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In the older literature, imine refers to the aza-analogue of an epoxide. Thus, ethylenimine is the three-membered ring species aziridine C 2 H 4 NH. [8] The relationship of imines to amines having double and single bonds can be correlated with imides and amides, as in succinimide vs acetamide.
One plausible reaction mechanism is depicted below: [15]. Detailed Ugi mechanism. Amine 1 and ketone 2 form the imine 3 with loss of one equivalent of water. Proton exchange with carboxylic acid 4 activates the iminium ion 5 for nucleophilic addition of the isocyanide 6 with its terminal carbon atom to nitrilium ion 7.
First, the nickel metal dehydrogenates the alcohol to form a ketone and Ni-H complex. Then, the ketone reacts with ammonia to form an imine. Finally, the imine reacts with Ni-H to regenerate catalyst and form primary amine. An example of a homogeneous catalytic system is the reductive amination of ketones done with an iridium catalyst. [20]
amides: 1650 associated amides carboxylates (salts) 1550–1610 amino acid zwitterions 1550–1610 O─H alcohols, phenols: low concentration 3610–3670 high concentration 3200–3400 broad carboxylic acids low concentration 3500–3560 high concentration 3000 broad N─H primary amines: any 3400–3500 strong 1560–1640 strong secondary ...
The Forster–Decker method is a series of chemical reactions that have the effect of mono-alkylating a primary amine (1), forming a secondary amine (6). [ 1 ] [ 2 ] The process occurs by way of transient formation of an imine ( 3 ) that undergoes the actual alkylation reaction.
Treatment of the resulting compound with ammonia then completes the conversion to the amidine. [1] Instead of using a Bronsted acid, Lewis acids such as aluminium trichloride promote the direct amination of nitriles, [2] or, in certain exceptional cases, of amides. [3] Dimethylformamide acetal reacts with primary amines to give amidines: [4]
Primary amines are usually not used for enamine synthesis due to the preferential formation of the more thermodynamically stable imine species. [11] Methyl ketone self-condensation is a side-reaction which can be avoided through the addition of TiCl 4 [ 12 ] into the reaction mixture (to act as a water scavenger ).
The Eschweiler–Clarke reaction (also called the Eschweiler–Clarke methylation) is a chemical reaction whereby a primary (or secondary) amine is methylated using excess formic acid and formaldehyde. [1] [2] Reductive amination reactions such as this one will not produce quaternary ammonium salts, but instead will stop at the tertiary amine ...