(a) Benzene reacts with tert-butyl cation [(CH3)3 C^+] by a...

(a) Benzene reacts with tert-butyl cation $\left[\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}^{+}\right]$ by a two-step electrophilic aromatic substitution mechanism to yield tertbutylbenzene $\left[\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{C}\left(\mathrm{CH}_{3}\right)_{3}\right] .$ Write a chemical equation for each step in the mechanism and use curved arrows to track electron flow. (b) Electrophilic addition of hydrogen chloride to styrene gives the product shown. Write the mechanism for this reaction including curved arrows.

(a) Benzene reacts with tert-butyl cation $\left[\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}^{+}\right]$ by a two-step electrophilic aromatic substitution mechanism to yield tertbutylbenzene $\left[\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{C}\left(\mathrm{CH}_{3}\right)_{3}\right] .$ Write a chemical equation for each step in the mechanism and use curved arrows to track electron flow.
(b) Electrophilic addition of hydrogen chloride to styrene gives the product shown. Write the mechanism for this reaction including curved arrows.

Key Concepts

Electrophilic Aromatic Substitution

This reaction mechanism involves the attack of an aromatic ring by an electrophile to form a non-aromatic, positively charged intermediate (often called the sigma complex), which subsequently loses a proton to restore aromaticity. It proceeds through two main steps and exemplifies how aromatic compounds accommodate substitution while preserving their overall stability.

Electrophilic Addition

In electrophilic addition, an electrophile attacks a carbon-carbon multiple bond (typically an alkene), breaking the ? bond to form a carbocation intermediate. The carbocation is then attacked by a nucleophile, resulting in the addition of new atoms across the double bond. This mechanism is guided by factors such as regioselectivity, often explained by Markovnikov's rule.

Carbocation Intermediate

The carbocation intermediate is a key electron-deficient species formed during various organic reaction mechanisms, including electrophilic aromatic substitution and electrophilic addition. Its formation and subsequent reactions determine the pathway and outcome of many chemical processes, where stabilization of the positively charged center is a critical factor.

Curved Arrow Notation

Curved arrow notation is a visual tool used to represent the movement of electrons during chemical reactions. It clearly indicates the transfer of electron pairs from one atom or bond to another, thereby outlining each step of a reaction mechanism and helping to understand how bonds are formed and broken throughout the process.

Transcript

00:01 Hey guys, so in this question, we're given two reactions.

00:05 We're in part a, we're given the reaction between benzene and turkbutyl, a turkbutyl cation.

00:12 And it's a two -step electrophilic reaction, yielding a substitution mechanism.

00:18 And in part b, we're given the electrophilic addition of hydrochloric acid and styrene, which is shown.

00:28 So i've written out the basic, um, reactions for both of them and i'll go through the mechanisms and draw in curved arrows where appropriate to show the movement of electrons to how we're getting each of these products.

00:44 So in part a, we have our benzene molecule and our turkbeel cat ion.

00:51 So the first thing i'm going to do is i like to identify my nucleophiles and my electrophiles.

00:57 So starting off with our electrophile, we know that the turkbeetle cat -ion is an electrophile since it has a positive charge on this carbon right here.

01:09 And this benzene is our nucleophile since it is rich in electrons because of our double bonds.

01:21 So now that i have that, i can go ahead and add in my curved arrows to denote the movement of electrons.

01:29 So whenever we have these types of reactions, we know that the nucleophile is going to be attacking the electrophile.

01:38 So to do that, i'm going to take one of my bonds, my double bonds, and i'm going to do just that.

01:45 I'm going to attack the electrophile.

01:50 So the double bond is going to be breaking apart, and its electrons are going to be forming a bond with this turk butel...

Please give Ace some feedback