In view of the diminishing oil resources and the ongoing climate change, the use of efficient and environmentally benign technologies for the utilization of renewable resources has become indispensible. Therein, hydrogenolysis reactions offer a promising possibility for future biorefinery concepts. These reactions result in the cleavage of C-C and C-O bonds by hydrogen and allow direct access to valuable platform chemicals already integrated in today's value chains. Thus, hydrogenolysis bears the potential to bridge currently available technologies and future biomass-based refinery concepts. This Review highlights past and present developments in this field, with special emphasis on the direct utilization of cellulosic feedstocks.

Hydrogenolysis Goes Bio: From Carbohydrates and Sugar Alcohols to Platform Chemicals

Although the use of CO as a reductant had been in the past confined to few reactions, its use in organic synthesis, especially in the reductive carbonylation of nitro aromatics and the oxidative carbonylation of aromatic amines, has increased dramatically. Since the discovery of CO-induced reduction of nitro groups, there has been a wide spread increase of interest in the application and mechanistic understanding of this reaction. In a major review published in 1988 it was noted, that in practice no studies of the mechanism of N-carbonylation of aromatic nitro compounds with alcohols leading to carbamates have been carried out. This review clearly shows a major change since that publication. Indeed, metal-catalyzed reductive carbonylation of nitro aromatics using CO as reducing agent has been in the past 10 years the subject of intense investigation both in academia and in the chemical industry. Several articles and reviews have covered the subject up to the late 1980s. The authors will concentrate on more recent literature, but sometimes older data will be used to establish an understanding of these reactions. 127 refs.

A Review of the Selective Catalytic Reduction of Aromatic Nitro Compounds into Aromatic Amines, Isocyanates, Carbamates, and Ureas Using CO.

Asymmetric transfer hydrogenation has become a practically useful tool in reduction chemistry in the last decade or so. This was largely triggered by the seminal work of Noyori and co-workers in the mid-1990s and is driven by its complementing chemistry to hydrogenation employing H2. This Focus Review attempts to present a “holistic” overview on the advances in the area, focusing on the achievements recorded around the last three years. These include more-efficient and “greener” metal catalysts, catalysts that enable hydrogenation as well as transfer hydrogenation, biomimetic and organocatalysts, and their applications in the reduction of CO, CN, and CC bonds. Also highlighted are efforts in the development of environmentally benign and reusable catalytic systems.

Broader, Greener, and More Efficient: Recent Advances in Asymmetric Transfer Hydrogenation

Oxidation of sulfamethoxazole and related antimicrobial agents by TiO2 photocatalysis

Highly Efficient Catalyst Systems Using Iron Complexes with a Tetradentate PNNP Ligand for the Asymmetric Hydrogenation of Polar Bonds

Mechanism for transfer hydrogenation of ketones to alcohols catalysed by hydridotri-ironundecacarbonylate anion under phase transfer conditions

Phase transfer-catalysed transfer hydrogenation of ketones using iron carbonyls as catalysts

RuCl2(PPh3)3-catalyzed transfer hydrogenation of d-glucose

Hydrogenation and transfer hydrogenation of d-fructose catalyzed by dichlorotris (triphenylphosphine) ruthenium (II)

Rate constants for the reaction of carbonate radical with aniline and some parasubstituted anilines have been determined by the flash photolysis technique. Using σ+ para values the rate constants at pH 8.5 correlate very well with the Hammett equation yielding ρ= − 1. The carbonate radical oxidises aniline giving the anilino radical. The products so formed have been identified through studies under conditions of continuous irradiation.

S. Vancheesan

Papers

Mechanism for transfer hydrogenation of ketones to alcohols catalysed by hydridotri-ironundecacarbonylate anion under phase transfer conditions

Phase transfer-catalysed transfer hydrogenation of ketones using iron carbonyls as catalysts

RuCl2(PPh3)3-catalyzed transfer hydrogenation of d-glucose

Hydrogenation and transfer hydrogenation of d-fructose catalyzed by dichlorotris (triphenylphosphine) ruthenium (II)

Reaction of the carbonate radical with substituted anilines