28 Two C4H6 isomers give the same C4H8O product from HgSO4 catalyzed hydration in aqueous acid.
However, these isomers give different C4H6Br4 products with excess bromine.
What are these isomeric hydrocarbons?
A) cyclobutene and methylenecyclopropane
B) 1,2-butadiene and 1,3-butadiene
C) 1-butyne and 2-butyne
D) 2-butyne and cyclobutene
30 Two C5H8 isomers undergo catalytic (Pt) hydrogenation to form the same C5H10 product. On ozonolysis followed by oxidative workup (H2O2), one isomer gave a C5H8O4 diacid, while the other isomer gave a C5H8O3 ketoacid.
Which of the following isomeric pairs correspond to this evidence?
A) cyclopentene and 1-pentyne
B) cyclopentene and 1-methylcyclobutene
C) 1-methylcyclobutene and 3-methylcyclobutene
D) cyclopentene and 3-methylcyclobutene
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31 Considering that the angles of a regular pentagon are 108º, why is cyclopentane not planar?
A) all the carbons are sp2 hybridized, so there is considerable angle strain.
B) The C-C bonds are formed by overlap of p-orbitals, so the 90º angle results in large angle strain.
C) The cyclic overlap of bonding orbitals results in anti-aromaticity destabilization.
D) The five C-C bonds have eclipsing strain.
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32 Which reaction conditions would best convert 3-hexyne to cis-3-hexene?
A) Pt catalyst and H2.
B) Lindlar's Pd catalyst and H2.
C) Na in liquid NH3.
D) NaNH2 in liquid NH3.
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33 Reaction of 1-hexene with NBS (N-bromosuccinimide) forms two isomeric bromohexenes, one of which is 3-bromo-1-hexene.
Which of the following is the other isomer?
A) 1-bromo-2-hexene.
B) 6-bromo-1-hexene.
C) 1-bromo-1-hexene.
D) 2-bromo-1-hexene.
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34 A C6H10 hydrocarbon forms an insoluble silver salt when treated with silver nitrate in ethanolic ammonia.
Acid catalyzed hydration with a HgSO4 catalyst generates a single C6H12O ketone, and pemanganate oxidation yields a C5H10O2 carboxylic acid
This compound is most likely which of the following?
A) cyclohexene.
B) methylenecyclopentane.
C) 1-hexyne.
D) 3-hexyne.
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35 Peroxide induced reaction of carbon tetrachloride with 1-butene produces which of the following?
A) 1,1,1,3-tetrachloropentane.
B) 1,1,1,2-tetrachloropentane.
C) 1-chloro-2-trichloromethylbutane.
D) 1,1-dichloro-2-ethylcyclopropane.
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36 Which of the following isomeric hexenes will have the smallest heat of hydrogenation?
A) 4-methyl-1-pentene.
B) (E)-4-methyl-2-pentene.
C) (Z)-4-methyl-2-pentene.
D) 2-methyl-2-pentene.
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37 A C8H14 hydrocarbon (X) is reduced by sodium in liquid ammonia to a single C8H16 product (Y).
Both of these compounds undergo hydrogenation (Pt catalyst) to give 2,5-dimethylhexane.
Ozonolysis of Y with an oxidative workup produces a single C4H8O2 carboxylic acid.
Reaction of Y with perbenzoic acid (C6H5CO3H) gives a chiral C8H14O product, but reaction with bromine gives an achiral C8H14Br2 product
What are X and Y?
A) X is 2,5-dimethyl-3-hexyne ; Y is cis-2,5-dimethyl-3-hexene.
B) X is 2,5-dimethyl-3-hexyne ; Y is trans-2,5-dimethyl-3-hexene.
C) X is 2.5-dimethyl-1,5-hexadiene ; Y is 2,5-dimethyl-3-hexyne.
D) X is 2,5-dimethyl-2,4-hexadiene ; Y is cis-2,5-dimethyl-3-hexene.
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