A solid state reaction, also called a dry media reaction or a solventless reaction, is a chemical reaction in which solvents are not used. In a normal reaction, the reacting agents, also called the reactants, are placed in a solvent before the reaction can take place. These reactants react to form a new substance. After the reaction is completed, scientists are able to remove the new product from the solvent. A solid-state reaction, however, allows the reactants to chemically react without the presence of a solvent.
The advantages of solid state reactions ripple throughout many industries. It is important to economics because the elimination of solvents means that products will cost less. This, in turn, will make those products cheaper to buy. With normal reactions, scientists need to remove the residual solvent from the resulting product after a reaction has finished. Producing materials from a solid state reaction will mean that scientists are able to bypass the purification process.
Eliminating the solvent from the reaction means that a solid state reaction produces more product than a normal reaction can. It also is more environmentally friendly. Since there is no solvent, there is no waste to eliminate at the end of the reaction.
An example of a solid state reaction revolutionizing other industries is the development of a recyclable catalyst. This catalyst is able to be completely removed and reused at the end of the reaction. The catalyst is first dissolved in the reactants. Once the reactants are introduced to one another, the catalyst slowly precipitates into a sticky solid. The reactants are able to fully react with each other, and the catalyst separates itself from the resulting products and is able to be separated and recycled.
There are several conditions under which this type of reaction can take place. Oven techniques use high temperatures to encourage reactions without solvents. In a melt technique, the reactants are melted together. The melted reactants interact in the liquid state and become a paste which then hardens into a solid. Some reactants are highly reactive in the presence of a gas. Therefore, scientists expose the substance to a stream of reactive gas. This process is called a gas reaction.
Although there are many benefits to developing solid state reactions, there are also many drawbacks. The ideal process should result in a homogeneous, or uniform, substance, and some solid state reactions do not. In addition, these reactions are, for obvious reasons, useless for reactions requiring solvents.