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    Various Organic Chemistry Questions

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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:


    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
    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

    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

    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
    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
    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
    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
    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

    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

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

    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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    Solution Preview

    These are my views:

    C is the intermediate - this is in an energy trough - it has a relative stability compared to B and D
    B and D are transition states - these are at the peaks in energy (i.e. they are not stable!)
    A is the starting material
    E is the product
    B is correct.
    If you look at the mechanism, a nucleophile attacks, in terms of projector, from behind the leaving group. This causes the overall stereochemistry to switch!
    I would go for A, mass spec. The others would all give inconclusive and similar results for both compounds. In mass spec, the molecular ion would be the same, but any fragmentation would be unique!
    The product is A. Deprotonation between the esters generates an anion that is alkylated. The acid then decarboxylates and hydrolyses the remaining ester to a carboxylic acid.
    A meso compound has chiral centres and a plane of ...

    Solution Summary

    The solution assists with answering and explaining various organic chemistry questions.