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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 ...
Vladimir Markovnikov was born on December 22, 1837, in Chernorechye near Nizhny Novgorod, Russian Empire (now Dzerzhinsk, Nizhny Novgorod Oblast, Russian Federation). Soon after his birth, his father retired and settled in a family estate received as a dowry from his wife's family at marriage, in the village of Ivanovo, Knyagininsky district of the Nizhny Novgorod province, where Markovnikov ...
In 1869, a Russian chemist named Vladimir Markovnikov demonstrated that the addition of HBr to alkenes usually but not always resulted in a specific orientation. Markovnikov's rule, which stems from these observations, states that in the addition of HBr or another hydrogen halide to an alkene, the acidic proton will add to the less substituted carbon of the double bond. [3]
Russian Civil War: The Czecho-Slovak Legions began its revolt against the Bolshevik government. 28 May: Armenia and Azerbaijan declared their mutual independence. 8 June: Russian Civil War: An anti-Bolshevik government, the Committee of Members of the Constituent Assembly, was established in Samara under the protection of the Czecho-Slovak ...
Products in chemistry that follow this rule are considered Markovnikov products and those that did not are considered anti-Markovnikov products. [88] Markovnikov's rule was an early example of regioselectivity in organic synthesis and the modern understanding of it continues to be important in the chemical industry, where catalysts have been ...
Anti-Markovnikov selectivity is also observed in styrenyl substrates (i.e. Figure 3, C), [39] presumably via η 4-palladium-styrene complex after water attacks anti-Markovnikov. More examples of substrate-controlled, anti-Markovnikov Tsuji-Wacker Oxidation of olefins are given in reviews by Namboothiri, [40] Feringa, [36] and Muzart. [41]
The formal end to Tatar rule over Russia was the defeat of the Tatars at the Great Stand on the Ugra River in 1480. Ivan III (r. 1462–1505) and Vasili III (r. 1505–1533) had consolidated the centralized Russian state following the annexations of the Novgorod Republic in 1478, Tver in 1485, the Pskov Republic in 1510, Volokolamsk in 1513, Ryazan in 1521, and Novgorod-Seversk in 1522.
During this first period, progress was rapid by European standards and per capita growth within the Eastern Bloc increased by 2.4 times the European average. [184] Eastern Europe accounted for 12.3 percent of European production in 1950 but 14.4 in 1970. [184] However, the system was resistant to change and did not easily adapt to new conditions.