Functional group equivalents

Functional group Equivalents. Functional groups from which a particular functional group can be produced chemically. 

Next, we solvate all the functional groups (equivalently, we turn on the interactions U(k, X,) that were turned off in the first step]. One way to do this is to solvate all the functional groups simultaneously. The resulting free-energy change would be AG and the total solvation Gibbs energy would have been written... 

Distribution of amine functional groups equivalent to epoxide functionality. 

The relationship between number average degree of polymerization and p (Equation 5-3) only applies to polymerizations where there are exactly equal numbers of A and B functional groups. Equivalence is obtained directly in step-growth polymerizations of type I (A-B), but is more difficult to achieve for polymerizations of type II (A-A and B-B). However, if the number of functional groups is not exactly the same, we still... 

Tab. 4.1 Examples of commonly defined functional group equivalences and the corresponding pharmacophoric definition.

The moderate-concern reactive functional groups can be present in an exempt polymer, but only if the polymer has a combined total functional group equivalent weight greater than or equal to one thousand, that is, provided that there are at least one thousand daltons of molecular weight in... 

The necessary functional group equivalence required for the poly condensation is achieved by first producing the salt from molar equivalents of the diamine and dicarboxylic acid. For example, adipic acid and hexamethylene diamine form what is known as the AH salt. The purified salt is directly used in the melt polycondensation. The amidation equilibrium is so favorable that the polycondensation can take place in the presence of water, which is therefore used as a heat sink. A typical industrial synthesis is, for example, the polycondensation of the AH salt a 60%-80% sludge of the salt is precondensed with a little acetic acid as regulator (see also Section 28.2.3.2) at 275-280° C for 1-2 hr at 13-17 bar, that is, at the vapor pressure of the steam produced. After a yield of 80%-90% has been reached, further condensation takes place above the melting temperature of 264° C under vacuum. 

For raw materials of reactive adhesives, the chemical equivalent values are very important to specify the reactivity, and often tested. Epoxy equivalents for epoxy resins, and functional group equivalents for hardeners are experimentally determined. Methods to measure the epoxy equivalents are described by industrial standards as follows International organization for standardization (ISO) 3001, Japan industrial standards (JIS) K 7236, and American society for testing and materials (ASTM) D 1652. For instance, JIS K 7236 indicates the methods using titration. In this process, an epoxy sample is solved with chloroform, mixed with acetic acid, tetraethylammonium bromide, and crystal violet solution. The epoxy sample solution is finally titrated with perchloric acid—acetic acid solution. If automatic titrators can be used, the epoxy... 

---