Reaction, degree topochemical

In this section, various types of topochemical behaviour such as the even-numbered degree of polymerization mechanism, topochemical induction into the syndiotactic structure, stereo- and enantio-selective reactions, and the formation of highly strained cyclophanes are described. 

Least atomic motion. Single-phase polymerizations will in general be more favorable for topochemical reactions than for nontopochemical reactions. That is, reactions which require only small degrees of atomic translation or reorientation are more likely to proceed without phase separation. 

Changes in the FT-Raman spectmm of 1,4-bis(3-quinolyl)buta-l,3-diyne as a function of gamma-ray dosage are used to monitor the degree of monomer to polymer conversion in a solid-state topochemical polymerisation reaction (i.e., polymerisation directed by the solid-state structure) (315). 

The kinetic modelling of reduction of metal oxides involves gas-solid reaction with possible topochemical i.e. interface advancement features. The reduction degree of solid material, a, is typically modelled in with the equation type [2] ... 

Much of the work on polydiacetylenes has centered on the kinetics and mechanism of the polymerization process. Due to the low degree of disorder in the crystals, experimental techniques such as high resolution optical and magnetic spectroscopy have yielded a great deal of information about the individual reaction steps and the intermediates involved in the polymerization process.(4) This has led to a better understanding of the dlace-tylene polymerization process and topochemical reactions in general. 

Examples of different types of topochemical effects in solid state reactions have been discussed. In each case an attempt has been made to elucidate the molecular mechanism of the reaction. In is clear that topochemical effects can range from complete control of the reaction to more limited structural differences between the product of a solid state reaction and that which would be produced by reaction in a disordered phase. The relationship between the structure of the reactant and that of the product is of primary importance in determining the degree of topochemical control. 

The first reported and one of the best examples of the use of Raman spectroscopy to follow drformation in polymers is the case of substituted polydiacetylene single crystals [8-12]. The macroscopic polymer crystals are produced by the solid-state polymerization of substituted diacetylene single crystal monomers. The reaction is a topochemical solid-state polymerization [13], and the oystals produced have a high degree of perfection [14]. 

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