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Chemistry 310M/318MDr. Brent Iverson1st MidtermSeptember 30, 2010
NAME (Print): _____________________________
SIGNATURE: _____________________________
Please Note: This test may be a bit long, but there is a reason. I would like to give you a lot of little questions, so you can find ones you can answer and show me what you know, rather than just a few questions that may be testing the one thing you forgot. I recommend you look the exam over and answer the questions you are sure of first, then go back and try to figure out the rest. Also make sure to look at the point totals on the questions as a guide to help budget your time.
Please print the first three letters of your last name in the three boxes
You must have your answers written in PERMANENT ink if you want a regrade!!!! This means no test written in pencil or ERASABLE INK will be regraded.
Please note: We routinely xerox a number of exams following initial grading to guard against receiving altered answers during the regrading process.
FINALLY, DUE TO SOME UNFORTUNATE RECENT INCIDENCTS YOU ARE NOT ALLOWED TO INTERACT WITH YOUR CELL PHONE IN ANY WAY. IF YOU TOUCH YOUR CELL PHONE DURING THE EXAM YOU WILL GET A "0" NO MATTER WHAT YOU ARE DOING WITH THE PHONE. PUT IT AWAY AND LEAVE IT THERE!!!
Honor Code
The core values of the University of Texas at Austin are learning, discovery, freedom, leadership, individual opportunity, and responsibility. Each member of the University is expected to uphold these values through integrity, honesty, trust, fairness, and respect toward peers and community.
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Pg 1 _____________(20)Signature_________________________
1. (4 points) What is the most important question in Organic Chemistry?
2. (8 pts each) For the following molecular formula, draw complete Lewis line structures in which all atoms (even H atoms) are drawn, lines are used as bonds, all lone pairs are drawn AND ALL FORMAL CHARGES ARE INDICATED.
1) (CH3)CCH2OCH2CH2NH3
2) H2NCHOHCO2
How many different stereoisomers are there for the above molecule?
How many different stereoisomers are there for the above molecule?
(You only need to draw one of the major contributing structures)
Pg 2 _____________(22)Signature_________________________
3. Provide an acceptable IUPAC name for the following molecules. You can ignore R and S for this one.
A) (6 pts)
C
CH3
CH3
CH2 CH2CH2 CH CH2 CH2CH2H3C
B) (6 pts)
C) (10 pts) H3C
CH3
CH3
CH2CH3C CH3
CH3
CH3
Although stereochemistry is not indicated on the above structure, how many stereoisomers are possible?
Although stereochemistry is not indicated on the above structure, how many stereoisomers are possible?
Is the molecule chiral? If you answered yes, then in the box provided, draw the enantiomer of the above structure.
Pg 3 _____________(15)Signature_________________________
5. (5pts each) For the following IUPAC names, draw the appropriate line angle drawing (you can ignore R and S for this).
A) 4-tert-butyl -5-ethyl-2-methylheptane
B) trans-1-methyl-3-(1-methylethyl)cyclopentane
C) (Challenge!!) R-5-isobutyl-2-methylnonane (Use wedges and dashes to indicate the appropriate stereochemistry)
Pg 4 _____________(20)Signature_________________________
6. (5pts each) The following molecules are best represented as the hybrid of contributing structures. Draw the second important contributing structure in the space provided, including all lone pairs and formal charges. For the structure on the left, use arrows to indicate the movement of electrons to give the structure you drew. Finally, if one of the two contributing structures makes a dominant (major) contribution to the resonance hybrid, draw a circle around the dominant (major) contributor. You might want to read these directions again to make sure you know what we want.
A.
CH
H
H
CO
O
B.
C.
C NH
HN
D.
HC
CC
H
H
HH
CH
H
H
CC
O
HH
Pg 5 _____________(20)Signature_________________________
7. (10 pts each) The following molecules are best represented as the hybrid of three contributing structures. Draw the second and third important contributing structures in the spaces provided, including all lone pairs and formal charges. For the two structures on the left in each problem, use arrows to indicate the movement of electrons to give the structures you drew. There is no need to draw any circles around any of these contributing strucures. You might want to read these directions again to make sure you know what we want.
A.
O CO
O
B.
C NO
O
H
H
OORibbit
Pg 6 _____________(31)Signature_________________________
8. (2 pts each) Fill in each blank with the word or words that best completes the sentences.
For organic chemistry, it is best to think of electrons as __________________.
According to the ________________________________ approach, the atomic orbitals on each atom
are combined (hybridized) first, and bonds are derived from overlap of hybridized orbitals.
It is best to think about all ____________________ bonding in molecules as being derived from the
overlap of hybridized orbitals and all __________________bonding as being derived from overlap
of unhybridized 2p orbitals.
9. (1 pt each) For the following molecules, write the hybridization state of each atom indicated by the arrow.
O
N
CC
CH
O
H
HH
In solution, alkane molecules are weakly attracted to each other due to___________________________
forces, which are the weakest of the electrostatic interactions (i.e. charge-charge interactions) and
are the result of attraction between _________________________ (induced) dipoles among adjacent
molecules.
CH
H H
N
N
H
CH3
Nicotine
O O
OO
NHH
HNa
MSG
Pg 7 _____________(32)Signature_________________________
9. (2 pts each) Describe each bond indicated with an arrow as the overlap of orbitals. For example, an
answer might be σCsp3-Csp3.
O
O
H
CH3
H3C
CH3
Ibuprofin
N
N
N
O
CH3
H
LSD
NH3C C
OMethyl
Isocyanate(the molecule that cuased the Bhopal tragedy in India in
1984)
Pg 8 _____________(22)Signature_________________________
10. (3 pts each) For the following molecules, use the dipole moment symbol to show the direction of the molecular dipole moment in all molecules that have an overall molecular dipole.
Cl
CH
HH
H
CCl
ClClH
CC
CH
O O
H H
For the moleculeabove list the molecular dipole for the
conformation shown.
11. (10 pts each) The following molecule is best represented as the hybrid of three contributing structures. Draw the second and third important contributing structures in the spaces provided, including all lone pairs and formal charges. For the two structures on the left use arrows to indicate the movement of electrons to give the structures you drew. There is no need to draw any circles around any of these contributing strucures. You might want to read these directions again to make sure you know what we want.
CHH
HCO
NH
H
CH
H
H
NO
O
Pg 9 _____________(14)Signature_________________________
12. (7 pts each) For the following cyclohexane derivatives, draw the two alternative chair conformations. If there is a difference in stability, draw a circle around the more stable conformation.
NH2
A)
B)
Pg 10 _____________(21)Signature_________________________
13. (7 pts) For the following molecule of glucose, draw both alternative chair conformations. Circle the one that is more stable. This is called α-D-glucose.
O OH
OH
OH
HO
HOH2C
14. (14 pts) For the following molecules, label each chiral center with an asterisk (*).
H3CCH3
OHH
H3C CH3
OHH
CO2H
CNH3H
H
CO2H
CNH3H3C
H
H3CCH3
Cl
Cl
Cl
CH3
CH3 CH3
CH3
CH3
Cl Br
HH
Cl Br
FH
HH
H
O
O "Andro"the steroid used by Mark McGwire and other sports stars
Pg 11 _____________(31)Signature_________________________
15. (3 pts) Label each chiral center as "R" or "S".
H3CC
H
Br Cl
H3CC
Br
H Cl
HC
Br
H3C Cl
H3CC
Cl
Br H
H3CCH3
H OHH3C H
16. (5 pts each) For the following conformations, draw the Newman Projection from the perspective indicated by the eye of the observer
CC
H
H3C
H3CH
CH3
Cl
CC
HH3C
HH3C CH3
Cl
CC
CH2SH
H CH3
O
HO
Pg 13 _____________(24)Signature_________________________
13. (4 pts each) For each pair of molecules, circle the one that has LESS STRAIN, then put an "X" in the box under the one or at most two types of strain that is/are most important to explain your answer:
Angle strain
Torsional strain
Steric strain
vs.H3C
CH3
vs.
CH3
HHCH2CH3
HHCH3
HHH
CH2CH3Hvs.
CC
H H
H HH H vs. CC
H
HH
H
HH
CC
H H
H3C CH3
H H vs. CC
H3C
HH
CH3
HH
vs. CC
H
HH3C
Br
HH
CC
H
HH3C
H
BrH
Pg 14 _____________(27)Signature_________________________
17. (27 pts) For each pair of molecules, on the line provided state whether they are (1) enantiomers, (2) diastereomers, (3) consitutional isomers,or (4) different conformations of the same molecule. Each pair of molecules will best be described by one of these four terms. Next draw a circle around all the molecules that would be optically active (i.e rotate the plane of plane polarized light), and write "MESO" under any meso compounds.
Relationship:
H3COH
H OH
H CH3
H3CCH3
HO H
HO H
H3COH
H OH
H CH3
H3CCH3
HO H
H OH
H3CCH3
H OH
H CH3
H3CCH3
HO H
H CH3
H3CCH3
H H
H HH
HH3C H
H CH3
CH3
C(CH3)3HH
CH3HCH3
C(CH3)3HH
HH3C
CH3
C(CH3)3HH
CH3HH
C(CH3)3H3CH
HH3C
Pg 15 _____________(15)Signature_________________________
20. (15 pts) Here is an "apply what you know" question. A series of alkanes are listed along with their boiling points.
A) From the data listed, draw two different conclusions regarding how boiling point changes with structure.
69° C
126°C
174°C
58°C108°C
160°C138°C
B) The boiling point of 2,2,3,3-tetramethylbutane is 106°C, in line with the other alkanes. However, 2,2,3,3-tetramethylbutane is a solid at room tempterature, not a liquid like the others, because it has a melting point of 104°C. It is only a liquid for the span of 2°C!! For comparison, octane is only a solid below -57°C. Briefly explain why 2,2,3,3-tetramethylbutane exhibits this unsual behavior.
Boiling point 106°CMelting Point 104°C
Boiling point 126°CMelting Point -57°C
Pg 16 _____________(20)Signature_________________________
21. (10 pts) Here is another "apply what you know" problem. If you get this correct, you will understand the basis for most of the chemistry in Chapter 16!! Remember the most important question in Chemistry! Shown below are the acetone molecule, a proton, and the hydroxide anion. Draw all the appropriate bond dipole moments on the acetone and hydroxide anion molecules for all the polar covalent bonds. Draw a BOX around the atom on the acetone molecule that is most likely to interact with the proton, and draw a CIRCLE around the atom on the acetone molecule most likely to interact with the hydroxide anion. Read these directions again to make sure you know what we want!
CH
H
H
C
O
C
H
H
H
O H H
Acetone
Hydroxideanion
22. (10 pts) Draw a circle around the following structures that represent molecules that are optically active when placed in solution. Draw a box around those structures that represent molecules that are not optically active when placed in solution.
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