Halo-de-halogenation

Formation of Acyl Halides from Acid Derivatives Halo-de-acyloxy-substitution Halo-de-halogenation... 

Hydrogen as Leaving Group A. Substitution by Haiogen 14-1 Halogenation at an Alkyl Carbon Halogenation or Halo-de-hydrogenation... 

Halogenation of Aldehydes and Ketones Halogenation or Halo-de-hydrogenation... 

Attack by Halogen Formation of Sulfonyl Halides S-Halo-de-hydroxylation... 

Thus this empirical relation is closely related to that of Van Arkel and De Boer, but also it can be expected to hold only for tetrahalides, completely halo-genated hydrocarbons etc., because the relation a 00 r5 is valid only for the halogen atoms. 

The pseudopara dichloro- and dibromo- [2.2]paracyclophanes are also available in modest yields ( 20 %), and free from other regioisomers, from Winberg 1,6-elimination-dimerization [80, 81], of (2-halo-4-methylbenzyl)lrimethylammonium hydroxides (Fig. 14) [82]. Similarly, reaction of (2,5-dihalo-4-methylbenzyl)trimethyl-ammonium hydroxides affords the cross tetrahalo[2.2]paracyclophane substitution pattern previously reported by de Meijere [79]. Additional value of this route might also lie in the ability to prepare new highly halogenated [2.2]paracyclophanes, including 4,8,12,16-telrabromo[2.2]paracyclophane and 4,5,7,8,12,13,15,16-octabromo[2.2] paracyclophane. 

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