Predict the major products of the following reactions, and pro...

Question

Predict the major products of the following reactions, and propose mechanisms to support your predictions.

(b)

HINT: Remember to write out complete structures, including all bonds and charges, when writing a mechanism or determining the course of a reaction.

Accepted Answer

Hey everyone and welcome back in today's video, we are going to look at the following problem which states predict the major product of the reaction between styrene and hydrogen chloride with a catalytic amount of hydrogen peroxide, right. A mechanism that accounts for the formation of the major product. If we draw styrene according to the problem, it reacts with hydrogen chloride and hydrogen peroxide. Recall that whenever we have a double bond reacting with hydrogen chloride, we are dealing with an electra filic edition mechanism that falls the more cosmic of school where hydrogen is added to a less substituted position and chlorine is added to a more substantive position. But in this case re geochemistry is reversed. So knowing that this follows the reverse ree geochemistry, we may simply draw our final product. We would add hydrogen to a more substituted position over here and chlorine to a less substituted position. So the final product and the major product that we get in this reaction is this one. We may label it as our final product. Well done. So now the only difference is that more cop Nicholas rule is based on the electra filic edition. But here we are dealing with free radicals and let's draw the mechanism for that free radical reaction. In particular. The welfare step is called the initiation step. If you recall during the initiation stop, we are taking a molecule of hydrogen peroxide and we are expanding the oxygen oxygen bond. We need to apply heat or light for the initiation step to take place and the two bonding electrons are essentially UNP aired. We are forming to the two radicals. The two electrons are impaired equally. That's why we call this a home elliptic cleavage. So we are forming two hydroxy radicals to oh age and each hydraulic still has an impaired electron. So this is our initiation stop. In addition to that, one of the two radicals formed reacts with a molecule of H. C. L. Hydrogen chloride. Now we have a reaction between that radical and the molecule in which the radical attacks and the electrons from that bond are also separated. One of the electrons forms a bond between hydrogen and hydroxyl that B O H H. O. H. That's a water molecule and another electron will form a new radical which is a chlorine radical. So let's draw our products. As we previously stated. One of them is a water molecule And another one is a chlorine radical. Now we are done with the initiation stop. Our next step is the chain propagation stop during the propagation stuff. This is where we are actually taking into account styrene itself. So if we draw styrene, it attacks that chlorine radical released and the initiation stop now to draw the arrows correctly. First of all, let's understand that one of the pi electrons will be used in the formation of the carbon chlorine bond and the other electron will form a radical at a more substituted position, forming a stable residence stabilized radical. So we are now ready to draw that radical. Now this carbon forms a carbon chlorine bond and there's a radical at this position. Now the next step is a reaction between this newly formed radical and a molecule of hydrogen chloride. So we are going to redraw the radical form and hydrogen chloride. The radical attacks the molecule and we may indicate that by the presence of the following arrows, there's an attack and one of the bonding electrons will form a new bond. There will be carbon hydrogen bond formed while another electron in the original covalin bond will form a chlorine radical. So now we are ready to throw the product for the propagation stop. You may notice that this is indeed our final product. Already. There's still that chlorine radical released meaning we need a chain termination stop and the termination stop. We essentially want to recombine radicals present in that solution. In particular. We have multiple possibilities to terminate our chain using any radicals involved. But due to stoke geometry reasons we are going to take that glory in released in the initiation step and one of the hydroxyl radicals in particular, we will call it a termination step and we will stay that Hi track Cell reacts with chlorine radical. Now they will recombine into a molecule and you notice that we obtain hipAA Cloris asset H O cl Well done. So that's how a mechanism which explains how the reaction takes place and we may also stay that based on what we previously explained, there's it's our final product. The correct answer to this multiple choice question is C and if you have any questions, don't hesitate to leave them down below in the comments section. Thank you for watching.

Predict the major products of the following reactions, and propose mechanisms to support your predictions.
(b)
HINT: Remember to write out complete structures, including all bonds and charges, when writing a mechanism or determining the course of a reaction.

Key Concepts

Electrophilic Addition Reactions

Radical Mechanisms

Markovnikov's Rule

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