NEET Study Notes for aldehydes, ketones, and carboxylic acid: The carbonyl compounds that consist of carbon-oxygen double bonds include Aldehydes, Ketones, and Carboxylic Acid. The functional group of Aldehydes, ketones and carboxylic acids is the carboxyl group (CO). These are essential in organic chemistry and also applicable for industrial purposes.

• NEET Chemistry Syllabus is divided into Physical, Organic, and Inorganic chemistry. Aldehydes, Ketones and Carboxylic Acids is a part of the Inorganic chemistry which contains a weightage of around 34%.
• As per the previous year’s analysis, candidates can expect at least 2-3 questions in NEET 2022.

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NEET Study Notes for Aldehydes, Ketones, and Carboxylic Acid: Important Topics

Carbonyl Compounds

Compounds with carbon-oxygen double bonds are known as carbonyl compounds. This property gives Aldehydes, Ketones, and Carboxylic acids similar chemical properties. However, aldehydes are more reactive due to the presence of a free hydrogen atom.

The bond in Aldehydes is that of the carbonyl group with carbon and hydrogen while in ketones, the bond is carbonyl with two carbon atoms. On bonding of the carbonyl compounds, carbonyl group, with oxygen, carboxylic acids are formed. The derivatives of carboxylic acids include esters, anhydrides, etc. On carbon and nitrogen or halogen bonding, amides and acyl halides are formed respectively.

Nature of Carbonyl Group

In the carbonyl group, carbon and oxygen have 1 s and two p orbitals that form new hybrid orbitals that are strong. Whereas the carbon double bond consists of onr bond each of s and p. Carbo oxygen bond is of polar nature and dipole moment is observed.

Read NEET Notes for Organic Chemistry

Aldehydes

Aldehydes consist of a central carbonyl carbon that doubly bonds to oxygen and single bond with the R group or an alkyl group and also single bonded with a hydrogen atom.

Nomenclature of Aldehydes

The two general methods of naming aldehydes are

• Common System- In this method, they are named after carboxylic acid’s common name. Aldehydes are given the same name. However, the suffix -ic acid is replaced by -aldehyde. Examples- are formaldehyde, benzaldehyde.
• IUPAC System- The assumption of the longest chain of a carbon atom with carbonyl group as parent alkaline is assumed here. The suffix -e is replaced with suffix -al. Example Formaldehyde methanal, acetaldehyde ethanal.

Methods of Preparation of Aldehydes

Aldehydes can be prepared in a lot of ways. Some of the most common methods of preparation of Aldehydes are:

• Reduction of acid chlorides (with hydrogen) in the presence of palladium catalyst with barium sulfate produces Aldehydes. This is known as the Rosemund reaction. It is used in preparing aromatic aldehydes. Rosemund Reaction cannot be used for Ketone or Formadehyde formation.
• Aldehydes can also be produced through Etard reaction, by using hydrocarbons. Gaterman- Koch reaction can also be used for benzaldehyde preparation.
• Aldehydes can also be prepared from esters and nitriles. This is also called Stephen’s reaction or Stephen’s reduction of nitriles.

Properties of Aldehydes

• Solubility in the water of small aldehydes is higher.
• Important aldehydes that have industrial applications are formaldehyde and acetaldehyde.
• Aldehydes possess a polar nature, as the electron in the center has the tendency to displace.
• Oligomerization and polymerization properties are exhibited by Aldehydes.

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NEET Study Notes on Structure of Atom

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Ketones

Ketones consist of central carbonyl carbon that is bonded doubly with oxygen and single bond with the R group or alkali group.

Nomenclature of Ketones

• While naming Ketones, their parent alkalines are considered. The suffix used is - anone. A particular number is used to denote the carbonyl’s group position, This lends a particular name to the ketone.
• Alkyl groups names are also included in carbonyl compounds while naming Ketones. The third word added is Ketone. Example- Burtanone (Methyl Ethyl Ketone).

Preparation of Ketones

Ketones can be prepared in the following ways:

• Ketones can be prepared by reaction of acid chlorides with dialkyl cadmium. Grignard Reagents are used for the preparation of this Dialykyl cadmium.
• Ketones can also be prepared from nitriles. Ketones preparation can also be done by benzene or substituted benzene. This process is called Friedels- Crafts acylation reaction.
• Ketones can also be prepared with the use of acid

Properties of Ketones

• Due to the presence of a polar carbonyl group, Ketones are of polar nature. This causes them to have high boiling points.
• Due to no bonding of hydrogen-oxygen atom, intermolecular hydrogen bond cannot be formed.
• Due to the displacement of π electrons, ketones exhibit large dipole moments.
• Cyanohydrins are formed on the reaction of Ketones with hydrogen cyanide, A catalyst like a base is used to increase the rate of reaction.
• When ketones and sodium bisulfite are combined, bisulfite addition products are formed.

Must Read NEET Study Notes on Hydrogen

Physical Properties of Aldehydes and Ketones

• The boiling points of Aldehydes and Ketones are higher in comparison to ethers and hydrocarbons whose mass is similar to Aldehydes and Ketones.
• At room temperature, aldehyde and ketones are in the state of solid or liquid. However certain aldehydes and ketones like methanal and ethanal exhibit gaseous and volatile liquid properties respectively.
• When the alkyl chain length increases, compound solubility also shows an increase.

Chemical Properties of Aldehydes and Ketones

• Nucleophilic reactions are seen in Aldehydes and Ketones.
• Aldehydes are more reactive than Ketones.
• Aldehydes and Ketones also react with ammonia and its derivatives as well as Grignard Regents.
• Oxidation and Reduction reactions are also seen in Aldehydes and Ketones.

Uses of Aldehydes and Ketones

• Ketones like propane are used in the production of perspex polymer.
• Ketones are used as a solvent or to start the organic compound synthesis.
• Ketones like acetones and ethyl, methyl are used for industrial purposes.
• Formaldehyde is used for the production of plastics of several varieties and disinfectants as well as for preserving biological specimens.

Also Read

• NEET Study Notes for Reaction Mechanism
• NEET Study Notes for Chemical Equilibrium

Carboxylic Acids

Compounds with carboxyl function group are called Carboxylic acids, Carboxylic acids are composed of carboxyl and hydroxyl. On the basis of the parent carbo chain structure, carboxylic acids can be aromatic and aliphatic.

On the basis of the number of -COOH groups, carboxylic acids can be classified:

• Monocarboxylic Acids- These contain one -COOH group
• Dicarboxylic Acid- They contain two-COOH groups. Examples are aspartic and glutamic acid.
• Fatty Acids- Fatty acids are carboxylic acids with an aliphatic chain.

Nomenclature

• Addition of -oic acid suffix to the parent carbon chain. Example- Butanoic Acid
• Presence of other substituents does not affect the first position of carboxylic acid in the parent chain. Example 3- Chloropropanoic Acid.
• The carboxylic acid can also be called carboxy replacing the name of the present structure. Example- 2-furoic acid can also be called 2-carboxy furan.

What is the structure of Carboxylic Acid?

Carboxylic acids consist of carbon compounds that are concentrated in a single plane. Bonds are at a distance of 12- degrees from each other. Due to the resonating structure, the electrophylic property of carboxylic carbon is less.

Preparation of Carboxylic Acid

• Carboxylic acids can be prepared with primary alcohols and acids in the presence of a strong oxidizing agent.
• With the use of oxidising agent, carboxylic acids can also be prepared from alkyl benzene.
• Nitriles, amides, grignard reagents can also be used for preparation of carboxyllic acids.

Physical Properties of Carboxylic Acids

• Solubility- Carboxylic acids are soluble. However, with an increase in carbon atoms, solubility decreases. However aromatic carboxylic acids are not soluble in cold water.
• Carboxylic acids with up to 10 carbon atoms are in a liquid state with an unpleasant odor.
• Higher carboxylic acids are mostly without odor and in a solid-waxy-like structure.
• With an increase in molecular weight, the boiling point of carboxylic acid increases. Alcohol also has a similar molecular weight however the boiling point of the carboxylic acid is higher.

Must Read

NEET Study Notes on Carbonyl Compounds

NEET Study Notes on IUPAC and Isomerism

Chemical Properties of Carboxylic Acid

• Hydrogen gas is released on the reaction of the carboxylic acid with metal and metal salts. Carbon dioxide gas is also released in reaction of the carboxylic acid with carbonate and bicarbonates.
• On reacting with alcohols or phenols in the presence of a catalyst, carboxylic acids undergo an esterification reaction.
• Ammonium salts are formed in a carboxylic reaction with ammonia. Carboxylic acids also undergo reactions like halogenation, decarboxylation reaction, and reduction.
• Carboxylic acids are highly acidic among all organic acids.

Uses of Carboxylic Acids:

• Higher fatty acids are required for soap manufacturing,
• Organic acids are used for a variety of purposes in the food industry. Acetic acid is used for the production of vinegar,
• Organic acids are used for the production of drugs like aspirin, phenacetin, etc.
• For rubber manufacturing, acetic acids are used as coagulants.

NEET Sample Questions for Aldehydes, Ketones, and Carboxylic Acids

Question: Reaction of which substances cause the formation of Ester?

1. Alkane and Alcohol
2. Acid and base
3. Acid and alcohol
4. Base and alcohol

Answer: Acid and Alcohol

Question: Carboxyl Group presence is seen in which of the following organic compounds?

1. Ethanoic Acid
2. Formaldehyde
3. Ethanol
4. Ethylene

Answer: Ethanoic Acid

Question: In which of the following, the COOH group is not present?

1. Tartaric Acid
2. Lactic Acid
3. Citric Acid
4. Ascorbic Acid

Answer: Ascorbic Acid

Question: What is cyanohydrin formation from ketone an example of?

1. Electrophilic substitution
2. Nucleophilic addition
3. Nucleophilic substitution
4. Electrophilic addition

Answer: Nucleophilic Addition

Question: What is produced when sodium acetate is heated with soda lime>

1. Acetylene
2. Methane
3. Benzene
4. Ethane

Answer: Methane

Question: Which acid is formed from spinach?

1. Tartaric Acid
2. Acetic Acid
3. Oxalic Acid
4. Citric Acid

Answer: Oxalic Acid

Question: Which reaction distinguishes formic and acetic acid?

1. Sodium
2. HgCl2
3. Sodium ethoxide
4. 2, 4- dinitrophenylhydrazine

Answer: HgCl2

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