Solvents, acidic molecular, classification

Solubility. According to our classification system, all intra-molecular bonded materials should be Class AB. Consequently, they should be soluble in solvents from Classes AB, B, and A, provided the solvent can successfully compete with the internal H bonding. Because of the internal satisfaction of the H bonding tendency. Class N solvents should be better solvents for internally H bonded materials than for nonchelated compounds. This is the behavior observed, as shown in Table 5-V for dihydroxybenzenes in CCh. In the stronger acid and base solvents, the loss of chelation is suggested. Further, for this case, the table shows a similarity in the solubilities of ortho and meta isomers. 

A simple classification scheme of solids is given in Fig. 7.1. In order to differentiate between the types of solids, we have to consider the Gibbs phase rule, which is discussed in any physical chemistry textbook. The basic question is whether the solid substance consists of only one chemical entity (component) or more than one. Usually the component is one molecular unit, with only covalent bonded atoms. However, a component can also consist of more constituents if their concentration cannot be varied independently. An example of this is a salt. The hydrochloride salt of a base must be regarded as a one-component system as long as the acid and the base are present in a stoichiometric ratio. A deficiency of hydrochloric acid results in a mixture of the salt and the free base, which behave as two completely different substances (i.e. two different systems). Polymorphic forms, the glassy state, or the melt of the base (or the salt) are considered as different phases within such a system (a phase is defined as the portion of a system that itself is homogeneous in composition but physically distinguishable from other phases). When the base (or salt) is dissolved in a solvent, a new system is obtained this is also tme when a solvent is part of the crystal lattice, as in the case of a solvate. Thus, each solvate represents a different multicomponent system of a compound, whereas, polymorphic forms are different phases. The variables in the solvate are the kind of solvate (hydrate. 

The classification of solvent-extraction systems has been considered in most of these reviews and usually consists of a division according to the extracted species molecular (covalent) and electrovalent (ionic or ion-associated) species. The molecular covalent species include covalent compounds such as I2, HgCl2, RUO4, CH3COOH, and metal-chelate complexes. The electrovalent species include halometallic acids such as HFeCl4, and ion pairs, e.g., Cs (C0115)46 . 

---