Dhristi JEE 2022-24

What is an Amide?

Amide is a nitrogen-containing compound that belongs to one of two classes: ammonia and amines. When the hydroxyl group (OH) of an acid is replaced by an amino group, the result is a neutral or very weakly acidic compound (NR2, in which R may represent either as a hydrogen atom or an organic combining group, which is such as methyl, CH3). The most important group is carboxamides (R′CONR2), which are derived from carboxylic acids (R′COOH). Sulfonamides (RSO2NR2) are related to sulfonic acids in structure (RSO3H).

Ionic amides, also known as saltlike amides, are extremely alkaline compounds made by reacting ammonia, an amine, or a covalent amide with a reactive metal such as sodium. The amide formula or the amide group formula is CO-NH.


Covalent Amides

With the exception of formamide, which is a liquid, covalent amides produced from ammonia are solids; those with fewer than five carbon atoms are water soluble. They are nonconductors of electricity and are both organic and inorganic solvents.Even covalent amides with low molecular weight have high boiling points.

Although polyamides (amides joined together to create huge molecules called polymers) are abundant as the protein of living systems, there are no practicable natural sources of simple covalent amides. Simple amides are usually created by reacting acids or acid halides with ammonia or amines. They can also be created when water reacts with nitriles.

Hydrolysis (a chemical reaction with water) is the reaction by which covalent amides are changed to acids and amines; this reaction is usually slow unless it is catalysed by a strong acid, an alkali, or an enzyme. Amides can also be dehydrated to produce nitriles. Amides are difficult to oxidise or reduce, however hydrogenation (the addition of hydrogen at high temperatures and pressures) will convert most carboxylic acid amides to amines in the presence of a catalyst.

Lithium aluminium hydride, a powerful reducing agent, converts amides to amines. Imides are compounds having two carbonyl (CO) groups linked to the same nitrogen atom created by reacting amides with acid chlorides or anhydrides.

Acetamide, also known as ethanamide (CH3CONH2), and dimethylformamide HCON(CH3)2, which are used as solvents, sulfa drugs, and nylons, are among the commercially important amides. Urea, also known as carbamide [CO(NH2)2], is a crystalline compound produced as a byproduct of protein synthesis and removed in the urine of mammals. It's made from ammonia and carbon dioxide in large quantities for use in fertilisers, animal feed, and the production of urea-formaldehyde resins, which are used to make plastics.


Amide Nomenclature

Let us study what is an amide and the amide nomenclature. The term "amide" is added to the stem of the parent acid's name in standard nomenclature. Acetamide, for example, is the amide derived from acetic acid (CH3CONH2). Although the IUPAC recommends ethanamide, this and other formal names are rarely used. The nitrogen substituents occur first in the name of an amide produced from a primary or secondary amine.

The amide formula or the acid amide formula is CO-NH.

N,N-dimethylacetamide (CH3CONMe2, where Me = CH3) is the amide formed from dimethylamine and acetic acid. Even the name is usually shortened to dimethylacetamide. Lactams are cyclic amides that are either secondary or tertiary in nature.


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Production of Amide

Amides are compounds with nitrogen atoms attached to the carbonyl group's carbon atom. Various nomenclature requirements apply to amides, just as they do to amines, but they all include the class-specific suffix –amide:


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In the process of amidation, carboxylic acids react with amines or ammonia to produce amides. The amide is formed from the residual bits of the carboxylic acid and the amine when a water molecule is removed from the reaction:


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The production of amides from amines and carboxylic acids is a biologically relevant process. Amino acids (molecules with both amine and carboxylic acid substituents) link together in a polymer to make proteins through this process.


Types of Amides

When visiting an amide, there are a few things you should know about nomenclature, whether it's a name or a structure. Primary amine, secondary amine, and tertiary amine are the three types of amines based on their names. The differences are classified according to the position of the nitrogen atom in relation to the carbon atom in the chain of a molecule. When identifying a primary amide, use 'ic acid' or 'oic acid' at the end, followed by a 'amide'.

To show that nitrogen is related to an alkyl group, the Secondary amide is termed by integrating an N. A hydrocarbon chain with hydrogen and carbon atoms is known as an alkyl group.


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Amide Functional Group

The amide functional groups lead to the identification and recognition of a specific group of atoms within a larger molecule. Alkanes to alcohols, including our special friend, amide, are examples of functional groups. An amide is a functional group with a carbonyl group and a nitrogen atom that can be generated from various carboxylic acid functional groups.


Amide Structure

Let us look at the amide structure.


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To remember the amide structure, all you need to remember is that an amide compound must have a nitrogen atom.

  • The carbonyl group is composed of two carbon atoms that are double bonded to an oxygen atom.

  • The amine group, in which a nitrogen atom shares a single bond with R groups, is the second. R groups can be regarded of as substituents for other atoms or molecules in a structure.

  • Finally, there is a single bond, which is also an amide's defining functional group.

The structure of three different types of amides is shown in the diagram above. For three different amides, the nitrogen atom is not in the same position. In the case of a primary amide, a nitrogen atom is linked to a single carbon atom. In the case of secondary amine, the nitrogen atom is linked to two carbon atoms. The nitrogen in tertiary amide is linked to three carbon atoms.


Basicity

Amides are very weak bases as compared to amines. An amine's conjugate acid has a pKa of roughly 9.5, whereas an amide's conjugate acid has a pKa of around 0.5. As a result, amides don't have as clear acid–base characteristics in water. The carbonyl withdraws electrons from the amine, which explains the relative lack of basicity. Amides, on the other hand, are far more powerful bases than carboxylic acids, esters, aldehydes, and ketones (their conjugate acids' pKas range from 6 to 10).


Key Points of Amide

  • A nitrogen atom is bonded to a carbonyl carbon atom in the typical structure of amides.

  • The acid amide formula or the amide group formula is CO-NH.

  • An amide's functional group is as follows:


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  • The -ic acid of the common name or the -oic ending of the IUPAC for the corresponding carboxylic acid is replaced by -amide in the names for amides.

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FAQs (Frequently Asked Questions)

1. What is an Amide?

Amides are an acid derivative compound, composed of nitrogen, carboxylic group, and alkyl groups.

2. What are the Chemical Properties of Amides?

The chemical properties of amides are given below:

  • The amide group exhibits resonance due to the presence of a lone pair on the nitrogen.

  • Due to the partial double bond, amides exhibit planner restriction.

  • Amides are amphoteric in nature, acting as both acid and base. 

  • The presence of a high electronegative element (oxygen) in the amide group, amides participate in the hydrogen bonding.

  • Amides undergo several chemical reactions. These chemical reactions include Hofmann rearrangement reaction, amide reduction reaction, Vilsmeier- Haack reaction.

  • Hydrolysis Reaction- - When amides heated with water, acids, or alkalies, it gives a hydrolysis reaction and forms carboxylic acids and free ammonia as a product. 

  • Dehydration- Amides gives dehydration reaction on heating with a dehydrating agent like phosphorus pentoxide (P2O5), Phosphorus trichloride POCl3, and sulfonyl dichloride SOCl2, amides lose a molecule of water to form nitriles (cyanides).

3. Give the applications of amides?

Let us look at the applications and occurrence of amide.

Amides are widely used in technology as structural materials. An amide relation is simple to develop, resistant to hydrolysis, and provides structural stiffness. The most resilient materials are polyamides and nylons. Various medications, such as penicillin, LSD, and paracetamol, are amides. Furthermore, plant N-alkylamides have a wide range of biological functions.

4. Give some examples of Amides?


Carboxamides, sulfonamides, and phosphoramidites are examples of amides. Polyamides, such as nylon, are a type of polymer. LCD, penicillin, and paracetamol are all examples of amides.

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