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Microsoft Word - CHEM2720-2021S-Project 2-information Univ. of Guelph CHEM*2720 – Professor William Tam 1 CHEM*2720 Fundamental Organic Chemistry (Summer Semester 2021) Project 2: Virtual Lab – Molecular Modelling Due Date: June 19, 2021 (Saturday) by 11:30pm (worth 4% of your final grade in this course) 1. Get a MOLECULAR ORGANIC MODEL KIT (can be purchased from the University Bookstore) and learn to use it. It is important to visualize organic molecules in a 3-dimensional view. Being able to see organic molecules in a 3-dimensional view will help you to understand the properties and reactivities of organic molecules and to have a better understanding of reaction mechanisms. The purpose of this virtual lab is to help you to see organic molecules in a 3- dimensional view by using molecular models. This virtual lab is divided into two parts: Part 1: Building Molecular Models and determine relationships between molecules; Part 2: Using ChemDraw & other tools to answer questions about isomers and stereochemistry of molecules. Each student will need to have a MOLECULAR ORGANIC MODEL KIT (ISBN 9780470149157). (This Organic Model Kit is a part of the Solomons text book package if you purchase it from the University Bookstore. You will also be able to purchase these Organic Model Kits separately from the University Bookstore.) **If you do not want to purchase a molecular model set, you could try to use the following free software that can model structures: https://avogadro.cc/ 2. What do you need to do in Project 2 – Part 1: Answer the following questions Part 1 - Building Molecular Models and Determine Relationships Between Molecules Question 1 (a) Build molecular models of the following two different forms of butane (A & B). H3C CH3 H H H H (A) H3C CH3 H H H H (B) 23 3 2 (b) Look through the C2-C3 bond and draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) a Newman projection of each of these two molecules. Which one is a staggered conformation and which one is an eclipsed conformation? (c) How would you describe the relationship between these two structures? (d) Which of these two structures has a lower energy (more stable)? Why? (e) Can you convert molecule (A) to molecule (B) without breaking a bond? How? Univ. of Guelph CHEM*2720 – Professor William Tam 2 Question 2 (a) Build molecular models of the two different forms of 2-butene (C & D). H3C CH3 (C) H3C CH3 (D) (b) How would you describe the relationship between these two molecules? (c) Can you convert molecule (C) to molecule (D) without breaking a bond? Why? Question 3 (a) Build and draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) the two different chair forms of methylcyclohexane (equatorial and axial). (b) How would you describe the relationship between these two molecules? (c) Which chair form of the methylcyclohexane is more stable? Why? (d) Can you interconvert these two different forms of methylcyclohexane without breaking a bond? How? (e) Using the chair equatorial methylcyclohexane model, convert this chair form to a boat form (without breaking a bond) by moving only C-4 up or down (C-1 is the carbon bearing the methyl group). Draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) this boat form and call it as molecule (E). Explain why this is less stable than the chair equatorial methylcyclohexane. (f) Using the chair axial methylcyclohexane model convert this chair form to a boat form (without breaking a bond) by moving only C-4 up or down (C-1 is the carbon bearing the methyl group). Draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) this boat form and call it as molecule (F). Explain why this is less stable than the chair equatorial methylcyclohexane. (g) Which boat form (E or F) is less stable? Explain briefly. Univ. of Guelph CHEM*2720 – Professor William Tam 3 Question 4 (a) Build molecular models of molecules (G) and (H). CH2CH3 C CH3 HO H (G) CH2CH3 C H3C OH H CH2CH3 C H CH3 OH CH3 C CH2CH3 HO H (J)(H) (I) 2 3 (i) How would you describe the relationship between these two molecules? (ii) Is molecule (G) optically active? (iii) If (G) has a specific (optical) rotation of –13.5°, can you estimate the specific rotation of (H)? (iv) If you have a 1:1 mixture of (G) and (H), what is the specific (optical) rotation of this mixture? (b) Using the molecular model of molecule (H), holding the C2-C3 bond and rotate the CH3, OH and H groups anti-clockwise 120°, you will get molecule (I). So you can see that (H) and (I) are in fact identical. Another simple way to determine if (H) and (I) are identical or enantiomers with each other is by checking the absolute configuration of the chiral carbon of these molecules. Assign the absolute configuration (R or S) of these structures (H) and (I). (c) Try to convert the molecular model of molecule (H) to (J) by holding the C2-OH bond and rotate the CH3, CH2CH3 and H groups clockwise 120°. Assign the absolute configuration (R or S) of (J). How would you describe the relationship between (G) and (J)? (d) With the help of the molecular models, draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) Fisher projections of (G) and (H) with the CH2CH3 group on the top and CH3 group at the bottom. Question 5 (a) Build a molecular model of (K). With the help of the molecular model, draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) the Fisher projections of (K) with the COOH group on the top and CH3 group at the bottom. Assign the absolute configuration (R or S) of the chiral carbons in (K). How many chiral carbons are there in molecule (K) and how many different stereoisomers do you expect (K) to have? (b) Build a molecular model of the enantiomer of (K) (call it L). With the help of the molecular model, draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) the Fisher projections of (L) with the COOH group on the top Univ. of Guelph CHEM*2720 – Professor William Tam 4 and CH3 group at the bottom. Assign the absolute configuration (R or S) of the chiral carbons in (L). C COOH C CH3Cl Cl H H (K) (c) Build molecular models of the two diastereosiomers of (K) (call them M and N). Draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) the staggered “Sawhorse projection” and the Fisher projections of (M) and (N) with the COOH group on the top and CH3 group at the bottom. Assign the absolute configuration (R or S) of the chiral carbons in (L). (d) How would you describe the relationship between (M) and (N)? Question 6 (a) Build molecular models of molecules (O) and (P). C COOH C COOH Cl Cl H H (O) C HOOC C HOOC Cl Cl H H (P) (b) How would you describe the relationship between (O) and (P)? (c) Is the molecule (O) chiral? Explain. (d) Build molecular models and draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) the “Sawhorse projection” of the two diastereosiomers of (O) (call them Q and R). Are these molecules (Q and R) chiral? Explain. (e) How many chiral carbons are there in molecule (O)? How many different stereoisomers does (O) has? Compare with Question (5a), explain why (K) has more stereoisomers than (O) even though both (K) and (O) have the same number of chiral carbons. Univ. of Guelph CHEM*2720 – Professor William Tam 5 Question 7 (a) Stereoisomerism of 1,4-dibromocyclohexane. (i) Build a molecular model and draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) the chair form of cis-1,4- dibromocyclohexane. Is this molecule chiral? Explain. (ii) Build molecular models and draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) the two different chair form of trans- 1,4-dibromocyclohexane. Which chair form is more stable? Are these two molecules chiral? Explain. (b) Stereoisomerism of 1,3-dibromocyclohexane. (i) Build molecular models and draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) the two different chair forms of cis-1,3- dibromocyclohexane. Which chair form is more stable? Are these two molecules chiral? Explain. (ii) Build molecular models of the two different chair forms (S and T) of trans-1,3- dibromocyclohexane. How would you describe the relationship between these two different chair forms? Are these molecules chiral? Explain. Br Br Br Br (S) (T) (c) Stereoisomerism of 1,2-dibromocyclohexane. (i) Build molecular models and draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) the two different chair forms of trans-1,2- dibromocyclohexane (one with both Br equitorial, call this U; and one with both Br axial, call this V). How would you describe the relationship (ii) Build molecular models and draw by hand (on a paper and take photo of your drawing and paste it on the MS Word document with all other answers) the structures of the enantiomers of