Nomenclature covalent compounds

Adds and Bases. Generally, acids react according to the rules for replacement and double replacement reactions. They are so important however, that a special nomenclature has developed for acids and their reactions. Acids were introduced in Chapter 5. They may be identified by their formulas, which have the H representing hydrogen written first, and by their names, which contain the word acid. An acid will react with a base to form a salt and a water. The process is called neutralization. The driving force for such reactions is the formation of water, a covalent compound. For example. 

Ollis and Ramsden state that A compound may be appropriately called mesoionic if it is a five-membered heterocycle which cannot be represented satisfactorily by any one covalent or polar structure and possesses a sextet of electrons in association with the five atoms comprising the ring . From the point of view of systematic nomenclature, compounds of this type are difficult to deal with, since most available nomenclature systems are designed so as to name one particular bond- and charge-localized canonical form. 

Unfortunately the name phosphorane according to IUPAC (and Chemical Abstracts) nomenclature is not restricted to phosphorus compounds with five covalent bonded ligands,... 

Another point which needs to be clarified from the start is the nomenclature of metalated silanes We will frequently use the term silyl anion in this chapter when we talk about metalated silanes. Although the term anion defines, literally taken, an ionic compound, this expression, when used by us, does not necessarily imply that the compound in question is of ionic nature, but covers, as well, in analogy to the use of the term carbanion , silicon compounds with a polarized covalent silicon-metal bond. 

The first group is formed by the compounds with exclusively covalent bonds. Examples of this group are water, sulphur dioxide and carbon monoxide. The nomenclature or systematic naming of these compounds is quite simple, as appears from the following examples ... 

Instead attention is next directed to polycyclic compounds for which there is a different formal bond order than that which simplistic graph theory would imply. Unlike the subject matter introduced in Chapter 2, here traditional covalent bonds, in contradistinction to consideration of hydrogen bonds, are an integral part of the nomenclature. As a first example, note that, unlike the larger propellanes, the bond order is equal to zero between the bridgehead carbon atoms in [l,l,l]-propellane [40] (Figure 7). This "anomoly" is accounted for in the nomenclature by the name ... 

The nomenclature for molecular compounds is much less complicated than for ionic compounds. Molecular compounds are formed from covalently bonded nonmetallic elements. The formula for a molecule represents a stable unit of atoms, unlike a formula for an ionic compound, which only represents the simplest whole number ratio of ions. As a result, molecular formulas cannot be simplified like formulas for ionic compounds. An example would... 

Because most of the covalent hydrides consist of molecular units with only weak intermolecular forces between them, they are volatile compounds. Accordingly, the covalent hydrides are sometimes referred to as the volatile hydrides. The nomenclature, melting points, and boiling points of several covalent hydrides are shown in Table 6.6. 

It is not wise to infer the detailed physical nature of a compound from the name alone. In this system the name of the (electropositive) metal is not modified from that of the element, but the name of the electronegative element is, and in the way described in the Substitutive Nomenclature section, above. Similarly we derive oxide and sulfide, for example, from oxygen and sulfur. The same division between electronegative and electropositive parts is evident in the covalent nonionic compotmd SiC, which can be named silicon tetrachloride, though an equally valid substitutive name is tetrachlorosilane. 

Graphite oxide (GO) is a collective name for covalent layered C—O—H compounds made by oxidation of graphite in strong acids. First mentioned in 1859, the nomenclature varies—graphitic acid, graphite oxyhydroxide, carbon oxide and pyrogra-phitic acid are outdated synonyms for GO. 

The term carbohydrate includes a wide range of molecules which in many cases are quite complex structures. In chemical terms a carbohydrate is either a polyhydroxy aldehyde, a polyhydroxy ketone or, alternatively, it is a compound that can be hydrolysed to such a structure. The smallest unit that cannot be hydrolysed any further is called a monosaccharide. Glucose (Fig. 11.4.1) is the most abundant monosaccharide known and is by far the most important. Other examples include fructose and mannose. A carbohydrate which has been hydrolysed to two monosaccharide units is cabled a disaccharide and the best known example is sucrose, which is composed of a unit of glucose covalently linked to a unit of fructose. The nomenclature system continues in a logical fashion until one can refer to an ohgosaccharide as being a chain composed of several monosaccharide units. Depending upon whether a monosaccharide is an aldehyde or a... 

This chapter will introduce hydrocarbon organic molecules that involve 7i-bonding. Compounds composed of carbon bonded to other atoms (heteroatoms) such as oxygen and nitrogen have both o- and Ji-bonds. The rules of nomenclature will be extended to accommodate each new functional group. The physical properties that result from polarized covalent bonds and Ji-bonds will be discussed, using simple hydrocarbons as a starting point. 

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