Oxygen systematics

Red lead is insoluble in water. Like lead(II) oxide it can readily be reduced to lead. The structure of the solid, as the systematic name suggests, consists of two interpenetrating oxide structures, in which each Pb atom is surrounded octahedrally by six oxygen atoms, and each Pb" by three (pyramidal) oxygen atoms, the oxygen atoms being shared between these two units of structure. With dilute nitric acid the lead(ll) part dissolves, and the lead(IV) part precipitates as lead(IV) oxide ... 

The strength of this bonding depends on the kind of ether Simple ethers form relatively weak complexes with metal ions but Charles J Pedersen of Du Pont discovered that cer tain polyethers form much more stable complexes with metal ions than do simple ethers Pedersen prepared a series of macrocyclic polyethers cyclic compounds contain mg four or more oxygens m a ring of 12 or more atoms He called these compounds crown ethers, because their molecular models resemble crowns Systematic nomencla ture of crown ethers is somewhat cumbersome and so Pedersen devised a shorthand description whereby the word crown is preceded by the total number of atoms m the ring and is followed by the number of oxygen atoms... 

Other 2,3-Diphosphoglycerate Pocket Cross-Linkers. The reactivity of the valine NAl(l)a and lysine EF6(82)p residues in the 2,3-DPG pocket shown by NFPLP and (bis-PL)P4 has stimulated the search for other reagents that react similarly but have potential for greater efficiency and ease of scaleup. The systematic study of four different dicarboxyhc acid derivatives, cross-linked in both oxygenated and deoxygenated conditions, has been reported (92). Each of these derivatives presents problems in purification, and proof of the sites of reaction is tedious. 

The thermodynamic data pertinent to the corrosion of metals in aqueous media have been systematically assembled in a form that has become known as Pourbaix diagrams (11). The data include the potential and pH dependence of metal, metal oxide, and metal hydroxide reactions and, in some cases, complex ions. The potential and pH dependence of the hydrogen and oxygen reactions are also suppHed because these are the common corrosion cathodic reactions. The Pourbaix diagram for the iron—water system is given as Figure 1. 

Oxygen (oxide ions) in crystal lattices can be progressively removed by systematically... 

The reactivity of sulfur clearly depends sensitively on the molecular ctimplexity of the reacting species. Little systematic work has been done. Cyc/<7-Ss is obviously less reactive than the diradical catenas, and smaller oligomers in the liquid or vapour phase also complicate the picture. In the limit atomic sulfur, which can readily be generated photolytically, is an extremely reactive specie.s. As with atomic oxygen and the various... 

According to the systematic nomenclature these substances were first named l-f-triazolo[d] pyrimidines in compliance with the general principles of the Ring Index/ More recent papers and Chemical Abstracts indexes use the term i -triazolo[4,5-d]pyrimidine (147) in accord with the lUPAC nomenclature. The numbering of substituents when using the last-mentioned name is different from that of the 8-aza analogs. For the formulas of oxygen and sulfur derivatives names derived from the lactim or thiolactim form are almost exclusively in use (in common with the purine derivatives). These derivatives are thus described as hydroxy and mercapto derivatives, respectively. The name 1,2,3,4,6-pentaazaindene is used only rarely for this system. 

Huisgen has reported in 1963 about a systematic treatment of the 1,3-dipolar cycloaddition reaction as a general principle for the construction of five-membered heterocycles. This reaction is the addition of a 1,3-dipolar species 1 to a multiple bond, e. g. a double bond 2 the resulting product is a heterocyclic compound 3. The 1,3-dipolar species can consist of carbon, nitrogen and oxygen atoms (seldom sulfur) in various combinations, and has four non-dienic r-electrons. The 1,3-dipolar cycloaddition is thus An +2n cycloaddition reaction, as is the Diels-Alder reaction. 

Ethylene oxide, the simplest epoxide, is an intermediate in the manufacture of both ethylene glycol, used for automobile antifreeze, and polyester polymers. More than 4 million tons of ethylene oxide is produced each year in the United States by air oxidation of ethylene over a silver oxide catalyst at 300 °C. This process is not useful for other epoxides, however, and is of little value in the laboratory. Note that the name ethylene oxide is not a systematic one because the -ene ending implies the presence of a double bond in the molecule. The name is frequently used, however, because ethylene oxide is derived pom ethylene by addition of an oxygen atom. Other simple epoxides are named similarly. The systematic name for ethylene oxide is 1,2-epoxyethane. 

The wave numbers of both niobium-oxygen and niobium-fluorine modes change slightly, but systematically, upon heating. The value of vs(NbO) increases, indicating an inflection point at about 490K, whereas vs(NbF) decreases slowly, ultimately reaching a constant wave number value. Fig. 106... 

The alkali chlorates melt before decomposition [844], The catalytic properties of Co304 in promoting [865] the solid phase decomposition of NaC103 are attributed to the ability of the oxide to donate an electron to an oxygen atom, temporarily accepted at its surface from a CIO ion, prior to molecular oxygen formation and desorption. The progressive increase in E during reaction (from 120 to 200 kJ mole-1) is associated with systematic deactivation of the surface. 

Thiirane oxides (3 x = 1) were rather rare and not well characterized until about 20 years ago20. Since 1965 synthetic methods for their preparation have been consistently and systematically explored2. They are rather thermodynamically stable compounds— compared to their closely-related thiirane dioxides—provided they have an anticonfiguration with respect to the substituents and the sulfinyl oxygen. Also they are more resistant than the corresponding sulfones toward ring opening by either nucleophiles or electrophiles. 

A systematic study632 in which substituted thiiranes were oxidized to the corresponding thiirane oxides determined the geometrical position of the oxygen atom by complete NMR and microwave analysis. 

The principal product of the reaction of the alkali metals with oxygen varies systematically down the group (Fig. 14.15). Ionic compounds formed from cations and anions of similar radius are commonly found to he more stable than those formed from ions with markedly different radii. Such is the case here. Lithium forms mainly the oxide, Li20. Sodium, which has a larger cation, forms predominantly the very pale yellow sodium peroxide, Na202. Potassium, with an even bigger cation, forms mainly the superoxide, K02, which contains the superoxide ion, O,. ... 

Replacement of a hydroxy oxygen atom of an aldose or ketose, or of the oxygen atom of the carbonyl group of the acyclic form of an aldose or ketose, by sulfur is indicated by placing the prefix thio , preceded by the appropriate locant, before the systematic or trivial name of the aldose or ketose. 

Both of these forms of representation are symbohc although words are more familiar symbols to students. Both of these forms present difficulties to learners. Although word equations may seem a more direct way for novices to represent chemical reactions, they may sometimes make more demands on learners. So, for example in completing equations, non-systematic names - such as ammonia - may not provide strong clues to the elements present, and there is a need to learn, recall and apply such rules as -ate implies oxygen present, etc. 

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