CHE 230: Organic Chemistry I Instructor: Andy Mitchell Study Guide #1 (CH 1-5)

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1 CHE 230: Organic Chemistry I Instructor: Andy Mitchell Study Guide #1 (CH 1-5) These are past exam questions, but please use this as a STUDY GUIDE ONLY. You should also work end of chapter problems.

2 1) Draw the following clearly and label nodes: p-orbital: sp 3 -orbital: 2) Draw the best Lewis structure (two-dimensions only) for each of the following molecules with two-electron bonds represented by a single line. Include lone pairs and formal charges: CH 3 CH 2 OH [CH 3 CO 2 ] CH 3 Br 1

3 3) Add a formal charge to each of the following molecules at the appropriate atom in each: 4) Draw three possible isomers for C 3 H 8 O: 5) In relation to the molecule in the box, indicate if each structure is an isomer, a resonance contributor, or neither: 2

4 6) Draw the best resonance contributor that correlates to the structure given and show the movement of electrons with curved arrows on the given structure only: 3

5 7) Draw the following molecules in three-dimensions using wedges and dashes. Include empty orbitals, lone pairs, and formal charges as necessary: BF 3 CH 4 NH 3 [BF 4 ] 8) Draw the skeletal structure corresponding to condensed: (CH 3 ) 3 C(CH 2 ) 4 CH 3 4

6 9) Label orbitals used for each bond with an arrow: 10) Predict the hybridization of each labeled atom: H 3 C CH 3 CH 3 H H N CH3 H H H H CH 3 O H H 3C O H H 11) Based on electronegativity, draw a partial positive (δ + ) and partial negative (δ ) on each non-hydrogen atom below: 12) Show why 1,4-dichlorobenzene has no NET dipole: 5

7 13) Each of the following is a TRUE statement; explain by matching it with the first letter of one of the four acidity effects: element (E), inductive (I), resonance (R), or hybridization (H): CH 3 CH 3 is a weaker acid than H 2 C=CH 2 CH 3 CH 2 OH is a weaker acid than CF 3 CH 2 OH H 2 O is a stronger acid than CH 4 CH 3 C(O)CH 3 is a stronger acid than CH 3 CH 2 CH 3 14) Fill in the appropriate terms below: 6

8 15) Add equilibrium arrows to the following reactions to indicate if reactants or products are favored: 7

9 16) Draw the structure of the Brønsted conjugate acid: 17) Draw the Brønsted conj. base as a resonance hybrid: 18) Explain the pk a difference caused by an inductive effect primarily with structural explanations and very few words: 8

10 19) Explain the pk a difference caused by a resonance effect primarily with structural explanations and very few words: 20) Show all products in two-dimensions only (include formal charges and lone pairs) after a single Lewis acid-lewis base interaction using no more than 2 curved arrows: 9

11 21) For each generic name, draw the functional group with all pertinent bonds shown and a generic R group. There is no need to show lone pairs: carboxylic acid: alcohol: 22) For each functional group, write the generic name: 10

12 23) Circle the compound with the highest boiling point: 24) Circle the compound with the highest melting point: 25) Assign IUPAC names to the following compounds: 26) Draw skeletal structures for each IUPAC name: 11

13 27) Draw a single molecule for the following descriptions (you should have only one molecule for each and all three should be different): a) Possesses ONLY van der Waals (VDW) forces: b) Possesses BOTH van der Waals (VDW) and Dipole-Dipole (DD) forces: c) Possesses ALL of van der Waals (VDW), Dipole-Dipole (DD), and Hydrogen Bonding (HB) forces: 12

14 28) Draw all three isomers of pentane, C 5 H 12 : 29) Draw cyclopentane and one other isomer of C 5 H 10 : 13

15 30) Using a single word above each example, label the specific type of strain indicated by the arrows: 31) (a) Draw both chair conformers of methylcyclohexane with both the methyl group and the hydrogen attached to that carbon in each conformer, indicate which is more stable using uneven equilibrium arrows (6 points) and (b) calculate the energy difference based on the fact that one gauche interaction = 0.9 kcal/mol: 14

16 32) Draw the single most stable chair conformation corresponding to each planar structure; you must show the proper orientation of all groups including methyl, t-butyl, and H: 15

17 33) Draw the chair conformation that correlates to the planar structure shown: 34) Circle the molecule that is less soluble in water and explain your answer with one drawing and a very brief explanation: 35) Show both products (you do not need to show stoichiometry) for the following reaction: 16

18 36) For the energy diagram of butane rotation, very clearly draw all six Newman projections (1-6) in the space below the diagram and circle all gauche conformations: 17

19 37) Draw the following molecule as two mirror images with wedges and dashes and describe their relationship as enantiomers or identical: 38) What is the maximum number of stereoisomers for the following molecule? 39) Assign priorities (1-4) and indicate R or S configuration at each stereocenter: 18

20 40) Draw all stereoisomers of 2,3-dibromopentane and label one set of enantiomers and one set of diastereomers: Br H 3 C Br CH 3 41) Draw all stereoisomers of 1,4-dimethylcyclohexane and label them as enantiomers or diastereomers: 19

21 42) Consider the following single enantiomer with an optical rotation (of plane-polarized light) of +45 : a) What is the optical rotation of the opposite enantiomer? b) What is the optical rotation of the racemic mixture? c) What is the enantiomeric excess of a 95:5 mixture? 43) Draw BOTH products and label them as either enantiomers or diastereomers: Me OH H NH 2 O racemic mixture pka~5 (R)-sec-butylamine pka(conj.acid)~11 20

Chapter 2 Polar Covalent Bonds: Acids and Bases

John E. McMurry www.cengage.com/chemistry/mcmurry Chapter 2 Polar Covalent Bonds: Acids and Bases Modified by Dr. Daniela R. Radu Why This Chapter? Description of basic ways chemists account for chemical