Conformations of ethane organic chemistry khan academy. In fact, the staggered conformation corresponds to the energy minimum of alkane and the eclipsed one to the energy maximum. The most important shapes are chair, halfchair, boat, and twistboat. Newman projections a method of depicting organic molecules 2. Moe is a molecular modeling program, which is specifically. Illustration and interconversion of staggered and eclipsed ethane conformatiobs with space ffilling and ball stick models. Conformations of ethane newman projection chemtube3d. Dec 29, 2014 lets start with a wedgedash view of the staggered conformation of ethane. Here we have the staggered conformation of ethane, looking at it from a wedge and dash perspective.
Conformations of ethane 3d scene mozaik digital learning. Ethane can have two possible conformations, the staggered conformation and the eclipsed conformation. Conformations of cycloalkanes cycloalkanes are not always planar structures. Conformational analysis college of saint benedict and saint. Chapter 4alkanes and cycloalkanes flashcards quizlet. Petroleum petroleum is the primary source of alkanes.
Cyclopropane cl h hihd f i l id l b f liicyclopropane has a high degree of torsional strain due to large number of eclipsing. This structure is illustrated in the jmol animation linked below. Colby college molecular mechanics exercises moe molecular. Its chief use is as feedstock for ethylene production. Butane favors the anti conformation, but the gauche conformers are only 0. So the staggered conformations are lower in energy than the eclipsed conformations. In the case of ethane, the staggered and eclipsed conformations can sufficiently describe the features of its conformational analysis. Upon completion of this exercise, students should be well acquainted with the effect of conformation on stability and with the technique of drawing organic molecules. Actually, the difference is 12 kilojoules per mole. The most stable low energy conformation is the one in which all six ch bonds are as far away from each other as possible staggered when viewed endon in a newman projection.
Conformations of 2methyl pentane i the conformers i and ii are stable enough for isolation at room temperature. What is the staggered conformation of ethane using. It is a colorless and odor gas at a standard temperature. Question from chemistry,cbse,class11,chemistry,neet,isomers. We know that ethane can exist in two conformations the staggered conformation and the eclipsed conformation. Chem 350 principles of organic chemistry i lab modified from prof. Ultra highresolution display wall can aid molecular forcefield ff research. Gamess is a program for ab initio molecular quantum chemistry calculations. Although there are seven sigma bonds in the ethane molecule, rotation about the six carbonhydrogen bonds does not result in any change in the shape of the molecule because the hydrogen atoms are essentially spherical. The differences in these two conformations for ethane can easily be seen by viewing them both on the screen simultaneously. Holding a model of ethane or two in your hand would really help you here. For the love of physics walter lewin may 16, 2011 duration. Conformations of organic molecules columbia university. Babub alecturer, chemical engineering group, birla institute of.
Simultaneous viewing of many pe curves and conformations enhances ff evaluations. They are in rapid conformational flux pseudorotation which causes the molecule to appear to have a single. Chemtube3d contains interactive 3d chemistry animations and structures, with supporting information, for students studying some of the most important topics in advanced school chemistry and university chemistry courses. In the case of butane, however, two conformations are not enough to. The staggered conformation of ethane is more stable than the eclipsed conformation. Conformations of ethane ws10 questions key chem 211 dr.
Ab initio calculations on conformations corresponding to the torsional energy minima and maxima of ethane, methylamine, methanol, hydrazine, hydroxylamine, and hydrogen peroxide were carried out. Click on the symmetry element to go to explainations. So lets watch the video and look at the different conformations of ethane. Organic chemistry computational modeling experiment. Energy of eclipsed and staggered conformations of ethane. All objects in the model the two methane fragments are centered around the origin of. Comparison of amber ff in reproducing saturated hydrocarbon hf631gd data.
Eclipsed ethane has 12 kj per mol more energy than the staggered conformation. Conformational analysis structures that can be interconverted by rotation about single bonds are conformations of the same molecule. Conformational analysis of ethane video khan academy. Therefore, the cyclohexane ring tends to assume certain nonplanar warped conformations, which have all angles closer to 109. These projections are further divided into two extremes. How to represent the staggered and eclipsed conformations of ethane. Click the filmstrip icon in the geometry sequence table to begin the animation. Draw the staggered conformation of ethane chemistry. We know that theres free rotation around this carboncarbon single bond. Conformational searching in molecular mechanics calculations most molecules can adopt more than one lowenergy conformation.
Which points on the given energy diagram represents eclipsed confirmation of ethane and staggered confirmation of propane respectively. Organic chemistry computational modeling experiment webmo. Conformations of ethane university of wisconsinoshkosh. If ethane gets too cheap, it can become uneconomic to remove it from the raw natural gas stream, and the decision to leave ethane in the raw natural gas stream is called ethane rejection.
Since they are different compounds, they should lie on different energy diagrams. It is a complex mixture of mostly alkanes and aromatic hydrocarbons with small amounts of. Would the eclipse conformation ever occur on its own. Therefore, we say that these are degenerate in terms of energy. The rotation barrier between the two conformations, known as rotamers, is the energy difference between two conformations. What is the staggered conformation of ethane using the. Until december 20, when the new mariner west pipeline provided a route to the canadian market by bringing marcellus ethane from southwestern pennsylvania through ohio and michigan to ontario, gulf coast petrochemical plants were the only outlet for domestically produced ethane. Ethane production and its effects on natural gas processors. Eclipsed conformation of ethane this eclipsed conformation of ethane is illustrated below in three different types of structural representations. Ethane is an alkane comprising of two carbon atoms. These pages are essentially based upon the jmol application, and its jsmol variant, developped for websites you can play on this first page by searching molecules on the nci, pubchem or rscb servers.
Ppt conformational analysis powerpoint presentation. We have implemented ethane in both hardware and software, supporting both wired and wireless hosts. The three bonds around each carbon atom are shown by three lines. Remove a hydrogen from the ethane model and add a ch 3 group in its place. The energetically staggered conformation is more stable than eclipsed conformation as in staggered conformation there is minimum repulsion on neighbouring h. A wedgedash formula of the model should look like the figure below. In this organic chemistry lesson, learn about different conformations and energies of ethane and butane.
Comparison of the numbers and kinds of symmetry elements in eclipsed and staggered ethane. Conformations representing energy minima are termed conformers. Chem 350 principles of organic chemistry i lab modified. The energy barrier must be small for conformational isomerism to occur. Conformational isomerism involves rotation about sigma bonds, and.
Jun 09, 2010 illustration and interconversion of staggered and eclipsed ethane conformatiobs with space ffilling and ball stick models. Visualizing potential energy curves and conformations on. The two conformational energy diagrams shown below are staggered ethane and eclipsed ethane. While radical, this design is backwardscompatible with existing hosts and switches. Apr 14, 2014 if ethane gets too cheap, it can become uneconomic to remove it from the raw natural gas stream, and the decision to leave ethane in the raw natural gas stream is called ethane rejection. Ax2 ax3 ax4 ax5 ax6 axnem types and pi systems tests. Nomenclature, conformational analysis, and an introduction to synthesis a free powerpoint ppt presentation displayed as a flash slide show on id. Conformations and configurations never mistake them. In the case of butane, however, two conformations are not. Rotation about the cc bond in ethane see the jsmol animation to the right produces different conformations. Ethene can be converted into ethane by addition of hydrogen in presence of nickel. Conformations of ethane and butane conformational isomerism.
By clicking on the appropriate parts of the scheme and rotating the structures in 3d, you can explore the geometry of a molecule. The differences in these two conformations for ethane can easily be seen by. The newman projection corresponding to forms ad is shown below 58. There will be a change in the shape of the molecule when there is a rotation o. May 22, 2015 how to represent the staggered and eclipsed conformations of ethane. Being planar requires large variations in bond angles from the ideal value of 109. Since then, the completion of the vantage pipeline. At standard temperature and pressure, ethane is a colorless, odorless gas. All of these staggered conformations, if i draw a line in here, have the same potential energy. And this wedge and dash drawing right now represents whats called the staggered conformation of ethane. Interactive 3d animations of ethane conformations and newman projections for students studying university chemistry courses.
The bond between the two carbon atoms is a single bond which is formed by two sp 3 hybrid orbitals overlapping head to head. From the given diagram, either r or s could represent eclipsed confirmation of ethane and p or q could represent staggered confirmation of propane. Click on the energy diagrams to see a movie of the conformers with their relative energies. Torsional strain repulsion between bonds ethane 12 kjmole chch bond interaction 4 kjmole. These are the lowest energy structure, called the staggered conformation, and the highest energy structure, called the eclipsed conformation. A sawhorse projection is a view of a molecule down a particular carboncarbon bond.
Conformations of ethane ethane is an organic chemical compound. There is an infinite number of intermediate conformations between these two extreme conformations. The sawhorse formula, depicted in the middle, shows how the hydrogen atoms on each carbon are positioned relative to each other. Try rotating the 3d model of the animation so that you are looking directly along the cc bond to see. Excerpted without audio from the full interactive unit ethane rotation. Although an infinite number of conformations are possible, the staggered and eclipsed conformations which represent the most and least stable respectively are the two most important. It has a role as a refrigerant and a plant metabolite. Energetics of rotation about sigma bonds staggered and eclipsed conformations a. Each carbon is bonded to two hydrogens as well as the other carbon. Conformations are different arrangements of atoms that result from bond rotation. Rotate each of the cc bonds so that both of these bonds are staggered. If we rotate this a little bit, well see the staggered conformation of ethane from a sawhorse perspective. Ethane is a classical example to study stereochemistry. The energetically staggered conformation is more stable than eclipsed conformation as in staggered conformation there is.
Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petrochemical byproduct of petroleum refining. Lets start with a wedgedash view of the staggered conformation of ethane. Ethane h3cch3 and substituted ethane the ethane molecule, c2h6, can exist in both the staggered and eclipsed conformations where the staggered conformation is slightly more stable. As the hydrogen has a partial positive charge would any of the other carbon bonded hydrogens also. Upon completion of this exercise, students should be well acquainted with the. Two possible conformations of ethane are shown in figure 5. Poutsma 1 worksheet 10 answer key conformations of ethane what is the overall 3d structure of ethane. Butane can undergo several types of conformations at a very high speed at room temperature. Energy of eclipsed and staggered conformations of ethane and.
Conformational searching in molecular mechanics calculations. Rotation about the carboncarbon bond, however, results in many different possible molecular conformations. The actual dihedral angles are distorted from the 60 angles shown in the. The staggered conformer is lower in energy than the eclipsed conformer. Substituted cyclohexanes can adopt two chair conformers in which substitutents are either equatorial or axial. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The least stable high energy conformation is the one in which the six carbonhydrogen bonds are. Simulation and analysis of ethane cracking process ashish m.
The staggered conformation of ethane is more stable by 12. Construct an explanation of why conformer a is called staggered and conformer b is called eclipsed. Ethene ch 2 ch 2 contains two trigonal planar carbon atoms. In this tutorial, we will learn the relative stability of ethane conformations as a result of single bond rotation. Conformational analysis college of saint benedict and. Since rotation around the cc bond of ethane is continuous, there are an infinite number of conformations, but only two are of major interest.