Carbonyls Flashcards
Carboxylic acid and metal hydroxide
Metal replaces alcohol and water
Oxidation of primary alcohols
Distil
K2Cr207 and H2SO4 distil to form aldehyde and water
Oxidation of primary alcohol under reflux
2[O] K2Cr2O7. Forms carboxylic acid and water
Oxidation of secondary alcohol
Under reflux with potassium dichromate and H2 SO4 forms a ketone and water
Reducing agent of ketones and aldehydes
N a BH4
Sodium tetra hydido borate
Aldehyde or ketone is usually warmed with the reducing agent
Reduction of aldehyde
With NaBH4/H2O
Forms primary alcohol
Reduction of Keytone
With N a BH4 and H2O forms a secondary alcohol
Oxidation of aldehydes
Forms carboxylic acid under reflux with potassium dichromate and H2 SO4
Reaction of cyanide with aldehydes and ketones
Aldehyde plus HCN goes to hydroxy nitrile with N a CN/H2SO4
Hydroxy nitrile
When a hydroxyl group and a CN group are attached to the same carbon
Acidic Ester hydrolysis
Keytone plus H2 SO4 dilute acid Forms carboxylic acid and alcohol in a reversible reaction
Alkaline hydrolysis
Esther plus NaOH Forms carboxylic acid with OH group replaced with ONa Product easy to separate as no ester leftover to get rid of Na add strong acid to flood with H+ ions
Acid anhydride
When to carboxylic. Acids react form and Esther and eliminate water
Acyl chloride
When a carboxylic acid reacts with thionyl chloride Replaces hydroxyl group with chlorine
Acyl chloride reactions
When they react with amines phenols and water the chlorine gets replaced
Oxidation reagents
Potassium dichromate and H2 SO4
Oxidisation of aldehydes and ketones
Ketones are less reactive and do not undergo oxidation reactions
Reducing agent
NaBH4 Sodium tetrahydridoborate And water solution is warmed
When aldehydes and ketones are reduced what did they form
Alcohols
Reactions with HCN
Add across C=O bond
Cyanide
Colourless and poisonous gas oil is just above room temperature increases the length of a carbon chain
Aldehyde plus HCN
H2SO4/NaCN
Forms hydroxynitrile
Test for carbonyls
2,4-DNP
Brady’s reagent
Dissolved in methanol and sulphuric acid as a pale solution
Positive result for presence of carbonyls
Orange precipitate
Distinguishing between aldehydes and ketones
Tollings reagent solution of silver nitrate and aqueous ammonia forms a silver mirror when an aldehyde is present
Tollings reagent reaction
AG act as an oxidising agent with NH3 silver ions reduced to silver Aldehyde oxidised to carboxylic acid
Carboxylic acid solubility
Soluble up to 4 carbons as polar C=O and 0H bonds form hydrogen bonds as chain length increases nonpolar carbon chain has a greater effect and solubility decreases
Strength of carboxylic acids
Weak acids only partially dissociates in water
Carboxylic acid plus base
Forms carboxylate salt and water magnesium ethanoate
Test for carboxylic acids
Only sufficiently acidic organic compound to react with carbonates produces carbon dioxide is test with limewater
Esterification conditions
Requires high temperature and concentrated acid catalyst
Esther
Alcohol plus carboxylic acid warmed with H2 SO4
Propanoic acid plus ethanol
Ethyl propanoate
Hydrolysis of esters
By acid or alkali
Acid hydrolysis of Astors
Reflux with die loot aqueous acid forms carboxylic acid and alcohol broken down by water with acid catalyst reversible reaction in equilibrium
Alkaline hydrolysis of Astors
Irreversible heated under reflux’s with NAOOH forms carboxylate salt and alcohol
NaBH4
Sodium tetrahydridoborate
2,4 DNP
2,4- dinitrophenyhydrazine