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Addition of HBr to 2-Methylpropene

This reaction does not occur to any appreciable extent  [Pg.337]

With this understanding of the mechanism for the ionic addition of hydrogen halides to alkenes, we can now give the following modern statement of Markovnikov s rule. [Pg.337]

Because addition of the electrophile occurs first (before the addition of the nucleophilic portion of the adding reagent), it determines the overall orientation of the addition. [Pg.338]

Notice that this formnlation of Markovnikov s rule allows us to predict the outcome of the addition of a reagent snch as ICI. Becanse of the greater electronegativity of chlorine, the positive portion of this molecule is iodine. The addition of ICI to 2-methylpropene takes place in the following way and produces 2-chloro-l-iodo-2-methylpropane  [Pg.338]

Give the structure and name of the product that would be obtained from the ionic addition of IBr to propene. [Pg.338]


Figure 6.8 Energy diagram for the two-step electrophilic addition of HBr to 2-methylpropene. The first step is slower than the second step. Figure 6.8 Energy diagram for the two-step electrophilic addition of HBr to 2-methylpropene. The first step is slower than the second step.
Addition of HBr to 2-methylpropene gives mainly tert-butyl bromide, because the product with the more stable carbocation intermediate always predominates in this type of reaction. [Pg.201]

A MECHANISM FOR THE REACTION ] Addition of a Hydrogen Halide to an Alkene 341 [ A MECHANISM FOR THE REACTION ] Addition of HBr to 2-Methylpropene 343... [Pg.11]

Now let s draw the forward scheme. Addition of HBr to irai/is-2-butene produces 2-bromobutane, which is subsequently treated with terf-butoxide to give 1-butene. /ift-Markovnrkov addition of water (via hydroboration/oxidation) followed by PCC oxidation gives the aldehyde. Reaction with the Gngnard reagent (produced by awn-Markovnikov addition of HBr to 2-methylpropene, then magnesium, as shown) gives 2-methyl-4-heptanol after water workup. Oxidation with PCC produces the target ketone. [Pg.449]

When the addition of hydrogen halides to alkenes was first studied systematically in the 1930s, chemists observed that the addition of HBr sometimes gave Markovnikov addition and sometimes gave non-Markovnikov addition. These two modes of addition of HBr are illustrated for 2-methylpropene (isobutylene). [Pg.362]

Addition of HX to an unsymmetrical alkene could, in principle, give two different products. The ionic reaction between hydrogen bromide (HBr) and 2-methylpropene (isobutylene [(CH3)2CH=CH2]), where both l-bromo-2-methylpropane (isobutyl bromide [BrCH2CH(CH3)2]) and 2-bromo-2-methylpropane (r-butyl bromide [(CH3)3CBr]) could have formed is shown in Equation 6.26. [Pg.324]

In 1870, the Russian chemist Vladimir Markovnikov observed that reagents add to imsymmetrical alkenes in a specific way. Markovnikov s rule states that a molecule of the general formula HX adds to a double bond so that the hydrogen atom forms a bond to the unsaturated carbon atom with the largest number of directly bonded hydrogen atoms. This is the less substimted double-bonded carbon atom. The addition reactions of HCl with 2-methylpropene and 1-methylcyclohexene with HBr are two examples of Markovnikov s rule. [Pg.198]

Now let s draw the forward scheme. The 3° alcohol is converted to 2-methylpropene using strong acid. Anti-Markovnikov addition of HBr (with peroxides) produces l-bromo-2-methylpropane. Subsequent reaction with sodium acetylide (produced from the 1° alcohol by dehydration, bromination and double elimation/deprotonation as shown) produces 4-methyl-1-pentyne. Deprotonation with sodium amide followed by reaction with 1-bromopentane (made from the 2° alcohol by tosylation, elimination and anfi -Markovnikov addition) yields 2-methyl-4-decyne. Reduction using sodium in liquid ammonia produces the E alkene. Ozonolysis followed by treatment with dimethylsulfide produces an equimolar ratio of the two products, 3-methylbutanal and hexanal. [Pg.402]

Reaction of 2-methylpropene with HBr might, in principle, lead to a mixture of two alkyl bromide addition products. Name them, and draw their structures. [Pg.171]

Before beginning a detailed discussion of alkene reactions, let s review briefly some conclusions from the previous chapter. We said in Section 5.5 that alkenes behave as nucleophiles (Lewis bases) in polar reactions. The carbon-carbon double bond is electron-rich and can donate a pair of electrons to an electrophile (Lewis acid), for example, reaction of 2-methylpropene with HBr yields 2-bromo-2-methylpropane. A careful study of this and similar reactions by Christopher Ingold and others in the 1930s led to the generally accepted mechanism shown in Figure 6.7 for electrophilic addition reactions. [Pg.188]


See other pages where Addition of HBr to 2-Methylpropene is mentioned: [Pg.322]    [Pg.326]    [Pg.343]    [Pg.1207]    [Pg.337]    [Pg.449]    [Pg.322]    [Pg.326]    [Pg.343]    [Pg.1207]    [Pg.337]    [Pg.449]    [Pg.328]    [Pg.392]    [Pg.392]    [Pg.337]    [Pg.340]   


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