Organic Chemistry 2 – Assignment
Organic Concepts
1.0 Isonitriles (A) are an important class of compounds because of the versatile reactivity of the
functional group, enabling the preparation of numerous new compounds and natural
products. Isonitriles can be converted to isonitrile dihalides (B), which represents a useful
procedure for temporarily hiding the reactivity of an isonitrile.
1.1 Identify the hybridization state for each highlighted atom in A.
It is sp hybridized.
1.2 One of the carbon atoms in A exhibits a lone pair. In what type of atomic orbital does this
lone pair reside?
The highlighted carbon atom is sp hybridized, so the lone pair occupies an sp hybridized
orbital.
1.3 Predict the C−N−C bond angle in compound A.
The C-N-C bond angle in A is expected to be 180°.
1.4 Identify the hybridization state for each highlighted atom in B.
The nitrogen is sp2 hybridized, carbon atom is sp2 hybridized, and the chlorine atoms are
sp3 hybridized.
1.5 The nitrogen atom in B exhibits a lone pair. In what type of atomic orbital does this lone pair
reside?
The nitrogen atom is sp2 hybridized, so the lone pair occupies an sp2 hybridized orbital.
1.6 Predict the C−N−C bond angle in compound B.
The C-N-C bond angle in B is expected to be approximately 120°.
2.1 On the basis of MO theory, explain why Li2 molecules can exist, but Be2 molecules cannot.
Could the ion Be2+ exist?
The Be2 molecule has eight electrons, of which four are core electrons. The four core electrons
are assigned to σ1s and σ*1s molecular orbitals.) The remaining four electrons are assigned to
the σ2s and σ*2s molecular orbitals, so the MO electron configuration for Be2 is {core
electrons}(σ2s)2(σ*2s)2. This leads to net bond order of 0, so the Be2 molecule does not exist.
Be2+ ion has only four electrons, of which two are core, therefore its electronic configuration
is (σ1s)2(σ*1s)2. The bond order is 0, so Be2+ does not exist.
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, 3.1 Determine the relationship between the two structures below. Are they resonance
structures or are they constitutional isomers?
These structures do not differ in their connectivity of atoms. They differ only in the placement
of electrons. Therefore, these structures are resonance structures, as shown here:
4.1 A mixture of sulfuric acid and nitric acid will produce small quantities of the nitronium ion
(NO2+):
Does the nitronium ion have any significant resonance structures? Why or why not?
The nitronium ion does not have any significant resonance structures because any attempts
to draw a resonance structure will either 1) exceed an octet for the nitrogen atom or 2)
generate a nitrogen atom with less than an octet of electrons, or 3) generate a structure with
three charges. The first of these would not be a valid resonance structure, and the latter two
would not be significant resonance structures.
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Organic Concepts
1.0 Isonitriles (A) are an important class of compounds because of the versatile reactivity of the
functional group, enabling the preparation of numerous new compounds and natural
products. Isonitriles can be converted to isonitrile dihalides (B), which represents a useful
procedure for temporarily hiding the reactivity of an isonitrile.
1.1 Identify the hybridization state for each highlighted atom in A.
It is sp hybridized.
1.2 One of the carbon atoms in A exhibits a lone pair. In what type of atomic orbital does this
lone pair reside?
The highlighted carbon atom is sp hybridized, so the lone pair occupies an sp hybridized
orbital.
1.3 Predict the C−N−C bond angle in compound A.
The C-N-C bond angle in A is expected to be 180°.
1.4 Identify the hybridization state for each highlighted atom in B.
The nitrogen is sp2 hybridized, carbon atom is sp2 hybridized, and the chlorine atoms are
sp3 hybridized.
1.5 The nitrogen atom in B exhibits a lone pair. In what type of atomic orbital does this lone pair
reside?
The nitrogen atom is sp2 hybridized, so the lone pair occupies an sp2 hybridized orbital.
1.6 Predict the C−N−C bond angle in compound B.
The C-N-C bond angle in B is expected to be approximately 120°.
2.1 On the basis of MO theory, explain why Li2 molecules can exist, but Be2 molecules cannot.
Could the ion Be2+ exist?
The Be2 molecule has eight electrons, of which four are core electrons. The four core electrons
are assigned to σ1s and σ*1s molecular orbitals.) The remaining four electrons are assigned to
the σ2s and σ*2s molecular orbitals, so the MO electron configuration for Be2 is {core
electrons}(σ2s)2(σ*2s)2. This leads to net bond order of 0, so the Be2 molecule does not exist.
Be2+ ion has only four electrons, of which two are core, therefore its electronic configuration
is (σ1s)2(σ*1s)2. The bond order is 0, so Be2+ does not exist.
1
, 3.1 Determine the relationship between the two structures below. Are they resonance
structures or are they constitutional isomers?
These structures do not differ in their connectivity of atoms. They differ only in the placement
of electrons. Therefore, these structures are resonance structures, as shown here:
4.1 A mixture of sulfuric acid and nitric acid will produce small quantities of the nitronium ion
(NO2+):
Does the nitronium ion have any significant resonance structures? Why or why not?
The nitronium ion does not have any significant resonance structures because any attempts
to draw a resonance structure will either 1) exceed an octet for the nitrogen atom or 2)
generate a nitrogen atom with less than an octet of electrons, or 3) generate a structure with
three charges. The first of these would not be a valid resonance structure, and the latter two
would not be significant resonance structures.
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