Propene belongs to lớn the alkene compound group. Propene readily reacts with HBr và producean alkyl bromidecompound. Reaction of propene and HBr belongs to lớn thenucleophilicaddition reaction type. This is explained in detail in the mechanism section of the reaction.

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Products of propene & HBr reactionMechanism of propene and HBr reactionProducts given when aqueous HBr is usedReaction và products in the presence of organic peroxideHow products are given in aqueous phase or aqueous NaCl medium when propene reacts with HBr

Reactants & products

Propene is an unsymmetrical alkene with three carbon atoms. With HBr, propenereadily reacts and give2-bromopropane as the major product & 1-bromopropane as the minor product.

CH3CH=CH2 + HBr → CH3CHBrCH3CH3CHBrCH3 (2-bromopropane) is given as the major product.

HBr molecule is added across the double bond of propene. Marconikov rule is used to lớn find the locations(to which carbon atom in the double bond) of hydrogen và bromine atoms are added.

Markovnikov"s rule

Markovnikov"s rule explains us how hydrogen & bromine atoms are added to lớn carbon atoms of unsymmetrical alkenes.

Hydrogen atom of HBr prefer khổng lồ bond khổng lồ the carbon whichcontains most number of hydrogen atoms while bromine prefer lớn bond to other carbon atom which have less number of hydrogen atoms.This rule will be explained in detail in the example.


As propene andHBr reaction, propene reacts with in same fashion with HI and give products.

Mechanism of HBr addition of propene

HBr molecule is polarized because there is a electronegativity difference between hydrogen & bromine atoms.Also, electrons mật độ trùng lặp từ khóa of double bond is higher in alkene.


Electrophile(H+ ion) attacks the propene molecule và has the possibility to form two carbocations.Secondary carbocation is more stable than primary carbocation. Therefore, the attack of electrophile (H+ion) on propene results in the formation of more stable secondary carbocation.Then, formed bromide ion reacts with the carbocation carbon to form the final product.

The electrophilic addition of HBr to an unsymmetrical alkene always occurs through the most stable carbocationformation và it is indirectly expressed in Markovnikov"s rule.

Addition of HBr to propene in the aqueous state


In the mechanism, you may see, bromide ion is added khổng lồ a carbon atom as the final step. In the aqueous state,hydroxyl ions (OH-) are also with bromide ions in the reactants medium. So there is a chance lớn getjoin hydroxyl ions instead of bromide ions. Also, if aqueous solution contains anions such aschloride, iodide with bromide, one of these anions will be added to lớn the carbon atom in the second step ofthe mechanism.

Possible products2-propanol & 2-bromopropane can be given as products when HBr is used in aqueous state
.In the presence of aqueous sodium chloride (NaCl) và HBr, propene may give 2-propanol, 2-chloropropane and 2-bromopropane as products.

Propene and HBr reaction in the presence of organic peroxides

When organic peroxides are with reactant, reaction takes place opposite to lớn the Markovnikov rule. This isknown as, anti-Markovnikov rule or peroxide effect or Kharasch effect.Due to lớn this effect, Br atom joints to lớn the carbon which carries the more hydrogen atoms while H joins lớn the carbonwhich has less hydrogen atoms in the double bond.

So 1-bromopropane is given as the major sản phẩm when propene reacts with HBr in the presence of organic peroxides.

Questions asked by students. Ask your question không tính tiền and find the answer.

Propene + hydrogen bromide (in the presence of hydrogen peroxide ) = 1-bromopropane

Addition of hydrogen bromide khổng lồ unsymmetrical alkenes in the presence of organic peroxide happens according to the anti-Markovniv rule. There is a research done to study Oxidation of alkenes with hydrogen peroxide, catalyzed by boron trifluoride. Synthesis of vicinal methoxyalkanols


What is the difference of propene + HBr và propene và Br2 / CCl4?

With HBr, propene gives 2-bromopropane as the product. This product only contain one bromine atom. But with Br2 / CCl4, two bromine atoms are added across the double bond to give dialkyl halide. With Br2 / CCl4, propene gives 1,2-dibromopropane as the dialkyl halide compound.

Is it similar lớn propene + hbr reaction to lớn ethene + hbr

Propene is an unsymmetrical molecule. But, ethene is a symmetrical molecule. In HBr và unsymmetrical alkene reactions, Markovnikov"s rule is applied to find the loctions of hydrogen và bromine atoms which are joined across the double bond.

what happens when propene is treated with hbr?

Propene reacts with HBr và produce CH3CHBrCH3 (2-bromopropane). It is an alkyl haalide compound and this reation is an addition reation. Also, you can treat HBr in the presence of organic peroxides to lớn change the location where bromine atom is joint.

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Does this reaction happen? ch3ch=ch2 + hbr

Yes. This reaction happen and give the product as CH3CHBrCH3.

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