Heteroatom-Containing Functional Groups

I promise this is the last chapter on formal nomenclature. 

Amines are the class of compounds obtained when the hydrogen atoms of ammonia are replaced by carbon functionality. We describe amines as primary, secondary, and tertiary according to the number of the hydrogens that are replaced. Thus, RNHj is a primary amine, RjNH is a secondary amine, and R3N is a tertiary amine. If all of the hydrogen atoms of the ammonium ion, [NHJ+, are replaced by alkyl groups, this is described as quaternary ammonium salt, [R NJ+X . 

As we saw in Chapter 2, ammonia has a pyramidal structure with a lone pair of electrons that is associated with its basicity (4.3). The arrow next to the molecule shows the direction of the resultant molecular dipole moment. One of the earliest pieces of evidence for the structure of ammonia was that it has a dipole moment, symbol p. The N-H bond is polarized such that there is a small positive charge on hydrogen and a small negative charge on nitrogen. The resultant molecular dipole when these three bond dipoles are summed lies along the threefold symmetry axis of the molecule. For those of you who have studied vector algebra, this is a vector sum. 

Quick Digression on Dipole Moments and Hydrogen Bonds 

Because dipoles are attracted to each other (the positive end of one dipole is attracted to the negative end of another), compounds with permanent dipole moments tend to have higher melting and boiling points than those that do not. Thus, 1,2-dichlorobenzene, which has a dipole moment, boils at 180 °C, while 1,4-dichlorobenzene, which has no dipole, boils at 174 °C. 

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Hetastarch, 4 112 Heter-ionic interactions, 8 77 Heteroatom-containing functional groups, flash vacuum pyrolysis and,... 

As shown by Gaylord, lithium aluminum hydride reduces virtually every heteroatom containing functional group known. This section will explore the reduction of several heteroatom-containing functional groups that are commonly seen in synthesis. 

Table 4.3 H and chemical shifts in and near heteroatom-containing functional groups. ...

Radical ROP is expected to be a useful tool for constmcting various polymers bearing heteroatom-containing functional groups, which are not attained by chain polymerization of vinyl monomers. Those functional groups incorporated into the polymers serve as cleavable points, leading to the... 

Some heteroatom-containing functional groups that possess double bonds can be electron donating if the heteroatom rather than the double-bonded carbon is attached to the electron-deficient system by a single bond. Esters (shown in Figure 3.18), amides, carbonates, carbamates, amidines, and guanidines are a few of the functional groups for which this is true. It should be... 

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