Organic Chemistry (markovnikov's rule) Help!!?

Question

It is clear that reactions do not follow Markovnikov's Rule. Briefly state the true guiding priniciple behind all alkene addition reactions. In other words, state the one thing that is true about all alkene additions which allows us to predict the major products...

Thanks!

Answer 1

The guiding factor in which product is favored will be based on the stability of the resulting carbocation. Electrophilic addition to an alkene first involves the attack on the electrophile by the pi-bond, which results in the formation of the carbocation. Now, remember that carbocation stability runs from benzylic>tertiary>allylic~secondary>primary. In short, the cation is favored to be formed on the more substituted carbon atom. By defult, the less substituted carbon atom (usually the one with more H's) receives the electrophile. I'm finishing my PhD in Organic chem, so you can trust the answer :) Hope it helps.

Answer 2

Markovnikov's rule states that in addition of a hydrogen halide to an asymmetric alkene, the Hydrogen is added to the side that has already more no. of Hydrogen atoms attached to. hence, e.g, for CH2=CH(CH3), when HCl is added to it, the H will add to the left side and Cl to the right, because the no.of hydrogen atoms attached to the carbon involved in C=C double bond on the left side has 2 H but the one on the right has only1.
so with this rule we, can predict the major product.
the actual reason for this major product to form is, because the carbocation formed, for this major product to form, is more stable than the one for the minor product, because the carbocation for the production of the major product, is a secondary carbocation, the two alkyl groups cause a positive inductive effect, by releasing electrons to the carbocation, hence, it rate of formation is higher, so the major product is formed in this way at a faster rate.

Answer 3

As far as I know, all alkene reactions have their reactions across the double bond......they may not all follow Markovnikov's rule, but they all change the double bond to a single bond and then add or whatever on either side of it. This allows you to decide where products will be added (where the double bond used to be).

Answer 4

In organic and organic chemistry, Markovnikov's rule or Markownikoff's rule is an remark in line with Zaitsev's rule. It replaced into formulated by ability of the Russian chemist Vladimir Vasilevich Markovnikov in 1870 [a million][2]. the guideline states that with the addition of a protic acid alongside with H-X to an alkene, the acid hydrogen (H) turns into linked to the carbon atom with the desirable style of hydrogens , and the halide (X) team turns into linked to the carbon with the fewest hydrogens[3].In different words the adverse area of the addendum attaches itself to the carbon atom with the fewest hydrogen atoms. the comparable is real while an alkene reacts with water in an addition reaction to form alcohol. The hydroxyl team (OH) bonds to the carbon that has the greater effective style of carbon-carbon bonds, on a similar time as the hydrogen bonds to the carbon on the different end of the double bond, that has greater carbon-hydrogen bonds. The chemical foundation for Markovnikov's Rule is the formation of the main sturdy carbocation in the process the addition technique. The addition of the hydrogen to a minimum of one carbon atom interior the alkene creates a very good fee on the different carbon, forming a carbocation intermediate. The greater substituted the carbocation (the greater bonds it has to carbon or to electron-donating substituents) the greater sturdy this is, by way of induction and hyperconjugation. the foremost manufactured from the addition reaction could be the only shaped from the greater sturdy intermediate. subsequently, the foremost manufactured from the addition of HX (the place X is a few atom greater electronegative than H) to an alkene has the hydrogen atom interior the fewer substituted place and X interior the greater substituted place. this is substantial be conscious, in spite of if, that the different much less substituted, much less sturdy carbocation will nonetheless be shaped to a pair degree, and could proceed to form the minor product with the different attachment of X. the guideline could be summarized as "the prosperous get richer and the adverse get poorer": a carbon prosperous in substituents will benefit greater substituents and the carbon with greater hydrogens linked gets the hydrogen in many organic and organic addition reactions.