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Chemistry 251/253 |
Homework 12 Answer Key |
1)
O=C(NCc1ccccc1)c2ccccc2
2.
CCOC(=O)c1ccc(C)cc1
3.
CC(C)OC(=O)Nc1ccccc1
4.
CC(C)c1ccc(Cc2ccc(cc2)C(C)C)cc1
5.
CCOc1ccc(cc1)C(C)(C)c2ccc(OCC)cc2 This reaction
parallels the one presented in Figure 5 of the topic Biopolymers I
.
6.
CCNCc1ccccc1
7.
CC(=O)NCC(=O)OCc1ccccc1
8
CCNC(=O)Nc1ccccc1C
9. Glycolysis, the breakdown of D-glucose into acetic acid, begins with this isomerization: Draw the structure of the likely intermediate in this reaction
OCC(O)C(O)C(O)C(=CO)O The reaction involves keto-enol
tautomerization. The likely intermediate is the enol form of
D-glucose.
10.* Another step in glycolysis
involves the following reaction:
Draw the structure of compound A. OC[C@@H](O)C=O
11.* Draw the structure of
glycylalanine.
C[C@H](NC(=O)CN)C(=O)O
12. Assume you had a basic solution which contained the amino acid
arginine in the following form:
As you begin to
acidify the solution, which atom will be protonated first? Enter the
number of the atom in the appropriate text field. 5 Protonation of this nitrogen produces a cation that
is resonance stabilized.
13. Which atom would be protonated second? 2
14. Mutations in DNA may result from changes in the structure of one of the heterocyclic bases attached to the backbone of the nucelic acid. One such mutation involves the hydrolytic deamination of cytosine. Draw the product of the hydrolytic deamination of the the cytosine analog shown in the following reaction:
Cn1ccc(=O)nc1O or Cn1ccc(O)nc1=O or
Cn1ccc(=O)[nH]c1=O I accepted different tautomeric forms of this
structure.
15. Draw the structure of the DNA fragment that is complementary
to
.
Nc1nc2n(cnc2c(=O)[nH]1)C3CC(OP(=O)([O-])[O-])C(OP(=O)([O-])[O-])O3
16. The amino acid histidine, 
, is
found at the active site of many enzymes, where it functions as a
base in the transfer of a proton from a substrate. Which of the
nitrogen atoms in histidine is the proton transferred to? Enter the
number in the text field. 3 The lone pair of
electrons on N-2 is part of the aromatic pi system. The lone pair on
N-3 is not. It is perpendicular to the pi system.
17. Of the 19 L-amino acids, 18 have the S configuration at the a-carbon. What is the name of the amino acid that has the R configuration? Enter just the name, e.g. glycine. Do not enter any stereochemical designation. Watch your spelling.
CYSTEINE or CYSTINE
18.
COC(=O)C(C)NC(=Nc1ccccc1)S or COC(=O)C(C)NC(=S)Nc1ccccc1
19. How many of the following compounds qualify as monoterpenes? 1 or 0 The first choice is the only one that contains 10 carbons, but they two 5-carbon fragments are not connected in a head-to-tail manner, so I accepted either 0 or 1 as correct.
20. A monoterpene with the molecular formula C10H18 did not decolorize a 2% solution of Br2/CCl4. The 13C-NMR spectrum of this material showed 7 peaks, all in the 19-50 ppm range. Draw a structure that is consistent with this data.
CC1(C)C2CCC1(C)CC2 or CC1(CCCC2CCC1)C2
21. In the following reaction, compound Bhas
the molecular formula C10H11D. Draw the structure
of this compound.
[2H]C(=C(C)c1ccccc1)C
22.
COCc1ccccc1
23. The following reaction produces a mixture
of products with the molecular formula C12H13Br. Draw the structure
of the compound that should be formed in the greatest amount.
CC1=CC(C)(Br)Cc2ccccc12 A Br atom will abstract a tertiary hydrogen preferentially.
24.
CC1CCCC(C)(O)O1
25*. Deduce the structure of
compound C:
CC(C)(C)/C(=C\c1ccccc1)/c2ccccc2
26. Enter the number of the compound that would undergo dehydrobromination faster when treated with an ethanolic solution of KOH: 2 The elimination requires the molecules to adopt the other chair conformation so that the dihedral angle between the H and Br atoms is 180 degrees. In compound 1, this forces the t-butyl group to come up against the methyl group.
27. Al Kane was investigating the reduction of aldehydes and ketones with a chiral reducing agent. In a test run, he reduced 2-butanone to 2-butanol. The optical rotation of the product he obtained was -11.37 degrees. What was the enantiomeric excess of this reaction? The specific rotation of (R)-2-butanol is -13.52 degrees. Enter your answer as a 3-digit number. Do not include any units. 84.0
28. How many chiral ethers are there with the
molecular formula C4H8O? 3
29. Draw the structure of compound D.
CC1=C(C)CCC1 Compound E undergoes an intramolecular aldol condensation.
30*.
COC(=O)[C@H]1CC=C(C)C[C@@H]1C(=O)OC or COC(=O)[C@@H]1CC=C(C)C[C@H]1C(=O)OC