Displacement/competition reactions

Although peroxide initiated reactions can produce preparative yields of organomercury salts, a mixture of products was usually obtained due to chain mechanism/radical displacement competition and to the prevalence of side reactions [Eqs. (24), (25), and (109)]. An alternative to the... 

In another reaction, metals compete with each other for other anions. This type of reaction is known as a displacement reaction. As in the previous type of competitive reaction, the reactivity series can be used to predict which of the metals will win . 

Displacement of Pt-S-Bound L-Methionine by 5 -GMP. In an effort to understand why cisplatin reacts with 5 -GMP even in the presence of methionine, Barnham et al. [83] performed a competitive reaction experiment between [Pt(dien)Cl]Cl, L-methionine, and 5 -GMP. They observed that, in the first 40 hours of the reaction, the methionine was platinated to yield [Pt(dien)(Met-S )]2+, whereas only little of the 5 -GMP had reacted. In the latter stages of the reaction, this complex disappears as the platinum binds to 5 -GMP, resulting in the complex [Pt(dien)(5 -GMP, N(7))]2+ and free methionine. The kinetics of the displacement reaction were studied and the half-life of the reaction was determined to be 167 h at 310 K. The calculated 77 and. S values for this displacement reaction are indicative of a sub-... 

Khisamutdinov et al. showed that the difluoramino group in various (di-fluoramino)dinitromethane derivatives could be displaced by azide anion to make azidodinitromethyl derivatives [88,89]. In contrast, a nitro group in (di-fluoramino)trinitromethane was displaced by nucleophiles such as fluoride and nitrite [90,91]. The nitrite by-product keeps yields low by competitive reaction with the starting material, resulting in (difluoramino)dinitromethane anion side product. With bromide nucleophile, the course of reaction was unexpectedly complex, as the initial bromo(difluoramino)dinitromethane im-... 

The ease of reaction of halopyridazines is indicated by the exothermic nature of the reaction of 3,6-dichloropyridazine with sodium methoxide at room temperature to yield 3-chloro-6-methoxy-pyridazine. Displacement of the deactivated chloro group in the latter required heating (66°, < 8 hr) the reaction mixture. Competitive methoxy-dechlorination (20°, 12 hr) of 3,4,6-trichloropyridazine shows the superior reactivity of the 4-position the 3,6-dichloro-4-methoxy analog (296) was isolated in high yield. The greater reactivity of the... 

Differences in chirality of substrate, and nature of solvent, have no effect on the competitive nature of the displacement of 0-alkyl and S-methyl groups in the reactions between (+)-pinacolyl alkoxide and 0-ethyl (and methyl) S-methyl methylphosphonothioates (Scheme 23). For the (R)-( + ) esters, e.g. (210), the displacements are highly stereoselective and occur with configurational inversion,but the enantiomeric esters do not display such stereoselectivity. (-)-Menthol might be considered a mirror image of (S)-pinacol, and similar reactions with the sodium salt of (-)-menthol occur highly stereoselectively... 

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