Advances in selective activation and application of ammonia in homogeneous catalysis

Abstract

Recent developments toward selective N-H cleavage and the use of ammonia as a substrate in homogeneous catalysis are discussed in this critical review (134 references).

On-line Ammonia Sensor and Invisible Security Ink by Fluorescent Zwitterionic Spirocyclic Meisenheimer Complex

“…Ammonia (NH 3 ), a low cost but efficient refrigerant is highly important gas for its application in agriculture, cold storage, fertilizer, anti-fungal agent and other chemical industries123. The worldwide production of ammonia is about 100 million tons.…”

E–H Bond Activation of Ammonia and Water by a Geometrically Constrained Phosphorus(III) Compound

“…[29] This chemical shift falls within the characteristic range exhibited for compounds A, B,a nd C (d = 187.0, 159.8 and 173.2 ppm, respectively). Additionally, 1 HNMR analysis confirmed that the molecule had as ymmetric ligand environment (see the Supporting Information for full experimental details).…”

“…Thereaction between H 3 [ONO],PCl 3 ,a nd triethylamine (Scheme 1) leads to the quantitative formation of as ingle product (1). As inglet for the product was detected in the 31 PNMR spectrum at d = 168.6 ppm.…”

“…[1,2] Theprocesses required to carry out such transformations (for example,o xidative addition and reductive elimination) are most commonly associated with precious-metal catalysts,f or which crustal abundance,e xpense,a nd toxicity are significant issues. Consequently,t he last decade has seen significant advances in the development of main group species that are capable of activating an umber of challenging small-molecule substrates.…”

CHAPTER 5. Ancillary Ligand Design in the Development of Palladium Catalysts for Challenging Selective Monoarylation Reactions

“…[27][28][29] Difficulties associated with the use of ammonia in BHA chemistry include, but are not restricted to: deactivation of the catalyst resulting from the formation of Werner-type ammine adducts; aggregation of amido intermediates of type D ( Figure 5.1, where R ¼ H) leading to inactive bridged polynuclear species; the slow rate of reductive elimination from sterically unencumbered intermediates of type D; 30 and, as alluded to in Section 5.1, uncontrolled polyarylation arising due to the competitive nature of the product (hetero)arylamines relative to ammonia when using most commonly employed BHA catalysts. [27][28][29] Although the use of copper-based catalysts does allow for the direct cross-coupling of (hetero)aryl bromides and iodides with ammonia, 29,31 such catalysts are not able to accommodate analogous chloride or sulfonate reagents in a useful manner, thereby restricting significantly the utility of such methods. Notwithstanding these notable challenges, the development of useful BHA protocols that allow the selective monoarylation of ammonia with a broad range of (hetero)aryl (pseudo)halides has been achieved in recent years, resulting from the design and/or application of new classes of sterically demanding ancillary ligands.…”