oxidative cleavage of alkenes that's going to be the topic of this lesson and we're going to go through ozonolysis both under reducing conditions and oxidizing conditions and we'll also talk about permanganate cleavage which gives the same product as ozonolysis under oxidizing conditions now this lesson is part of my new organic chemistry playlist i'll be releasing these lessons weekly throughout the 2020-21 school year so if you don't want to miss one subscribe to the channel click the bell notifications you'll be notified every time i post a new lesson so now we've got one last set of reactions for alkenes to cover and technically these are not addition reactions so it's what's referred to as oxidative cleavage and the most common way to do this is called ozonolysis and involves ozone which is o3 the structure of which is right here so we're not going to show the entire mechanism but we'll show just a little bit of it to get our appetite wet here so your alkene actually reacts with ozone here and does something looking like this so to form what's called a melosinide this melozonite is going to rearrange to an ozonite it takes a couple of steps and again i'm not going to show the whole mechanism but you get this lovely ozonide and it's this ozonide that actually is going to undergo step two and so typically for ozonolysis you've got step one which is ozone and then step two you've got some variability there and you might add a reducing agent or you might add an oxidizing agent and so we have two different sets of conditions for ozonolysis we've got reducing conditions so we've got oxidizing conditions and it's all about whatever you add in step two now for reducing conditions we're typically going to use so dimethyl sulfide which might be written as dms that could be step number two so or you might see commonly zinc and water used for step two as well so there's your ozonolysis under reducing conditions under oxidizing conditions we'll use a mild oxidizing agent in this case for step two we use hydrogen peroxide and this is going to slightly affect what products we get now if you look at what's kind of going on here so i like to think when i look back at my original alkene if i want to predict products of ozonolysis i just cleave that alkene in half hence the name oxidative cleavage so i'll cleave it in half and then i will oxidize both sides to make it oxidative cleavage and so if we did that here so cleave both sides and so and then oxidize both sides that means give a double bond to oxygen to both sides and so if you look the top product here is a ketone and the bottom one here is an aldehyde and for the aldehyde you typically want to draw in the hydrogen that it's also bonded to one time we draw a carbon hydrogen bond and i don't know why so but get a ketone and aldehyde now ketones are ketones they're not oxidizable under any normal means but aldehydes can be oxidized to carboxylic acids so when you do this under reducing conditions either with dimethyl sulfide or zinc so an aldehyde stays an aldehyde you're reducing agents keeps it from getting oxidized and so you get your aldehyde but if we did this under oxidizing conditions instead so your ketone again is still a ketone not going to change but your aldehyde is going to get oxidized to a carboxylic acid instead so again your ketone is still a ketone but instead of an aldehyde you get a carboxylic acid cool so if you're predicting the products of ozonolysis here again just cleave your carbon-carbon double bond in half so and then give both sides a double one to oxygen if either side is a ketone great that's never gonna change regardless of the conditions but if one of them turns out to be an aldehyde or both so that's when the conditions matter so if you use reducing agents aldehydes stay aldehydes if you use an oxidizing agent peroxide then your aldehyde is going to become a carboxylic acid for your product instead cool we got one other way we can pull this off instead of ozonolysis turns out we can do the same cleavage oxidative cleavage with permanganate so if you recall we used permanganate a little bit ago to do syn dihydroxylation but we used it and it was cold and dilute well now we're using it under much harsher conditions we're using it with hot concentrated and under acidic conditions here so and this does the same thing as ozonolysis under uh oxidizing conditions so permanganate's definitely a strong oxidizing agent and so again we get a ketone just like we did before and ketones are always going to be ketones for oxidative cleavage but instead of getting the aldehyde again we get the carboxylic acid cool don't have to know the mechanism for the second one so the truth is i've never seen students responsible for the mechanism on ozonolysis either i'm not saying it's not possible i'm just saying it's unlikely now if you found this lesson helpful consider giving me a like and a share a couple of the most helpful things you can do to 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