Functional groups naming precedence

Systematic names formed by applying the principles of substitutive nomenclature are single words except for compounds named as acids. First one selects the parent compound, and thus the suffix, from the characteristic group listed earliest in Table 1.7. All remaining functional groups are handled as prefixes that precede, in alphabetical order, the parent name. Two examples may be helpful ... 

Among oxygen containing groups, a higher oxidation state takes precedence over a lower one in deter-rnining the suffix of the substitutive nane. Thus, a compound that contains both an alcohol and an aldehyde function is named as an aldehyde. 

Name Part 1. The Suffix Functional-Group Precedence... 

The second compound above raises an important issue how do you name the functional group when you have two functional groups in a compound One will go in the suffix of the name and the other will be a prefix in the substituent part of the name. But how do we choose which one goes as the suffix of the name There is a hierarchy that needs to be followed. The six groups shown above are listed according to their hierarchy, so a carboxylic acid takes precedence over an alcohol. A compound with both of these groups is named as a ketone and we put the term hydroxy in the substituent part of the name. 

The hydroxyl group has precedence over double bonds and triple bonds in deciding which functional group to name as the suffix. 

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. 

Radicofunctional Nomenclature. The procedures of radicofunctional nomenclature are identical with those of substitutive nomenclature except that suffixes are never used. Instead, the functional class name (Table 1.9) of the compound is expressed as one word and the remainder of the molecule as another that precedes the class name. When the functional class name refers to a characteristic group that is bivalent, the two radicals attached to it are each named, and when different, they are written as separate words arranged in alphabetical order. When a compound contains more than one kind of group listed in Table 1.9, that kind is cited as the functional group or class name that occurs higher in the table, all others being expressed as prefixes. 

The naming precedence for the functional groups is based on the most oxidized, as shown in the table below. The prefix identifies the position and groups attached to the root chain. The suffix identifies the functional group. Numbering is from the end of the root chain that gives the functional group the lowest number. 

Compounds with two functional groups are named using the higher-precedence group for determining the root numbering and for the group suffix. 

When necessary, the position of the functional group is indicated by a number immediately preceding the name of the alcohol or immediately preceding the suffix. The most recently approved lUPAC names are those with the number immediately preceding the suffix. However, names with the number preceding the name of the alcohol have been in use for a long time, so those are the ones most likely to appear in the literature, on reagent bottles, and on standardized tests. They will also be the ones that appear most often in this book. 

The lUPAC system uses a suffix to denote the amine functional group. The e at the end of the name of the parent hydrocarbon is replaced by amine —similar to the way in which alcohols are named. A number identifies the carbon to which the nitrogen is attached. The number can appear before the name of the parent hydrocarbon or before amine. The name of any alkyl group bonded to nitrogen is preceded by an N (in italics) to indicate that the group is bonded to a nitrogen rather than to a carbon. 

The lists of regulated dangerous goods in transportation include many chemical prefixes that codify the structure of molecules, usually organic. Over time, many conventions have arisen that result in the acceptance of today s somewhat inconsistent scheme. On occasion, these prefixes may be placed in the centre of a chemical name, preceding a functional group or atom, or, very rarely, at the end of a name. 

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