Tacticity definition

Arensberg, Cryptography of Dante, 400-01 for some other tactical definitions, see also his chapter 2, Acrostics, 23ff. 

Suits and Bueche conclude their case-histories with a superb analysis of the sources, tactics and uses of applied research, and make the comment The case histories just summarised show, first of all, the futility of trying to label various elements of the research and development process as basic , applied or development . Given almost any definition of these terms, one can find variations or exceptions among the examples. ... 

This value chain management definition relies on a three-level structure for strategic, tactical and operative company control introduced by Anthony (1965) and used in controlling and supply chain management literature (Rohde et al. 2000). 

To conclude, kinetic measurements and structural analysis of the copolymers have allowed a quantitative and self-consistent description of the reaction of RCI Li species on PMMA taking into account PMMA chain reactivity through the simplified model of the nearest neighbouring group effects. Two main features are particularly relevant the definite influence of tacticity, and the independance of the reaction process on the total charge of the copolymer. In this sense, the R-C Li/PMMA systems are closed to the PMMA basic hydrolysis in presence of excess base. (29,31). 

In semi dilute (c>c, [B] = 0.3-0.5 mole.l- ) or dilute (c< c, [B] = 10-2 mole.l- -) solution, Kp is significantly greater for copolymers than for the model compounds whatever the solvent is. For semi-dilute solution in a given solvent, the complex influences of composition, unit distribution and tacticity do not result in definite trends on K, values, as illustrated in table 6 by some representative Kj data related to keto-2-picolyl structures at 25°C. 

The butadiene polymers represent another cornerstone of macromolecular stereochemistry. Butadiene gives rise to four different types of stereoregular polymers two with 1,2 linkage and two with 1,4. The first two, isotactic (62) and syndiotactic (25), conform to the definitions given for vinyl polymers, while the latter have, for eveiy monomer unit, a disubstituted double bond that can exist in the two different, cis and trans, configurations (these terms are defined with reference to the polymer chain). If the monomer units all have the same cis or trans configuration the polymers are called cis- or trans-tactic (30 and 31). The first examples of these stereoisomers were cited in the patent literature as early as 1955-1956 (63). Structural and mechanistic studies in the field have been made by Natta, Porri, Corradini, and associates (65-68). 

It should be mentioned, in connection with definitions of stereoregular and tactic polymers, that a stereoregular polymer is always a tactic polymer, but... 

The definitions of chiral and the associated terms homochiral and heterochiral made their first appearance in a footnote of a lecture, entitled The Molecular Tactics of a Crystal, that Sir William Thomson, who had been elevated to Lord Kelvin in 1892, delivered to the Oxford University Junior Scientific Club on May 16, 1893. The famous footnote reads ... 

For parents, the point of this conflict with their child is to resolve an issue by agreeing on a definition of what is or is not going to happen. For the young substance abuser, evasion and distraction are tactics commonly used to keep parents from reaching this definition point they seek. Consider the following dialogue as an illustration. 

In these types of polymer reaction, quantitative conversion is a definite requirement otherwise, there would be a possibility that the tacticity of the derived polymer differs from the original one owing to the tacticity dependence of the reaction. 

According to the lUPAC definition, a tactic polymer is a regular polymer the molecules of which can be described in terms of only one species of configurational repeating unit in a single sequential arrangement. 

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