Green chemistry oxygen

Zhu, Y., J. Patel, S. Mujdnovic, W.R. Jackson and A.J. Robinson, Preparation of Terminal Oxygenates from Renewable Natural Oils by a One-Pot Metathesis-Isomerisation-Methoxycarbonylation-Transesterification Reaction Sequence, Green Chemistry, 8, 746-749 (2006a). 

Megammonia A process for making ammonia. It uses oxygen instead of steam, and novel axial-radial reactors that reduce pressure-drop and catalyst quantities. Developed by Lurgi Oel-Gas-Chemie and Ammonia Casale, for which they received the AstraZeneca Award for Green Chemistry in 2003. 

The catalytic oxidation of alcohols to carbonyl compounds using the oxygen in air as an oxidant is an example of Green Chemistry, since no toxic by-products, such as reduced... 

In order to achieve the goal, the use of stoichiometric amount of a promoter is avoided and the use of just a catalytic amount of promoter (catalyst) is desirable (Figure 10.1). Metal-based catalysts have played important roles in synthetic organic chemistry. Due to the potential toxicity and sensitivity towards oxygen and moisture of metal-based catalysts, the development of metal-free catalysts has attracted much attention from synthetic organic chemists and is desired from the standpoint of green chemistry. 

The metal-catalyzed oxidation of carbohydrates with molecular oxygen is a remarkable example of green chemistry because reactants are obtained from renewable resources, processes are conducted under mild conditions with air as oxidizing agent and water as solvent, and reaction products are environmentally benign because of their biodegradability. In addition oxidized carbohydrate derivatives can often be obtained with high selectivity, and the catalysts are recyclable. These catalytic processes are, therefore, potentially very attractive for the preparation of specialties or intermediates employed in the food, cosmetic, pharmaceutical, and chemical industries. 

This process makes use of a catalytic reaction using an environmentally friendly oxidant and fits nicely into the context of green chemistry. The main problems of this type of reaction are, however, the danger of an explosion due to oxygen-rich gas phase, the danger of runaway reactions due to the exothermic nature of the reaction, and overoxidation of the product, especially at high conversions. 

Different methods can be used to synthesize oxygenated heterocycles. Nowadays, the reagents have to be employed in catalytic amounts, and transition metal catalysts have to be considered to form either C—C bonds or C—O bonds. Chemists have to tune up efficient catalytic reactions to be in accordance with the green chemistry principles. 

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