Naming, acid anhydrides acyl groups

In naming carboxylic acid anhydrides in which both acyl groups are the same we simply specify the acid and replace acid by anhydride When the acyl groups are dif ferent they are cited m alphabetical order... 

Acid anhydrides, as their name implies, are formed from the dehydration reaction of two carboxylic acid groups (Fig. 72). Anhydrides are highly reactive toward nucleophiles and are able to acylate a number of the important functional groups of proteins and other macromolecules. Upon nucleophilic attack, the anhydride yields one carboxylic acid for every acylated product. If the anhydride was formed from monocar-boxylic acids, such as acetic anhydride, then the acylation occurs with release of one carboxylate group. However for dicarboxylic acid anhydrides, such as succinic anhydride, upon reaction with a nucleophile the ring structure of the anhydride opens, forming the acylated product modified to contain a newly formed carboxylate group. 

Unsymmetrical anhydrides are those having two different acyl groups. They are named by arranging the names of the two parent carboxylic acids and following them with the word anhydride. The names of the carboxylic acids may be arranged by size or alphabetically. For example ... 

Acid anhydrides are classified as symmetrical if both acyl groups are the same. Symmetrical acid anhydrides are named by replacing the acid ending of the carboxylic acid with the word anhydride. For example,... 

Mixed anhydrides are named by identifying the two parent carboxylic acids from both acyl groups and placing those names in succession, in alphabetical order, without the acid part of the name followed by the word anhydride. 

In this chapter, we will be discussing the chemistry of carboxylic acids, esters, acyl halides, anhydrides, and amides. This is dominated by substitution, where one group is exchanged with another. Substitution is NOT possible for aldehydes and ketones, as you can t displace H or — they are hopeless leaving groups. First, let s review some nomenclature. The suffix for carboxylic acids is -oic acid and the carbonyl of the acid is always numbered as C-1. The acid takes precedence over most other functional groups. Some examples are shown in Figure 15.1. Notice that when we have both a ketone and an acid in the molecule, it is named as a carboxylic acid, and the ketone is described as oxo. ... 

Oxazolones are simply cyclic anhydrides of A-acyl-a-amino acids, and are constructed in the way that this implies. If the nitrogen also carries an aUcyl group, cyclisation " can only lead to an overall neutral product by adopting a zwitterionic stracture, for which no neutral canonical form can be written - a mesoionic structure. Mesoionic oxazolones (named miinchnones by Huisgen after their discovery at the University of Munchen, Germany) undergo ready dipolar cycloadditions,with loss of carbon dioxide from the initial adduct the examples" show the conversion of a miinchnone into a mesoionic thiazolone and into an imidazole. 

The introduction of 0-acyl thiohydroxamates (mixed anhydrides of carboxylic acids with thiohydroxamic acids) by the Barton group in 1983 [1] has provided one of the mildest and most convenient and versatile sources of carbon-centered radicals which fulfill the above criteria, and can hence, in Sir Derek s own words, be described as disciplined . Since their preparation from carboxylic acids is extremely straightforward, and since they have demonstrated a rapacious radicophilicity in a wide variety of very useful transformations, it is no surprise that these derivatives are commonly named either as Barton esters or by the acronym PTOC (pyridine thiocarbonyl) esters. The ongoing development of this chemistry has been summarized over the years in several useful reviews [2], and some of the tried and tested experimental procedures have also been collated [3]. 

---