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Catalytic hydrogenation [ edit ] Catalytic hydrogenation can be used to reduce amides to amines ; however, the process often requires high hydrogenation pressures and reaction temperatures to be effective (i.e. often requiring pressures above 197 atm and temperatures exceeding 200 °C). [ 1 ]
In chemistry, the hydrogenation of carbon–nitrogen double bonds is the addition of the elements of dihydrogen (H 2) across a carbon–nitrogen double bond, forming amines or amine derivatives. [1] Although a variety of general methods have been developed for the enantioselective hydrogenation of ketones, [ 2 ] methods for the hydrogenation of ...
Catalytic hydrogenation using platinum(IV) oxide (PtO 2) [23] or Raney nickel [24] Iron metal in refluxing acetic acid [25] Samarium diiodide [26] Raney nickel, platinum on carbon, or zinc dust and formic acid or ammonium formate [6] α,β-Unsaturated nitro compounds can be reduced to saturated amines by: Catalytic hydrogenation over palladium ...
The hydride reagent Diisobutylaluminium hydride, or DIBAL-H, is commonly used to convert nitriles to the aldehyde. [14] Regarding the proposed mechanism, DIBAL forms a Lewis acid-base adduct with the nitrile by formation of an N-Al bond. The hydride is then transferred to the carbon of the nitrile.
An example of a homogeneous catalytic system is the reductive amination of ketones done with an iridium catalyst. [20] Homogenous Iridium (III) catalysts have been shown to be effective in the reductive amination of carboxylic acids , which in the past has been more difficult than aldehydes and ketones. [ 16 ]
For example, in the three-component coupling of aldehydes, amines, and activated alkenes, the aldehyde reacts with the amine to produce an imine prior to forming the aza-MBH adduct, as in the reaction of aryl aldehydes, diphenylphosphinamide, and methyl vinyl ketone, in the presence of TiCl 4, triphenylphosphine, and triethylamine: [19]
In a similar fashion, the intermediate isocyanate can be trapped by tert-butyl alcohol, yielding the tert-butoxycarbonyl (Boc)-protected amine. The Hofmann Rearrangement also can be used to yield carbamates from α,β - unsaturated or α- hydroxy amides [ 2 ] [ 8 ] or nitriles from α,β- acetylenic amides [ 2 ] [ 9 ] in good yields (≈70%).
An imine can be reduced to an amine via hydrogenation for example in a synthesis of m-tolylbenzylamine: [32] Other reducing agents are lithium aluminium hydride and sodium borohydride. [33] The asymmetric reduction of imines has been achieved by hydrosilylation using a rhodium-DIOP catalyst. [34] Many systems have since been investigated. [35] [36]