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Chapter 18
Carbonyl Compounds II

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18-00-09T01
Title
Table 18.1 Summary of functional group nomencalture
Caption
Summary of functional group nomenclature.
Notes
Functional groups with higher nomenclature priority are listed first.
Keywords
table, 18.1, functional, group, nomenclature
18-00-28UN
Title
Electrophilicity of Carbonyl Compounds
Caption
Electrostatic potential maps of formaldehyde, acetaldehyde, and acetone.
Notes
A carbonyl carbon is partially positively charged because oxygen is more electronegative than carbon and electrons in the C–O pi bond can be drawn by resonance into an sp3 nonbonding atomic orbital on oxygen, leaving a vacant p orbital on carbon bearing a positive charge. The molecular orbital holding the electrons in the second bond between C and O is a resonance hybrid of a vacant p orbital on carbon next to an occupied sp3 nonbonding orbital on oxygen, and a pi molecular orbital between carbon and oxygen. Carbons attached to the carbonyl carbon alleviate (delocalize) some positive charge on the carbonyl carbon by hyperconjugation but hydrogens attached to the carbonyl carbon cannot do this. Thus, the more hydrogens (and fewer carbons) attached to the carbonyl carbon, the more positive charge on this carbon, and the greater the electrophilicity of the carbonyl compound. Notice that in this figure formaldehyde has more positive charge (blue color) on the carbonyl carbon than acetaldehyde, which in turn has more positive charge than acetone. Formaldehyde is more electrophilic than other aldehydes, which are in turn more electrophilic than ketones.
Keywords
electrophilicity, carbonyl, compounds, formaldehyde, acetaldehyde, acetone, potential, maps
18-01
Title
Figure 18.1
Caption
Orbital picture of bonding in an imine.
Notes
Imines have chemical properties similar to carbonyl compounds because the orbital picture of an imine is similar to the orbital picture of a carbonyl compound. Imines are, however, less electrophilic than carbonyl compounds because nitrogen is less electronegative than oxygen, and does not deplete carbon of as much electron density in an imine as oxygen does in a carbonyl compound.
Keywords
Figure, 18.1, orbital, picture, bonding, imine
18-02
Title
Figure 18.2
Caption
pH-Rate profile for the reaction of acetone with hydroxylamine.
Notes
The pH-rate profile is bell-shaped because at too low a pH the hydroxylamine nucleophile is protonated and unreactive, but at too high a pH a critical O-protonated carbinolamine intermediate cannot be formed, and the reaction never progresses beyond this point to form product. At the optimum pH some unprotonated hydroxylamine is available to initiate the reaction and some O-protonated carbinolamine intermediate can form to complete the reaction sequence.
Keywords
figure, 18.2, pH, reaction, rate, hydroxylamine, acetone
18-02-08UN
Title
In-Chapter Problem 21
Caption
E and Z Stereoisomers of a generalized imine with orbital containing lone pair on nitrogen drawn explicitly.
Notes
The lone pair of electrons has the lowest priority when naming E and Z isomers of imines. In-chapter Problem 21 asks the reader to replace R, R', and X in the generalized pictures in the figure with whatever is necessary to draw the structures of (E)-benzaldehyde semicarbazone, (Z)-propiophenone oxime, and cyclohexanone 2,4-dinitrophenylhydrazone
Keywords
in-chapter, problem, 21, stereoisomers, imine, orbital, lone, pair
18-03
Title
Figure 18.3
Caption
Electrostatic potential maps of acetaldehyde and protonated acetaldehyde.
Notes
Potential maps show that there is more positive charge on a carbonyl carbon when the carbonyl oxygen is protonated than when it is not. O-protonated carbonyls are more electrophilic (susceptible to nucleophilic attack) than neutral carbonyls.
Keywords
figure, 18.3, potential, maps, carbonyl, protonated, aldehyde
18-03-048UN
Title
Retrosynthetic Analysis
Caption
Retrosynthetic analysis involves starting with a product and working backwards step by step to figure out what starting materials need to be used to make the product.
Notes
A useful kind of backward step in retrosynthetic analysis involves what is called "disconnection," the breaking of a bond to produce two fragments, typically a nucleophilic fragment and an electrophilic fragment. These fragments are normally expected to react with one another in the forward reaction sequence, to produce a new bond.
Keywords
retrosynthetic, analysis, disconnection, backward
18-03-149P49
Title
End-of-Chapter Problem 50
Caption
Proton NMR spectrum associated with end-of-chapter Problem 50.
Notes
The proton NMR spectrum in the figure is produced by a compound which results from reacting a precursor with phenylmagnesium bromide followed by acid followed by hot manganese dioxide. Identify the precursor.
Keywords
end-of-chapter, problem, 50, NMR
18-03-161P56
Title
End-of-Chapter Problem 57
Caption
IR and proton NMR spectra associated with end-of-chapter Problem 57.
Notes
A compound with the IR spectrum in the figure undergoes reduction with sodium borohydride followed by acidification. The product produces the NMR spectrum shown in the figure. Identify the starting material producing the IR spectrum and the product producing the NMR spectrum.
Keywords
end-of-chapter, problem, 57, IR, NMR
18-03-162P56
Title
End-of-Chapter Problem 57
Caption
IR and proton NMR spectra associated with end-of-chapter Problem 57.
Notes
A compound with the IR spectrum in the figure undergoes reduction with sodium borohydride followed by acidification. The product produces the NMR spectrum shown in the figure. Identify the starting material producing the IR spectrum and the product producing the NMR spectrum.
Keywords
end-of-chapter, problem, 57, IR, NMR
18-03-182P67
Title
End-of-Chapter Problem 68
Caption
Proton NMR spectrum associated with end-of-chapter Problem 68.
Notes
A compound with the molecular formula C9H10O reacts with methylmagnesium bromide and produces, after acidic workup, a product which generates the proton NMR spectrum shown in the figure. Identify the starting compound.
Keywords
end-of-chapter, problem, 68, NMR
18-03-193P72
Title
End-of-Chapter Problem 73
Caption
Generalized structure of morpholine enamine starting materials referred to in end-of-chapter Problem 73 and plot of Hammett kinetic results referred to in this problem.
Notes
When the morpholine enamines are hydrolyzed under acidic conditions, the Hammett results show that electron-withdrawing groups in the "Z" position speed up the hydrolysis, whereas the hydrolysis is slowed down by electron-withdrawing groups in the "Z" position under basic conditions. Write out the mechanism for the hydrolysis of the enamine shown in the figure and determine which step is rate-determining under acidic conditions and which step is rate-determining under basic conditions.
Keywords
end-of-chapter, problem, 73, Hammett, morpholine, enamine, hydrolysis
18-00-09T01
Title
Table 18.1 Summary of functional group nomencalture
Caption
Summary of functional group nomenclature.
Notes
Functional groups with higher nomenclature priority are listed first.
Keywords
table, 18.1, functional, group, nomenclature

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