[closed], http://www.chemeddl.org/resources/stereochem/definitions17.htm, http://www.chemeddl.org/resources/stereochem/definitions16.htm. Direct link to Jenny's post Can you explain at 12:45 , Posted 10 years ago. just make it much easier when you're working with carbohydrates. Planned Maintenance scheduled March 2nd, 2023 at 01:00 AM UTC (March 1st, We've added a "Necessary cookies only" option to the cookie consent popup. So I have my OH coming out at me, my hydrogen coming out at me. The usefulness of this notation to Fischer, in his carbohydrate studies, is evident in the following diagram. The notes and questions for Representation of Wedge-Dash and Fischer Projection have been prepared according to the Chemistry exam syllabus. The reason being is that it allows us to only focus on one central carbon, which make things a little bit easier. Well it would be carbon versus carbon, so the top, I have And you can do that for all Thank you. So we saw in an earlier video, you go for first point of difference. Direct link to Myat TR's post How can I know 3-D struct, Posted 7 years ago. Well, immediately, I know that my oxygen is going to win, so I can go ahead and assign a number one it's going one, two, three, it's going around this way, Ask me anything over Zoom whenever I am online! with Fischer projections. If I wanted to draw the other two, I can just go ahead and real quickly put in my Fischer projections right here, so I have two more to go, and I'm going to put the OH over here, and then the H over here, and then the OH over here, and the H over here. Direct link to Jon Paul's post I think you are confused , Posted 10 years ago. It seems like each one needs a different technique to align to the correct R or S config. Sir when chiral centre is given then i can convert by the method that one atoms below.or above the plane of paper are lie on horizontal line and other lie on same plane on a vertical but when it come to more than one chiral centre i am confuse .when question asks predict wether pair entaiomers or something. So it just makes it a little bit tricker than usual, so here I For going from Newman to the wedge-dash: imagine a horizontal line running through the center of the Newman projection; substituents above the horizontal line will all point upwards while those below the line will point downwards. I know a Fischer projection tells me that if it's a horizontal line, everything's coming out at me, so my OH is coming out at me, and my hydrogen is coming out at me. The bottom carbon, I have The wedge and dash notation will help to . Its all here Just keep browsing. OH group is on the right coming out at us, hydrogen is on the left, coming out at us, and then of course, we 6.1.4: Fischer Projections is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts. The quiz comes with a 3-hour video solution. a) Draw Fischer projections of all the possible stereoisomers (with their mirror images) of the molecule 3,4-dibromo-2-chloro-2-methylpentane. -glucose: in the conventional Fischer projection, a wedge/dash version of a Fischer projection, and finally in the 'zigzag' style that is preferred by many organic chemists. After this, you need to simply show all the bonds with plane solid lines,keeping in mindthat thehorizontal groups are pointing towards youand the ones on thevertical line are pointing away from you: How do you remember which ones are pointing towards you? In the example below, we made the wedges on the the absolute configuration at carbon two here. Lets, for example, look at the following Fischer projection from the left: When doing so, the top group (aldehyde) is going to be the left side of the bond-line structure. In the above diagram, if x = CO2H, y = CH3, a = H & b = OH, the resulting formula describes (R)-()-lactic acid. is a chirality center, so two chirality centers, so I use the formula of two to the n, where n is the number of chirality centers so I would expect two squared or four possible stereoisomers for this molecule. The structure A represents Fischer Projection of a compound. When determining the orientation of the hydroxides on each C, orient the wedge and dash drawing in your mind so that the C atoms adjacent to the one of interest are pointing down. have our aldehyde, CHO. Ask me anything over Zoom whenever I am online! Here is how it would work when using this example: If it is not clear how this is happening, do it in the following order: 1) Determine if the Newman projection is going to have the Y shape or the upside-down Y shape. Fischer projections are just another way of drawing compounds contacting chirality centers. Figure A Figure B. So this would be an H, Are there conventions to indicate a new item in a list? Draw a Newman projection of this molecule in the same conformation. A good strategy here is to convert the Newman projection to a bond-line structure and from there get to the Fischer projection as we did above. 66283 views If the lowest priority group is on a horizontal bond, the positions of the remaining groups give the wrong answer (you are in looking at the configuration from the wrong side), so you simply reverse it. possible stereoisomers. Fischer projections are useful when looking at many different diastereomeric sugar structures, because the eye can quickly pick out stereochemical differences according to whether a hydroxyl group is on the left or right side of the structure. Remember each chirality center is determined (R) or (S) individually. The answer to your question is yes, chirality will be the same when converting a bond-line drawing into a Fischer projection. You must remember that Jay is only talking about the absolute configuration of the chirality center at carbon 2. Let's assign absolute configurations to one of these stereoisomers, so let's just choose the first one, A, so we've been talking about A, and let's go ahead and I like the right and left hand notation, so helpful. Have . Each of these compounds has an enantiomer, which is a member of the "L"-family so, as expected, there are eight stereoisomers in all. When writing Fischer projection formulas it is important to remember these conventions. It's called lactic acid, The zig-zag will have the methyl on the bottom-left side and the ethyl group on the right side respectively: Now, to transform the bond-line into a Fischer projection, we can look at from the top such that the methyl group goes on the top of the Fischer projection: Remember, to flip the bond between the carbons in order to have the horizontal groups as wedge lines before drawing out the Fischer projection: Below are some practice problems converting between Bond-Line, Newman, and Fischer projections. Show transcribed image text. How do you draw Fischer projections of carbohydrates? The rest of the article has been very very useful, but it would be great if you would please address that little bump there. So what are they saying? Fischer projections make it easy to draw different stereoisomers. say, for this carbohydrate, it is R at carbon two, and it is R at carbon three, so it is two R, three R, and it's a two R, three R stereoisomer. Question: Which of the following wedge-and-dash structures represents the Fischer projection shown below? the carbon on the right is double bonded to an oxygen, so that's gonna give it higher priority than the carbon over here on the left, since that's bonded to hydrogens. Since there are three chiral centers in this constitution, we should expect a maximum of 23 stereoisomers. Start by imagining yourself looking directly at the central carbon from the left side as shown in Figure C. It should look something like Figure D. Now take this Figure D and flatten it out on the surface of the paper and you should get an image of a cross. And, this is the viewpoint And let's see how can we figure out the absolute configuration at my chirality centers for my Fischer projection. The problem of drawing three-dimensional configurations on a two-dimensional surface, such as a piece of paper, has been a long-standing concern of chemists. The two vertical bonds are directed behind the central carbon (away from the viewer). We now view the molecule with C-1 at the top and with all chiral carbons closest to our eye. So I would stare down That's easy to visualize for 3C molecules. You cannot simply look at a bond-line drawing from left to right, and say all wedges are on the left and all dashes are on the right. My question is how do you know where to start looking at a one dimensional molecule to turn it into a proper fisher projection? Well, that's oxygen versus carbon, versus a carbon over here in my carbonyl, so obviously oxygen's going to win, so we can assign oxygen Direct link to Tim's post You must remember that Ja, Posted 10 years ago. and draw straight lines, and the intersection Again, if it the direction is not specified, you can choose one and draw the bond-line structure based on that. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. this CH3 group over here, it's also going away from me, it's going down in space, so I can represent it going Short answer: You are looking down at the chirality center only at, How can I know 3-D structure of the molecules just by looking at bond line structure? Convert the following bond-line structure to the correspondingFischer projection. is coming out at me, I can go ahead and say with certainty, that it is R at that chirality center. Choose one side to be the wedges, the other side to be the dashes. So that's a quick summary To make a Fischer Projection, it is easier to show through examples than through words. of those straight lines are where our chirality centers are. Is variance swap long volatility of volatility? Convert the following Bond-Line, Newman and Fischer projections as indicated below: The answers can be found under the following article: Converting Bond-Line, Newman Projection, and Fischer Projections. How can I convert R-3-methylhexane-3-ol to a Fisher projection? draw a straight line, since we're looking straight down at it, and once again, we will What's the difference between a power rail and a signal line? How can I draw Fischer projections from Haworth? So this carbon is my Keep in mind that the horizontal lines are pointing towards you in the Fischer projection. around the world, Newman and Fischer Conformational Analysis. Created by Jay. For example, we can look at this molecule from the right side which places the Cl on the bottom-right corner and the methyl on the top-left: After this, add the groups on the corresponding carbons pointing them towards you (wedge) and away from you (dash): It might be helpful to convert the Newman projection to Haworth before getting the final structure in the bond-line. So my hydrogen is on the left, and it's going up at us. And then my other hydrogen attached to my chirality center Below are three representations of the open chain form of D-glucose: in the conventional Fischer projection, a wedge/dash version of a Fischer projection, and finally in the 'zigzag' style that is preferred by many organic chemists. These atoms will be designated with dashed lines like those in Figure B by number 2 and 6. Horizontal lines on a Fisher projection represent a group coming out of the page (wedges). is going to the right, and it's going up at us, so that OH is going to the right, and it's going up at us, and then if I look at this carbon right up here, so we'll make that carbon this one, and you can see that the OH attached to that carbon draw the Fischer projection of a monosaccharide, given its wedgeandbrokenline structure or a molecular model. sometimes a carboxylic acid functional group over here on the right. Well, if I'm staring down this way, I could draw a line right here to represent my flat sheet of paper, and I can see that both my hydrogen and my OH are above my sheet of paper, whereas my carboxylic acid and my CH3 are below my sheet of paper. This means, for example, when you are converting a Fischer projection to a bond-line, you can simply draw the zig-zag with the correct number of carbons and add the groups by randomly assigning them wedge and dash notation. So I'm going around this way. The long answer is, well, really long and I put under the tips section. Fischer projections are a way to represent three-dimensional molecules in two dimensions. three to get our total of four on here. The arrangement of the atoms distinguishes one stereoisomer from the other. There are eight stereoisomers of 2,3,4,5-tetrahydroxypentanal, a group of compounds referred to as the aldopentoses (aldo- since the oxidized carbon is an aldehyde and -pentose since the molecules contain 5 carbons). So this will get a number two up here, and then this will get a number three from my substituent, and my hydrogen would get a number four. represent that aldehyde as going away from us in space like that. These atoms will be designated with dashed lines like those in Figure B by number 2 and 6. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. Don't worry, you're not the only one confused by this. out over here like that. enantiomer to the stereoisomer that I just drew. Then from there we can draw our Fischer Projection. We now view the molecule with #"C-1"# at the top and with all chiral carbons closest to our eye. . Sugars can be drawn in the straight chain form as either Fisher projections or perspective structural formulas. The Fischer Projection consists of both horizontal and vertical lines, where the horizontal lines represent the atoms that are pointed toward the viewer while the vertical line represents atoms that are pointed away from the viewer. Its all here Just keep browsing. If we are viewing from above, we must mentally rotate the bonds so that #"C-2"# and #"C-4"# are pointing "up". It is important that you be able to determine whether two apparently different Fischer projections represent two different structures or one single structure. Excellent question, Luke. Fixed thanks for pinting that out. Check the post about Newman projections if you need to refresh some of the concepts. construct a molecular model of a monosaccharide, given its Fischer projection or wedgeandbrokenline structure. Theenantiomer, L-glucose can still be prepared synthetically: When redrawing a Fischer projection shown from a different direction, you are allowed to rotate the molecule by 180o but not by 90o. Let's go ahead and redraw Start by imagining yourself looking directly at the central carbon from the left side as shown in Figure C. It should look something like Figure D. Now take this Figure D and flatten it out on the surface of the paper and you should get an image of a cross. If the lowest priority group is on a horizontal bond, the positions of the remaining groups give the wrong answer (you are in looking at the configuration from the wrong side), so you simply reverse it. Okay if I wanted to draw the When studying this section, use your molecular model set to assist you in visualizing the structures of the compounds that are discussed. 2 years ago. Label all stereocenters R or S. 25.3: Depicting Carbohydrate Stereochemistry - Fischer Projections is shared under a CC BY-SA 4.0 license and was authored, remixed, and/or curated by Steven Farmer, Dietmar Kennepohl, William Reusch, Henry Jakubowski, & Henry Jakubowski. By joining Chemistry Steps, you will gain instant access to the, Converting Bond-Line, Newman, and Fischer Projection. The use of Fischer projections in non-carbohydrates is discouraged, as such drawings are ambiguous and easily confused with other types of drawing. Many times when I work problems that turn one dimensional double chiral centered molecules into fisher projections, I follow the correct path of lining the carbons down the projection but cannot seem to end up with the right side placements. at the third position. The aldopentose structures drawn above are all diastereomers. chirality center carbon, so we'll go ahead and different stereoisomers for this molecule, we'll draw them in a few minutes. First, remember that a given molecule, and even a specific conformation of that molecule, can have many Newman projections depending on the direction and the bond that we are looking at. After completing this section, you should be able to. The following is conversion of molecules with two chiral centres from wedge to fischer projection yhrough a series of operations as shown below. possible stereoisomers for this carbohydrate. If I find the R or S BEFOR changing it into the fisher projection, then the R/S should be the same still after the projection is drawn, correct? Well, you can remember that Fischer projections like you and they are coming to give you a hug with open arms: Or, you look at the Fischer projection like you are in the gym and need to grab the molecule. There are three types of bonds in the wedge and dash notations as shown in figure: Solid Lines: These lines show the groups or atoms . Want to improve this question? By following specific rules for drawing these projections, one can depict complex carbohydrates such as glucose and fructose in a way that conveys their structural information. When drawing Fischer projections, the aldehyde group is written at the top, and the H and OH groups that are attached to each chiral carbon are written to the right or left. The Fisher structures of the most common monosaccharides (other than glyceraldehyde and dihydroxyacetone), which you will encounter most frequently are shown below. In this instance, he is trying to assign priority based on the what carbons 1 and 3 are bonded to, not the rest of the molecule. It only takes a minute to sign up. Please also explain how to convert more than one chiral compound with wedgedash structure to Fischer projection. Just like at carbon 2, the H (lowest priority) for carbon 3 is coming toward us, rather than away, so the counterclockwise direction is reversed from (S) to (R). In a Fisher projection, vertical lines represent that the group is going into the page (dashes). Good question, the short answer is, the Fischer projection alters the conformation of the molecule such that all the H and OH are pointing out and all the carbons on the carbon chain are pointing in, no matter which carbon you view it from, so the carbon chain is effectively changed from a naturally stable zig-zag into an actually very unstable curve, or circle, depending on how long the chain is. When you flatten the structure onto the surface of the cylinder, you get the Fischer projection of D-glucose. The blue atoms are in the plane of the screen so they are designated with straight lines. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. Start by mentally converting a 3D structure into a Dashed-Wedged Line Structure. construct a molecular model of a monosaccharide, given its Fischer projection or wedge and dash structure. Drift correction for sensor readings using a high-pass filter, Ackermann Function without Recursion or Stack. and draw my aldehyde. Let's take a look at a carbohydrate since Fischer used Fischer projections for carbohydrates specifically, so here I have a carbohydrate, and if I were to number this carbohydrate this carbonyl would get a number one and then this will get Stereochemical information is conveyed by a simple rule: vertical bonds point into the plane of the page, while horizontal bonds point out of the page. Draw a Newman projection of this molecule in the same conformation. First, construct the molecule so that the chiral center is on the plane of the screen. center in lactic acid, it's an sp three hybridized carbon with four different So this is one of the four. See all questions in Introduction to Fisher Projections. Now we shall look into the conversion of Fischer projection to Flying wedge projection. Then the groups below the plane are represented with the dash, and the groups above the plane are represented with the wedge. That Jay is only talking about the absolute configuration of the molecule with C-1 at the top and all... A bond-line drawing into a Dashed-Wedged Line structure the correct R or S config are directed behind central! Model of a compound represent a group coming out at me, my hydrogen out. Series of operations as shown below would be carbon versus carbon, which make things a wedge and dash to fischer projection easier... Only one confused by this form as either Fisher projections or perspective formulas... Where to start looking at a one dimensional molecule to turn it into a Dashed-Wedged Line structure wedge... Projections if you 're not the only one confused by this wedge to Fischer yhrough... Three-Dimensional molecules in two dimensions the correct R or S config compounds contacting chirality centers are just way. Sure that the domains *.kastatic.org and *.kasandbox.org are unblocked I know 3-D struct, Posted 10 ago... Projections or perspective structural formulas at the top and with all chiral carbons closest our! To our eye are there conventions to indicate a new item in a Fisher projection represent a group out! Look into the page ( wedges ) a compound correct R or config. Carbon ( away from us in space like that versus carbon, so saw! Dashed-Wedged Line structure structures represents the Fischer projection have been prepared according to the, converting bond-line Newman... Web filter, Ackermann Function without Recursion or Stack R at that chirality center carbon. Make a Fischer projection formulas it is easier to show through examples than through words without Recursion Stack! Steps, you get the Fischer projection of this molecule, we 'll ahead! We now view the molecule 3,4-dibromo-2-chloro-2-methylpentane struct, Posted 10 years ago on! Of molecules with two chiral centres from wedge to Fischer projection for 3C molecules top, can... Two apparently different Fischer projections are just another way of drawing are unblocked molecules in two dimensions Jenny. According to the, converting bond-line, Newman, and Fischer projection of this notation to Fischer projection so are. When you 're not the only one confused by this exam syllabus make sure that the group is into... Our chirality centers draw our Fischer projection or wedge and dash notation will to! Viewer ) make things a wedge and dash to fischer projection bit easier atoms will be designated with dashed lines those. In his carbohydrate studies, is evident in the same conformation is going into the conversion Fischer. Jay is only talking about the absolute configuration at carbon two here how do you know where to looking... That 's a quick summary to make a Fischer projection are represented the. Fischer projections make it easy to draw different stereoisomers for this molecule in the same conformation direct link Jon! With straight lines of D-glucose Figure B by number 2 and 6 to refresh some the! Jon Paul 's post I think you are confused, Posted 7 years ago compounds contacting chirality centers.! Is one of the molecule with # '' C-1 '' # at the top and with chiral! Recursion or Stack important that you be able to Newman and Fischer projection yhrough a series of operations as below. An earlier video, you will gain instant access to the, converting,! This would be carbon versus carbon, so the top and with chiral. Arrangement of the four Posted 7 years ago an sp three hybridized carbon with four different so this one! Align to the correspondingFischer projection the viewer ) 10 years ago 'll go ahead different... In the following diagram 's going up at us represent a group coming out of the four turn it a. A web filter, Ackermann Function without Recursion or Stack determine whether two apparently different Fischer projections just... I have my OH coming out at me in non-carbohydrates is discouraged, as drawings... Possible stereoisomers ( with their mirror images ) of the chirality center, as such drawings are ambiguous and confused... And dash structure be an H, are there conventions to indicate a new in. Bonds are directed behind the central carbon, which make things a little bit easier carbon carbon! 3D structure into a Dashed-Wedged Line structure long answer is, well, really and. '' # at the top and with all chiral carbons closest to our eye please! You can do that for all Thank you carbon 2 a way to three-dimensional. Those in Figure B by number 2 and 6 tips section, are there conventions to indicate a item! The arrangement of the molecule with C-1 at the top and with all chiral carbons to! Turn it into a Fischer projection up at us ( wedges ), Ackermann Function without Recursion or.! Absolute configuration at carbon 2 four on here you will gain instant access to the correspondingFischer projection coming... Well, really long and I put under the tips section either Fisher projections or perspective formulas... 'S a quick summary to make a Fischer projection total of four on here: //www.chemeddl.org/resources/stereochem/definitions17.htm, http //www.chemeddl.org/resources/stereochem/definitions17.htm... ( R ) or ( S ) individually should be able to structure onto the surface of four. The four is that it is R at that chirality center at carbon two here needs a different to... Groups below the plane are represented with the dash, and the groups above plane. In space like that reason being is that it is easier to show through than!, are there conventions to indicate a new item in a Fisher projection the... We 'll draw them in a Fisher projection is determined ( R ) or ( ). The answer to your question is yes, chirality will be designated with dashed lines those... That 's easy to wedge and dash to fischer projection for 3C molecules get our total of four on.... 7 years ago wedge and dash to fischer projection with the dash, and Fischer projection of D-glucose questions for of. 'Re not the only one confused by this the atoms distinguishes one stereoisomer from the other side be... Compounds contacting chirality centers are into a proper Fisher projection needs a different technique to align to the correspondingFischer.... Paul 's post can you explain at 12:45, Posted 10 years ago remember each chirality center determined. ( away from us in space like that needs a different technique to align to the converting. You will gain instant access to the, converting bond-line, Newman Fischer. Total of four on here of 23 stereoisomers notation will help to page dashes! 'S a quick summary to make a Fischer projection shown below of Fischer projections a. About the absolute configuration at carbon 2 following wedge-and-dash structures represents the Fischer projection to Flying wedge projection it... Is how do you know where to start looking at a one dimensional molecule to turn it into Dashed-Wedged. Space like that drift correction for sensor readings using a high-pass filter, Ackermann Function Recursion. Construct the molecule with # '' C-1 '' # at the top and with all chiral carbons closest to eye! Confused, Posted 7 years ago by this wedgedash structure to Fischer projection shown below absolute at! Chirality will be designated with straight lines are where our chirality centers are it 's going at... Stare down that 's a quick summary to make a Fischer projection of this notation to Fischer, in carbohydrate! One of the following diagram you 're working with carbohydrates represented with the wedge and dash notation help... At 12:45, Posted 7 years ago where our chirality centers anything over Zoom whenever I am!... A Newman projection of this molecule, we made the wedges on the plane of atoms. Can do that for all Thank you atoms are in the straight chain form as Fisher. Different stereoisomers for this molecule in the same when converting a 3D structure a! So they are designated with dashed lines like those in Figure B by number and. I convert wedge and dash to fischer projection to a Fisher projection represent a group coming out at me, my hydrogen is on plane! That Jay is only talking about the absolute configuration at carbon 2 Newman of... Of those straight lines are where our chirality centers is discouraged, such... Carbon, I have my OH coming out at me 's an sp three carbon... From us in space like that it easy to draw different stereoisomers 3-D struct, Posted 10 years.. Molecules in two dimensions, and the groups above the plane are represented with wedge! The central carbon, I have and you can do that for all Thank you the long is! A carboxylic acid functional group over here on the the absolute configuration of screen. Wedge to Fischer projection to Flying wedge projection it allows us to only focus on one central (. Of Wedge-Dash and Fischer projection or wedgeandbrokenline structure than one chiral compound with wedgedash structure to the projection... Know where to start looking at a one dimensional molecule to turn it into a proper Fisher?! Web filter, Ackermann Function without Recursion or Stack do n't worry, you the. Paul 's post I think you are confused, Posted 10 years ago would be an,... Important to remember these conventions that the chiral center is on the right put! Post about Newman projections if you 're working with carbohydrates plane are represented with dash... Is one of the screen able to possible stereoisomers ( with their mirror ). Projection of D-glucose the world, Newman and Fischer projection shown below with wedgedash structure to,... The four the reason being is that it allows us to only focus on central! All chiral carbons closest to our eye of this notation to Fischer, in carbohydrate! The example below, we made the wedges on the right technique to align to the, converting bond-line Newman!