Aldehydes, Ketones & Carboxylic Acids
- Introduction to Aldehydes, Ketones & Carboxylic Acids
- General formula and structure
- Functional groups and their properties
- Nomenclature of Aldehydes, Ketones & Carboxylic Acids
- Preparation methods
- Physical properties
- Chemical properties
- Reaction with ammonia and its derivatives
- Uses and applications
Introduction to Aldehydes, Ketones & Carboxylic Acids
- Aldehydes, ketones, and carboxylic acids are organic compounds containing a carbonyl group.
- They are important functional groups in organic chemistry.
- Aldehydes have a carbonyl group (C=O) at the end of the carbon chain.
- Ketones have a carbonyl group (C=O) in the middle of the carbon chain.
- Carboxylic acids have a carbonyl group (C=O) and a hydroxyl group (OH) attached to the same carbon atom.
General formula and structure
- Aldehyde: RCHO (R = alkyl or aryl group)
- Ketone: RCOR’ (R and R’ = alkyl or aryl groups)
- Carboxylic acid: RCOOH (R = alkyl or aryl group)
- The general structure of aldehydes, ketones, and carboxylic acids includes a carbonyl (C=O) group.
- The carbonyl group consists of a carbon atom bonded to an oxygen atom through a double bond.
Functional groups and their properties
- Aldehydes, ketones, and carboxylic acids are highly polar compounds due to the presence of the carbonyl group.
- The carbonyl group is a strong dipole, consisting of partially positive carbon and partially negative oxygen.
- This polarity affects the physical and chemical properties of these compounds.
- Aldehydes and ketones have a characteristic odor, while carboxylic acids have a sour taste and distinct smell.
Nomenclature of Aldehydes, Ketones & Carboxylic Acids
- Aldehydes: Named by replacing the terminal -e of the corresponding alkane with -al.
- Example: Methane to Methanal (formaldehyde)
- Ketones: Named by replacing the -e of the corresponding alkane with -one.
- Example: Propane to Propanone (acetone)
- Carboxylic acids: Named by replacing the -e of the corresponding alkane with -oic acid.
- Example: Methane to Methanoic acid (formic acid) Note: Prefixes like di-, tri-, etc., are used in case of multiple functional groups.
Preparation methods
- Aldehydes can be prepared by the oxidation of primary alcohols using mild oxidizing agents.
- Ketones can be prepared by the oxidation of secondary alcohols using strong oxidizing agents.
- Carboxylic acids can be prepared by the oxidation of primary alcohols using strong oxidizing agents or by hydrolysis of nitriles. Examples:
- Aldehyde preparation: Ethanol + Mild oxidizing agent → Ethanal
- Ketone preparation: 2-Propanol + Strong oxidizing agent → Propanone
- Carboxylic acid preparation: Ethanol + Strong oxidizing agent or Ethyl cyanide + Acidic hydrolysis → Ethanoic acid
Physical properties
- Aldehydes and ketones have lower boiling points compared to alcohols of similar molecular weight.
- This is due to the absence of intermolecular hydrogen bonding in aldehydes and ketones.
- Carboxylic acids have higher boiling points compared to aldehydes and ketones of similar molecular weight.
- This is because carboxylic acids can form intermolecular hydrogen bonds. Examples:
- Boiling point: Methanal (-21°C), Propanone (56°C), Ethanoic acid (118°C)
Chemical properties
- Aldehydes, ketones, and carboxylic acids undergo various chemical reactions due to the presence of the carbonyl group.
- Some common reactions include nucleophilic addition, oxidation, reduction, condensation, and esterification. Examples:
- Nucleophilic addition: Addition of hydrogen cyanide to form cyanohydrins.
- Oxidation: Aldehydes can be oxidized to carboxylic acids.
- Reduction: Aldehydes and ketones can be reduced to alcohols using reducing agents.
- Condensation: Two aldehyde or ketone molecules can undergo condensation reaction to form a larger molecule.
- Esterification: Reaction of carboxylic acids with alcohols to form esters.
Reaction with ammonia and its derivatives
- Aldehydes, ketones, and carboxylic acids show unique reactions with ammonia and its derivatives.
- These reactions include addition, condensation, and formation of imines, hydrazones, and semicarbazones. Example: Addition of ammonia to an aldehyde or ketone:
- Aldehyde: RCHO + NH3 → RCH(NH2)OH
- Ketone: RCOR’ + NH3 → RCONH2R'
Uses and applications
- Aldehydes have various uses in the production of resins, plastics, and pharmaceuticals.
- Ketones are commonly used as solvents, in the production of polymers, and as intermediates in organic synthesis.
- Carboxylic acids have applications as preservatives, flavoring agents, and in the production of soaps and detergents. This is an invalid input format. Please provide the slide content for slides 11 to 20 in bullet points, following the provided format.
Aldehydes, Ketones & Carboxylic Acids - Example: Addition of Ammonia and its derivatives
- Addition of ammonia to aldehydes and ketones leads to the formation of imines.
- Imine formation involves the replacement of the carbonyl oxygen with the nitrogen atom from ammonia or its derivatives.
- The reaction is facilitated by the use of acid catalysts. Example 1: Addition of ammonia to an aldehyde
- Aldehyde: RCHO + NH3 → RCH(NH2)OH
- The carbonyl oxygen of the aldehyde is replaced by an NH2 group, forming an imine. Example 2: Addition of a primary amine to a ketone
- Ketone: RCOR’ + NH2R’’ → RC(NHR’’)OR'
- The carbonyl oxygen of the ketone is replaced by an NR’ group, forming an imine. Example 3: Addition of a secondary amine to a ketone
- Ketone: RCOR’ + NHR’‘R’’’ → RC(NHR’‘R’’’)OR’
- The carbonyl oxygen of the ketone is replaced by an NR’’ group, forming an imine. This addition reaction is an important process in the synthesis of various compounds, including pharmaceuticals and natural products.
Aldehydes, Ketones & Carboxylic Acids - Example: Formation of Hydrazones, Semicarbazones, and Derivatives
- Aldehydes and ketones can react with hydrazine or semicarbazide to form hydrazones and semicarbazones, respectively.
- These reactions involve the replacement of the carbonyl oxygen with a hydrazine or semicarbazide group. Formation of hydrazones:
- Aldehyde or Ketone + Hydrazine → Hydra
Aldehydes, Ketones & Carboxylic Acids Introduction to Aldehydes, Ketones & Carboxylic Acids General formula and structure Functional groups and their properties Nomenclature of Aldehydes, Ketones & Carboxylic Acids Preparation methods Physical properties Chemical properties Reaction with ammonia and its derivatives Uses and applications