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The anti-Markovnikov rule can be illustrated using the addition of hydrogen bromide to isobutylene in the presence of benzoyl peroxide or hydrogen peroxide. The reaction of HBr with substituted alkenes was prototypical in the study of free-radical additions. Early chemists discovered that the reason for the variability in the ratio of ...
The reaction follows Markovnikov's rule (the hydroxy group will always be added to the more substituted carbon). The oxymercuration part of the reaction involves anti addition of OH group but the demercuration part of the reaction involves free radical mechanism and is not stereospecific, i.e. H and OH may be syn or anti to each other. [2] [3] [4]
If an epoxide mechanism is followed, hydroxide groups are added in an anti fashion. Neither Markovnikov or anti-Markovnikov because the substituents are the same. Hydrobromination: Stereospecific: Can be syn or anti addition, depending on situation. When alkenes undergo hydrobromination, the alkyl bromides are formed Markovnikov.
Hydroboration–oxidation is an anti-Markovnikov reaction, with the hydroxyl group attaching to the less-substituted carbon. The reaction thus provides a more stereospecific and complementary regiochemical alternative to other hydration reactions such as acid-catalyzed addition and the oxymercuration–reduction process.
In terms of regiochemistry, hydroboration is typically anti-Markovnikov, i.e. the hydrogen adds to the most substituted carbon of the double bond. That the regiochemistry is reverse of a typical HX addition reflects the polarity of the B δ+-H δ− bonds. Hydroboration proceeds via a four-membered transition state: the hydrogen and the boron ...
He defined the peroxide effect, explaining how an anti-Markovnikov orientation could be achieved via free radical addition. [1] Kharasch was born in the Russian Empire in 1895 and immigrated to the United States at the age of 13. In 1919, he completed his Ph.D. in chemistry at the University of Chicago and spent most of his professional career ...
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For terminal olefins (or acetylenes), the regioselectivity of the process can be described as Markovnikov (addition of X at the substituted end) or anti-Markovnikov (addition of X at the unsubstituted end). Catalysts are frequently employed to control the chemo-, regio-, and stereoselectivity of hydrofunctionalization reactions.