Precedence of functional groups

There are no simple rules to follow that dictate which is the parent function, and we suggest that the order of precedence of functional groups set by Chemical Abstracts be used whenever possible (see Table 7-1). By this system, the OH group takes precedence over hydrocarbons, and Compound 1 therefore is named as an alcohol, not as an alkene. 

In naming compounds that contain more than one functional group, the IUPAC has established an order of precedence of functional groups. Table 12.1 gives the order of precedence for the functional groups we have studied so far. 

Order of precedence of functional groups A system for ranking functional groups in order of priority for the purposes of IUPAC nomenclature. 

The symbol preceding a functional group means that the values refer to the substitution of that group on an aromatic ring. 

The symbol preceding a functional group means that the values refer to the substitution of that group on an aromatic ring. A % symbol preceding a functional group indicates that the substituent can be added in either of two orientations and that the correct choice needs to be made. 

Since quenching the reaction or adding a stoichiometric excess of one reactant is seldom economical, the commercial practice is to add a specific amount of a monofunctional reactant in the synthesis of polyesters, nylons, and other similar polymers. In these cases, a functionality factor / is used that is equal to the average number of functional groups present per reactive molecule. While the value of / in the preceding examples has been 2.0, it may be reduced to lower values and used in the following modified Carothers equation ... 

In aliphatic compounds, reactions of functional groups are often modified very significantly by an adjacent carbonyl group. As would be expected from the discussion in the preceding section, the reactions of certain substituents a and y to pyridine-like nitrogen atoms in azole rings are similarly influenced. Such effects on substituents can be classified into six groups. 

The presence of functional groups in the heterocycle frequently determines the nature of the photoreaction observed. The major product of irradiation of 2-methoxyfuran (191) in the gas phase or in solution is the lactone (192).157 Similarly, 2-nitrofuran (193) undergoes a photoreaction typical of a,f -unsaturated nitro compounds to give the oxime (194) by the pathway shown in Scheme 13.158 A different process is observed, however, on irradiation of thenitrovinylbenzo[6]furan(195) to give the 6-hydroxy-l,2-oxazine(196)159 this transformation is viewed as proceeding via an electrocyclization pathway (Scheme 14) for which there is a precedent in the known photochromism of nitrostyrenes. 

The preceding volume on The Chemistry of Organic Germanium, Tin and Lead Compounds in The Chemistry of Functional Groups series (S. Patai, Ed.) appeared in 1995. The appearance of the present two-part volume seven years later reflects the rapid growth of the field. 

The preceding volume on The chemistry of organic silicon compounds (Vol. 2) in The Chemistry of Functional Groups series (Z. Rappoport and Y. Apeloig, Eds.) appeared in 1998. It followed an earlier volume with the same title (S. Patai and Z. Rappoport, Eds.) published in 1989 (now referred to as Vol. 1) and an update volume The silicon-heteroatom bond in 1991. The appearance of the present volume only three years after the three parts of Vol. 2 reflects the continuing rapid growth of many sub-fields of organosilicon compounds and their chemistry. 

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