Ziegler-Ruggli principle

From the idea that the solvent only provides an indifferent reaction medium, comes the Ruggli-Ziegler dilution principle, long known to the organic chemist. According to this principle, in the case of cyclization reactions, the desired intramolecular reaction will be favoured over the undesired intermolecular reaction by high dilution with an inert solvent [18, 310]. 

The reaction is carried out in solution in an ether (diethyl, diisopropyl, or di-n-propyl ether), at a temperature that must not exceed 100°. To induce intramolecular cyclization at the expense of intermolecular polymerization, the dinitrile is added in a continuous but slow stream to the stirred reaction medium (the Ruggli-Ziegler dilution principle). The decisive factors are the stationary concentration and thus the rate of reaction of the reactants high dilution favours intramolecular cyclization and disfavors intermolecular chain formation, and this dilution is achieved by adding the cyclizing material gradually into a relatively small reaction space. 

The intramolecular Thorpe-Ziegler reaction of hexadecadinitrile with lithium l -ethylanHide according to the Ruggli-Ziegler dilution principle provided a technical advancement. At a concentration of 0.067 mole/1 the yield ranged around 60-70%. 

Thus, the ring fraction decreases with increasing monomer concentration (quantitative definition of the Ruggli-Ziegler dilution principle). The ratio kcjkr of rate constants has the units of inverse molar concentration. It is the molar concentration at which rings and chains are formed with equal probability. 

Ruggli-Zieglersches Verdiinnungsprinzip Ruggli-Ziegler dilution principle... 

At a fixed conversion, the number of rings increases with decreasing IMC as predicted by the Ruggli-Ziegler Dilution Principle (RZDP). 

From Equation 6.19 it follows that the lower the concentration of the activated acid, the higher the selectivity with which the lactone is produced versus the acyclic ester, oligo- and polyesters. Macrolactones are therefore produced in very dilute (<1 /xmol/L) solutions (high dilution principle according to Ziegler and Ruggli). 

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