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30-448: N -Acetylglucosamine (GlcNAc) is an amide derivative of the monosaccharide glucose . It is a secondary amide between glucosamine and acetic acid . It is significant in several biological systems. It is part of a biopolymer in the bacterial cell wall , which is built from alternating units of GlcNAc and N -acetylmuramic acid (MurNAc), cross-linked with oligopeptides at the lactic acid residue of MurNAc. This layered structure

60-400: A mixture of dimethylamine hydrochloride and potassium formate . DMF is prepared by combining methyl formate and dimethylamine or by reaction of dimethylamine with carbon monoxide . Although currently impractical, DMF can be prepared from supercritical carbon dioxide using ruthenium -based catalysts. The primary use of DMF is as a solvent with low evaporation rate. DMF is used in

90-485: A p K a of roughly −1. It is not only because of the positive charge on the nitrogen but also because of the negative charge on the oxygen gained through resonance. Because of the greater electronegativity of oxygen than nitrogen, the carbonyl (C=O) is a stronger dipole than the N–C dipole. The presence of a C=O dipole and, to a lesser extent a N–C dipole, allows amides to act as H-bond acceptors. In primary and secondary amides,

120-484: A variety of Lewis acids such as the soft acid I 2 , and the hard acid phenol . It is classified as a hard Lewis base and its ECW model base parameters are E B = 2.19 and C B = 1.31. Its relative donor strength toward a series of acids, versus other Lewis bases, can be illustrated by C-B plots . DMF was first prepared in 1893 by the French chemist Albert Verley (8 January 1867 – 27 November 1959), by distilling

150-407: Is a means of activating or deactivating enzymes or transcription factors . In fact, O -GlcNAcylation and phosphorylation often compete for the same serine/threonine sites. O -GlcNAcylation most often occurs on chromatin proteins, and is often seen as a response to stress. Hyperglycemia increases O -GlcNAcylation, leading to insulin resistance . Increased O -GlcNAcylation due to hyperglycemia

180-410: Is a poor leaving group, the intermediate does not collapse and another nucleophilic addition does not occur. Upon acidic workup, the alkoxide is protonated to give 4 , then the amine is protonated to give 5 . Elimination of a neutral molecule of dimethylamine and loss of a proton give benzaldehyde, 6 . Amides hydrolyse in hot alkali as well as in strong acidic conditions. Acidic conditions yield

210-400: Is also a hydrogen bond present between the hydrogen and nitrogen atoms in the active groups. Resonance is largely prevented in the very strained quinuclidone . In their IR spectra, amides exhibit a moderately intense ν CO band near 1650 cm . The energy of this band is about 60 cm -1 lower than for the ν CO of esters and ketones. This difference reflects the contribution of

240-546: Is called peptidoglycan (formerly called murein). GlcNAc is the monomeric unit of the polymer chitin , which forms the exoskeletons of arthropods like insects and crustaceans . It is the main component of the radulas of mollusks , the beaks of cephalopods , and a major component of the cell walls of most fungi . Polymerized with glucuronic acid , it forms hyaluronan . GlcNAc has been reported to be an inhibitor of elastase release from human polymorphonuclear leukocytes (range 8–17% inhibition), however this

270-819: Is called a peptide bond when it is part of the main chain of a protein , and an isopeptide bond when it occurs in a side chain , as in asparagine and glutamine . It can be viewed as a derivative of a carboxylic acid ( R−C(=O)−OH ) with the hydroxyl group ( −OH ) replaced by an amine group ( −NR′R″ ); or, equivalently, an acyl (alkanoyl) group ( R−C(=O)− ) joined to an amine group. Common of amides are formamide ( H−C(=O)−NH 2 ), acetamide ( H 3 C−C(=O)−NH 2 ), benzamide ( C 6 H 5 −C(=O)−NH 2 ), and dimethylformamide ( H−C(=O)−N(−CH 3 ) 2 ). Some uncommon examples of amides are N -chloroacetamide ( H 3 C−C(=O)−NH−Cl ) and chloroformamide ( Cl−C(=O)−NH 2 ). Amides are qualified as primary , secondary , and tertiary according to

300-668: Is catalyzed by both Brønsted acids and Lewis acids . Peptidase enzymes and some synthetic catalysts often operate by attachment of electrophiles to the carbonyl oxygen. Amides are usually prepared by coupling a carboxylic acid with an amine . The direct reaction generally requires high temperatures to drive off the water: Esters are far superior substrates relative to carboxylic acids. Further "activating" both acid chlorides ( Schotten-Baumann reaction ) and anhydrides ( Lumière–Barbier method ) react with amines to give amides: Peptide synthesis use coupling agents such as HATU , HOBt , or PyBOP . The hydrolysis of nitriles

330-465: Is conducted on an industrial scale to produce fatty amides. Laboratory procedures are also available. Many specialized methods also yield amides. A variety of reagents, e.g. tris(2,2,2-trifluoroethyl) borate have been developed for specialized applications. Dimethylformamide As for most amides , the spectroscopic evidence indicates partial double bond character for the C−N and C−O bonds. Thus,

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360-534: Is evidently a dysfunctional form of O -GlcNAcylation. O -GlcNAcylation decline in the brain with age is associated with cognitive decline . When O -GlcNAcylation was increased in the hippocampus of aged mice, spatial learning and memory improved. Amide In organic chemistry , an amide , also known as an organic amide or a carboxamide , is a compound with the general formula R−C(=O)−NR′R″ , where R, R', and R″ represent any group, typically organyl groups or hydrogen atoms. The amide group

390-402: Is much weaker than the inhibition seen with N -acetylgalactosamine (range 92–100%). It has been proposed as a treatment for autoimmune diseases and recent tests have claimed some success. O -GlcNAcylation is the process of adding a single N -acetylglucosamine sugar to the serine or threonine of a protein. Comparable to phosphorylation , addition or removal of N -acetylglucosamine

420-399: Is not expected. DMF is hydrolyzed by strong acids and bases, especially at elevated temperatures. With sodium hydroxide , DMF converts to formate and dimethylamine. DMF undergoes decarbonylation near its boiling point to give dimethylamine. Distillation is therefore conducted under reduced pressure at lower temperatures. In one of its main uses in organic synthesis , DMF is a reagent in

450-499: Is shorter than the C-N distance by almost 10%. The structure of an amide can be described also as a resonance between two alternative structures: neutral (A) and zwitterionic (B). It is estimated that for acetamide , structure A makes a 62% contribution to the structure, while structure B makes a 28% contribution (these figures do not sum to 100% because there are additional less-important resonance forms that are not depicted above). There

480-493: The Vilsmeier–Haack reaction , which is used to formylate aromatic compounds. The process involves initial conversion of DMF to a chloroiminium ion, [(CH 3 ) 2 N=CH(Cl)] , known as a Vilsmeier reagent , which attacks arenes. Organolithium compounds and Grignard reagents react with DMF to give aldehydes after hydrolysis in a reaction called Bouveault aldehyde synthesis . Dimethylformamide forms 1:1 adducts with

510-399: The amide anion (NR 2 ) is a very strong base and thus a very poor leaving group, so nucleophilic attack only occurs once. When reacted with carbon nucleophiles, N , N -dimethylformamide (DMF) can be used to introduce a formyl group. [REDACTED] Here, phenyllithium 1 attacks the carbonyl group of DMF 2 , giving tetrahedral intermediate 3 . Because the dimethylamide anion

540-419: The infrared spectrum shows a C=O stretching frequency at only 1675 cm , whereas a ketone would absorb near 1700 cm . DMF is a classic example of a fluxional molecule . The ambient temperature H NMR spectrum shows two methyl signals, indicative of hindered rotation about the (O)C−N bond. At temperatures near 100 °C, the 500 MHz NMR spectrum of this compound shows only one signal for

570-593: The secondary structure of proteins. The solubilities of amides and esters are roughly comparable. Typically amides are less soluble than comparable amines and carboxylic acids since these compounds can both donate and accept hydrogen bonds. Tertiary amides, with the important exception of N , N -dimethylformamide , exhibit low solubility in water. Amides do not readily participate in nucleophilic substitution reactions. Amides are stable to water, and are roughly 100 times more stable towards hydrolysis than esters. Amides can, however, be hydrolyzed to carboxylic acids in

600-399: The N linkage and thus has important consequences for the mechanical properties of bulk material of such molecules, and also for the configurational properties of macromolecules built by such bonds. The inability to rotate distinguishes amide groups from ester groups which allow rotation and thus create more flexible bulk material. The C-C(O)NR 2 core of amides is planar. The C=O distance

630-931: The amide is derived from a primary or secondary amine, the substituents on nitrogen are indicated first in the name. Thus, the amide formed from dimethylamine and acetic acid is N , N -dimethylacetamide (CH 3 CONMe 2 , where Me = CH 3 ). Usually even this name is simplified to dimethylacetamide . Cyclic amides are called lactams ; they are necessarily secondary or tertiary amides. Amides are pervasive in nature and technology. Proteins and important plastics like nylons , aramids , Twaron , and Kevlar are polymers whose units are connected by amide groups ( polyamides ); these linkages are easily formed, confer structural rigidity, and resist hydrolysis . Amides include many other important biological compounds, as well as many drugs like paracetamol , penicillin and LSD . Low-molecular-weight amides, such as dimethylformamide, are common solvents. The lone pair of electrons on

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660-410: The amine by the carbonyl. On the other hand, amides are much stronger bases than carboxylic acids , esters , aldehydes , and ketones (their conjugate acids' p K a s are between −6 and −10). The proton of a primary or secondary amide does not dissociate readily; its p K a is usually well above 15. Conversely, under extremely acidic conditions, the carbonyl oxygen can become protonated with

690-428: The carboxylic acid and the ammonium ion while basic hydrolysis yield the carboxylate ion and ammonia. The protonation of the initially generated amine under acidic conditions and the deprotonation of the initially generated carboxylic acid under basic conditions render these processes non-catalytic and irreversible. Electrophiles other than protons react with the carbonyl oxygen. This step often precedes hydrolysis, which

720-482: The methyl groups. DMF is miscible with water. The vapour pressure at 20 °C is 3.5 hPa. A Henry's law constant of 7.47 × 10 hPa·m /mol can be deduced from an experimentally determined equilibrium constant at 25 °C. The partition coefficient log  P OW is measured to −0.85. Since the density of DMF (0.95 g·cm at 20 °C ) is similar to that of water, significant flotation or stratification in surface waters in case of accidental losses

750-453: The nitrogen atom is delocalized into the Carbonyl group , thus forming a partial double bond between nitrogen and carbon. In fact the O, C and N atoms have molecular orbitals occupied by delocalized electrons , forming a conjugated system . Consequently, the three bonds of the nitrogen in amides is not pyramidal (as in the amines ) but planar. This planar restriction prevents rotations about

780-451: The number of carbonyl group(s) −CO bounded to the nitrogen atom. The core −C(=O)−(N) of amides is called the amide group (specifically, carboxamide group ). In the usual nomenclature, one adds the term "amide" to the stem of the parent acid's name. For instance, the amide derived from acetic acid is named acetamide (CH 3 CONH 2 ). IUPAC recommends ethanamide , but this and related formal names are rarely encountered. When

810-491: The presence of N–H dipoles allows amides to function as H-bond donors as well. Thus amides can participate in hydrogen bonding with water and other protic solvents; the oxygen atom can accept hydrogen bonds from water and the N–H hydrogen atoms can donate H-bonds. As a result of interactions such as these, the water solubility of amides is greater than that of corresponding hydrocarbons. These hydrogen bonds also have an important role in

840-575: The presence of acid or base. The stability of amide bonds has biological implications, since the amino acids that make up proteins are linked with amide bonds. Amide bonds are resistant enough to hydrolysis to maintain protein structure in aqueous environments but are susceptible to catalyzed hydrolysis. Primary and secondary amides do not react usefully with carbon nucleophiles. Instead, Grignard reagents and organolithiums deprotonate an amide N-H bond. Tertiary amides do not experience this problem, and react with carbon nucleophiles to give ketones ;

870-475: The production of acrylic fibers and plastics . It is also used as a solvent in peptide coupling for pharmaceuticals, in the development and production of pesticides , and in the manufacture of adhesives , synthetic leathers , fibers, films, and surface coatings. As a cheap and common reagent, DMF has many uses in a research laboratory. Dimethylformamide vapor exposure has shown reduced alcohol tolerance and skin irritation in some cases. On 20 June 2018,

900-415: The zwitterionic resonance structure. Compared to amines , amides are very weak bases . While the conjugate acid of an amine has a p K a of about 9.5, the conjugate acid of an amide has a p K a around −0.5. Therefore, compared to amines, amides do not have acid–base properties that are as noticeable in water . This relative lack of basicity is explained by the withdrawing of electrons from

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