HOBr

Definition

HOBr, or hypobromous acid, is a chemical compound formed by the addition of hydrogen (H) and bromine (Br) to an oxygen (O) atom. It is an important intermediate in the context of the addition of HO-X to alkenes, specifically in the formation of halohydrins.

5 Must Know Facts For Your Next Test

1. HOBr is formed as an intermediate during the electrophilic addition of hydrogen bromide (HBr) to alkenes, resulting in the formation of halohydrins.
2. The addition of HOBr to an alkene is a two-step process, where the bromonium ion intermediate is first formed, followed by nucleophilic attack of water to yield the halohydrin.
3. Halohydrins are important synthetic precursors for the preparation of various other organic compounds, such as epoxides and diols.
4. The regioselectivity of the HOBr addition to alkenes is determined by the stability of the bromonium ion intermediate, following Markovnikov's rule.
5. HOBr is a stronger electrophile than water, making it more reactive towards the carbon-carbon double bond of alkenes.

Review Questions

• Explain the role of HOBr in the formation of halohydrins from alkenes.
  • HOBr, or hypobromous acid, is a key intermediate in the electrophilic addition of hydrogen bromide (HBr) to alkenes, resulting in the formation of halohydrins. The addition of HOBr to the alkene occurs in a two-step process, where a bromonium ion intermediate is first formed, followed by nucleophilic attack of water to yield the final halohydrin product. The regioselectivity of the addition is determined by the stability of the bromonium ion, following Markovnikov's rule.
• Describe the relationship between HOBr and other hypohalous acids, and how they differ in their reactivity towards alkenes.
  • HOBr is a member of the hypohalous acid family, which includes compounds with the general formula HO-X, where X is a halogen (e.g., chlorine, bromine, iodine). While these hypohalous acids share structural similarities, they can differ in their reactivity towards alkenes. Specifically, HOBr is a stronger electrophile than water, making it more reactive towards the carbon-carbon double bond of alkenes compared to other hypohalous acids. This difference in reactivity is an important factor in the formation of halohydrins from the addition of HO-X to alkenes.
• Discuss the importance of halohydrins as synthetic precursors and how the formation of halohydrins from the addition of HOBr to alkenes is a key step in their preparation.
  • Halohydrins are important synthetic precursors for the preparation of various other organic compounds, such as epoxides and diols. The formation of halohydrins through the addition of HOBr to alkenes is a crucial step in the synthesis of these valuable intermediates. The two-step process involving the formation of a bromonium ion intermediate and the subsequent nucleophilic attack of water allows for the regioselective formation of halohydrins, which can then be further transformed into other useful organic compounds. The ability to control the regiochemistry of the addition reaction is a key advantage in the synthetic utility of halohydrins derived from the addition of HOBr to alkenes.

Related terms

Halohydrin:

A halohydrin is an organic compound containing both a halogen (e.g., bromine) and a hydroxyl group (-OH) attached to adjacent carbon atoms.

Electrophilic Addition:

Electrophilic addition is a type of organic reaction where an electrophile adds to the carbon-carbon double bond of an alkene, forming a new product.

Hypohalous Acid: Hypohalous acids are a class of chemical compounds with the general formula HO-X, where X is a halogen (e.g., chlorine, bromine, iodine).