CEM 341: rganic Chemistry I at North Dakota State University Midterm Exam 01 - Fri, Feb 10, 2012!! Name:! Please read through each question carefully and answer in the spaces provided. A good strategy is to go through the test and answer all the questions you can do easily. Then go back and tackle the more difficult problems. Please make sure your structures are drawn clearly and indicate any necessary stereochemistry with bold or dashed bonds. Finally, think about what you know. Common sense and reason can often help you out. Go BISN! You may use the blank pages of your test for scratch paper. Problem 1 10 pts Problem 7 8 pts Problem 2 10 pts Problem 8 8 pts Problem 3 6 pts Problem 9 8 pts Problem 4 20 pts Problem 10 12 pts Problem 5 6 pts BNUS 5 pts Problem 6 12 pts TTAL 100 pts Chem 341 Midterm Exam 01! page 1! spring 2012
1. Identify the relationship between the following pairs of molecules as Identical, Resonance Forms, Constitutional Isomers, Stereoisomers, Conformers or completely Different compounds (check the appropriate box) (10 pts). identical resonance forms constitutional isomers stereoisomers conformers completely different a) b) C 3 C 3 C 3 C 3 c) d) C 3 C 3 C 3 3 C C 3 C 3 e) N 2 N 2 2. Consider the following molecule. Answer the questions pertaining to this molecules structure. (10 pts) ow many primary (1 ) carbons are present in the molecule? ow many tertiary hydrogens are present in the molecule? ow many sp hybridized atoms are present in the molecule? ow many sp 2 hybridized atoms are present in the molecule? ow many sp 3 hybridized atoms are present in the molecule? Chem 341 Midterm Exam 01! page 2! spring 2012
3. For the following Brønsted acid base equilibrium indicate which side of the equation the equilibrium will favor by circling the reactants (left side) or the products (right side). In the boxes below each molecule indicate its role in the reaction as shown as either the acid, conjugate acid, base or conjugate base. (6 pts) 3 C C + 3 C C 3 C C + 3 C C 4. Provide the correct IUPAC name for each of the following molecules. (20 pts) a) b) c) C 3 C 3 C 3 d) e) Chem 341 Midterm Exam 01! page 3! spring 2012
5. Although you haven t seen this two step reaction before, you should be able to see which bonds get broken and which bonds get formed. And you should be able to determine where the electrons flow during these bond changes. For each of these two steps, draw the curved arrows (on the species below) showing how the electrons move.. (6 pts) C C + Br C C + Br Br C C step 1 step 2 draw arrows on these for the first step draw arrows on these for the second step 6. The chlorinated hydrocarbon with the molecular formula C49 has four possible constitutional isomers. In the boxes below draw the structures for these isomers. (12 pts) Chem 341 Midterm Exam 01! page 4! spring 2012
7. In the box below, draw the structure for 4-ethyl-2-(1-methylethyl)hexane. Although this name allows you to draw a correct structure, it is not a correct IUPAC name for the molecule. Provide the correct name. (8 pts) Correct IUPAC name 8. For each set of molecules below circle the sets that represent valid resonance forms. (8 pts) N N 9. The acid base reaction below is an example of a Lewis acid/base. In the boxes below each reagent indicate whether it is a Lewis Acid or a Lewis Base. The product of this reaction will have formal charges on the atoms indicated. Give the formal charge for these atoms in the attached boxes. (8 pts) N 2 + Al Al N 2 Chem 341 Midterm Exam 01! page 5! spring 2012
10. For each pair of conformations, circle the one conformation that is the least stable (highest in energy). (12 pts) C 3 3 C C 3 a) or c) or 3 C C 3 C 3 b) or 3 C C 3 3 C C 3 d) 3 C C 3 or C 3 C3 BNUS: Draw a chair cyclohexane structure for cis,cis-1,2,3-trimethylcyclohexane in its lowest energy conformation. (5 pts) (note: to get the extra credit, your chair and all bond angles should be correct.) Chem 341 Midterm Exam 01! page 6! spring 2012