Amides are the most stable of all the carbonyl functional groups.
Many chemists make a pronunciation distinction between the two, saying (for the carbonyl-nitrogen compound and for the anion. Others substitute one of these pronunciations with /ˈæmɨd/, while still others pronounce both /ˈæmɨd/, making them homonyms.
In the first sense referred to above, an amide is an amine where one of the nitrogen substituents is an acyl group; it is generally represented by the formula: R1(CO)NR2R3 , where either or both R2 and R3 may be hydrogen. Specifically, an amide can also be regarded as a derivative of a carboxylic acid in which the hydroxyl group has been replaced by an amine or ammonia.
Compounds in which a hydrogen atom on nitrogen from ammonia or an amine is replaced by a metal cation are also known as amides or azanides.
The second sense of the word amide is the amide anion, which is a deprotonated form of ammonia (NH3) or an amine. It is generally represented by the formula: [R1NR2]-, and is an extremely strong base, due to the extreme weakness of ammonia and its analogues as Brønsted acids.
Owing to their resonance stabilization, amides are relatively unreactive under physiological conditions, even less than similar compounds such as esters. Nevertheless, amides can undergo chemical reactions, usually through an attack of an electronegative atom on the carbonyl carbon, breaking the carbonyl double bond and forming a tetrahedral intermediate. When the functional group attacking the amide is a thiol, hydroxyl or amine, the resulting molecule may be called a cyclol or, more specifically, a thiacyclol, an oxacyclol or an azacyclol, respectively.
The proton of an amide does not dissociate readily under normal conditions; its pKa is usually well above 15. However, under extremely acidic conditions, the carbonyl oxygen can become protonated with a pKa of roughly -1.
Amides will react with nitrous acid (HONO) forming the carboxylic acid and yielding nitrogen. Nitrous acid is formed by addition of a strong acid to a nitrate (III) salt in solution at temperatures of between 0 and 10 degrees.
Amides undergo the Hofmann rearrangement in which an amine with one less carbon atom is produced upon reaction with bromine and sodium hydroxide. On the other hand, reacting the amide with the strong reducing agent lithium aluminium hydride yields an amine with the same number of carbon atoms.
Amides are dehydrated with phosphorus (V) oxide forming the nitrile. Care should be taken when performing such a reaction since phosphorus (V) oxide smoulders when in contact with organic matter.
While hydrogen bonding may enhance the water solubility of amides relative to hydrocarbons (alkanes, alkenes, alkynes and aromatic compounds), amides typically are regarded as compounds with low water solubility. They are significantly less water soluble than comparable acids or alcohols due to: 1). their non-ionic character 2). the presence of nonpolar hydrocarbon functionality, and 3). the inability of tertiary amides to donate hydrogen bonds to water (they can only be H-bond acceptors). Thus amides have water solubilities roughly comparable to esters. Typically amides are less soluble than comparable amines and carboxylic acids since these compounds can both donate and accept hydrogen bonds, and can ionize at appropriate pHs to further enhance solubility
Cyclic amides are called lactams.
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Jun 10, 2011; GENEVA, June 10 -- Publication No. WO/2011/067415 was published on June 09. Title of the invention: "Kinetically STABLE...
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