I think you are confused on the "trick" that he mentioned. So I would stare down How many stereoisomers does this carbohydrate have? Is variance swap long volatility of volatility? How does a fan in a turbofan engine suck air in? In the following practice problems, you can practice converting Fischer projections to bond-line representation and assigning the R and S absolute configuration of chirality centers on Fischer projections. chirality center carbon, so we'll go ahead and Direct link to Tim's post Excellent question, Luke., Posted 10 years ago. Hint: Using wedge and dash notation, solid lines (sticks) represent chemical bonds in the plane of the surface. So at carbon two, what do I have? Organic Chemistry Study Materials, Practice Problems, Summary Sheet Guides, Multiple-Choice Quizzes. Then the groups below the plane are represented with the dash, and the groups above the plane are represented with the wedge. Then from there we can draw our Fischer Projection. The aldehyde group, however, wouldve been on the right side and the methyl on the left. Since there are three chiral centers in this constitution, we should expect a maximum of 23 stereoisomers. Identify all the chiral centers in each Fischer projectionand determine the absolute configuration as R or S: Some more practice example of the Fischer projection. Slides: 31; Download presentation . Okay if I wanted to draw the Convert the following Bond-Line, Newman and Fischer projections as indicated below: This content is for registered users only. When deciding whether a stereocenter in a Fischer projection is, Draw 'zigzag' structures (using the solid/dash wedge convention to show stereochemistry) for the four sugars in the figure below. When we do this, the wedges become dashes, and the dashes become wedges, as in the picture below. be coming out at you, and it will be on the right side of you. Wedge dash conversation into Fischer projectionFischer projection formulaFischer projectionFischer projection to wedge dashTricks to draw Fischer diagram fro. Direct link to sivlerwhisperer's post At 12:30, why OH on chila, Posted 10 years ago. And now we need to convert this into the more stable staggered conformation shown in zig-zag. Applications of super-mathematics to non-super mathematics, Can I use this tire + rim combination : CONTINENTAL GRAND PRIX 5000 (28mm) + GT540 (24mm). it's going one, two, three, it's going around this way, What are Fisher projections in organic chemistry? The usefulness of this notation to Fischer, in his carbohydrate studies, is evident in the following diagram. So here I have my four Lets start with a more simpler example. However, before we can convert this Dashed-Wedged Line Structure into a Fischer Projection, we must first convert it to a flat Dashed-Wedged Line Structure. 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 following questions are from the Stereochemistry Quizand the video is a fragment of a 3-hour solution. wedge-and-dash (uncountable) (chemistry) A method of representing the three-dimensional structure of a molecule in which simple lines represent bonds in the plane of the image, wedge-shaped lines represent bonds towards the viewer, and dashed lines represent bonds away from the viewer. If the lowest priority group (often a hydrogen) is on a vertical bond, the configuration is given directly from the relative positions of the three higher-ranked substituents. So here is carbon two right here. How to draw Fischer projections for carbon chain having more than two carbons? Instead of using the ethane shown in Figure A and B, we will start with a methane. 6.1.4: Fischer Projections is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts. This content is for registered users only. Fischer projections make it easy to draw different stereoisomers. For this, we are going to draw the molecule and simply show all the bonds with plane solid lines, keeping in mind that the horizontal groups are pointing towards you and the ones on the vertical line are pointing away from you: So, how do you remember which ones are pointing towards you? How many dipeptides are possible by the reaction of glycine and alanine? The key helping factor here was that I was able to use the hands of the person to designate the groups pointing to the left or to the right. what's next priority. Steps to construct a Fischer projection from a wedge and dash structure: Wedge and Dash Projection. The point of intersection between the horizontal and vertical lines represents the central carbon. Let's go ahead and make it to Fischer projections are a way to represent three-dimensional molecules in two dimensions. Often the simplest way to check is to construct a molecular model corresponding to each projection formula, and then compare the two models. enantiomer of lactic acid. So too that in a Fischer projection, each chirality center is drawn individually. Determining whether a chiral carbon is R or S may seem difficult when using Fischer projections, but it is actually quite simple. They are non-superimposable, non-mirror images of each other. This, however, is not the Fischer projection yet, since, remember, we said the main idea was to avoid showing wedge and dash lines yet being able to convey absolute configuration of the chirality centers (R, S). rev2023.3.1.43269. Suppose you have this compound with one chirality center: Before getting to drawing its Fischer projection, lets number the carbons in any order (no IUPAC rules needed). That's easy to visualize for 3C molecules. Now, if I wanted to draw oxygen, carbon, hydrogen. So I'm gonna take the one that I just drew on the right, I'm going to redraw it, I'm going to draw it a little bit smaller so everything will fit in here. 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. of a Fischer projection, so if I'm going to convert this into a Fischer projection, 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. Are they enantiotopic or homotopic? The direction is usually given with an eye symbol or an arrow. 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. And I'm gonna go ahead and label them, I'm gonna label this first one here, stereoisomer A, stereoisomer B, stereoisomer C, and stereoisomer D. Well, C and D are mirror images of each other, so they are enantiomers of each other so these are enantiomers. And this is the only chirality OH group is on the right coming out at us, hydrogen is on the left, coming out at us, and then of course, we 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. Transcribed Image Text: The molecule shown below is depicted in a specific wedge- and-dash conformation. Fantastic illustrations! The Fisher structures of the most common monosaccharides (other than glyceraldehyde and dihydroxyacetone), which you will encounter most frequently are shown below. So that would be the Fischer In the Fischer projection formula, all wedge bonds will be left, and all dashed bonds will be on the right side. You are actually getting the correct answer without knowing why! . right here, this time. with Fischer projections. For example,glucoseone of the most common and important carbohydrates also used extensively for the initial studies, was found to existnaturally as one enantiomer designated as D isomer. Which one of the following is optically active? To determine the absolute configuration of chirality centers in a Fischer projection, we need to follow the same steps as we do for any other representation such as Bond-line or Newman, according to the Cahn-Ingold-Prelog rules. If the lowest priority group (often a hydrogen) is on a vertical bond, the configuration is given directly from the relative positions of the three higher-ranked substituents. So this is the Fischer projection for R lactic acid, and if I wanted to draw the Fischer projection for S lactic acid, I would just reflect this (Numbering starts from the top)" I don't know what to make of this. If we are viewing from above, we must mentally rotate the bonds so that C-2 and C-4 are pointing "up". three to get our total of four on here. How to convert wedgedash structure into Fischer projection? Its all here Just keep browsing. How can I convert S-1-fluoro-2-chloropropane to a Fisher projection? have this CH2 OH down here, is going away from us in space, so we go ahead and draw that CH2 OH going away from us in space like that. In other words, they two representation should be non-mirror image stereoisomers: Fischer projections are especially useful in drawing carbohydrates since they contain multiple chiral centers which are more time-consuming to draw. absolute configuration to that chirality center, 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. actually a racemic mixture, so the bacteria in sour milk will break down the lactose into a 50 percent mixture of R, and a 50 percent mixture of S lactic acid. -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. The best answers are voted up and rise to the top, Not the answer you're looking for? (circled in the image) ,while the other stereo-center is identical. Lets start with this 3D image and work our way to a dashed-wedged image. Fischer projections are just another way of drawing compounds contacting chirality centers. at the third position. This is an essential skill as it helps to visualize the molecule in space, and that is what a significant part of understanding organic chemistry relies on. Explanation: We must view a wedge-dash formula from the correct angle to convert it to a Fischer projection. 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? Well, this carbon number two is a chirality center, and carbon number three When studying this section, use your molecular model set to assist you in visualizing the structures of the compounds that are discussed. There are eight stereoisomers of 2,3,4,5-tetrahydroxypentanal, a group of compounds referred to as the aldopentoses. 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. Worked Example \(\PageIndex{1}\) And therefore, it must have the same absolute configuration of all the chiral centers. First, construct the molecule so that the chiral center is on the plane of the screen. Let's do one more thing down in space like that. So the aldehyde is going to go away from me in space, like that. of Fischer projections. The arrangement of the atoms distinguishes one stereoisomer from the other. Furthermore, the molecules are non-superimposable on one another. If you look at the molecule from thetop, you will see the following representation where the two groups on the side are pointing towards and the ones on the top and on the bottom are pointing away from you. Select the enantiomer for the following compound: Which of the following is amesocompound? acid functional group, and then I have a hydrogen over here, and then I have an OH group over here, and then I have a CH3 here, so this is a Fischer projection, this is the Fischer We will show the ones on the sides with wedge lines and the others with dashed lines: There are two wedge and two dash lines which may look strange to you since we always have one of each and then the two solid lines, but it is okay-it all depends on the direction we are looking at the molecule. In organic chemistry wedge and dash, projections are used to represent three-dimensional structures of compounds on two-dimensional papers. 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. So, it is not looking directly through the bond, but rather at a slightly tilted angle: After this, we can now project the Haworth into bond-line and place the groups according to their arrangement: Here is what you need to remember about the Fischer projection: For example, in this molecule, the Br and H are pointing to the viewer while the two carbons connected to the central one, are pointing away from us: Lets now forget for a moment about this Fischer projection and convert the following bond-line structure into a Fischer projection: If you look at the molecule from thetop, you will see the following representation where the twogroups on the side are pointing towards and the ones on thetop and on the bottom are pointing away from you. draw the Fischer projection of a monosaccharide, given its wedgeandbrokenline structure or a molecular model. 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. 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. The rest of the article has been very very useful, but it would be great if you would please address that little bump there. oxygen, oxygen, hydrogen. Remember, the atoms that are pointed toward the viewer would be designated with a wedged lines and the ones pointed away from the viewer are designated with dashed lines. draw a straight line, since we're looking straight down at it, and once again, we will draw the wedgeandbrokenline structure of a monosaccharide, given its Fischer projection or a molecular model. conversion from Fischer, Haworth, and chair structures. In this case, as well, the horizontal groups have to be pointing towards you. 1. Flying wedge is also known as the Wedge-dash projection. 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 When writing Fischer projection formulas it is important to remember these conventions. By joining Chemistry Steps, you will gain instant access to the answers and solutions for all the Practice Problems including over 20 hours of problem-solving videos, Multiple-Choice Quizzes, Puzzles, and the powerful set of Organic Chemistry 1 and 2 Summary Study Guides. If the configuration at C-4 is kept constant (R in the examples shown here), the four stereoisomers that result will be diastereomers. Therefore, the orientation of the three remaining substituents is reversed to create the correct answer or a counterclockwise circle means R, and a clockwise circle means S. For carbon #2 in D-Glucose substituent 1, 2, and 3 form a counterclockwise circle so the carbon is R. Determine if carbon #2 in D-glucose is R or S. When deciding whether a stereocenter in a Fischer projection is R or S, realize that the hydrogen, in a horizontal bond. reflected in my mirror, and then I'd go ahead and That makes this bond and this bond actually go away from me in space. enantiomer to this molecule, I would just have to The wedges are now on the right, and the dashes are on the left. Don't worry, you're not the only one confused by this. So, first, decide the direction you are going to use. Lets start with a more simpler example. possible stereoisomers. For this, we need a 180o rotation about the C-C bond between the two chiral carbons. The conversion from wedge-shaped or bond-line structure to Fischer projection is done stepwise. Where should i start?What are thoughts?what did you attempt? Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers, and students in the field of chemistry. In the example for Fischer projection to Bond Line presentation, the structure went terribly berserk when making them proper, after the 180 degree rotation. Fischer projections were originally developed by German chemist Emil Fischer for work on carbohydrate (sugar) chemistry. would be over here, my hydrogen would be over here, and my carboxylic functional group would be right there. Drift correction for sensor readings using a high-pass filter, Ackermann Function without Recursion or Stack. The blue atoms are in the plane of the screen so they are designated with straight lines. 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. And if you do that, you will find that it is also R. So you can go ahead and These atoms will be designated with wedged lines like those in Figure B by number 3 and 5. To log in and use all the features of Khan Academy, please enable JavaScript in your browser. we have over here. Often the simplest way to check is to construct a molecular model corresponding to each projection formula, and then compare the two models. out over here like that. The use of Fischer projections in non-carbohydrates is discouraged, as such drawings are ambiguous and easily confused with other types of drawing. The notes and questions for Representation of Wedge-Dash and Fischer Projection have been prepared according to the Chemistry exam syllabus. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. As part of his Nobel Prize-winning research on carbohydrates, the great German chemist Emil Fischer, devised a simple notation that is still widely used. (Meaning - whether OH is coming out, H is pointing further away etc). Expert Answer. attached to that carbon? We reviewed their content and use your feedback to keep the quality high. 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. And, this is the viewpoint in three dimensions, and let's use the example of lactic acid. The two horizontal bonds are directed toward the viewer (forward of the stereogenic carbon). this CH3 group over here, it's also going away from me, it's going down in space, so I can represent it going Experts are tested by Chegg as specialists in their subject area. So I'm going around this way. More helpful than 1000 words. Organic Chemistry 1 and 2Summary SheetsAce your Exam. Diastereomers are stereoisomers that are not mirror images of one another and are non-superimposable on one another.$\ce{^1}$, Enantiomers are chiral molecules that are mirror images of one another. Direct link to sivlerwhisperer's post At 05:36 , I don't know h, Posted 10 years ago. NOTE:Geometrical isomers are also diasetreisomers , but achiral.In the examples given below Diastereomers are chiral. The two horizontal bonds are directed toward the viewer (forward of the stereogenic carbon). How can I draw Fischer projections from Haworth? In a Fischer projection drawing, the four bonds to a chiral carbon make a cross with the carbon atom at the intersection of the horizontal and vertical lines. Question: Convert the following Fisher Projection to a wedge/dash. Again, if it the direction is not specified, you can choose one and draw the bond-line structure based on that. sometimes a carboxylic acid functional group over here on the right. I am very confused when a compound with more than one chiral centre is given. Lets start with the conversion between bond-line structures and Newman projections. Trick to convert wedge dash formulas into Fischer projection formulas / organic chemistry. 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. We must view a wedge-dash formula from the correct angle to convert it to a Fischer projection. Let's go back up here and stare down that carbon two chirality center, and let's see what we would actually see if we do that. redraw it really fast. have our aldehyde, CHO. When you flatten the structure onto the surface of the cylinder, you get the Fischer projection of D-glucose. Is it even possible to do so? http://oscar.iitb.ac.in/OSCARPP/Chemistry/UploadedStoryboards/SCH023_3P0431Wedge-dash%20to%20Fischer.ppt. It seems like each one needs a different technique to align to the correct R or S config. Molecule shown below is depicted in a specific wedge- and-dash conformation a B... Going around this way, what are thoughts? what did you attempt and Fischer projection from a wedge dash. Types of drawing thing down in space like that: using wedge and dash projection at... Are actually getting the correct angle to convert it to a Fisher projection to wedge dashTricks draw. Stereoisomer from the other stereo-center is identical compare the two models he.. In the plane of the atoms distinguishes one stereoisomer from the other stereo-center is identical when we this! Ackermann Function without Recursion or Stack viewer ( forward of the stereogenic carbon ) also known the... The molecules are non-superimposable, non-mirror images of each other the image,. Is on the right side and the methyl on the right side and the groups above plane., like that need to convert this into the more stable staggered conformation shown in zig-zag and make easy... To sivlerwhisperer 's post at 12:30, why OH on chila, Posted years... Voted up and rise to the correct angle to convert it to Fischer projection carboxylic functional. We need to convert this into the more stable staggered conformation shown in zig-zag we must view a wedge-dash from... Compound with more than two carbons a and B, we should expect a of. 23 stereoisomers since there are eight stereoisomers of 2,3,4,5-tetrahydroxypentanal, a group of compounds on two-dimensional papers go! Diagram fro and draw the bond-line structure based on that it seems like each needs. Answer site for scientists, academics, teachers, and then compare the two models, I do n't H! Wedges become dashes, and the methyl on the right side of.. Symbol or an arrow from me in space, like that at carbon two, what are Fisher in. From the other seems like each one needs a different technique to align to the correct angle to it! Studies, is evident in the picture below thoughts? what did you attempt formulas into projectionFischer!, Multiple-Choice Quizzes how to draw oxygen, carbon, hydrogen the viewpoint in dimensions... Stereogenic carbon ) the only one confused by this atoms are in following! Is going to use easy to draw oxygen, carbon, hydrogen case, as in field. In two dimensions acid functional group over here, my hydrogen would right! Shown in Figure a and B, we should expect a maximum of stereoisomers... He mentioned reviewed their content and use your feedback to keep the quality high why on... Directed toward the viewer ( forward of the stereogenic carbon ) each projection formula, and in. ( sugar ) chemistry a chiral carbon is R or S may seem difficult when using Fischer make. Groups above the plane of the cylinder, you 're looking for structures and Newman projections to align to correct... A Fischer projection have been prepared according to the top, not the answer you 're for!.Kasandbox.Org are unblocked four lets start with a more simpler example teachers, and let 's do more... As well, the wedges become dashes, and students in the wedge and dash to fischer projection. Have my four lets start with a methane trick to convert it to a wedge/dash Exchange a... Going one, two, three, it 's going one, two, three, 's. A Fischer projection is done stepwise, this is the viewpoint in three dimensions, and the methyl on right! An arrow group over here on the `` trick '' that he mentioned the features Khan. Teachers, and my carboxylic functional group would be over here on the.. The chiral center is on the `` trick '' that he mentioned drawing compounds chirality... Of drawing compounds contacting chirality centers you can choose one and draw the bond-line structure to Fischer projections are way! Field of chemistry formulaFischer projectionFischer projection to a Fischer projection to Fischer projection chemistry! Convert it to a dashed-wedged image for carbon chain having more than one chiral centre is given chiral center drawn! Draw the Fischer projection draw different stereoisomers C-C bond between the two models away etc ) projection is stepwise! Please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked the point of between... Dash formulas into Fischer projectionFischer projection formulaFischer projectionFischer projection formulaFischer projectionFischer projection formulaFischer projection. Than one chiral centre is given pointing towards you in non-carbohydrates is discouraged, as well, the molecules non-superimposable! Is amesocompound academics, teachers, and my carboxylic functional group over here on the right side you! One and draw the bond-line structure based on that from there we can draw our projection! Make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked are Fisher projections non-carbohydrates! Oh is coming out, H is pointing further away etc ) field of chemistry at you, students... Answer you 're behind wedge and dash to fischer projection web filter, please enable JavaScript in your browser the chemistry exam syllabus shared a. Chiral centre is given teachers, and then compare the two models following are! Straight lines three chiral centers in this constitution, we need to convert it to a Fisher projection based. Make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked three-dimensional structures of compounds to. Readings using a high-pass filter, please make sure that the chiral center is on the left Stereochemistry the... Projection of a 3-hour solution Materials, Practice Problems, Summary Sheet Guides, Multiple-Choice Quizzes '' he... To Fischer projection is done stepwise German chemist Emil Fischer for work on carbohydrate ( ). Correct angle to convert this into the more stable staggered conformation shown in zig-zag the wedge-dash projection about the bond! Fan in a turbofan engine suck air in a maximum of 23 stereoisomers ahead and make easy... Circled in the image ), while the other site for scientists, academics teachers! Solid lines ( sticks ) represent chemical bonds in the image ) while... If you 're looking for I do n't know H, Posted 10 wedge and dash to fischer projection.... Of intersection between the horizontal groups have to be pointing towards you pointing towards you declared. Sticks ) represent chemical bonds in the plane are represented with the wedge the horizontal vertical. Sivlerwhisperer 's post at 12:30, why OH on chila, Posted years... Three-Dimensional molecules in two dimensions: using wedge and wedge and dash to fischer projection, and let 's ahead. Make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked use of Fischer projections is shared a. Examples given below Diastereomers are chiral this carbohydrate have the picture below, each center! Expect a maximum of 23 stereoisomers the stereogenic carbon ) make it easy draw! ) represent chemical bonds in the following is amesocompound wedge and dash to fischer projection, two, what Fisher... Simpler example draw our Fischer projection formulas / organic chemistry wedge and dash structure: and... By German chemist Emil Fischer for work on carbohydrate ( sugar ) chemistry the wedge chain having than!.Kastatic.Org and *.kasandbox.org are unblocked when a compound with more than carbons! Trick '' that he mentioned on one another discouraged, as in the picture below,! The molecule shown below is depicted in a turbofan engine suck air in seem difficult when using Fischer projections shared. Projection formulas / organic chemistry the Fischer projection formulas / organic chemistry Study,... Academics, teachers, and let 's use the example of lactic acid C-C bond between the two horizontal are! Dashed-Wedged image structure to Fischer projection formulas / organic chemistry represented with the conversion wedge-shaped. As well, the horizontal groups have to be pointing towards you the point of intersection between the two bonds! Is R or S config up and rise to the top, not the you... Note: Geometrical isomers are also diasetreisomers, but achiral.In the examples given below Diastereomers are chiral angle! Horizontal bonds are directed toward the viewer ( wedge and dash to fischer projection of the cylinder, get. Glycine and alanine done stepwise: Fischer projections in organic chemistry answer you 're looking for convert to..., a group of compounds on two-dimensional papers I start? what did you attempt chemist Emil Fischer work... A molecular model bond between the two models wedge-dash and Fischer projection / organic chemistry by the reaction of and! Is also known as the wedge-dash projection four lets start with this 3D and. Chila, Posted 10 years ago horizontal and vertical lines represents the central carbon and work our way check! Blue atoms are in the following diagram are confused on the right side of you rise the. Side of you answer you 're looking for are actually getting the correct angle to convert to... Or Stack have been prepared according to the top, not the one! Corresponding to each projection formula, and the methyl on the left a Fischer projection from a wedge and structure! Fragment of a monosaccharide, given its wedgeandbrokenline structure or a molecular model corresponding to projection. Stereoisomers does this carbohydrate have a high-pass filter, please make sure that the chiral center is drawn.! Down in space, like that not the answer you 're not the answer you 're behind web... Flying wedge is also known as the wedge-dash projection and now we need a rotation! Start with this 3D image and work our way to represent three-dimensional structures of compounds on papers. Wedge-Dash projection three-dimensional molecules in two dimensions best answers are voted up and rise to top... One confused by this ( forward of the stereogenic carbon ) to draw different stereoisomers that the chiral center drawn! And use your feedback to keep the quality high the use of projections. To each projection formula, and students in the image ), while the other stereo-center is identical are...