Give the major products that would be obtained from heating each of the following ethers with HI

Give the major products that would be obtained from heating...

Key Concepts

Regioselectivity in Unsymmetrical Ethers

For unsymmetrical ethers, the selectivity of the reaction is determined by the steric and electronic factors influencing the mechanism. In an SN2 pathway, the nucleophile preferentially attacks the less hindered carbon, leading to more efficient displacement. In contrast, an SN1 pathway favors the formation of the more stable carbocation, and the iodide ion subsequently attaches at that position. This regioselectivity is key to predicting the major products when heating ethers with HI.

Ether Cleavage Reaction

Ethers react with hydrogen halides like HI through a cleavage process that involves the protonation of the oxygen atom. This protonation increases the electrophilicity of the adjacent carbon atoms, making them more susceptible to attack by the iodide ion. The overall reaction leads to the breaking of the C–O bond, resulting in the formation of an alkyl iodide and an alcohol (or its protonated form, which subsequently deprotonates).

Reaction Mechanisms: SN1 vs SN2

The mechanism by which an ether undergoes cleavage depends on the nature of the alkyl groups attached to the oxygen. In cases where one or both alkyl groups are primary, the reaction typically follows an SN2 pathway, where the iodide directly attacks the less sterically hindered carbon after protonation of the oxygen. Conversely, when a tertiary or a highly stabilized carbocation is involved, the reaction may proceed via an SN1 mechanism where the protonated ether loses a leaving group to form a carbocation intermediate, which is then attacked by iodide.

Transcript

00:01 Okay, so i want to give the products and the following reactions when treating these ethers with hydro -oietic acid.

00:06 The first one is this alkene, and with heat.

00:19 So it's first going to depred into the acid, the oxygen.

00:23 It turns up into a better leaving group, and then the iodide is going to attack at the sp3 carbon as opposed to sp2, and expel the leaving group, which is oh, with positive charge.

00:39 So we're going to get phenol and ethanol, i mean, iodideoethane.

00:48 So the phenol is going to rearrange because an aldehyde is more stable than a enel.

01:01 So we'll get the structure.

01:07 F for b.

01:31 So again, first deep -priting in the acid.

01:34 And iodide is going to attack right here to open up the ether.

01:43 So we'll get this with phenol.

01:57 Okay, for c.

02:02 We have a three or four carbon ether.

02:14 So it's never going, the iodide's never going to attack the benzene ring because we have sp2 carbons.

02:21 It's going to attack right here.

02:24 And again, open up the ether.