Carbonyl compounds

• What is a carbonyl compound?

  Any compound with a C=O bond in it
• What is an aldehyde?


  It is a compound which has a C=O bond at the end of the carbon chain, it is usually written as (CHO)
• What is a Ketone?

  It is a compound which has a C=O bond in the middle of the carbon chain, the ketone group is written as CO
• How to name a carbonyl compound?

  Find the longest carbon chain, then add al or one to the end of the name
• What can aldehydes be oxidised into?

  Carboxylic acids, conditions needed are acidified potassium dichromate (K2Cr2O7/H2SO4 )
• How can aldehydes and ketones be distinguished?


  Aldehydes undergo oxidations, ketones do not, therefore when you add potassium dichromate the aldehyde will change colour from orange to green and the ketone wont
• How do mechanisms with carbonyl compounds vary from mechanisms that happen to alkenes?

  Alkenes have a C=C bond which is NON polar

  Carbonyls have a C=O bond which is polar, the oxygen is more electronegative than carbon meaning that the electrons lie closer to the oxygen, this makes them react with nucleophiles, they undergo nucleophilic addition where as alkenes undergo electrophilic addition instead
• Reaction of carbonyls with NaBH4?

  Used as a reducing agent to reduce aldehydes and ketones, aldehydes are reduced to primary alcohols where as ketones are reduced to secondary alcohols
• Reaction of carbonyls with HCN?


  It reacts with the c=o double bond with the presence of NaCN, this forms a hydroxynitrile
• What is the mechanism for NaBH4?

  Nucleophilic addition,

  1. The lone pair from the hydride is attracted and donated to the carbon in the aldehyde or ketone
  2. A dative covalent bond then forms between the hydride and the carbon
  3. The pi bond in the c=o bond breaks and a negatively charged intermediate forms
  4. The oxygen then donates a lone pair of electrons to the hydrogen forming an OH- ion
• The mechanism for the reaction of NaCN/H+?

  Lone pair attracted to the positive carbon nucleus

  Dative covalent bond forms

  The pi bond in the c=o breaks by heterolytic fission forming a negatively charged intermediate.

  This intermediate is then protonated and forms a hydroxynitrile
• How do you test for a Carbonyl group?

  Using brady's reagent, it forms and orange precipitate, this precipitate can then be tested for melting point and be compared to known values, this will then help distinguish it from other compounds
• How do you distinguish between aldehydes and ketones?

  Tollens reagent, a solution of silver nitrate, if it is in the presence of an aldehyde it will form a silver mirror, this is due to it being oxidised
• Ionic equation for tollens reagent?

  Ag+(aq)+ e- -> Ag(s)
• What is a carboxylic acid?

  It is a compound which contains a C-OH bond and a C=O bond
• How to name a carboxylic acid?

  Using the suffix "-oic acid" after the root name of the alkane chain.
• Are carboxylic acids soluble?

  Yes, up until a carbon chain which is 4 carbons long, this is due to the ability for it to hydrogen bond with water
• Strength of carboxylic acids?

  Carboxylic acids are weak acids as when they are dissolved in water, they only partially disasociate into their ions
• What reactions do carboxylic acids undergo?

  Redox reactions with metals, neutrilisation reactions with bases
• Carboxylic acid + metal?

  salt + hydrogen
• Carboxylic acid + Base?

  Neutral salt + wayter
• Carboxylic acid + metal oxide?

  Salt + water
• Carboxylic acid + alkali?

  Salt + water
• Carboxylic acid + Metal carbonate?

  Salt + water + carbon dioxide
• How can the carboxylic acid + metal carbonate be used to show a carboxylic acid?

  It is the only organic product that is sufficiently acidic enough to react with a carbonate, as phenols aren't acidic enough
• What is a derivative of a carboxylic acid?

  A compound which can be hydrolyzed to form the parent carboxylic acid
• What are examples of carboxylic acid derivatives?

  Esters, acyl chlorides, acid anhydrides and amides
• What is an ester?

  An ester is a compound formed by the reaction between an alcohol and an organic acid, resulting in the formation of a unique functional group, with a O chain
• What is an acyl chloride?

  A chain named after the parent carboxylic acid from which it is derived, to name it remove the oic acid and add oyl chloride
• What is an acid anhydride?

  Removal of water from from two carboxylic acid molecules
• What is esterification?

  The reaction of an alcohol and a carboxylic acid to form an ester, an alcohol is warmed with a carboxylic acid with a sulfuric acid which acts a catalyst
• Ester hydrolysis?

  It is the chemical break down of a compound in the presence of water, it can be done in a few ways, acid or alkaline
• Acid hydrolysis?

  Reverse of esterification, ester is heated under reflux with aqueous acid the ester is broken by water with the acid acting as a catalyst
• Alkali hydrolysis?

  Saponification, irreversible process where ester is heated under reflux with hydroxide ions, an ethanoate ion and alcohol is formed
• How are acyl chlorides prepared?

  Carboxylic acid is reacted with thionyl chloride, the other products of so2 and hcl are gases meaning that the acyl chloride is the only one left, this should be done in a fume cupboard as the chemicals are dangerous
• Reactions of acyl chlorides?

  acyl chlorides+ alcohols -> esters + Hcl
• Acyl chloride + phenol?

  ester + Hcl
• Acyl chloride + water?

  Carboxylic acid + water
• Reaction of acyl chlorides with ammonia and amines?

  ethanoyl chloride + Ammonia -> Primary amide + ammonium chloride
• Primary amine + ethanoyl chloride?

  Forms a secondary amide, with a methylammoniumchloride