In organic reaction, the hydride shift is the rearrangement reaction in which the hydride ion (H–) is transferred from one carbon atom to another. This shifting led to the formation of a more stable carbocation. It involves the formation of structural isomers. There are various types such as 1,2 and 1,3 hydride shifts.
This process typically occurs in the presence of a strong acid and results in the formation of a new carbon-carbon bond. The reaction is most commonly observed in carbonation rearrangement to a more stable intermediate. Hydride shift reactions are also important in the metabolism of certain organic compounds in living organisms.
Types of hydride shift
There are the following types of hydride shifts:
1,2 hydride shift
The requirement for the process is the availability of the secondary carbocation adjacent to the tertiary carbon atom which is bearing the hydrogen atom.
The hydrogen atom from the tertiary carbon atom is shifted to the secondary atom. This is because of the formation of a more stable tertiary carbocation.
Mechanism
The shifting of hydrogen ions is shown by the arrow.
1,3 hydride shift
The 1,3 shift involves the transfer of hydrogen from the first atom to the 3rd atom.
1,5 hydride shift
The 1,5 shift involves the shifting of hydrogen from the first atom to the 5th atom.
- In cyclic compounds
- In open-chain compounds
1,7 hydride shift
The 1,7 shift involves shifting hydrogen from the first atom to the 7th atom, being shifted 7 times.
Examples of hydride shifts in chemical reactions
Wegner Mervin rearrangement
The Wegner Mervein rearrangement involves the hydride ion shift. This reaction involves the conversion of the alcohol to the alkene.
Hydration of alkenes
The hydration of alkenes undergoes a hydride shift. This is because of the formation of the most stable carbocation.
Related Resources
- Carbocation Stability
- Enolates: Preparation, Stability, and Reactions
- Types of Organic Reactions and their Examples
- Carbene: Types, Preparation, and Reactions
Concepts Berg
What is Wagner-Meerwein Rearrangement?
Wagner-Meerwein is a type of rearrangement reaction.
Can a shift occur twice?
Yes, it is possible to do a shift twice. There are some reactions that involve multiple hydride shifts.
What are the conditions of the intramolecular transfer of hydride ions?
When the cationic carbon is attached to the more substituted carbon atom. Then the positive charge will shift to the more substituted atom. This is because more substituted carbocation is more stable.
What are the hydride shifts and methyl shift?
Hydride shifts are those in which hydrogen moves from one carbon atom to another to form a more stable carbocation. Whereas methyl shift is the transfer of methyl group from one carbon atom to another to form a more stable carbocation.
What is the order of shifting rearrangement in hydride alkyl and phenyl shifts?
The migratory aptitude for the phenyl and hydride is the following:
Hydride > phenyl
The hydride has greater migratory aptitude than phenyl. This is because of the small size of the hydride.
Why would hydride shifts occur?
Hydride shifts occur to form a more stable carbocation.
Reference
- Organic chemistry by T.W. Graham Solomons and Craig B. Frhyle and Scott A. Snyder
