Fischer Projections

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Video in TIB AV-Portal: Fischer Projections

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Fischer Projections
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24
Number of Parts
27
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CC Attribution - ShareAlike 3.0 USA:
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2015
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English

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Abstract
This is the third (and final) quarter of the organic chemistry series. Topics covered include: Fundamental concepts relating to carbon compounds with emphasis on structural theory and the nature of chemical bonding, stereochemistry, reaction mechanisms, and spectroscopic, physical, and chemical properties of the principal classes of carbon compounds. Index of Topics: 00:41 - Monosaccharides 01:08 - Fischer Projection 12:16 - Disaccharide 13:04 - Oligosaccharide 13:35 - Polysaccharide 14:01 - Monosaccharide can be Classified by Three Criteria 15:33 - The D Family of Sugars 17:39 - The L Family of Sugars 23:09 - Epimers 25:01 - Cyclic Structures of Monosaccharides 44:08 - Haworth Projection 45:15 - Chair Conformation
Aldehyde Computer animation Carbohydrate Ketone Monosaccharide Aldehyde Ketosen
Enantiomere Glucose Cheminformatics Deformation (mechanics) Kohlenstoff-14 Lot <Werkstoff> Left-wing politics Chemical property Stereochemistry Carbohydrate Carboxylate Oligosaccharide Glykogen Hydroxyl Polysaccharide Wursthülle Methylgruppe Optische Aktivität Saccharose Molecule Lewis structure Monosaccharide Fructose Ketone Carbon (fiber) Aldehyde Hydrogen Acid Computer animation Functional group Azo coupling Disaccharide Polymer Carboxylierung
Glucose Kohlenstoff-14 Chain (unit) Left-wing politics Carbohydrate Stereochemistry Hydroxyl Gold Chiralität <Chemie> Fischer, Emil Optische Aktivität Molecule Lead Triosen Glycerinaldehyd Pentose Fructose Ketone Carbon (fiber) Aldehyde Carbonylverbindungen Aldose Electronegativity Ketosen Wine tasting descriptors Computer animation Chemical compound Polymer Cobaltoxide Chemist Surface roughness Diclofenac
Glucose Furanosen Acetate Left-wing politics Chain (unit) Nitrogen fixation Carbohydrate Stereochemistry Reaction mechanism Hydroxyl Aromaticity Chemistry Alpha particle Sample (material) Beta sheet Setzen <Verfahrenstechnik> Asset Aldehyde Aldose Solution Ketosen Acid Computer animation Arzneimitteldosis Cobaltoxide Pyranose Thermoforming
Glucose Hydrocarboxylierung Stereochemistry Carbohydrate Carbon (fiber) Hydroxyl Multiple chemical sensitivity Aldehyde Alpha particle Optische Aktivität Systemic therapy Computer animation Nomifensine Functional group Konstitutionsisomerie Cobaltoxide Biochemistry
Glucose Conformational isomerism Substituent Left-wing politics Carbohydrate Carbon (fiber) Hydroxyl Alpha particle Deterrence (legal) Computer animation Functional group Chemical compound Monosaccharide Beta sheet Cobaltoxide Pyranose Roque de los Muchachos Observatory Process (computing)
Glucose Conformational isomerism Ionenbindung Carbohydrate Hydroxyl Carbon (fiber) Death Electronic cigarette Methylgruppe Wine tasting descriptors Sample (material) Hydrogen Computer animation Match Cobaltoxide Process (computing) Mannose Hope, Arkansas
we're gonna talk about carbohydrates today anybody have questions before we get started anybody know carbohydrates today okay and the first part we're going to talk about some it's kind of nomenclature it's not I you pack nomenclatures but it's the way we just talk about carbohydrates they actually give us a lot of information about their structure okay so each classification we can classify four so four monosaccharides monosaccharides are either going to be aldehydes I don't know they're either gonna have an aldehyde or a ketone if they have an aldehyde it's an aldose if they have the ketone it's a ketose and the us means carbohydrate or sugar all right so that's our first classification
and what we're gonna use is Fischer projections to to draw carbohydrates otherwise it takes a lot longer to draw them now there are some problems in the book where they have you go from a 3d dash wedge to a Fischer projection and back again I'm not going to ask you to do that for the final but I do want you to understand if you have a Fischer projection what that means but you won't have to go back and forth between zigzag or 3d dash wedge to Fischer and back and forth so you can just skip over those problems entirely where they do that all right so Fischer projections I did assume that you haven't talked about it in any classes you've had and maybe you have maybe you haven't but there are some rules for a Fischer projection that allows us to save a lot of time when we're drawing structures so the first rule is that the most highly oxidized carbon is on the top or towards the top and so that would be an aldehyde or a ketone so if it's an aldehyde it will be absolutely on the top if it's a ketose it will have will have the ketone second from the top horizontal lines are understood to be wedges to which project towards the viewer and vertical lines are dashed lines which project away from the viewer it is not the same thing as a lewis structure but it looks like a lewis structure and remember in the lewis structure we don't convey any stereochemical information and so but this is actually conveying stereochemical and information so for d-glucose for example we have the CH oh it's a it's a vertical line so that's dashed that's going back in space and this whole carbon chain I guess we could call that dashed and then these groups that are are horizontal or wedges so these would all be wedges and you're going to see how long it takes to draw this and you're going to be glad that you don't have to do this every time now of course you can take this and make it into a zigzag 3d dash wedge this is a Det 3d dash wedge but you could make it zigzag and that's going to change the orientation of these groups but again we're not gonna you're not going to need to do that so the ch2oh that's on the bottom is going back and so that we can just fill in the hydroxyls here again a lot longer to draw so that's what that means it is not the same thing as the lewis structure because the Lewis structure does not convey stereochemical information and a Fisher official projection does it conveys stereochemical information so it's just a little shortcut just like drawing skeletal structures allows us to draw things a lot more quickly and this is the same thing all right so there's some as long as we understand that a Fischer projection convey stereochemical information we can treat it without having to convert it into a dash wedge stretch structure we can treat it as something that's conveying stereochemical information and if we're comparing Fischer projections as long as we follow a couple of rules we don't have to convert it into dash wedge so here's the here's the rule in comparing Fischer projections you can you can rotate the drawing 180 degrees in the plane of the paper you cannot flip it and you cannot rotate it by 90 degrees if you flip it or rotate it by 90 degrees you're changing the stereochemical information that's conveyed and your flip in you're turning it into its enantiomer not allowed okay so let me prove this to you and once you once you once you've had this proven if you just remember not to do these things with Fischer projections you're gonna be in good shape but let's let's just just go ahead and prove these two things here and so and in order to do that I'm going to convert this into dash wedge so that means vertical lines are going back so methyl is going back carboxylic acid is going back Oh H is coming forward and the hydrogen is also coming forward all right so that's what that is and if we assign configuration that is going to be the r configuration now what we're going to do is we're going to rotate this 180 degrees in the plane of the paper so we're not going to do a full 360 we're just going to rotate 180 degrees and I'm gonna rotate the Fischer projection okay so that means that this is down this is up and I'm going to go and if I'm going this direction for example then the OAH would be here and the hydrogen would be here and by doing 180 degree of rotation we still have the same information here vertical lines are still coming forward and horizontal lines I mean vertical lines are still going back and horizontal lines are still coming forward and so that's why it doesn't change anything so this is what it would look like after we rotate and if you assign configuration here you will find that it is still our and that's why that's allowed ok now let's do the things you can't do and prove that you can't do them now remember when you have it drawn - wedge you can flip you can rotate you can spin you could rotate at any angle you want when you have dashes and wedges drawn in it's just when you have it in a Fischer projection you have to be careful about how you move it so let's go let's rotate let's do a none allowed thing here and let's rotate 90 degrees ok so we know this isn't our configuration so we're gonna we're gonna rotate this 90 degrees and so what it's going to look like after we rotate it going this way so carboxylic acid here o H here methyl ch3 here and hydrogen here ok and now that is equivalent to because it's a Fischer projection that is equivalent to this hydrogen going back hydroxyl coming forward carboxylic acid and methyl so can you see how we've switched the orientation of every single group hydrogen's hydrogen's before we rotated we're coming forward the hydrogen was coming forward the hydroxyl was also coming forward and now they're going back so we've we've actually changed the configuration and so if you assign
configuration here you're going to see that you now have the S configuration and so you change configuration by rotating a Fischer projection 90 degrees and that's why you can't rotate a Fischer projection 90 degrees because you're going to be changing it into its enantiomer let's do the second thing flip it over okay all right so we know this is our configuration I know we're going to flip over and so basically what I'm going to do is I'm just gonna like turn it like a turn if I'm turning the page of a book so this will still be on top the methyl will still be here but now the hydroxyl is on the left and the hydrogen is on the right and if you look at this you can see that these are mirror images of each other and because those lines are conveying stereo chemical information if they're if they're mirror images of each other then they have the opposite configuration but just in case we don't see that we can convert this into what it means and that means this you know carboxyl the acid is going back vertical lines are coming forward and if we have some configuration this is now asked configuration and so you changed configuration when you white flipping over and so that's why it's not in a lot of configuration so now that we understand that now that we've had that proven to us we can now stick completely with Fischer projections and just remember not to do these two things that were not supposed to do questions anybody about Fischer projections all right so disaccharide a sugar that can be hydrolyzed to two monosaccharides so a good example of that is sucrose table sugar notice the oaths ending for sugar or carbohydrate so this is just C NH table sugar and you can hide it you if you hydrolyze that you will get glucose plus fructose in a one to one ratio so because it creek has sucrose is composed of glucose and fructose that means that it's a disaccharide okay oligosaccharide it contains relatively few monosaccharides I've had it I've had a little trouble finding what exactly what they mean by few but what I found is it's more than two but less than many okay honestly there's no I'm sure there's something out there but I wasn't able to find him more than two but less than many you will not be tested on what if this is a legal sac right or a polysaccharide polysaccharide means you have many many monosaccharide units they're naturally occurring polymers and monosaccharides so the cellulose and starch these are polysaccharides made of glycogen DS D glucose units and we have vastly different physical properties just from the subtle difference in one stereocenter on each of those d glucose molecules so we'll talk about that coming up but continuing with classification monosaccharides can be classified by three criteria we already
talked to one of them oh this thing likes is very touchy for scrolling we know that we if we have a ketose it contains a ketone we already talked about that now we know that we we have an if we have an aldose it contains an aldehyde we can also classify by the number of the carbons in the carbon chain so this is a common classification if you have three carbons you have a triose if you have four carbons you have a tete Rousse if you have five you have a pentose if you have six you have a hexose and if you have seven you have a hep tose and pretty much those are the only ones that we will say so notice that tells you how many carbons in the chain and the O's tells you that it's a sugar or a carbohydrate and what you're going to find is with me when you classify the carbohydrates the one and two are often combined so for example glucose is an aldehyde with six carbons so it is therefore an aldohexose so the classification is telling us a lot about the the it's telling a lot of us a lot about glucose it has an aldehyde and it has six carbons and the other way that we classifies the stereochemical configuration of the chiral carbon atom farthest from the carbonyl group which is going to be this one right here second from the bottom and for the D sugars this will always be on the right and that does not mean that it's rotating the plane of polarized light in the positive direction this has nothing to do with that it has to do with the stereochemical containing configuration at this carbon is though this is the key carbon here so this carbon signifies whether it is a D or an L sugar and where this this nomenclature came from a long time ago before we actually knew what all the configurations of each of these carbons was for glucose for example back in back in the day when they didn't have the techniques that we had they used something called a rough degradation there's also a gold degradation but a rough day gradation and what they would do is they would break down the sugar until they only had three carbons left and then they would do an optical rotation and when they did the D sugars and did this they all resulted in D + glyceraldehyde so yes if you take any D sugar and you break it down to glyceraldehyde it will have a positive rotation that does not mean that the that D sugar before you degraded it will have a positive rotation it could have a negative or a positive because we have many stereocenters here okay the L family sugars is the opposite so the L family of sugars this hydroxyl is on the left hand side and again that came from chemists who work with sugars a long long time ago with them one of the main person people that did this was Emil Fischer and for the Dell sugars on this hydroxyl is always on the left so again it doesn't matter what the other configurations of any of the other carbons are this is the one that signifies whether it's a deer in else sugar so we have this here that carbon here and we know this because if we do too rough degradation we break this down so there's only three carbons we get l- glyceraldehyde DRL configuration has nothing to do with
whether the compound is dextrorotatory our laboratory okay so that's that's a key point some d sugars have positive rotations and some d sugars have negative rotation and likewise for L sugars all right so what they but what the D sugars all have in common is if you degrade them down to three carbons they will all have a positive rotation but before you degrade them you're not necessarily going to have a positive or a negative rotation questions so far on that point anybody so it's a little bit strange all right so here's an example here yes because it just it's all good because in our bodies it's all D sugars and it's just it's just an old way of stating things that still still fits yeah all right so here's an example here is this is the one on the left of G sugar or an L sugar it's a d sugar right so on this one so I'm not going to have you memorize all the sugars I'm gonna have you memorize two sugars glucose and fructose you think you can handle that you can trust me you can handle it notice okay so this is D this is a D sugar and so the one on the right this is D plus glucose and this is D minus fructose and so what you'll notice that they have in common is the bottom one two three four carbons are identical that sure makes it easier to remember right so this part of the molecule for d-glucose and this part of molecule for D fructose is exactly the same so really if you memorize the glucose that will be easy to UM drop the fructose and so this part is the same for both and notice D glucose it's a bit sad II sure it has a positive rotation d fructose has a negative rotation and that's because how many stereo centers do we have in D glucose we've got this one right here one two three four and the one that we're using for the D sugar is only one of those stereo centers so there's no way that that one stereo Center is going to dictate the optical rotation for the entire molecule okay so so that's the key here there's nay there's as - this is positive then answer morbid D sugar is always an el sugar though so that's really good to know so this is a d3 else and so all I'm doing is drawing the mirror image and I can because these are these are Lu these are Fischer projections so they do convey stereochemical information and so you'll notice this is Al three OHS but if I wanted to draw the D the L if I wanted to draw L glucose I would just draw the mirror images mirror image of d-glucose so that that's one thing that's always the always going to be true all right that leads us to a perverse many of the common sugars are closely related to each other differing only in the stereochemistry at a single carbon atom sugars that differ only by the stereochemistry at a single carbon atom are called epimers so there's a lot of new terminology in this chapter that you do need to know so the carbon at which they differ is generally stated so if you compare these two sugars you'll notice that the only thing that's different than if you work up for our way from the bottom bottoms the same here same that's the same the only thing that's different is right here so of those four stereocenters we differ at only one and we when we number we start numbering from the top so this would be 1 2 3 4 5 6 1 2 3 4 5 6 and so these are what we call c2 epimers need to know that terminology and it turns out this one is d-mannose and this is d-glucose so de manos is the c2fo remote glucose and here's the beautiful thing about this because I can tell you on an exam draw the structure of d-mannose the c2 epimer of glucose I don't have to you don't have to memorize Manos because I told you what it is if you know glucose you can draw Manos right does it's got its the c2 epimer okay and that's a beautiful thing because you'd have to memorize all the sugars like I did I didn't memorize all the sugar okay alright so we've drawn a lot of open chain sugars most of the time sugars are not opened up in a long chain there's cyclized so that's the next thing we want to talk about cyclic structures and if you go back to chapter 21 we talked about hemiacetals are generally unstable unless they could be in a five or six membered ring so what that means is that sugars have many opportunities to form hemiacetals and if
they can make a five or six membered ring they they will and so what you'll find is that a lot of sugars have six membered ring forms some of them have five membered ring forms okay because again hemiacetals are more stable when their inner ring so if we just take a regular aldehyde here this goes back to chapter 21 here's a hemiacetal and you can also get some asset owl and you can also and you get water and as we talked about way back in Chapter 2021 that we generally can't isolate this so hemiacetal ah doesn't want me to write that go ahead and you write it on your say maybe I'm off the page let's fix that so hemiacetal generally can't isolate and then if we want the asset at we drive to equilibrium so here's the asset owl here isolate by driving equilibrium so if you go back to the page where we first introduced acid towels I think you'll probably have the same exact drawing here this is directly off of chapter 21 alright so here's the five evergreen form so what those would look like and I'm not showing the full mechanism here but we're gonna protonate the oxygen and we're gonna have that attack intramolecular hemiacetal formation so if we have this sort of set up long arrow to the right short arrow to the left and again long arrow to the right short arrow to the left six membered rings are more stable than five membered rings so we would expect the six membered ring to be more predominant so this is 94% at equilibrium and the five membered ring is 89% at equilibrium and of course these are cyclic hemiacetals same is true for Aldo aldoses and ketoses a exists primarily as cyclic hemiacetals notes that for most sugar you can actually get five or six membered ring the six membered ring is usually favored all those five membered ring cyclic acetal czar also important so here are some examples here this is d glucose well we'll call the open chain form and if you have a sample of d-glucose in solution you'll have a small amount that is in the open chain form a very small amount will talk about the mounts coming up and so here's your here's your out aldehyde and if we count one two three four five six if we have this hydroxyl right here attack the aldehyde that would be one two three four five six that will make a six membered ring that would look like this well we'll do stereochemistry coming up but that's what the six membered ring would look like and or on the other hand we could cycle eyes to make a five membered ring we would use this hydroxyl to attack the aldehyde and that would make a five membered ring and so the hit this is what the five membered ring would look like all right we have some names for these guys that you need to know this is a furanose ring notice that OHS keeps appearing that's telling us it's a carbohydrate pure dose and that nomenclature comes from fear and this is fear an which is an aromatic compound and so that's where that name comes from that's fear an and the six membered ring also has a name that is a pyranose or pyranose however you want to say that and this is from a PI R an ring that's PI R an and so this is appear in house so the name the Piron else is telling you that the open chain sugar has cyclized into a six membered ring and if you say you have a furanose it tells you that the open chain sugar has cyclized into a five membered ring and so and so it turns out that when you form the hemiacetal if you look right here what I'm going to mark this with that I haven't used already right here when you cycle eyes you form a new stereo Center right here so that's a new stereo Center and that's a new stereo Center so if you thought you were done with stereo chemistry you're wrong sorry about that new stereo Center so information of the heavy asana introduced a new stereo Center there are two possible configurations alpha and beta the
hemiacetal carpet is called an an American and the two possible isomers are called an averse so the new this is our new stereo Center it is and also it's called it's an an America carbon and this one here is an anti Merit carbon so more terminology that you need to know so let's look at this let's look at glucose in a little more detail here because we are going to need to show stereochemistry on these sugars because that's how we're signifying what kind of sugar we have so let's look at the cyclic hemiacetal form of glucose so
here's glucose oh you recognize that already yeah see not too bad d glucose we start counting from the top carbon one carbon two carbon three carbon four five and six and let's cyclize it so what we're going to do is we're going to sort of tilt this down like this and lay it on its side okay so it's standing up we're gonna lay it on its side with the aldehyde on the right hand side ain't gotta kind of curl it up on itself so I wish I had my I left my hand my laser pointer today but let's see we'll pull point so if you look here if I'd laid this down carbon to the hydroxyls down carbon three the hydroxyls up carbon for the hydroxyl is down and carbon five the hydroxyl is down I'm just all I'm doing is taking it you're laying it down laying it down like that and so that's what we have here this is carbon one carbon two hydroxyls down carbon three hydroxyls up carbon four hydroxyls down carbon five hydroxyls down and that's what it would look like if I laid it on its side and kind of just curled it up because what it's going to have to do is cycle eyes so I just have it I could have laid it flat and then curled it up I guess I could do that but I have it curled up already so this is on its right side now I'm not in a good position to cyclize if I cycle eyes with this hydroxyl right here how many carbons would I have in the ring seven it's not going to make a seven membered ring we know seven membered rings aren't favored so what I need is this hydroxyl right here that's the one I want to get that I want to rotate this into a position so that it's it can attack so I want this hydroxyl where the ch2oh is so I have to rotate it okay so c6 is rotated up now some of you can't do that rotation some of you can some of you can't if you can't it's no big deal because for the D Surtur's when you do that rotation the ch2oh is always up so c6 is always up for the D sugars so now that I've done that rotation now then now this hydroxyl is in position to attack the carbonyl and to form a six membered ring so let's circle this here so long this is C six here and that's what we're talking about that's always up for the D sugars alright so then if you look here this this oxygen here is now in a position to attack the carbonyl and it can attack from it's attacking a PI system it could attack from below on the bottom part of the PI system or it can attack from above if it attacks from below then this group will pop up the oxygen will pop up if it attacks from the top this oxygen will go down okay so we've got there's our new stereo Center and we have two possibilities here so there's the new stereo Center right here so new stereo Center this is our an American and over here that's our new stereo this is the opposite okay so this is the oxygen is attacked from above and the hydroxyl spot in the oxygen has popped down so this is again our new stereo Center and it turns out if this hydroxyl is up its called beta and if the hydroxyl is down it's called alpha so that's how we signify the configuration at the anomeric carbon these are Haworth projections seen in bio textbooks of course we know that the ring is not really flat right it's a six membered ring flat no it's a chair so that's another that's another question why do we still use Haworth projections why do we still use dnl because people like it you know we know it's not flat like that it's not flat so we're gonna be able I want you to be able to draw things both
in Haworth projections and in chairs and it's actually not that difficult to do because you have to be able to navigate both you're going to see this in older textbooks you need to be able to draw both so we know of course that the ring is not really flat just like the world is not flat right okay so same thing so what we would call this is we can call it two things depending on how specifically wanna be this is beta-d-glucose the D tells you the configuration at carbon number five the beta tells you that it's the beta anamur or we could be more specific and we could call this veda d gluco pyranose so that gives this tells us that the glucose is cyclized into a six membered ring it has a beta configuration at the anomeric carbon and it has the d sugar so it is we just are adding them so so if I ask you something on the final and I say be specific I want as specific as you possibly can okay so they do that so this would be alpha D glucose and more specific would be alpha D glucopyranose all right so we know that those are actually in chairs and so let's look at see what the chair looks like so these guys are equivalent here all right it looks like a lots going on here so I'm gonna just cut through what you need to look at here so this is the chair conformation and we're gonna tell you what how you can do draw this really easily believe it or not all right so we're first of all we're gonna look for the an American and that's the carbon that's a hemiacetal so you got a lot of hydroxyls going on here it could be difficult to do so we just we're looking for the carbon that's bonded to an ORM a no H if you look at this carbon right here that's only bonded to an O H this carbon right here is oah oah oah this carbon right here is bonded to an O H and an O R so this is our hemiacetal carbon right here are our animerica Arbonne and this one is beta and beta is equatorial so in four beta-d-glucose pyranose the on an americorps vin the hydroxyl is equatorial have to know that in alpha D glucose here's our animerica Arbonne right here alpha equals XE 'el how about that so it's actually easier it's easier to get this from the chair than actually in the heyward a for axial alpha for axial so this is again beta-d-glucose pyranose and alpha D glucopyranose so how do you remember the chair conformation of beta-d-glucose pyranose all substituents are equatorial and by the way that when you're drawing these chair confirmations you always have to draw it in this orientation so the this oxygen here is as always has to be on the top right and then in the anime or carbon pointing down so that that's sort of the classic way to draw them and you may find some of you have trouble drawing any chairs but if you can draw chairs you'll find probably one chairs easier for you to draw depending on whether you're right-handed or left-handed this is the chair that I don't draw very well I draw the other chair a lot better so but it has to be drawn that way that's the way you'll see some rare exceptions but that's sort of the classic way it's drawn so you want to be able to draw it in that orientation and again these are what is the relationship between the two of these compounds they're an immerse okay all right so yes this is a ways to draw the cyclic monosaccharides you can go through this whole process lay it on its side cyclize it put it in the Haworth put it in a chair i don't do that when i draw these guys I'll show you a trick how to do it so for the Haworth projection you just go through the same
thing we just talked about see previous page so relate the Fischer projection on it's right side groups that were on the right where are down and ones that were on the left are up we rotated then we close the ring and drew the results so this is just exactly what we did okay so we went down like this on it's right side always up friend we rotated this always up for D sugars and then we drew this is one of two an America Poston one of two animal
alright so the chair conformation easily job I recognize the difference between the sugar in question and glucose so my recommendation is that you memorize and are able to draw the chair conformation of glucose and then we can look for differences and change them as we go so draw the chair conformation with the ring oxygen on the back right hand corner in the hemiacetal carbon down and so that like I just said we're gonna always draw this way so if you drop the other way you're not going to get credit for it in glucose all the hydroxy groups are in the equatorial position and to draw common sugars notice how the difference from glucose and make the appropriate changes so this is glucose so oxygen has to be in this position and right hand side must be drawn when drawing right hand side down all right so let's give you a sample up final question draw the cyclic hemiacetal for nevada d-mannose both as a chair conformation and the hayward projection my analyst is the c2 epimer of glucose you will have a problem like that on the final will it be Manos no there will be something else besides Manos okay so let's do it let's do so here's D glucose you'll recognize the glucose already okay and here's the chair of glucose to draw any of the the c6 sugars all deaths the only things you have to know here's the chair of glucose and America Arvin is on the right-hand side is down so right hand side down this is the anomeric carbon let me just add that and then we have all of the other hydroxyls and the ch2oh on carbon number six is on equatorial so let's number one two three four five six and we start counting from the anomeric carbon going clockwise one two three four five six got to know that numbering so d-mannose is the c2 epimer so if you know what that means you're not gonna have trouble with this so what that means is everything's gonna look the same as glucose so I'm gonna hang tight here and draw everything else but see to everything else is gonna match you want to make sure that you draw hydrogen's in okay so that's a really common mistake on the test if you draw it like that you don't put hydrogen's on the ends of those bonds what does that mean yes a methyl yeah so you just I would say when you get your admit when you get your final right in big letters on the front don't forget two hydrogens on fischer projections okay because it's just a really common mistake all right so a c2 epimer that means in d koukos the hydroxyl zone the right so that means that in d mammals the hydroxyl has to be on the left not hard right if you know d glucose let's draw the chair oh it's too
too late you try it and then we'll check and see if you did it right next time hope you guys have a great weekend you
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