L4 - Anhydrides

Anhydrides are formed from the reaction of two carboxylic acid as water is continuously being removed.  In Greek, hydride means "water" and anhydride means "without water".  The chemicals are often contained in spacial containers as they will react with anything that has enough water cause a reaction with the anhydride to revert it back to two carboxylic acids.  Since anhydrides do not have water in them, nor ions to make it, they are often favored in manufacturing as an intermediate that causes dissimilar molecules that would not normally react together to reaction and combine into something useful.  Two of the most common anhydrides used are acetic anhydride and maleic anhydride.

Acetic Anhydride

Acetic anhydride is a clear colorless liquid with a strong odor of acetic acid (vinegar).  It is highly corrosive and violently reacts with moisture, alcohols, and any other molecule with a -OH or -H ion that can be easily disassociated  It is primarily used in the manufacturing sector to produce cellulose acetate that can in turn be used to fibers meant for clothing.  Is it also marketed as a purity agent used in manufacturing pharmaceutical projects.   It is also used to make dyes for clothing and can be used in explosives where a source of heat is required to ignite the rest of the explosive.

Maleic Anhydride

According to Huntsman International, maleic anhydride is used in the manufacturing of unsaturated polyester resins (UPR), which in turn are used in the production of lighter, stronger, fiberglass composites for boats, cars, construction, wind turbine blades and a diverse range of consumer products. It is a key ingredient in the manufacture of copolymers that enable the use of more sustainable raw materials, for example to bind wood fibers into plastic, to inhibit corrosion, create protective coatings for wire and to repel water in sunscreens.

Through conversion to fumeric and malic acids, maleic anhydride is a vital component of gelling agents, flavor enhancers and food preservatives. It is also essential to the production of elastane (Spandex) fibers, artificial sweeteners, paper-sizing, water treatments, hardeners for epoxy curing, hairsprays, pharmaceuticals, agricultural chemicals and motor oil additives.

While this course does not require you to know its uses, it is important to know how anhydrides are formed.