALDEHYDES CAN BE REDUCED INTO _____?
PRIMARY ALCOHOLS
give the equations for the reduction of carboxylic acids to primary alcohol, as well as an aldehyde to primary alcohol as well as ketone to secondary alcohol.
carboxylic acids to primary alcohol: RCOOH + 4[H] —–> RCH2OH + 2H20
aldehyde to primary alcohol: RCOH +2 [H] ——> RCH2OH
KETONE TO SECONDARY ALCOHOL: RCOR + 2[H] —-> RCHOHR
THE OXIDATION OF PRIMARY ALCOHOLS TO ALDEHYDES, AND SECONDARY ALCOHOLS TO KETONES, PRODUCES WHAT AS A BY PRODUCT?
H20
FORMATION OF HYDROXY NITRILES FROM ALDEHYDES/KETONES IS WHAT TYPE OF REACTION MECHANISM?
NUCLEOPHILIC ADDITION REACTION ( CN- IS THE REAGENT)
DESPITE POTASSIUM DICHROMATE BEING CHEAPER THAN TOLLENS, TOLLENS IS STILL USED WHEN TESTING FOR ALDEHYDES. WHY?
AS POTASSIUM DICHROMATE OXIDISES PRIMARY AND SECONDARY ALCOHOLS.
GIVE 2 DISADVS OF USING AN ACID CHLORIDE TO PRODUCE AN AMIDE AND GIVE AN ALTERNATIVE REAGENT TO FORM AN AMIDE WHEN REACTED WITH AN AMINE.
ALTERNATIVE: ACID ANHYDRIDE
2 DISADVS: ACID CHLORIDES ARE MORE EXPENSIVE, AND MORE CORROSIVE.
GIVE 1 CONDITION TO FORM AMMONIUM SALT FROM CHLOROETHANE AND AMMONIA.
EXCESS CHLOROETHANE
