Group 16 elements oxygen molecule

The above schemes work reasonably well for certain enzyme reactions, especially for substrates where oxygen addition/loss occurs at a main group element (e.g., N, S, Se, Cl, see Table I). In addition to SO and nitrate reductase, key examples are DMSOR, trimethylamine oxide reductase, chlorate reductase, and selenate reductase. In the case of enzymes catalyzing C-based redox reactions of organic molecules, notably XDH and aldehyde oxidase, a direct OAT step is unlikely and is replaced by mechanistic steps typical of hydro-xylation (2). The essential features of the mechanism are shown in Fig. 10 for xanthine dehydrogenase/oxidase. 

Similarly to small molecules, polymers can be classified based on their chemical nature, i.e. based on the functional groups present in their molecule. However, different from small molecules, one important element in polymer classification is the chemical structure of the polymeric backbone. The attached side atoms or groups of atoms to the polymer backbone play a different role compared to that of the presence of various atom types or groups of atoms in the backbone. For example, it is a significant difference between poly(oxy-1,4-phenylene-oxy-ethylene) that contains phenyl groups and oxygen atoms in the polymer backbone and poly(phenyl vinyl ether) that is a vinyl type polymer with a carbon chain as backbone, although both polymers are ethers. The two polymers are synthesized differently and have quite different properties. Their structures are shown below ... 

Hydrocarbon derivatives are compounds that can be synthesized from a hydrocarbon. These derivatives contain not only carbon and hydrogen, but such additional elements as oxygen, nitrogen, or a halogen. The compounds in each class have similarities in structure and properties. We will consider the classes of hydrocarbon derivatives shown in Table 19.4, which is divided into two sections of different color. The compounds in the first section don t contain a C O group in their molecules, while those in the second section all contain a C O group. A carbon atom double bonded to an oxygen atom is called a carbonyl g roup. 

---