(••••) In addition to radicals, anions, and cations, a fourth ...

Question

(••••) In addition to radicals, anions, and cations, a fourth class of reactive intermediates is carbenes. A neutral species, the simplest carbene has a molecular formula of CH₂ .

(h) Of the reactions studied here in Chapter 8, cyclopropanation is most similar to which?

Accepted Answer

All right. Hi everyone. So this question says that the simplest carbine has a molecular formula of C two which is a class of reactive intermediate. Which reaction listed below is cyclopropane. Most similar to option A says radical hydro halogen nation. Option B says acid catalyzed hydration. Option C says oxy mercury reduction and option D says hydro beration oxidation. So starting off with the reaction being described here, let's say that Cyclin is our other starting material. Now, car beans are very interesting molecules because carbines contain a long pair of electrons on a carbon despite that carbon remaining neutral. Now, cyclopropane is an example of an All Keen addition reaction which is also true for all of the four reactions described in our answer choices. So because all of these are addition reactions and they all have that in common. Let's go ahead and examine how their mechanisms are different or similar from each other. Now, when it comes to cyclopropane nation, the group that's being added to the starting all keen is of course the carbon atom of the carving and the way that happens is with a concerted mechanism. So the pi bond is going to interact with the carbine itself. At the same time that the Carbines loan pairs form another bond with carbon from the A K. This is what produces a cyclopropane ring or a three carbon ring. So when it comes to answering this question, we want to consider the mechanisms for the following or for the other addition reactions and see which ones proceed in a similar manner to cyclopropane nation. First recall it hydro halogen or option A adds a halogen onto the starting alk. Whereas options BC and D all add a hydroxy group or A H group. Now, with regards to option A, the name itself radical hydro halogen nation tells us that radicals are involved in its mechanism. So we can eliminate this as a possibility because the cyclopropane mechanism does not involve radicals. On the other hand, acid catalyzed hydration is characterized by the formation of a carbo cion intermediate. So we can also eliminate option B because cyclopropane nation does not produce a carbo catti but oxy mercury reduction and hydro beration oxidation do have concerted first steps. So let's compare the, lets say that cyclops is my starting material once more. And when it comes to oxy mercury reduction, right, our other reagent is mercury acetate in which mercury is connecting to two acetate groups and it has a lone pair of electrons notice how mercury contains a lone pair of electrons just like our carving did previously. So at the same time, that the pi electrons of the achen interact with mercury. Mercury is using its electrons to create another bond to carbon and one of our acetate groups is subsequently removed from mercury. So this results in a cyclic intermediate in which mercury is connecting to both carbons of the starting a key. Now, this step is remarkably similar to our cyclopropane mechanism. But regardless, let's compare this to hydro beration oxidation. Say we have cyclo Pantene again. But this time in hydro beration oxidation, our other reagent is going to be bh three. Now, the main difference here is that boron does not actually contain any lone pairs. So even though the pi electrons of the ane create a bond between carbon and boron a hydride. In other words, hydrogen with a lone pair of electrons is what's going to create a bond to the second carbon of the a key because of this no cyclic intermediate actually forms in the case of hydro beration oxidation, one carbon of the starting alkene contains bh two while the other carbon simply contains a hydrogen attached to it. So even though both reactions involve a concerted first step, it's oxy mercury de mercury that is most similar to the reaction of cyclopropane or the mechanism of cyclopropane. This is because unlike aberration oxidation, oxy mercu operation reduction actually does produce a cyclic intermediate. So our answer here is going to be option c in the multiple choice and there you have it So, with that being said, thank you so very much for watching and I hope you found this helpful.

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(••••) In addition to radicals, anions, and cations, a fourth class of reactive intermediates is carbenes. A neutral species, the simplest carbene has a molecular formula of CH₂ .

(h) Of the reactions studied here in Chapter 8, cyclopropanation is most similar to which?