Effects of Halogenation

Because inductive effects operate through cr bonds and are dependent on distance, the effect of halogen substitution decreases as the substituent moves farther from the carboxyl. Thus, 2-chlorobutanoic acid has p/chlorobutanoic acid has p/chlorobutanoic acid has p/C., = 4.52, similar to that of butanoic acid itself. 

The rate coefficients obtained with hydrogen iodide show that the effectiveness of halogen acids in catalysing hydrogen exchange is HF > HBr > HI and, as noted above, this was attributed to the difference in dielectric constant of the media. 

Kennedy and co-workers10 studied model cationic polymerization initiation and termination. They determined the effect of halogens in f-BuX and MeX on the rate of reaction between f-BuX and Me3Al. The pseudo second order rate constant decreased (Table 1) as ... 

A number of other monomers may be employed as variations on the materials mentioned so far, to introduce specific properties into the finished resin. For example, halogenated molecules containing either chlorine or bromine atoms may be used to confer fire resistance. As described in Chapter 8, the effect of halogens in the polymer structure is to make the resins difficult to ignite and unable to sustain combustion. 

D. J. Edge and J. K. Kochi, Effects of halogen substitution on alkyl radicals conformational studies by electron spin resonance. J. Am. Chem. Soc. 94(18), 6485-6495 (1972). 

Studies have been extended to determine effect of halogens and halogen-releasing agents. Under similar laboratory conditions as previously described, the effect of these agents on NDPA destruction is shown in the following table. 

Thome, already quoted (note p.63), tried to estimate the possibilities of theoreticai forecasts of flashpoints by using hydrocarbon mixtures in a study that was carried out in order to modei fuel flashpoints and to study the effect of halogenous compounds on these hydrocarbons. 

Effect of halogens and halogenation agents on acetylene and toluene... 

With cyanuryl chloride, DMF forms a 1 1 complex that decomposes violently at a temperature starting at 60°C by releasing carbon dioxide, and is also thought to form an unsaturated quaternary ammonium salt (refer to the effect of bromine on DMF as a possible form of this ammonium in the effect of halogens) ... 

A very similar situation is encountered in the electrophilic addition of unsymmetrical adducts (e.g. HBr) to vinyl halides (e.g. CH2=CHBr), where the inductive effect of halogen controls the rate, but relative mesomeric stabilisation of the carbocationic intermediate controls the orientation, of addition (p. 185). 

Effect of Halogen-Halogen Interactions in Molecular Conducting Magnets... 

Nicolson, W.J., Moore, J.A. (eds) (1979) Health Effects of Halogenated Aromatic Hydrocarbons, New York Academy of Sciences, New York. 

Albro PW. 1979. Problems in analytic methodology Sample handling extraction and cleanup. In Nicholson WJ, Moore JA, eds. Annals of the New York Academy of Sciences, Health Effects of Halogenated Aromatic Hydrocarbons International Symposium, New York, NY, USA, June 24-27, 1978. New York, NY New York Academy of Sciences, 320 19-27. 

Erickson SJ, Flawkins CE. 1980. Effects of halogenated organic compounds on photosynthesis in estuarine phytoplankton. Bull Environ Contam Toxicol 24 910-915. 

Theberge, R. Bertrand, M.J. Beam-Induced Dehalogenation in LSIMS Effect of Halogen Type and Matrix Chemistry. J. Mass Spectrom. 1995, 30, 163-171. 

The Effect of Halogens on the Performance and Durability of Reverse-Osmosis Membranes... 

---