Hydride shifts and methyl shifts can occur in organic chemistry reactions if there is a carbocation intermediate. While Markovnikov’s rule placed the carbocation on the more substituted of the 2 former sp2 (double bound) carbon atoms, if there is an EVEN MORE substituted carbon nearby you’ll get a carbocation rearrangement.
Hydride and methanide shifts? What are those? Well, I'll tell you. Surely by now you've noticed that's what I'm doing here, no? Carbocation rearrangement is no exception. Learn Organic Chemistry ...
If you are wondering when do to use hydride shifts, methyl shifts, alkyl shifts, carbocation rearrangements, don’t worry I will go over some helpful tricks to get the right product. We’ll go ...
The 1,2-rearrangement belongs to a broad class of chemical reactions called rearrangement reactions. A rearrangement involving a hydrogen atom is called a 1,2-hydride shift. If the substituent being rearranged is an alkyl group, it is named according to the alkyl group's anion: i.e. 1,2-methanide shift, 1,2-ethanide shift, etc.
A 1,2-hydride shift is a carbocation rearrangement in which a hydrogen atom in a carbocation migrates to the carbon atom bearing the formal charge of +1 (carbon 2) from an adjacent carbon (carbon 1). eg: see also 1,2-alkyl shift, 1,2-aryl shift
hydride shift should occur. If a secondary carbocation is vicinal to a quaternary carbon, a 1,2-alkyl shift should occur. The general rule in alkyl shifts is: the smaller alkyl substituent tends to be the substituent that shifts. Therefore, the most common 1,2-alkyl shift is a 1,2-methyl shift.
Multiple rearrangements can happen if the resulting species is stabilized by it. In general hydride shift is more favourable over methyl shift because of its smaller size. The example proposed by James was not known to me but its truly an amazing example. James: It’s possible for multiple hydride/alkyl shifts to occur.
A hydride shift is a rearrangement of atoms in which an unstable carbocation is transformed into a more stable one. Carbocations are ions with positively charged carbon atoms and are often found in organic chemistry.
[1,7] sigmatropic shifts are predicted by the Woodward–Hoffmann rules to proceed in an antarafacial fashion, via a Mobius topology transition state. An antarafacial [1,7] shift is observed in the conversion of lumisterol to vitamin D 2, where following an electrocyclic ring opening to previtamin D 2, a methyl hydrogen shifts.
Comparing the stability of different kinds of carbocations using hyperconjugation. Mechanism of carbocation rearrangements including methyl and hydride shifts.