Carbonyl compounds

Carbonyl compounds

1. The Carbonyl group

   • C==O
     • Aldehyde-......al Ketone-.......one Carboxyllic acid-.........anoic acid Acyl chloride-........anoyl chloride Amide-.......amide Ester......anoate

2. Alcohols from aldehydes and ketones

   • Primary alcohols oxides to aldehydes and secondary to ketones
     • Acidified potassium dichromate with sulfuric acid - in equation just add (O) and make H20 in equation
       • Orange to green colour change
     • ROH+2(O)=RCOOH+H2O
   • Nucleophilic addition - C==0 becomes polar - eectronegativity so the C can be attacked by nucleophiles e.g. H-
     • : to C and == to O
       • O:- to H+
       • Same mechanism
         • Forms 2-hydroxy...........nitrile
     • RCHO+2(H)=RCH2OH

3. Hydroxynitriiles from aldehydes and ketones

   • Same but
   • RCHO+HCN=RCH(OH)CN
   • Can be turned into carboxylic acid
     • RCH(OH)CN+H2O+H+=RCH)OH)COOH+NH4+

4. Esterification

   • Test for carboxylic acids - reaction with carbonates - effervescence
   • Carboxylic acids + alcohol = ester + water
     • RCOOH+ROH=RCOOR+H2O
     • The OH from the carboxylic acid and H from alcohol for the H20
   • Name the bit next to the 0 and then the other bit and add oate

5. Uses of esters

   • Food flavourings
     • Manufacturing costs a lot less than extracting
   • Plasticizers
     • Added to polymers to let the molecules slide over each other more easily
       • Makes it ofter and more flexible e.g. PVC and uPVC

6. Oil fats and biodiesel

   • Acid catalysed hydrolysis
     • Heating under reflux conditions with dilute HCl
       • RCOOR+H2O=RCOOH+R2OH
         • Lies to the left so doesn't work very well
   • Base catalysed hydrolysis
     • Heating under reflux conditions with NaOH
       • RCOOR+NaOH=RCOO-Na++ROH
         • Lies to the right so works better but makes and acid and a salt
   • Vegetable oil
     • Triglycerols - triester
       • Hydrolysed by heating with 3NaOH
         • produces glycerol and sodium carboxylate
           • Glycerol used in cosmetics and toothpaste
           • Sodium carboxylate used as soap - long chain represents the hydrophobic end as its non polar so dissolves in oil and greece
       • Biodiesel
         • Heating with 3methanol and 3NaOH
           • Base-catalysed tranesterification
             • Makes methyl ester(biodiesel) lays on top as it's denser and glycerol