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Organic Chemistry Questions: stereochemistry and chirality centers

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1. Write the complete stepwise mechanism for this reaction. Be sure to show all intermediate structures and all electron flow using arrows.

2. Predict the products of the following reaction. Indicate regiochemistry and stereochemistry when relevant.

3. Provide a name for the compound below.

The compound below has been isolated from the safflower plant. Consider its structure to answer the following questions.

4. What is the molecular formula for this natural product?

5. What is the degree of unsaturation for this compound?

6. Assign E or Z configuration to each of the double bonds in the compound. Draw these above.

7. Provide the name for this unusual natural product.

8. Predict the product of the reaction below. Be sure to indicate stereochemistry when appropriate.

9. (2R,3S)-Dibromobutane is:

a. optically active
b. racemic
c. dextrorotory
d. a meso compound

10. Estriol, a potent estrogenic hormone, has been isolated from the urine of pregnant women. When 40 mg of estriol is dissolved in 1.0 mL of dioxane and placed in a sample tube with 1 dm path length a rotation of +2.32 is observed. Calculate the specific rotation for estriol.

11. (S)-()-Serine:

a. is dextrorotatory
b. rotates plane-polarized light in a counterclockwise direction
c. rotates plane-polarized light in a clockwise direction
d. is racemic

12. Draw the enantiomer of (S)-()-Serine in a wedge-dash projection.

13. Assign R, S configurations to each indicated chirality center in the molecule below. The configuration of this carbon atom is (red arrow)_______________.

14. Assign R, S configurations to each indicated chirality center in the molecule below. The configuration of this carbon atom is (red arrow)_______________.

15. Assign R, S configurations to each indicated chirality center in the molecule below. The configuration of this carbon atom is (red arrow)_______________.

16. Assign R, S configurations to each indicated chirality center in the molecule below. The configuration of this carbon atom is (red arrow)_______________.

Select the best reagent or sequence of reagents from the list provided which would best accomplish each transformation below (numbers 17 & 18).

a. H2, Lindlar
b. 1. BH3, THF
2. H2O2
c. 1. NaNH2, NH3
2. CH3CH2I
d. 1. Br2, CCl4
2. 2 NaNH2, NH3
e. 1. HCl
2. NaNH2, NH3
f. Li/NH3

17.

18.

19. Place asterisks at all the chirality centers in the molecule below.

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The solution answers 19 questions on organic chemistry including concepts on stepwise mechanisms, stereochemistry, and chirality centers.

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I am taking an entrance exam for graduate school next month and I've been out of school for over a year now and I really need help and indepth explanations on how to do these problems from the online practice test. I am also using review notes from class and notecards to help me, but I want more help on an actual practice exam.
I will post the questions as well as the website from which they came from.
Here it is:

https://www.ada.org/oat/oat_sample_test.pdf

71. In the reaction energy diagram shown below,
what is the intermediate species?
A. A
B. B
C. C
D. D
E. E

72. A characteristic feature of the SN2 reaction
mechanism is that
A. it follows first-order kinetics.
B. it produces stereochemical inversion of
configuration.
C. there is no rate-determining step.
D. steric factors have little influence on the
reaction rate constant.
E. collision of three or more particles is
required.

73. It is believed that an unlabeled bottle
containing an unknown liquid is either 2-
pentanone or 3-pentanone. What is the best
methodology to distinguish one compound
from the other?
A. Mass Spectroscopy
B. Infrared Spectroscopy
C. 13C NMR Spectroscopy
D. Thin Layer Chromatography
E. Melting Point Determination

74. What is the produce of the following reaction
sequence.

75. Which statement is true regarding a
compound that has multiple chiral centers and
a plane of symmetry?
A. It is chiral.
B. It is assymetric.
C. It is an enantiomer.
D. It is meso.
E. It rotates plan polarized light.

76. Nitration of toluene (Phâ?"CH3) with
HNO3/H2SO4 occurs
A. faster than nitration of benzene and
produces mostly ortho and para
products.
B. slower than nitration of benzene and
produces mostly meta product.
C. faster than nitration of benzene and
produces mostly meta product.
D. slower than nitration of benzene and
produces mostly ortho and para
products.
E. at the same rate as nitration of benzene
and produces mostly meta product.
77. Which of the following carbocations is the
most stable?

78. Which of the following does a strong infrared
absorption band between 1750 and
1700 cmâ?"1 (5.77 - 5.88m ) indicate the
presence of?

79. According to IUPAC rules, which functional
group is given the highest priority when
numbering the parent chain?
A. Amines
B. Alkenes
C. Aldehydes
D. Amides
E. Acid Anhydrides

80. Which of the compounds below would be
most soluble in water?

81. Which of the conformations of
1,3-dimethylcyclohexane is the least stable?
82. Which ONE of the following pure liquids
would be expected to show extensive
intermolecular hydrogen bonding?

83. Which of the following compounds is a tertiary
(3° ) amine?

84. Which of the following compounds best fits
the 1H NMR spectral data listed below?

85. Which of the following will undergo a free
radical bromination most rapidly?

86. How many Ï? molecular orbitals does pyridine
possess?
A. 3
B. 4
C. 5
D. 6
E. 7
87. Which combination of reagents will produce

88. Which of the following statements is true
regarding a pair of compounds that are
diasteromers of each other?
A. They are configurational isomers.
B. They have the same physical
properties.
C. They are mirror images.
D. They are always optically active.
E. They have equal but oppisite ? values.

89. The indicated H atom on imidazole is acidic.
This can best be explained by stabilization of
the conjugate base. Which of the following is
the greatest cause of this stabilization?
A. The inductive effect
B. Resonance
C. Conjugation
D. Aromaticity
E. Hyperconjugation

90. What is the product of the following sequence
of reactions?

91. Which reagent, followed by the appropriate
work-up procedure, could you use to effect
the following conversion?
92. What is the product of the following addition
reaction?

93. What is the hybridization of a nitrogen atom if
it forms two Ï? two Ï? bonds?
A. sp
B. sp2
C. sp3
D. sp3d2

94. Which of the following is a group that is both
deactivating and ortho, para directing in the
nitration reaction of substituted benzenes?
A. COOH
B. CH3
C. Br
D. NO2
E. OCH3

95. Which of the following functional groups can
act as both a BrÃ?nsted acid and BrÃ?nsted
base?

96. What is the major product of the following
reaction?
97. Which of the following ions is stabilized by
resonance?

98. Treatment of benzoic acid with thionyl
chloride followed by addition of ethanol gives
which of the following as the major product?

99. What is the major product (B) of the following
reaction sequence?

100. The most acidic hydrogen(s) in the following
compounds are attached to which of the
following carbons?
A. 1
B. 2
C. 3
D. 4
E. 5.

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