Secondary Amides
Secondary Amides - Related Videos
01:29
Preparation of Amides
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2023
Amides are synthesized by treating carboxylic acids with amines in the presence of dehydrating agents like dicyclohexylcarbodiimide (DCC). The DCC-promoted synthesis of amides begins with the protonation of DCC by carboxylic acid. The protonation makes it a better acceptor. Next, the addition of carboxylate to the protonated carbodiimide gives a reactive acylating agent. Subsequently, the amine acts as a nucleophile that attacks the acylating agent to form a tetrahedral intermediate. In the...
13:42
RNA Secondary Structure Prediction Using High-throughput SHAPE
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Cited by 16 •
2013
High-throughput selective 2' hydroxyl acylation analyzed by primer extension (SHAPE) utilizes a novel chemical probing technology, reverse transcription, capillary electrophoresis and secondary structure prediction software to determine the structures of RNAs from several hundred to several thousand nucleotides at single nucleotide resolution.
01:19
Amines to Amides: Acylation of Amines
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2025
Various carboxylic acid derivatives (such as acid chlorides, esters, and anhydrides) can be used for the acylation of amines to yield amides. The reaction requires two equivalents of amines. The first amine molecule functions as a nucleophile and attacks the carbonyl carbon to produce a tetrahedral intermediate. This is followed by the loss of the leaving group and restoration of the C=O bond. Next, the second equivalent of amine serves as a Brønsted base and deprotonates the quaternary amide...
01:28
Amides to Carboxylic Acids: Hydrolysis
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2023
Amides can undergo either acid-catalyzed hydrolysis or base-promoted hydrolysis through a typical nucleophilic acyl substitution. Each hydrolysis requires severe conditions. Acid-catalyzed hydrolysis: Hydrolysis of amides under acidic conditions yields carboxylic acids. Since the reaction occurs slowly, hydrolysis requires the conditions of heat. The mechanism begins with the protonation of the carbonyl oxygen by the acid catalyst. The protonation makes the amide carbonyl carbon more...
01:07
Acid Halides to Amides: Aminolysis
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2025
Aminolysis is a nucleophilic acyl substitution reaction, where ammonia or amines act as nucleophiles to give the substitution product. Acid halides react with ammonia, primary amines, and secondary amines to yield primary, secondary, and tertiary amides, respectively. In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
FAQs
Resonance delocalizes electron density between the carbonyl group and nitrogen, so the nitrogen lone pair is less available for bonding to a proton. This reduced basicity distinguishes secondary amides from more basic nitrogen compounds. The same electronic sharing also gives the carbonyl–nitrogen linkage partial double-bond character, influencing molecular geometry and chemical reactivity.
Electron delocalization gives the carbonyl–nitrogen bond partial double-bond character, making rotation more restricted than around an ordinary single bond. Consequently, secondary amides favor more defined molecular shapes rather than freely changing conformations. This structural constraint is important when analyzing the organization of peptide and protein structures or the geometry of synthetic molecules.
The hydrogen-bearing nitrogen can participate in strong hydrogen bonding, while the carbonyl group provides a complementary site for these interactions. Such intermolecular attractions help explain why secondary amides can show characteristic melting points and solubility behavior. Comparing these properties across compounds can therefore provide clues about hydrogen-bonding strength and molecular organization.
Molecular shape reflects several connected features: resonance restricts carbonyl–nitrogen rotation, substituents attached to the carbonyl and nitrogen influence the surrounding structure, and hydrogen bonding can organize neighboring molecules. Together, these effects determine how a secondary amide presents its functional groups, which helps explain its behavior in larger structures such as peptides, proteins, and polymers.
Their carbonyl and nitrogen arrangement makes secondary amides relevant to hydrolysis and acyl substitution, two reaction contexts involving changes at carbonyl-containing centers. Resonance helps explain why the nitrogen is less basic and why the carbonyl–nitrogen bond has restricted rotation. Studying these reactions connects electronic structure with the observed reactivity of amide-containing molecules.
Secondary amide linkages contribute structural organization in peptides and proteins because their restricted carbonyl–nitrogen rotation limits conformational freedom, while hydrogen bonding helps stabilize molecular arrangements. These features make the group more than a simple connecting unit: its electronic and geometric behavior influences how larger biological molecules adopt and maintain defined shapes.
In pharmaceutical molecules and polymers, secondary amides provide a combination of electronic, geometric, and intermolecular properties. Resonance affects nitrogen basicity and bond rotation, while hydrogen bonding influences solubility, melting behavior, and molecular organization. Incorporating this group can therefore alter how a larger molecule behaves without treating the amide linkage as an isolated functional group.
Synthetic chemistry takes advantage of the predictable relationship between secondary amide structure and reactivity. Carbonyl-centered reactions, including acyl substitution and hydrolysis, provide contexts for transforming or studying these compounds, while resonance and hydrogen bonding help explain the resulting behavior. Their presence in biologically relevant molecules, pharmaceuticals, polymers, and other targets makes this understanding broadly useful.