Below is a sawhorse projection of the gauche conformation of butane. Apr 23, 2018 this organic chemistry video tutorial provides a basic introduction into newman projections. The arrow pointing to the carbon signifies looking down the carbon. Another example unstable conformer stable conformers product redrawing the product newman projection into a newman projection with the main substituents me, tbu in this case opposite to each other often makes it easier to translate back into a normal zigzag structure me o et nabh 4 o meh tbu et o me tbu et h o me tbu h et h me tbu et h oh. Newman projections organic chemistry tutorial video series. H,brlabel each drawing as staggered or eclipsed overall and indicate any. For each of the following, draw the best and worst newman projection, relative to the bond. When looking at newman projection practice problems, there are a few areas that we need to make sure that we emphasize so you see the entire range of problems that might appear on an exam. Hopefully you can see the newman projection that we drew matches the picture from the video, and this is the same newman projection. Conformational analysis practice exercises 1 draw a newman projection of the most stable conformation of 2methylpropane. The main difference between staggered conformation and eclipsed conformation is that staggered conformation has a lower potential energy whereas eclipsed conformation has the maximum potential energy.
Chem 201beauchamp topic 6, conformations cyclohexanes 1. Two simultaneous newman projection views are now possible as shown below. Once the first bond is drawn in a newman projection of a chair conformation of. The figure below shows, as an example, a newman projection looking down the c 2c 3 bond of octane. An introduction to newman projections chemsurvival. In the video below, ive distilled the process for doing this, and i guide you through two examples. These videos will help you understand everything from newman projection basics, how to convert newman to other forms, how to analyze the energy of particular conformations, and of course how to draw an energy diagram. You can also create the same drawing using a template. Drawing and understanding diagrams university of calgary. Cyclohexane chair analysis newman projections and practic. If we want to examine the conformations about several different bonds, we must draw a different. Are the following compounds identical or constitutional isomers.
We depict the front atom as a dot, and the back atom as a larger circle. Problem 8 draw a 3d newman projection and a sawhorse representation for each the following fischer projections. For example, for our molecule, we can look through the c1c2 bond even though it can be through any bond. Draw newman projections of the lowest and highest energy conformations of propane. Stereoisomers a newman projection is used to represent or visualize conformations of carboncarbon bonds within a molecule. Label each drawing as staggered or eclipsed overall and indicate any gauche or antirelationships within each conformer. For every newman projections, you need to specify the bond and the direction from which you are looking. Draw a newman projection, looking down the c 2 c 3 bond, of 1butene in the conformation shown below c 2 should be your front carbon. We can use newman projections to determine which transition state of these three products is most stable, and therefore which subsequent product is most likely to form. Stereoselectivity in organic synthesis massey university. Newman projections 4 energy diagram and practice question. Draw newman projections of alkanes in staggered and eclipsed conformations, and arrange the order of stability for these conformations conformational isomers. A third type of projection is called the newman projection. Chdraw the least stable conformer and calculate the total interaction energy.
Particularly 1,2dicloroethane rotamers, but have no idea if there is any program to do that kind of things. Fischer projections with practice problems chemistry steps. The structure appears as viewed along the bond between these two atoms, and the bonds from them to other groups are drawn as projections in the plane of the paper. So in this situation, you would draw the carbon molecule in front, would just be the intersection of these bonds. Aug 07, 2017 the following instruction set will help an individual learn how to draw a newman projection in organic chemistry. Newman projections focus on any two carbons and the groups coming off them in a molecule by shifting the view from which the molecule is visualized. Pdf conformational analysis is one of the significant subjects in the organic chemistry curriculum.
For each of the following, draw the best most stable and worst least stable newman projection, relative to the bond indicated in each question. Find the chiral centers, assign the priorities and make your assignments. This same picture is seen when the projection is viewed down any c c bond. And to visualize it a little better, ill draw whats called a newman projection. In a newman projection, we look lengthwise down a specific bond of interest in this case, the carboncarbon bond in ethane. Draw the most stable conformer and calculate the total interaction energy. Newman projection practice problems with a free book of. So im going to draw this exact thing, but with a newman projection, you draw the carbon molecules directly in front or directly behind each other. Definition of newman projection a projection formula representing the spatial arrangement of bonds on two adjacent atoms in a molecular entity. Draw a newman projection sighting the bond as indicated. A newman projection focuses on one specific bond of the molecule, and note which atoms are attached to these carbon atoms.
Conformation around a carboncarbon single bond in which attached atoms are as close together as possible staggered. Consider the carbonoxygen bond in ethanol, for example. Just as with newman projections, you can draw sawhorse projections in eclipsed and staggered conformations. This projection is named after american chemist melvin spencer newman, who introduced it in 1952 as partial replacement for fischer projections, which are unable to represent conformations and thus conformers properly. Sighting along the c2c3 bond and using newman projections. A newman projection can be used to visualize any sort of bond, not just a single bond between carbons of an alkane.
However, this is only one example of a possible conformation a molecule can have. It explains how to draw the newman projections of ethane, butane, and 2,3dimethylpentane. By rotating the groups on the back carbon 60 degrees counterclockwise, an eclipsed newman projection can be written. The front carbon atom is called proximal, while the back atom is called distal. Once youve mastered the art of naming alkanes, sooner or later in organic chemistry, youre going to have to draw newman projections. Newman projections are one way to look at the conformation of a noncyclical molecule. Mar 20, 20 professor davis uses ethane to demonstrate how newman projections are created and why they contain useful information which is not available from other structural representations. Newman projections are used to represent the relationship between two carbons in a molecule. Quizlet flashcards, activities and games help you improve your grades. As an example, if you are asked to draw the enantiomer of the following molecule with three chiral centers, you can draw an imaginary mirror plane and draw the reflection of the molecule, which is achieved simply by swapping the two group of.
How do i draw a double newman projection for cyclohexane. Apr 01, 2014 to name an alkane from a newman projection, you convert the projection to a line structure. How to draw newman projections and newman projection practice. Conformation around a carboncarbon single bond in which attached atoms are as far apart as possible. Newmanprojectionpractice 1 organic chemistry i jasperse newman projection practice a. Everything from the basics of understanding newman projections, to energy diagrams staggered and eclipsed conformations for butane, guache, anti, and totaleclipsed interactions, to more difficult molecules, and finally, also to the conversions back into a line diagram is provided for. Isomerism and stereochemistry answers to worked examples we 18. Introduction to newman projections organic chemistry.
The graphic below shows the differences between the two. Note the british standard symbols for 1st angle and 3rd angle projection at the base of the drawing bs 8888. Newman projections are important in organic chemistry to help you understand one aspect of molecular conformations. Using the newman projection of the other enantiomer, draw its sawhorse projection using wedge and dash like i did. It contains plenty of notes, examples, and practice problems. Chem 210 sample exam 2 20 pennsylvania state university. You should be prepared to sketch various conformers using both sawhorse representations and newman projections. Remember, that any two bonds on opposite sides of the ring can be used and they can viewed from front or rear directions.
The structure on the left is staggered, and the structure on the right is eclipsed. I just made the ethyl groups red and the methyl group blue. Below are two newman projections of ethane, c 2 h 6. How to draw accurate newman projections tutorial first, lets define a newman projection and explain what all the parts of it mean. Newman projections anti, gauche, staggered, eclipsed energy.
Professor davis uses ethane to demonstrate how newman projections are created and why they contain useful information which is not available. From what i understand, if we have 1methylcyclohexane, we sight c1c2 and c5c4, as shown in my attempt b. This type of representation clearly illustrates the specific dihedral angle between the proximal and distal atoms. A newman projection is a way to take a snapshot of what a molecule looks like at a particular moment in time from a different angle than were used to. For this case, we will line up the 2 and 3 carbon as labeled on the above image. Lets work through an example, consider drawing a newman projection by looking at the following wedgedash diagram of propane from the left hand side. Newman projection of butane organic chemistry tutorial video. Newman projections this tutorial demonstrates how to draw a newman projection.
Visualizing long chains of hydrocarbons is easier with this video, which uses the newman projection of diagramming. Jan 25, 2014 determine the r and s configurations of newman projections with examples. Notice that when drawing the newman projection of the eclipsed conformation of ethane, you cannot draw the rear hydrogens exactly behind the front ones. Newman examples consider the following molecules and determine whether the newman projection is staggered or eclipsed, how many carbons are in the longest chain of the molecule, and what other groups are coming off the front and back carbons. Add an eye with an arrow looking down the carboncarbon bond being studied. Moving from a bond line notation to a newman projection can be tricky because the idea of depth has to be identified. Explain which conformation you would expect to have the higher energy. Any set could be used to draw two parallel newman projections. For each of the following, draw the best and worst newman projection, relative to the bond indicated. A newman projection visualizes different conformations of a carbon. Use the mclaurin method, which uses the pinky finger to mimic the tetrahedral shape of the newman projection molecule.
Introduction to newman projections organic chemistry socratic. At the carbon that is being pointed at by the arrow, there are 3 bonds to other carbons, all of which are in the same plane due to the absence of any dashed lines or solid. This molecule does not have any carboncarbon bond, so merely it can exist in one conformation structure note. Organic chemistry i jasperse newman projection practice. Fischer projections make it easy to draw different stereoisomers. Sep 27, 2012 newman projection of butane this tutorial video shows you step by step how to draw a newman projection from a sawhorse projection of the butane molecule, starting from both staggered and eclipsed conformations. The staggered arrangement of all the bonds can be seen clearly in the newman projection. In order to better visualize these different conformations, it is convenient to use a drawing convention called the newman projection. Sep 11, 2017 staggered conformation and eclipsed conformation are two types of newman projections that show the spatial arrangement of atoms. Use hands or model atoms to help you see these configurations whenever the low priority group is facing towards you the wrong way. A way of representing conformational isomers using an endon projection of a carboncarbon bond eclipsed. In order to draw a newman projection from a wedgedash diagram, it is useful to imagine putting your eye in line with the central bond in order to look along it. Convert the following bondline structure to the corresponding newman projection as seen from the indicated angle. Name the alkane shown in the following newman projection.
A sawhorse projection is similar to a newman projection, but it shows the carboncarbon bond that is hidden in a newman projection. A newman projection can be drawn such that the groups on the front carbon are staggered 60 degrees apart or eclipsed directly overlapping with the groups on the back carbon. Start with the antistaggered newman projection then draw and label each. Video 1 this video explains conformational isomers and how to visualize and draw newman projections also discussed are staggered and eclipsed conformations, along with a potential energy diagram for the conformational isomers of ethane from 0 360 degrees. And not just draw them, but convert between them and linebond aka bondline or zigzag structures. Designating the absolute configuration of the newman projection. Newman projections with practice problems chemistry steps. This type of projection is used mainly to show interaction leading to stress between atoms or groups in three. The name of the entire chemical structure molecule is. In this representation, a molecule is viewed from one end. Pick the longest chain attached to the front c atom. For chains, draw newman projections of all conformations around a given bond and determine their energy ocsl 6. The central carbon is used as a rotation center the circle in the newman projection and the anterior and posterior carbons and substituents are placed around it. Difference between staggered and eclipsed conformation.
Newman projections study guide by denisedemartino includes 18 questions covering vocabulary, terms and more. Check out the whole range of newman projection ex 2 draw the newman projections for a given molecule in order of increasing energy. Using ethane versus butane as an example, sal demonstrates how to label the multiple ch3 attachments according to their. In the video we moved the front carbon, we rotated the front carbon, we held the back carbon stationary, so this ethyl group in red would move over to. How to draw a newman projection in organic chemistry. The procedure can also be used to draw newman projections of other types of structural drawings. E2 and e1 chem 14d winter 2006 credit to professor steven hardingers chemistry 14d thinkbook winter 2006, blue version and paula bruices organic chemistry 4th edition from which information, diagrams, and examples for this project were used. Sawhorse projections sawhorse projections are very similar to newman projections, but are used more often because the carboncarbon bond that is compressed in a newman projection is fully drawn out in a sawhorse projection. Newman projections this is a compilation of my 5part video tutorial video series on newman projections. Convert the following newman projections back to skeletal structures. Newman projection practice 1 organic chemistry i jasperse newman projection practice a. Draw the least stable conformer and calculate the total interaction energy. Write the structures of constitutional or structural isomers of alkanes.
While organic chemistry knowledge and experience is not necessary to complete the instruction set, it is helpful. For this one, we will need to be able to draw newman projections as well as name the molecule using the rules of iupac nomenclature. First angle orthographic projection orthographic projection is a way of drawing an object from different directions. Newman projection is a representation of the molecule looking through a cc single bond. Professor davis uses ethane to demonstrate how newman projections are created and why they. To see the four steps for changing newman projections into fischer projections, click here. A newman projection, useful in alkane stereochemistry, visualizes the conformation of a chemical bond from front to back, with the front atom represented by a dot and the back carbon as a circle. Redraw each structure in a sawhorse projection of a stable conformation. Lets work through an example, consider drawing a newman projection by looking at the following. Therefore, the configuration of both stereocenters, located at c2 and c3, is the r configuration, written as 2r,3r. This definition may seem confusing at first, so lets explain it visually. As an example, the newman projection of the chair conformer. The most stable conformations will be staggered conformations with the largest groups anti to each other.
Im asked to convert the following line diagram into a newman projection. R and s nomemclature problem 3 classify the absolute configuration of all chiral centers as r or s in the molecules below. Label the three a, b, and c, and compare them in terms of their relative energy. Also write one newman diagram looking down the c2c3 bond. Explain why the view down the c3c4 bond is more informative in identifying the best conformation. Each method has its own advantages, depending upon the circumstances.
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