Organic Chemistry FINAL Tests #1 Flashcards

Terms Definitions
Which of the following is considered to be 'conjugated'?
1,3 butadiene
The anionic portion of the reagent 'potassium tert-butoxide' contains how many atoms?
14
Adding molecular hydrogen to 1,4-pentadiene is (fill in the blank) _______ than adding molecular hydrogen to 1,3-butadiene.
more exothermic
The 1,4-addition product resulting when HBr (1 eq) is allowed to react with 1,3-butadiene (1 eq) is...
1-bromo-2-butene
If reactant A can form two products (B and/or C)...and both reactions (A-->B and A-->C) are not reversible, this set of reactions is said to be under
Kinetic Control
The Diels-Alder reactions discussed in class occurs in
a single step
In the Diels-Alder sense, the molecule benzoquinone
has four hydrogen atoms and is a dienophile
T/F: the Diels-Alder reaction is considered to be stereospecific.
True
You think a given unknown may have a C=O bond. Which instrumental technique is preferred to confirm your thought?
IR
Benzaldehyde contains how many hydrogen atoms?
6
2,5-Dimethylphenol contains how many hydrogen atoms?
10
Is the cycloheptatrienyl cation aromatic?
yes
Consider the molecules pyridine and pyrrole and choose:
Both are aromatic
The 'best' Lewis Structure for NO2+ puts what formal charge on oxygen?
neutral
T/F: Friedel-Crafts acylation [electrophilic aromatic substitution] reactions require a Lewis Acid catalyst.
True
nitrobenzene is allowed to react with HNO3/H2SO4, a dinitrobenzene is formed. The 13C NMR spectrum of this dinitrobenzene has how many signals?
4
Simple alkyl groups, when attached to benzene in EAS reactions, are said to be
electron donating and ring activating
Halogen atoms are considered to be ortho-para directing groups (in EAS reactions) because, via resonance, they
donate electrons
Where would p-nitrotoluene be most likely to undergo monobromination?
ortho to the methyl group
Where would p-methylphenol be most likely to undergo monobromination?
ortho to the -OH group
presence of electron-withdrawing groups on the aromatic ring are necessary if one desires to complete a nucleophilic aromatic substitution reaction because the organic intermediate in this reaction is a...
Carbanion
T/F: benzynes are reactive intermediates that are likely to undergo elimination reactions.
False
When vinylbenzene is allowed to react with H2 (Pd catalyst) at atmospheric pressure and room temperature (mild conditions), the main organic product that results is
ethylbenzene
Consider the reagent NBS. The 'B' refers to
Bromo
Benzoic acid, when allowed to react with HNO3/H2SO4, is transformed into
m-nitrobenzoic acid
T/F: In the absence of an external magnetic field, the spins of magnetic nuclei are oriented randomly.
true
T/F: The energies required for NMR spectroscopy are much smaller than those required for IR spectroscopy.
true
T/F: A standard NMR spectrum has, on its left side, the downfield, deshielded side.
true
T/F: Signal averaging and FT-NMR are important techniques that aid in the collection of 13C NMR data.
true
How many carbon absorptions are observed in the 13C NMR spectrum of para-Bromoacetophenone?
6
How many carbon resonance lines would you expect in the 13C NMR spectrum of methylcyclopentane?
4
How many carbon resonance lines would you expect in the 13C NMR spectrum of 1-methylcyclohexene?
7
Consider the -CH2- and -CH3- hydrogens in butane. When comparing the -CH2- and -CH3- hydrogens in butane, it is said that they are...
non-equivalent
Consider the six -CH3- hydrogens in butane. These hydrogens are...
homotopic
Consider the four -CH2- hydrogens in butane. These hydrogens are...
enantiopic
Consider the two -CH2- hydrogen atoms in R-2-Butanol. These two hydrogens are...
diastereotopic
The proton bonded to oxygen in carboxylic acids, in 1H NMR, resonates
far downfield
Which of the following does not possess a conjugated system of pi electrons?
1,4 pentadiene
The bond between carbon atom #s 2 and 3 in butadiene is
shorter
Reaction conditions that include high temperatures generally favor
thermodynamic control
The molecule benzoquinone contains how many hydrogen atoms?
4
Benzoquinone, in Diels-Alder reactions, is a suitable...
dienophile
1,3-Cyclopentadiene, at room temperature, reacts with itself to form a molecule that has exactly how many hydrogen atoms bonded to sp2-hybridized carbon atoms?
4
Extended conjugation in an organic molecule results in
longer-wavelength uv-visible absorptions
The 'L' in LUMO represents.
?
The molecule anthracene contains how many carbon atoms that are bonded to exactly zero hydrogen atoms?
4
Aniline contains which of the following?
nitrogen
The hydrogenation of benzene is
exothermic and endothermic process
There are six benzene molecular orbitals. In the ground state of benzene, how many of these orbitals are bonding?
3
The most stable geometry for 1,3,5,7-cyclooctatetraene is one in which it is
non-planar
Is the cycloheptatrienyl cation aromatic?
yes
The molecule pyrrole contains how many hydrogen atoms?
5
The molecule naphthalene contains how many pi electrons?
10
How many constitutional isomers are there for 'dinitrobenzene'?
3
The hydrogenation reactions of alkenes (for example, hydrogen + ethene = ethane) are typically exothermic reactions. Which of the following dienes, when allowed to react with excess hydrogen, have heats of reaction that are the most negative (i.e. the mos
1,4 pentadiene
How many bonding molecular orbitals are there in 1,3-butadiene?
2
When 2-methyl-1,3-cyclohexadiene is allowed to react with HCl (1 eq), which of the following does not form?
5-chloro-1-methylcyclohexene
Consider reactant A, which can be converted into product B (in one reaction) or product C (in a different reaction). If A forms B reversibly, and A also forms C reversibly...the ratio of B formed to C formed (i.e. [B]/[C]) depends primarily on
relative product stabilities
Diels-Alder reactions require a diene and a dienophile. The reactions occur best when
the dienophile copntains electron withdrawing groups
The chlorine atoms in I (on the board) are
exo
Which of the following regions of the electromagnetic spectrum is the region of longest wavelength?
infrared
Which of the following alkenes has the longest max?
1,2,5,7-octatetraene
There are how many hydrogen atoms in a single molecule of naphthalene?
8
In 2-phenylheptane, how many carbon atoms are bonded to exactly two hydrogen atoms?
4
How many hydrogen atoms are there in a single molecule of p-bromoaniline?
6
Is the heat of hydrogenation of benzene
less negative than expected
1,3-cyclobutadiene is
an extremely unstable diene
1,3,5,7-cyclooctatetraene is
tub-shaped molecule
When 1,3-cyclopentadiene is allowed to react with a strong Bronsted base, the main product that forms is
the aromatic cyclopentadienide anion
Consider the cyclopropenyl cation, radical and anion (C3H3+; C3H3.; C3H3-, respectively). Which of the three of these is considered to be aromatic?
the cation
When molecular bromine reacts with FeBr3, a species forms which acts as an electrophile (and subsequently reacts with benzene). That species is
BR+
There are how many unshared pairs of electrons in the best Lewis Dot structure for the nitronium ion?
4
T/F: Friedel-Crafts alkylation and acylation reactions both result in the formation of new C-C bonds
true
Which of the following is most reactive in electrophilic aromatic bromination reactions?
aniline
Which of the following is least reactive in electrophilic aromatic bromination reactions?
nitrobenzene
The fact that halogen substituents are ortho-para directing substituents is due to their
electron-donating resonance effect
Consider the molecule 2-bromoaniline. Which carbon atom is most reactive toward further electrophilic aromatic substitution in 2-bromoaniline?
#4
Nucleophilic aromatic substitution reactions are best accomplished when the aromatic substrate contains
electron-withdrawing groups
The molecule 'benzyne' undergoes reactions that are best described as
addition reactions
The unsaturation present in benzene is
more difficult
The molecule 3-phenyl-2-butanol contains how many hydrogen atoms?
14
T/F: water is similar to alcohols and phenols in that all three are both weakly basic and weakly acidic.
true
T/F: 2,2,2-trifluoroethanol is a weaker acid than ethanol.
false
T/F: solvation effects play important roles in the relative aqueous-phase acidities of simple alcohols
true
When ketones are allowed to react with NaBH4, the organic product that forms is
secondary alcohol
When primary alcohols are allowed to react with CrO3, the organic product that forms is...
a carboxylic acid
Trimethylsilyl ethers are relatively unreactive but do react with
aqueous acids
Which of the following is most generally utilized when testing for the presence of C=O bonds?
IR spectroscopy
Consider the molecule 2-chloropropane...there are two 'sets' of signals in its 1H NMR spectrum. Which 'set' is more downfield
the set resulting from one hydrogen
There are how many peaks in the carbon-13 spectrum of cyclopentanol?
3
One of the following terms can describe a pair of hydrogen atoms that are likely to show different 1H NMR absorptions. Which one?
diastereotopic
1H NMR spectra for dimethyl ether (CH3OCH3) and acetone (CH3COCH3) each consist of one peak. Which peak is most downfield?
the ether
The molecule cyclobutane has how many peaks in its 13C NMR spectrum?
1
Consider the pi molecular orbitals for 1,3-butadiene. Which are lower in energy?
bonding orbitals
Which of the following does not form when 1,3-butadiene is allowed to react with HBr?
2-bromo-2-butene
The molecule 6-chloro-1-methylcyclohexene contains how many carbon atoms that are bonded to exactly two hydrogen atoms?
3
Generally speaking, if you have a reaction that can go to two products (one the 'kinetic product' and the other the 'thermodynamic product')...raising the temperature at which you carry out the reaction increases the likelihood that which product will for
the thermodynamically-controlled product
The Diels-Alder dimerization of 1,3-cyclopentadiene results in a product that has how many carbon atoms that are bonded to exactly one hydrogen atom?
8
A photon of infrared radiation has________energy than a photon of ultraviolet radiation (p 500)
less
Which of the following has a max with the longest wavelength?
1,3,5,7-octatetraene
The molecular formula for naphthalene is
C10H8
The molecular formula for aniline is
C6H7N
The molecular formula for 2,5-dimethylphenol contains how many hydrogen atoms?
10
Benzene is aromatic. Evidence for the 'aromaticity' of benzene is that its heat of hydrogenation (forming cyclohexane) is
less exothermic than expected
Pyridine..
contains five hydrogen and is aromatic
Which of the following is not aromatic?
benzene, cyclopentadienyl anion, cycloheptatrieny cation are all aromatic
When benzene is converted into chlorobenzene (using FeCl3 and Cl2), the reaction proceeds through a
carboncation intermediate
The best Lewis Dot structure for NO¬2+ is one that has what formal charge on N?
positive
The conversion of benzene into nitrobenzene requires nitric acid and what other reagent?
sulfuric acid
When benzene is allowed to react with acetyl chloride (in the presence of AlCl3), the molecular formula for the organic product that results is
C8H80
When nitrobenzene is allowed to react with chlorine (and FeCl3), the primary organic product that results is
m-chloronitrobenzene
Via resonance (when adjacent to a carbocation) a chlorine atom
donates electrons
Draw the molecule 1-chloro-2-nitrobenzene and number all six of the benzene carbons. Which carbon would you expect the next electrophilic aromatic substitution to occur? In other words, if 1-chloro-2-nitrobenzene is subjected to conditions resulting in it
#4 and #6
When 1-chloro-2-nitrobenzene is converted into 2-nitrophenol (using KOH), the reaction proceeds through a
carbanion intermediate
How many hydrogen atoms are there in benzyne?
4
Another name for styrene is vinyl benzene. When vinyl benzene is allowed to react with H2, Pd (in ethanol), the organic product that forms is
ethyl benzene
When tert-butylbenzene is allowed to react with KMnO¬4¬ (in water), what happens?
there is no reaction
/ 117
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