Aldehydes, Ketones & Carboxylic Acids - Example- Addition Of Sodium Hydrogen

Slide 1: Aldehydes, Ketones & Carboxylic Acids

This topic is part of the Organic Chemistry section.
Aldehydes, ketones, and carboxylic acids are important functional groups.
They contain the carbonyl group (-C=O) which plays a key role in their reactivity.
The presence of the carbonyl group leads to characteristic properties and reactions.
We will study the structure, nomenclature, and reactions of aldehydes, ketones, and carboxylic acids.

Slide 2: Structure of Aldehydes

Aldehydes have a carbonyl group at the end of the carbon chain.
The general formula for aldehydes is R-CHO, where R represents an alkyl or aryl group.
The carbon atom attached to the carbonyl group is called the alpha carbon.
The carbonyl carbon is sp2 hybridized, with a trigonal planar geometry.
Aldehydes can have various substituents attached to the alpha carbon.

Slide 3: Nomenclature of Aldehydes

IUPAC names of aldehydes are derived from the parent alkane or benzene name.
The suffix “-al” is added to indicate the presence of an aldehyde functional group.
For example, formaldehyde is the simplest aldehyde and its IUPAC name is methanal.
Aldehydes can also be named as derivatives of carboxylic acids, using the “-oyl” suffix.
Common names, such as acetaldehyde and benzaldehyde, are often used for some aldehydes.

Slide 4: Examples of Aldehydes

Examples of aldehydes include formaldehyde (methanal), acetaldehyde (ethanal), and benzaldehyde.
Formaldehyde is a gas at room temperature and is commonly used as a disinfectant and preservative.
Acetaldehyde is a colorless liquid with a fruity odor that is used in the production of plastics and resins.
Benzaldehyde has a characteristic almond-like odor and is used in the production of flavors and fragrances.

Slide 5: Structure of Ketones

Ketones have a carbonyl group in the middle of the carbon chain.
The general formula for ketones is R-CO-R’, where R and R’ represent alkyl or aryl groups.
The carbonyl carbon is sp2 hybridized, with a trigonal planar geometry.
Ketones can have different alkyl or aryl groups attached to the carbonyl carbon.

Slide 6: Nomenclature of Ketones

IUPAC names of ketones are derived from the parent alkane name.
The suffix “-one” is added to indicate the presence of a ketone functional group.
The carbon atoms attached to the carbonyl group are numbered, starting with the lowest number.
For example, the ketone with a three-carbon chain is called propanone (common name: acetone).
Ketones can also be named as derivatives of carboxylic acids, using the “-oyl” suffix.

Slide 7: Examples of Ketones

Examples of ketones include acetone (propanone), methylethyl ketone (butan-2-one), and benzophenone.
Acetone is a common solvent and is used in the production of plastics, fibers, and pharmaceuticals.
Methylethyl ketone has industrial applications as a solvent and in the production of paints and coatings.
Benzophenone is used in the production of sunscreens and as a photo-initiator in polymerization reactions.

Slide 8: Structure of Carboxylic Acids

Carboxylic acids have a carboxyl group at the end of the carbon chain.
The general formula for carboxylic acids is R-COOH, where R represents an alkyl or aryl group.
The carboxyl group consists of a carbonyl group (-C=O) and a hydroxyl group (-OH).
The carbonyl carbon is sp2 hybridized, with a trigonal planar geometry.
Carboxylic acids can have various substituents attached to the alpha carbon.

Slide 9: Nomenclature of Carboxylic Acids

IUPAC names of carboxylic acids are derived from the parent alkane or benzene name.
The suffix “-oic acid” is added to indicate the presence of a carboxylic acid functional group.
The carbon atoms attached to the carboxyl group are numbered, starting with the lowest number.
For example, the carboxylic acid with a three-carbon chain is called propanoic acid.
Carboxylic acids can also be named as derivatives of other carboxylic acids, using the “-oyl” suffix.

Slide 10: Examples of Carboxylic Acids

Examples of carboxylic acids include formic acid (methanoic acid), acetic acid (ethanoic acid), and benzoic acid.
Formic acid is found in the venom of certain ants and has industrial applications as a reducing agent.
Acetic acid is the main component of vinegar and is used in the production of plastics and solvents.
Benzoic acid is used as a food preservative and has applications in the production of dyes and pharmaceuticals.

Addition of Sodium Hydrogen

Aldehydes and ketones can react with sodium hydrogen (NaH) to form alcohols.
The reaction involves the addition of hydrogen to the carbonyl group.
The general equation for the reaction is: R-CHO (or R-CO-R’) + NaH → R-CH2OH (or R-C(OH)-R’) + NaX
NaX represents the sodium salt (X-) produced as a byproduct of the reaction.
Example: Propanal + NaH → Propan-2-ol + NaX

Addition of Water (Hydration)

Aldehydes and ketones can react with water to form hydrates.
The reaction involves the addition of water to the carbonyl group.
The general equation for the reaction is: R-CHO (or R-CO-R’) + H2O → R-CH(OH)2 (or R-C(OH)(OH)-R')
The reaction is usually catalyzed by an acid or base.
Example: Ethanal + H2O → Ethane-1,2-diol

Reduction to Alcohols

Aldehydes and ketones can be reduced to form alcohols.
The reaction involves the addition of hydrogen to the carbonyl group.
Various reducing agents can be used, such as sodium borohydride (NaBH4) or lithium aluminum hydride (LiAlH4).
The general equation for the reaction is: R-CHO (or R-CO-R’) + H2 (or H2 + catalyst) → R-CH2OH (or R-C(OH)-R')
Example: Propanal + NaBH4 → Propan-1-ol

Oxidation to Carboxylic Acids

Aldehydes can be oxidized to form carboxylic acids.
Ketones, on the other hand, are resistant to oxidation due to the absence of a hydrogen atom on the carbonyl carbon.
Various oxidizing agents can be used, such as potassium permanganate (KMnO4) or acidified dichromate (Cr2O72-).
The general equation for the oxidation of aldehydes is: R-CHO + [O] → R-COOH
Example: Ethanal + [O] → Ethanoic acid

Aldol Condensation

Aldehydes and ketones can undergo aldol condensation to form β-hydroxy aldehydes or β-hydroxy ketones.
The reaction involves the combination of two carbonyl compounds followed by a dehydration step.
The general equation for the reaction is: R1-CHO + R2-COH (or R1-CO-R2) → R1-CH(OH)-CHO (or R1-CH(OH)-C(O)-R2)
The reaction is usually catalyzed by a base.
Example: Propanal + Propanone → 2-Hydroxy-2-methylpentanal

Cannizzaro Reaction

Aldehydes which do not have an α-hydrogen atom can undergo a self-disproportionation reaction, known as Cannizzaro reaction.
The reaction involves the oxidation of one molecule of aldehyde to a carboxylic acid and reduction of another molecule to an alcohol.
The reaction is usually carried out in the presence of a strong base like NaOH or KOH.
Example: Benzaldehyde + NaOH → Benzoic acid + Benzyl alcohol

Clemmensen Reduction

Ketones can be reduced to alkanes using the Clemmensen reduction.
The reaction involves the treatment of the ketone with zinc amalgam and hydrochloric acid (HCl).
The reaction is carried out under high temperature and pressure conditions.
The general equation for the reduction is: R-CO-R’ + 2HCl + Zn → R-CH2-R’ + ZnCl2 + H2
Example: Propanone + HCl + Zn → Propane

Wolff-Kishner Reduction

Ketones can also be reduced to alkanes using the Wolff-Kishner reduction.
The reaction involves the treatment of the ketone with hydrazine (N2H4) followed by heating with a strong base, usually potassium hydroxide (KOH).
The reaction is carried out under high temperature conditions.
The general equation for the reduction is: R-CO-R’ + 2N2H4 → R-CH2-R’ + N2 + 4H2O
Example: Propanone + N2H4 → Propane + N2 + 4H2O

Esters: Preparation and Reactions

Esters are formed by the condensation reaction between carboxylic acids and alcohols.
This reaction is known as esterification and is catalyzed by an acid (commonly sulfuric acid or hydrochloric acid).
The general equation for esterification is: R-COOH + R’-OH → R-COOR’ + H2O
Esters can undergo various reactions, such as hydrolysis, saponification, and Fischer esterification.
Example: Ethanoic acid + Ethanol → Ethyl acetate + Water

Hydrolysis of Esters

Esters can undergo hydrolysis in the presence of water or a dilute acid or base.
The reaction can be either acid or base catalyzed.
In acid hydrolysis, the ester is converted back to the carboxylic acid and alcohol.
In base hydrolysis (saponification), the ester is converted to the corresponding carboxylate ion and alcohol.
Example: Ethyl acetate + Water (or NaOH) → Ethanoic acid (or Sodium acetate) + Ethanol

Acidity of Carboxylic Acids

Carboxylic acids are weak acids due to the presence of the carboxyl group.
They can ionize to release a hydrogen ion (H+) and form a carboxylate ion.
The ionization constant (Ka) of a carboxylic acid determines its acidity.
Ka is a measure of the extent to which the acid donates H+ ions in solution.
Examples:
- Ethanoic acid (CH3COOH) is a weak acid with a Ka of 1.8 x 10^-5.
- Benzoic acid (C6H5COOH) is also a weak acid with a Ka of 6.3 x 10^-5.

Reactions of Carboxylic Acids

Carboxylic acids can undergo various reactions due to the presence of the carboxyl group.
Some common reactions include:
- Esterification: Formation of an ester by reacting with an alcohol.
- Acid/Base Reactions: Reacting with bases to form carboxylate salts.
- Decarboxylation: Loss of carbon dioxide (CO2) to form a lower-carbon compound.
- Reduction: Conversion to an alcohol by the addition of hydrogen.
- Substitution: Replacing a hydrogen atom in the carboxyl group with another atom or group.
Examples: Ethanoic acid + Ethanol → Ethyl acetate (esterification)

Nomenclature of Carboxylic Acids

IUPAC names of carboxylic acids are derived from the parent alkane or benzene name.
The suffix “-oic acid” is added to indicate the presence of a carboxylic acid functional group.
The carbon atoms attached to the carboxyl group are numbered, starting with the lowest number.
For example, the carboxylic acid with a three-carbon chain is called propanoic acid.
Carboxylic acids can also be named as derivatives of other carboxylic acids, using the “-oyl” suffix.

Examples of Carboxylic Acids

Many carboxylic acids exist in nature and are found in various substances.
Examples include:
- Acetic acid: Found in vinegar and used in the food industry.
- Butyric acid: Present in rancid butter and responsible for its odor.
- Citric acid: Found in citrus fruits and used as a flavoring agent.
- Salicylic acid: Used in skincare products for its exfoliating properties.
- Benzoic acid: Used as a food preservative and found in fruits and spices.

Nomenclature of Aldehydes

IUPAC names of aldehydes are derived from the parent alkane or benzene name.
The suffix “-al” is added to indicate the presence of an aldehyde functional group.
For example, formaldehyde is the simplest aldehyde and its IUPAC name is methanal.
Aldehydes can also be named as derivatives of carboxylic acids, using the “-oyl” suffix.
Common names, such as acetaldehyde and benzaldehyde, are often used for some aldehydes.

Examples of Aldehydes

Examples of aldehydes include formaldehyde (methanal), acetaldehyde (ethanal), and benzaldehyde.
Formaldehyde is a gas at room temperature and is commonly used as a disinfectant and preservative.
Acetaldehyde is a colorless liquid with a fruity odor used in the production of plastics and resins.
Benzaldehyde has a characteristic almond-like odor and is used in the production of flavors and fragrances.

Nomenclature of Ketones

IUPAC names of ketones are derived from the parent alkane name.
The suffix “-one” is added to indicate the presence of a ketone functional group.
The carbon atoms attached to the carbonyl group are numbered, starting with the lowest number.
For example, the ketone with a three-carbon chain is called propanone (common name: acetone).
Ketones can also be named as derivatives of carboxylic acids, using the “-oyl” suffix.

Examples of Ketones

Examples of ketones include acetone (propanone), methylethyl ketone (butan-2-one), and benzophenone.
Acetone is a common solvent and is used in the production of plastics, fibers, and pharmaceuticals.
Methylethyl ketone has industrial applications as a solvent and in the production of paints and coatings.
Benzophenone is used in the production of sunscreens and as a photo-initiator in polymerization reactions.

Reactions of Aldehydes and Ketones

Aldehydes and ketones can undergo various reactions due to the presence of the carbonyl group.
Some common reactions include:
- Addition of Sodium Hydrogen: Formation of alcohols.
- Addition of Water (Hydration): Formation of hydrates.
- Reduction to Alcohols: Addition of hydrogen.
- Oxidation to Carboxylic Acids: Conversion to carboxylic acids.
- Aldol Condensation: Formation of β-hydroxy aldehydes or ketones.
- Cannizzaro Reaction: Self-disproportionation reaction of certain aldehydes.
- Clemmensen Reduction: Reduction of ketones to alkanes using zinc amalgam.
- Wolff-Kishner Reduction: Reduction of ketones to alkanes using hydrazine.

Summary

Aldehydes, ketones, and carboxylic acids are important functional groups in organic chemistry.
Aldehydes have a carbonyl group at the end of the carbon chain, while ketones have it in the middle.
Carboxylic acids have a carboxyl group at the end of the carbon chain.
These functional groups exhibit characteristic properties and reactions.
Naming conventions for aldehydes, ketones, and carboxylic acids follow IUPAC guidelines.
Examples and equations were provided to illustrate different reactions and nomenclature.
Understanding the structure and reactivity of these functional groups is essential for organic chemistry.