The nadir (UK: /ËnÃ¦dÉªÉr/), (US: /ËneÉªdÉªÉr/) (from Arabic: ÙØ¸ÙØ±ââ / ALA-LC: naáºÄ«r, meaning counterpart) is the direction pointing directly below a particular location; that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface there.
Asymmetric hydrogenation is a chemical reaction that adds two atoms of hydrogen preferentially to one of two faces of an unsaturated substrate molecule, such as an alkene or ketone.ne of these is in the asymmetric hydrogenation of N-unfunctionalized imines to give primary amines. Such species can be difficult to selectively reduce because they tend to exist in complex equilibria of imine and enamine tautomers, as well as (E) and (Z) isomers.
Whatever the reason, asymmetric synthesis is now big business. â¢ Strategies for synthesis of enantiomerically pure molecules 1. Resolution (often still used, but wasteful) 2. âChiral poolâ syntheses (limited in terms of starting materials and available enantiomers) 3.n alternative strategy would be to use a chiral catalyst to promote the asymmetric ring opening of either meso-epoxides (in desymmetrising mode) or racemic epoxides (in resolution mode). Several catalyst systems have been defined for this.