Hey everyone. In this video, we're going to talk about how you can use periodic acid to cleave or break apart a monosaccharide completely. Let's take a look. So guys, in general, periodic acid has the ability to cleave vicinal diols, and this is not a reaction that's unique to sugars. It's actually a reaction that occurs any time that you expose periodic acid, which I'll show you in a second, to a vicinal diol. It's always going to split the diol in half, leaving oxygens on both sides. Okay. Now what do we know about sugars? Sugars have multiple diols or multiple alcohols. And when I say diols here, I'm specifically saying vicinal diols. So, sugars have multiple alcohols that are next to each other that could potentially be cleaved. Okay? So what we're going to learn here is not a new reaction completely. What it really is, is it's an application of another reaction that already exists. That other reaction says that if you take a diol and you expose it to periodic acid, it's going to cleave. So now why don't we do that with sugars? And it turns out that the mechanism we're going to use is even identical to the general oxidative cleavage of diols with periodic acid. This This is just reinforcing what I'm saying, how this is not a brand new reaction. It's just an application of another reaction to sugars. Cool. So guys, let's start off with the basics. Vicinal diol. Remember that a vicinal diol is an alcohol, or it's a diol that the two alcohols are next to each other. They're not geminal. Geminal would be on the same carbon. Vicinal, they're next to each other. Okay. So you need a vicinal diol to make this work. We need to expose to some form of periodic acid. Now here, I've gone ahead and drawn out the periodic acid for you. This is what it should look like if you're given this form of periodic acid, which is the most common form. But guys, it turns out that lots of different professors and textbooks for some reason like to overcomplicate periodic acid and they like to draw it a bunch of different ways. So here what I did is I listed out all the different ways that I've seen it written and that I want you to think of as synonyms for periodic acid. So please don't, like I said, don't overcomplicate it, just think of them all as forms of periodic acid. So you could see, let's just go in order, you could see periodic acid and water. Same thing. You could see instead of 4 oxygens, 3 oxygens. That's called iodic acid, but that also functions very similarly. You could see it as IO4− which is the anion, so that's called periodate. And then finally, you could even see it with 6 oxygens, which is actually just another form of periodic acid. So again, don't worry too much about it. Just think if you see a lot of oxygens around an iodine, this is a form of periodic acid and this is going to be some form of cleavage if diols are present. Okay. So let's say that you expose the periodic acid to the diol, what you're going to wind up getting is this cyclic structure. Okay. Now you don't need to know the mechanism for this part but we are going to quickly go over the mechanism for the cyclic part because this part of the mechanism is shared with the general reaction of periodic acid cleaving diols. Okay? So first of all, let me just name this for you. This, structure here is called a cyclic periodic ester. Okay. The cyclic periodic ester is one of the intermediate steps of oxidative cleavage with periodic acid. Okay. And at this point, we formed our cyclic ester and now all we need to do is break apart the sigma bond that's holding the two carbons together. The sigma bond I'm talking about is this one. This is the one that we're going to try to break apart because that's what cleavage means. We're going to break carbons apart. So the mechanism for this is pretty straightforward. All it is is that you take the electrons that used to be connecting those carbons together and you make a carbonyl out of them. So you make a carbonyl out of one of them. Now if you can go either way. I could go to the left or to the right. It's going to be a cyclic mechanism and it's all concerted, meaning it all happens at the same time. Now if I make that double bond O, I'm going to have to break a bond. Right? So the way that that bond is going to break is that we're going to then take electrons and put them on the eye. Okay. So because that oxygen needs to break a bond in order to not be positively charged, so we're going to take those electrons away, put them on the eye, and now what we have to do is we have to basically keep the formal charge of the eye the same, so we're going to have to break a bond on the eye and we're going to take these electrons and make a carbonyl down here. So as you can see, we're just redistributing the same electrons that were already there and what we're going to get at the end is now two carbonyls with this bond breaking. Right? That bond is gone and now we're going to get two carbonyls. So let's draw what that would look like. So what this would look like is on the left side, I would have o double bond. Whatever that group was on the left, I'm just gonna keep it as a stick because I don't know what that is. And then on the right side, I'm gonna have an H. Now this H is this H right here. Okay. And I mean just to be super clear, this stick is this stick right here. Cool. And then on the other side, I would just get the same exact thing just flipped around. What I would get is then I have that stick there and this H here. That's that and oops. Almost perfect. There we go. So look what we've accomplished and then you get your iodic acid as a byproduct. Okay. So notice what we're accomplishing. We're cleaving because we're taking two carbons and we're separating them and we're also oxidizing. That's why this is called oxidative cleavage because I start off with alcohols and I'm ending up here with aldehydes. So guys, that's the general mechanism. Your professor may or may not want you to know that part of the reaction, but now in the next video what I'm going to do is I'm going to show you what you absolutely need to know, the four cleavage patterns for oxidative cleavage. Okay? So let's go to that video.
- 1. A Review of General Chemistry5h 9m
- Summary23m
- Intro to Organic Chemistry5m
- Atomic Structure16m
- Wave Function9m
- Molecular Orbitals17m
- Sigma and Pi Bonds9m
- Octet Rule12m
- Bonding Preferences12m
- Formal Charges6m
- Skeletal Structure14m
- Lewis Structure20m
- Condensed Structural Formula15m
- Degrees of Unsaturation15m
- Constitutional Isomers14m
- Resonance Structures46m
- Hybridization28m
- Molecular Geometry16m
- Electronegativity22m
- 2. Molecular Representations1h 14m
- 3. Acids and Bases2h 46m
- 4. Alkanes and Cycloalkanes4h 19m
- IUPAC Naming29m
- Alkyl Groups13m
- Naming Cycloalkanes10m
- Naming Bicyclic Compounds10m
- Naming Alkyl Halides7m
- Naming Alkenes3m
- Naming Alcohols8m
- Naming Amines15m
- Cis vs Trans21m
- Conformational Isomers13m
- Newman Projections14m
- Drawing Newman Projections16m
- Barrier To Rotation7m
- Ring Strain8m
- Axial vs Equatorial7m
- Cis vs Trans Conformations4m
- Equatorial Preference14m
- Chair Flip9m
- Calculating Energy Difference Between Chair Conformations17m
- A-Values17m
- Decalin7m
- 5. Chirality3h 39m
- Constitutional Isomers vs. Stereoisomers9m
- Chirality12m
- Test 1:Plane of Symmetry7m
- Test 2:Stereocenter Test17m
- R and S Configuration43m
- Enantiomers vs. Diastereomers13m
- Atropisomers9m
- Meso Compound12m
- Test 3:Disubstituted Cycloalkanes13m
- What is the Relationship Between Isomers?16m
- Fischer Projection10m
- R and S of Fischer Projections7m
- Optical Activity5m
- Enantiomeric Excess20m
- Calculations with Enantiomeric Percentages11m
- Non-Carbon Chiral Centers8m
- 6. Thermodynamics and Kinetics1h 22m
- 7. Substitution Reactions1h 48m
- 8. Elimination Reactions2h 30m
- 9. Alkenes and Alkynes2h 9m
- 10. Addition Reactions3h 18m
- Addition Reaction6m
- Markovnikov5m
- Hydrohalogenation6m
- Acid-Catalyzed Hydration17m
- Oxymercuration15m
- Hydroboration26m
- Hydrogenation6m
- Halogenation6m
- Halohydrin12m
- Carbene12m
- Epoxidation8m
- Epoxide Reactions9m
- Dihydroxylation8m
- Ozonolysis7m
- Ozonolysis Full Mechanism24m
- Oxidative Cleavage3m
- Alkyne Oxidative Cleavage6m
- Alkyne Hydrohalogenation3m
- Alkyne Halogenation2m
- Alkyne Hydration6m
- Alkyne Hydroboration2m
- 11. Radical Reactions1h 58m
- 12. Alcohols, Ethers, Epoxides and Thiols2h 42m
- Alcohol Nomenclature4m
- Naming Ethers6m
- Naming Epoxides18m
- Naming Thiols11m
- Alcohol Synthesis7m
- Leaving Group Conversions - Using HX11m
- Leaving Group Conversions - SOCl2 and PBr313m
- Leaving Group Conversions - Sulfonyl Chlorides7m
- Leaving Group Conversions Summary4m
- Williamson Ether Synthesis3m
- Making Ethers - Alkoxymercuration4m
- Making Ethers - Alcohol Condensation4m
- Making Ethers - Acid-Catalyzed Alkoxylation4m
- Making Ethers - Cumulative Practice10m
- Ether Cleavage8m
- Alcohol Protecting Groups3m
- t-Butyl Ether Protecting Groups5m
- Silyl Ether Protecting Groups10m
- Sharpless Epoxidation9m
- Thiol Reactions6m
- Sulfide Oxidation4m
- 13. Alcohols and Carbonyl Compounds2h 17m
- 14. Synthetic Techniques1h 26m
- 15. Analytical Techniques:IR, NMR, Mass Spect6h 50m
- Purpose of Analytical Techniques5m
- Infrared Spectroscopy16m
- Infrared Spectroscopy Table31m
- IR Spect:Drawing Spectra40m
- IR Spect:Extra Practice26m
- NMR Spectroscopy10m
- 1H NMR:Number of Signals26m
- 1H NMR:Q-Test26m
- 1H NMR:E/Z Diastereoisomerism8m
- H NMR Table21m
- 1H NMR:Spin-Splitting (N + 1) Rule17m
- 1H NMR:Spin-Splitting Simple Tree Diagrams11m
- 1H NMR:Spin-Splitting Complex Tree Diagrams8m
- 1H NMR:Spin-Splitting Patterns8m
- NMR Integration18m
- NMR Practice14m
- Carbon NMR4m
- Structure Determination without Mass Spect47m
- Mass Spectrometry12m
- Mass Spect:Fragmentation28m
- Mass Spect:Isotopes27m
- 16. Conjugated Systems6h 13m
- Conjugation Chemistry13m
- Stability of Conjugated Intermediates4m
- Allylic Halogenation12m
- Reactions at the Allylic Position39m
- Conjugated Hydrohalogenation (1,2 vs 1,4 addition)26m
- Diels-Alder Reaction9m
- Diels-Alder Forming Bridged Products11m
- Diels-Alder Retrosynthesis8m
- Molecular Orbital Theory9m
- Drawing Atomic Orbitals6m
- Drawing Molecular Orbitals17m
- HOMO LUMO4m
- Orbital Diagram:3-atoms- Allylic Ions13m
- Orbital Diagram:4-atoms- 1,3-butadiene11m
- Orbital Diagram:5-atoms- Allylic Ions10m
- Orbital Diagram:6-atoms- 1,3,5-hexatriene13m
- Orbital Diagram:Excited States4m
- Pericyclic Reaction10m
- Thermal Cycloaddition Reactions26m
- Photochemical Cycloaddition Reactions26m
- Thermal Electrocyclic Reactions14m
- Photochemical Electrocyclic Reactions10m
- Cumulative Electrocyclic Problems25m
- Sigmatropic Rearrangement17m
- Cope Rearrangement9m
- Claisen Rearrangement15m
- 17. Ultraviolet Spectroscopy51m
- 18. Aromaticity2h 31m
- 19. Reactions of Aromatics: EAS and Beyond5h 1m
- Electrophilic Aromatic Substitution9m
- Benzene Reactions11m
- EAS:Halogenation Mechanism6m
- EAS:Nitration Mechanism9m
- EAS:Friedel-Crafts Alkylation Mechanism6m
- EAS:Friedel-Crafts Acylation Mechanism5m
- EAS:Any Carbocation Mechanism7m
- Electron Withdrawing Groups22m
- EAS:Ortho vs. Para Positions4m
- Acylation of Aniline9m
- Limitations of Friedel-Crafts Alkyation19m
- Advantages of Friedel-Crafts Acylation6m
- Blocking Groups - Sulfonic Acid12m
- EAS:Synergistic and Competitive Groups13m
- Side-Chain Halogenation6m
- Side-Chain Oxidation4m
- Reactions at Benzylic Positions31m
- Birch Reduction10m
- EAS:Sequence Groups4m
- EAS:Retrosynthesis29m
- Diazo Replacement Reactions6m
- Diazo Sequence Groups5m
- Diazo Retrosynthesis13m
- Nucleophilic Aromatic Substitution28m
- Benzyne16m
- 20. Phenols55m
- 21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
- Naming Aldehydes8m
- Naming Ketones7m
- Oxidizing and Reducing Agents9m
- Oxidation of Alcohols28m
- Ozonolysis7m
- DIBAL5m
- Alkyne Hydration9m
- Nucleophilic Addition8m
- Cyanohydrin11m
- Organometallics on Ketones19m
- Overview of Nucleophilic Addition of Solvents13m
- Hydrates6m
- Hemiacetal9m
- Acetal12m
- Acetal Protecting Group16m
- Thioacetal6m
- Imine vs Enamine15m
- Addition of Amine Derivatives5m
- Wolff Kishner Reduction7m
- Baeyer-Villiger Oxidation39m
- Acid Chloride to Ketone7m
- Nitrile to Ketone9m
- Wittig Reaction18m
- Ketone and Aldehyde Synthesis Reactions14m
- 22. Carboxylic Acid Derivatives: NAS2h 51m
- Carboxylic Acid Derivatives7m
- Naming Carboxylic Acids9m
- Diacid Nomenclature6m
- Naming Esters5m
- Naming Nitriles3m
- Acid Chloride Nomenclature5m
- Naming Anhydrides7m
- Naming Amides5m
- Nucleophilic Acyl Substitution18m
- Carboxylic Acid to Acid Chloride6m
- Fischer Esterification5m
- Acid-Catalyzed Ester Hydrolysis4m
- Saponification3m
- Transesterification5m
- Lactones, Lactams and Cyclization Reactions10m
- Carboxylation5m
- Decarboxylation Mechanism14m
- Review of Nitriles46m
- 23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
- 24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
- Tautomerization9m
- Tautomers of Dicarbonyl Compounds6m
- Enolate4m
- Acid-Catalyzed Alpha-Halogentation4m
- Base-Catalyzed Alpha-Halogentation3m
- Haloform Reaction8m
- Hell-Volhard-Zelinski Reaction3m
- Overview of Alpha-Alkylations and Acylations5m
- Enolate Alkylation and Acylation12m
- Enamine Alkylation and Acylation16m
- Beta-Dicarbonyl Synthesis Pathway7m
- Acetoacetic Ester Synthesis13m
- Malonic Ester Synthesis15m
- 25. Condensation Chemistry2h 9m
- 26. Amines1h 43m
- 27. Heterocycles2h 0m
- Nomenclature of Heterocycles15m
- Acid-Base Properties of Nitrogen Heterocycles10m
- Reactions of Pyrrole, Furan, and Thiophene13m
- Directing Effects in Substituted Pyrroles, Furans, and Thiophenes16m
- Addition Reactions of Furan8m
- EAS Reactions of Pyridine17m
- SNAr Reactions of Pyridine18m
- Side-Chain Reactions of Substituted Pyridines20m
- 28. Carbohydrates5h 53m
- Monosaccharide20m
- Monosaccharides - D and L Isomerism9m
- Monosaccharides - Drawing Fischer Projections18m
- Monosaccharides - Common Structures6m
- Monosaccharides - Forming Cyclic Hemiacetals12m
- Monosaccharides - Cyclization18m
- Monosaccharides - Haworth Projections13m
- Mutarotation11m
- Epimerization9m
- Monosaccharides - Aldose-Ketose Rearrangement8m
- Monosaccharides - Alkylation10m
- Monosaccharides - Acylation7m
- Glycoside6m
- Monosaccharides - N-Glycosides18m
- Monosaccharides - Reduction (Alditols)12m
- Monosaccharides - Weak Oxidation (Aldonic Acid)7m
- Reducing Sugars23m
- Monosaccharides - Strong Oxidation (Aldaric Acid)11m
- Monosaccharides - Oxidative Cleavage27m
- Monosaccharides - Osazones10m
- Monosaccharides - Kiliani-Fischer23m
- Monosaccharides - Wohl Degradation12m
- Monosaccharides - Ruff Degradation12m
- Disaccharide30m
- Polysaccharide11m
- 29. Amino Acids3h 20m
- Proteins and Amino Acids19m
- L and D Amino Acids14m
- Polar Amino Acids14m
- Amino Acid Chart18m
- Acid-Base Properties of Amino Acids33m
- Isoelectric Point14m
- Amino Acid Synthesis: HVZ Method12m
- Synthesis of Amino Acids: Acetamidomalonic Ester Synthesis16m
- Synthesis of Amino Acids: N-Phthalimidomalonic Ester Synthesis13m
- Synthesis of Amino Acids: Strecker Synthesis13m
- Reactions of Amino Acids: Esterification7m
- Reactions of Amino Acids: Acylation3m
- Reactions of Amino Acids: Hydrogenolysis6m
- Reactions of Amino Acids: Nihydrin Test11m
- 32. Lipids 2h 50m
- 34. Nucleic Acids1h 32m
- 35. Transition Metals5h 33m
- Electron Configuration of Elements45m
- Coordination Complexes20m
- Ligands24m
- Electron Counting10m
- The 18 and 16 Electron Rule13m
- Cross-Coupling General Reactions40m
- Heck Reaction40m
- Stille Reaction13m
- Suzuki Reaction25m
- Sonogashira Coupling Reaction17m
- Fukuyama Coupling Reaction15m
- Kumada Coupling Reaction13m
- Negishi Coupling Reaction16m
- Buchwald-Hartwig Amination Reaction19m
- Eglinton Reaction17m
Monosaccharides - Oxidative Cleavage - Online Tutor, Practice Problems & Exam Prep
Periodic acid cleaves vicinal diols in sugars, leading to oxidative cleavage. Aldoses yield formic acid upon oxidation, while ketoses produce carbon dioxide. Internal alcohols also generate formic acid, whereas terminal alcohols result in formaldehyde. Understanding these cleavage patterns is crucial for predicting products when reacting monosaccharides with periodic acid. The mechanism involves forming a cyclic periodic ester, followed by breaking sigma bonds to create carbonyls, illustrating the relationship between oxidation and cleavage in carbohydrate chemistry.
You may remember that periodic acid has the ability to cleave vicinal diols. Sugars contain mutliple diols that can potentially be cleaved, but other functional groups can be cleaved as well. Below we will explore each of them in detail.
Monosaccharides - Oxidative Cleavage
Video transcript
Monosaccharides - Oxidative Cleavage
Video transcript
So, this is the part that can get a little bit tricky if you don't have everything mapped out already. It turns out that different types of alcohols and carbonyls on sugars respond differently to periodic acid. It's not like a one size fits all, that it's always an aldehyde. It's actually not. You have to kind of do a little bit of memorization here. So, what I've done is I'm trying to organize it for you in the easiest way possible so that you're going to just be able to look at this chart and know exactly what to do. Just to repeat, you can't just guess what the product will be. The product is very specific depending on what type of alcohol or carbonyl you're starting with.
So, what I'd like to start with is basically the difference between an aldose and a ketose. Okay, remember that most sugars always come in either the form of an aldose or a ketose. Remember, an aldose at the top is going to have an aldehyde. Remember, a ketose at the top is going to have a ketone, and that's what I've just drawn here. Okay. Well, that oxygen that's either in the aldose or the ketose will react with periodic acid. Now, this isn't the same exact reaction as the vicinal diols reaction because this is not an alcohol. It's a carbonyl, but it still is going to oxidize that carbonyl. Okay? So how would we oxidize these carbonyls?
Well, if you're starting off with an aldehyde, what you're gonna wind up getting at the end is, and I'm going to say this a lot, formic acid. Now, formic acid is the common name for this molecule. You could also call it methanoic acid, which would be the IUPAC name, but most commonly it's called formic acid and that's just the simplest carboxylic acid possible. It's a carboxylic acid that only has one carbon. So if you have an aldehyde at a terminal end, well, aldehydes are always terminal, you're going to get formic acid as your oxidation product.
Now if you start off with a ketone, for a ketose at the top, then you're not going to get formic acid, you're actually going to get CO2. So I'm just going to put here CO2. We all know that's carbon dioxide. So you can see that in both cases, we're oxidizing. We're adding more bonds to O, but the exact products are a little bit different.
So, everyone got that so far? We've got formic acid. We've got CO2. But now we have to look at the alcohols. Those are the carbonyls, but what about the alcohols? Well, if you have an alcohol, that is an internal alcohol. What do I mean by internal? There are things on both sides, so it has something on the top and something on the bottom. What you're going to wind up getting from that is also formic acid. You're also going to get one equivalent of formic acid for every internal alcohol that you have. Okay? Cool.
And let's say you have a terminal alcohol. Now by the way, this terminal alcohol I drew it as if it was the bottom, but we know that terminal alcohols could also exist on the top because maybe you have a ketone on the top, so then you have an alcohol there. That's fine. Whenever you have a terminal alcohol, your product is going to be this, which is the condensed formula for it is CH2O, which is also known as formaldehyde. Oops, let's try that again. Formaldehyde, and we know that formaldehyde is the simplest aldehyde. Okay. So, you're either going to get the smallest aldehyde or the smallest carboxylic acid, or CO2, carbon dioxide. Okay?
So, that's what you need to know, and if you know these four cleavage patterns, then you should be able to take any molecule, react any sugar, sorry, any monosaccharide, react it with periodic acid and predict exactly what products you're going to get. Okay. So why don't we go ahead and do an example of this together to get our practice in figuring out what the products would look like.
These are the 4 cleavage patterns of monosaccharides you should memorize:
Predict the products of the following oxidative cleavage
Video transcript
Alright. So here's our first reaction with periodic acid and a sugar. What we see is that we're actually starting off with a ketose here and we're reacting with periodic acid and water, which is just a form of periodic acid to react with, so this is perfect. We know that what we're going to get is oxidative cleavage, and actually you could predict ahead of time how many molecules you're going to get because how many carbons do we have total? 1, 2, 3, 4, 5. With oxidative cleavage of monosaccharides, you're never going to be cleaving at every single spot. If it's a monosaccharide that's in a straight chain, you should be cleaving at every single spot, meaning that every carbon should be its own molecule. Okay. Cool. So let's go ahead and just maybe we can start from top to bottom and you guys can tell me which oxidation product would you expect at each carbon. Let's start off with 1. What oxidation product and I'm going to actually use letters and then we'll put it all together. So at carbon A, what would we expect to be the oxidation product? Well, I see it's a terminal alcohol, so I would expect that this is going to be formaldehyde and I'm going to draw it on its side so that it looks a little bit more like it did originally. The O is going this way. I'm going to draw it this way as well. Maybe it will make it easier to visualize. Great job. You guys all said formaldehyde. Good job. Okay. So let's go to b. So then b is this carbon. What are we going to get from that ketone? Remember that ketone reacts with periodic acid to give what? CO2 . So let's go ahead and write that in. So now we have 1 mole of CO2 . This is getting cool. Let's start off. Let's go down to C. So what would we get with C? Well, what I see with C is that is this an internal alcohol or a terminal alcohol? It's internal because that has stuff on both sides, right? So that means that I'm going to get 1 mole of formic acid.
Predict the structure of the glycoside products
Video transcript
Guys, this is a hard problem. Let me go ahead and read it, and then we'll try to work through it together. In aqueous base, D-glucose has the ability to epimerize into small amounts of D-mannopyranose and also rearrange into D-fructofuranose. Fischer glycosylation can then transform these saccharides into O-glycosides. So the two-part question says, a) predict the structure of the glycoside products after treatment with acid and methanol, and b) how could the treatment of those glycosides with periodic acid distinguish if epimerization or rearrangement is more favored? Cool. So that was a mouthful.
Guys, so this is what it's basically saying in the first little sentence. It's saying that D-glucose, through two separate processes, can either become one thing or another. Okay. Now I have videos on both of these processes, on epimerization and rearrangement. So if you're really curious about how to get these exact cyclic sugars, then please go ahead and watch those videos. But because this is beyond the scope of this question, I'm not going to draw out the exact way that we got to these sugars in this question. Okay? Because what we're really trying to focus on is what happens after these form. Just take my word for it that D-glucose can provide these two cyclic sugars, a furanose and a pyranose.
Now where the question really starts is it says, okay, predict the structure of the O-glycosides that would form after each of these is treated with methanol and acid. This part is actually pretty easy because you should have learned about O-glycosylation already or also Fischer glycosylation, and you should be familiar with which alcohols react when you react with alcohol and acid. Do you remember? Notice that all of the Os are missing their Hs, so we're going to have to predict together if it remains as an alcohol or if it gets a methyl group on it. So what do you think? Here I have 1, 2, 3, 4, 5 potential