Amide
An amide is a functional group in organic chemistry consisting of a carbonyl group bonded to a nitrogen atom. It is commonly found in proteins and peptides, and is formed by the reaction of a carboxylic acid with an amine. Amides have diverse applications in pharmaceuticals, polymers, and materials science due to their stability and unique chemical properties.
4 Key excerpts on "Amide"
eBook - ePub- J Fisher, J.R.P. Arnold, Julie Fisher, John Arnold(Authors)
- 2020(Publication Date)
- Taylor & Francis(Publisher)
...The most important reaction of Amides is that of hydrolysis; this is the reverse reaction of Amide formation (Section J3). The product of hydrolysis depends on the reaction conditions utilized. The acid catalyzed reaction results in the formation of an amine salt. The base catalyzed reaction results in the formation of an amine (Figure 3). Figure 3 The dependence of reaction conditions on the products of Amide hydrolysis, (a) Acid catalyzed; (b) base catalyzed. Amide hydrolysis is very important in biology. It is a central reaction in the digestion of proteins. Biologically important amines and Amides Many naturally occurring compounds and pharmaceutical agents contain amine or Amide functions. Among the most important amine compounds are the neurotransmitters, such as dopamine and serotonin (Figure 4). These play an essential role in the transmission of nerve impulses throughout the body. Amphetamines, such as benzedrine, are generally powerful stimulators of the nervous system. Although many of these are used legally as drugs, they are also used illegally to heighten or stimulate emotions (Figure 4). Figure 4 Examples of biologically important amines. Alkaloids are amine-based compounds generally isolated from plants, and are among the most powerful psychotropic drugs. Some of these drugs are used to cure diseases, others, such as nicotine, cause them and are addictive (Figure 4). In addition to Amides being the key structural and functional unit of peptides (Section L1), they are the core of numerous medicinal products (Figure 5). For example, acetaminophen, marketed under a number of names including Panadol, is an effective alternative to aspirin, without the side effects of gastrointestinal bleeding! However, acetaminophen has no anti-inflammatory activity, therefore unlike aspirin cannot be used for the treatment of rheumatoid arthritis. Figure 5 Examples of medically important Amides....
eBook - ePubBiochemistry Explained
A Practical Guide to Learning Biochemistry
- Thomas Millar(Author)
- 2018(Publication Date)
- CRC Press(Publisher)
...4 Amino Acids and their Functions In this chapter you will learn: the functional groups: an amine and carboxyl groups to understand the general structure of amino acid the structures, names and single letter symbols for the 20 amino acids found in proteins how 2 cysteines may be oxidised to form the bridging amino acid cystine how the carbons of amino acids are named or numbered the terms ampholyte and zwitterion and how these relate to amino acids the structure of an Amide bond and the special case a peptide bond special functions of amino acids (e.g. neurotransmitters) and structural relationships between amino acids how ketones are formed from amino acids by removing ammonia from the αC the synthesis of the bioactive amines dopamine, noradrenaline, adrenaline and serotonin. to understand the basis for Parkinson’s disease and phenylketonuria that tyrosine, serine and threonine are phosphorylation sites in proteins the importance of decarboxylation in the formation of some active amines such as histamine how sugars may attach to the amino acids serine, threonine and asparagine Basic structure and nomencalture of amino acids The name amino acid suggests that these structures have an amine and an acid group. Indeed this is true; amino acids have an amino group and a carboxylic acid. The structure of a typical L-amino acid is illustrated below. This type of amino acid is the basis of proteins. Q&A 1 : Draw the chemical structures of a carboxylic acid, and an amine group. There is a central carbon that has bonds to an amine group, a carboxylic acid, an hydrogen and a variable R group. Since this central carbon has 4 different groups attached to it, it is a chiral carbon and hence there are 2 possible isomers, L and D. Nearly all amino acids in biochemistry are of the L-form (L for life). Note that this is the opposite of sugars, which nearly always occur as the D isomer. You need to learn their structure in this orientation...
- Wenyi Zhao(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
...10 Reagents for Amide Formation N -Acylation reactions of nitrogen for the preparation of Amides are frequently used in the synthesis of drug substances. Generally, the formation of C(O)−N Amide bond 1 between acids and amines needs to activate the acids prior to coupling with amines. Among various activation methods, conversion of the acids into the corresponding acid chlorides is by far the most common approach. The use of mixed anhydrides provides an inexpensive and readily scaled process for preparation of Amides that is particularly valuable for cases prone to epimerization. There has been increasing safety concern related to the use of triazole-based coupling agents, such as 1-[bis(dimethylamino)methylene]-1 H -1,2,3-triazolo[4,5- b ]pyridinium 3-oxid hexafluorophosphate (HATU) and O -(benzotriazol-1-yl)- N,N,N ′, N ′-tetramethyluronium hexafluorophosphate (HBTU), on a large scale due to the explosive nature of the reagents (>1500 J/g; maximum operating temperature approximately 50°C). 10.1 CDI-MEDIATED Amide PREPARATION Amide bond formation is one of the most valuable tools used to construct drug molecules. N,N- carbonyldiimidazole (CDI) as a coupling agent for Amide bond formation is increasingly applied to the large-scale synthesis of a number of pharmaceutical products, for example, sildenafil, 2 darifenacin, 3 and sunitinib. 4 The evolution of a carbon dioxide by-product provides a driving force for the reaction. In addition, the imidazole by-product can be removed by acidic wash. A disadvantage of using CDI is that the resulting imidazolide intermediate is less reactive than the corresponding acid chloride. Consequently, CDI-mediated Amide bond formation often requires a catalyst to promote the reaction. CDI 5 is a white crystalline solid and convenient to handle on scale. Compared with acid chlorides, CDI is less reactive and often used in the coupling of amino acids for peptide synthesis...
eBook - ePub- Greg T. Hermanson(Author)
- 2013(Publication Date)
- Academic Press(Publisher)
...The water-insoluble carbodiimides can be used in peptide synthesis or for the synthesis of other organic compounds. Carbodiimides are used to mediate the formation of Amide or phosphoramidate linkages between a carboxylate and an amine or a phosphate and an amine, respectively (Hoare and Koshland, 1966 ; Chu et al., 1986 ; Ghosh et al., 1990). Regardless of the type of carbodiimide, the reaction proceeds by the formation of an intermediate o -acylisourea that is highly reactive and short-lived in aqueous environments. The attack of an amine nucleophile on the carbonyl group of this ester results in the loss of an isourea derivative and formation of an Amide bond (see Reactions 3.11 and 3.12). The major competing reaction in water is hydrolysis. 4 Hydroxyl Reactions Hydroxyl-reactive chemical compounds include not only those modification agents able to directly form a stable linkage with an –OH group, but also a broad range of reagents that are designed to temporarily activate the group for coupling with a secondary functional group. Many of the chemical methods for modifying hydroxyls originally were developed for use with chromatography supports in the coupling of affinity ligands. Some of these same chemical reactions have found application in bioconjugate techniques for crosslinking a hydroxyl-containing molecule with another substance, usually containing a nucleophile. For instance, carbohydrate-containing molecules such as polysaccharides or glycoproteins can be coupled through their sugar residues using hydroxyl-specific reactions. In addition, polymers and other organic compounds containing hydroxyls (such as PEG) may be conjugated with another molecule using these chemistries. 4.1 Epoxides and Oxiranes An epoxide or oxirane group can react with nucleophiles in a ring-opening process. The reaction can take place with primary amines, sulfhydryls, or hydroxyl groups to create secondary amine, thioether, or ether bonds, respectively...
