2014 Exp 1 Data Sheet.pdf

    Page 1 of 5 CHM151Y: Experiment 1 Molecular Modelling and Computational Chemistry Data Sheets DUE DATE: At the beginning of your next lab (Tuesday September 30 or Monday October 6) Last Name: _________________________ Given Name: ____________________ Student number: Demo group: Date experiment was performed: *Notes* - All highlighted questions should be completed during the lab period. - You will have access to WebMO from any computer after the lab in order to access your data, however, jobs can only be submitted in LM 121. If you would like re-submit your job, please contact Dr. Morra or Dr. Staikova to arrange a time. If you submit calculations using WebMO from outside of LM 121, your account will be suspended.   ACADEMIC HONESTY PLEDGE I certify that this submitted laboratory report represents entirely my own efforts. I have read and understand the University of Toronto policies regarding, and sanctions for, plagiarism. Signature: _________________________________ Date: ________________    Page 2 of 5 PART 1: n-Butane Bond Rotations 1.1.   After building n -butane ( Part 1.1 , pg. 62-64 in the manual), optimize the geometry of the molecule ( Part 1.3 , pg. 65), then measure the bond lengths and angles of the optimized structure using the directions in Part 1.2 , pg. 64. a) Measure the following bond lengths (include units): C1-C2: ____________________ C1-H: __________________________ b) Measure the following bond angles (include units): C1-C2-C3: _____________ C1-C2-H: ______________ H-C1-H: ______________ 1.2.   a) Dihedral Angle Calculations: Perform the dihedral angle calculations according to Part 1.4  (pg. 66). b) Obtaining Your Data: Open the Scan job output, scroll to the Coordinate Scan table, and using the red icon, download the data as an Excel file. You will be able to access this information after the lab to construct your graph. c)   Construct a Graph:  Construct a line graph in Microsoft Excel with the conformational energy (y-axis) versus  the dihedral angle (x-axis) data. Staple your electronic graph to this data sheet package. *Note:  Be sure to include the following in your line graph: -  Your name and demo group -  A title -  Properly labelled axes with units 1.3.   The following questions refer to your graph. You should answer these questions after the lab  period while using your graph as a reference. a)  What is the lowest energy (minima) obtained and what dihedral angle does it correspond to? Draw the Newman projection corresponding to this conformation:    Page 3 of 5 b) What are the next lowest energies (local minima) and what dihedral angles do they correspond to? Draw the Newman projections corresponding to these conformations: c)  What are the highest energies (maxima) obtained and what dihedral angles do they correspond to? Draw the Newman projections corresponding to these conformations: d) What are the next highest energies (local maxima) and what dihedral angles do they correspond to? Draw the Newman projections corresponding to these conformations:    Page 4 of 5 PART 2: Substituted Cyclohexanes 2.1. Methylcyclohexane: a)  Draw a chair structure of methylcyclohexane with the methyl group in an equatorial  position and optimize the energy of the molecule. Repeat the process for methylcyclohexane with the methyl group in an axial   position ( Part 2.1 , pg. 67-68). What is the energy after minimization (with units) for e -methylcyclohexane?  ___________________________ What is the energy after minimization (with units) for a -methylcyclohexane?  ___________________________ b)  Draw the two chair conformations of methylcyclohexane, identify the most stable and briefly  explain your choice.  ______________________________________________________________________________  ______________________________________________________________________________ 2.2. 1,3-Dimethylcyclohexane:     a)  Draw the chair structure of trans -1,3-dimethylcyclohexane where one methyl group is in the axial   position while the other methyl is in the  equatorial   position. Optimize the energy of the molecule and record the energy below ( Part 2.2,  pg. 69). Repeat this process for the two conformations of cis -1,3-dimethylcyclohexane where both methyl groups are either in the axial   positions, or both in the equatoria l positions. What is the energy after minimization (with units) for a,e -1,3-dimethylcyclohexane?  __________________________ What is the energy after minimization (with units) for a,a -1,3-dimethylcyclohexane?  ___________________________ What is the energy after minimization (with units) for e,e -1,3-dimethylcyclohexane?  ___________________________