Acid Derivatives

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Acid Derivatives introduces five classes of organic compounds: acid chlorides, amides, acid anhydrides, esters, and nitriles. The structure, preparation, and reactions of each of these five classes are studied, as well as chemical and spectroscopic analysis. The unit concludes with presentation of organic group nomenclature priorities.

The unit begins with the structures of these five classes of compounds and how these structures are generally written. Students are reminded throughout the unit that these classes of compounds are strongly related. The reactions of one well may be seen again as the preparation for another. This helps the student understand that the mastering of five classes in one unit is not unreasonable. In each of the five classes, nomenclature, physical properties, preparations, and reactions are addressed. The unit concludes with a section on chemical and spectroscopic analysis of all five classes.

Following a discussion of the nomenclature of acid chlorides, the most commonly referenced preparation is presented: nucleophilic acyl substitution using a reagent such as thionyl chloride with carboxylic acid. The reactions of acid chlorides addressed include Friedel-Crafts acylation, reaction with organo cadmium, the Rosenmund reduction, and a series of substitution reactions.

The study of amides also begins with a section on nomenclature. In the preparations of amides, the nucleophilic acyl substitution using acid chlorides with ammonia or amines is addressed, as are those using esters and anhydrides with ammonia. Because amides are the most stable of the acid derivatives, they are not very reactive, so only two new reactions are addressed and several old ones are reviewed.

After a section addressing nomenclature and properties of esters, the preparations are considered. Most of these preparations are review, but several additional points are addressed. The preparations considered are preparation from acid chlorides, the Fischer esterifications, lactone formation, and the reaction of alcohols with anhydrides. Mechanisms for many of these are addressed, particularly the two mechanisms for the Fischer esterification and where beneficial, these mechanisms are animated. The reactions of esters considered include hydrolysis in an acid, hydrolysis in a base, trans-esterification, ammonolysis, reaction with Grignard, and reduction of esters. In this last one, four methods of reduction are considered with advantages and disadvantages of each.

Analysis of acid derivatives includes test tube analysis where feasible, such as the ability of acid chlorides to form precipitates with silver nitrate solutions. Spectroscopic analysis includes characteristic signals of infrared and NMR for the five classes. The unit concludes with a section addressing nomenclature priorities.



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