Dehydration of alcohols is the reverse reaction of the hydration of an alkene. Typical reaction conditions include heating the alcohol in the presence of a strong acid, which will produce an alkene product. In this tutorial we will explore 1. the dehydration of secondary and tertiary alcohols 2. when mixture of products are expected and how to determine the major product 3. when rearrangements are expected and how to determine the major product 4. the dehydration of primary alcohols 20 Secondary alcohols can also undergo elimination using the E1 mechanism. Since tertiary carbocations are more stable than secondary carbocations, you will need to watch out for the possibility of carbocation rearrangements. If a more stable carbocation can be formed by a hydride or alkyl shift, this will occur before the beta hydrogen abstraction to give the alkene. Draw the carbocation rearrangement product of the secondary carbocation shown.
Reactive Intermediates
In chemistry, reactive intermediates are termed as short-lived, highly reactive atoms with high energy. They rapidly transform into stable particles during a chemical reaction. In specific cases, by means of matrix isolation and at low-temperature reactive intermediates can be isolated.
Hydride Shift
A hydride shift is a rearrangement of a hydrogen atom in a carbocation that occurs to make the molecule more stable. In organic chemistry, rearrangement of the carbocation is very easily seen. This rearrangement can be because of the movement of a carbocation to attain stability in the compound. Such structural reorganization movement is called a shift within molecules. After the shifting of carbocation over the different carbon then they form structural isomers of the previous existing molecule.
Vinylic Carbocation
A carbocation where the positive charge is on the alkene carbon is known as the vinyl carbocation or vinyl cation. The empirical formula for vinyl cation is C2H3+. In the vinyl carbocation, the positive charge is on the carbon atom with the double bond therefore it is sp hybridized. It is known to be a part of various reactions, for example, electrophilic addition of alkynes and solvolysis as well. It plays the role of a reactive intermediate in these reactions.
Cycloheptatrienyl Cation
It is an aromatic carbocation having a general formula, [C7 H7]+. It is also known as the aromatic tropylium ion. Its name is derived from the molecule tropine, which is a seven membered carbon atom ring. Cycloheptatriene or tropylidene was first synthesized from tropine.
Stability of Vinyl Carbocation
Carbocations are positively charged carbon atoms. It is also known as a carbonium ion.
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Hi! It still says the answer is wrong and "a hydride shift will occur. a tertiary carbocation should be formed"
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