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Reaction is a common unit operation in chemical processing which occurs between reactants which can be in the solid, liquid or gaseous state. Reactions can be either exothermic or endothermic, dependent on whether the reaction proceeds with a not outflow of energy, usually heat, or with a net inflow of energy
The speed or rate at which a reaction occurs is dependent, among other variables, on temperature. In order to control a reaction rate, it is essential to have a well-controllable uniform temperature enviroment.
When the reaction occurs in the liquid phase, the principal method of heat distribution is by the use of stirrers or agitators.

Such agitators also serve to maintain a uniform concertration enviroment for the reaction, which is often important. Heat input is effected by the use of electrical heating or steam heating, by using immersion heaters.


The result of any reaction is the formation of one or more different chemical compounds. Consequeently, it may be necessary during a reaction to remove, by some other unit operation, one or more of the reaction products. This necessity is often encountered and it is frequently undertaken by distillation. Equipment designed specifically for this purpose is shown in Section 3 - Commercial Scale Reactors with Distillation Equipment.

In the pharmaceutical and fine chemical industries, reaction chemistry is normally developed in the laboratory, using small scale laboratory type equipment, until it becomes important to scale up the manufacturing level to pilot plant level. The major function of such a pilot plant is to synthesise multi-kilogram quantities of more therapeutic agents needed for toxicological and clinical evalutions.

Borosilicate glass equipment has been used for chemical reactions successfully for many years. The inertness of borosilicate glass is critical where high product purity is essential. Furthemore, the modular construction of glass reaction units permits the high degree of flexbility, especially with smaller scale units. Reactions such as esterification are commonly executed in borosilicate glass.

The consitituent parts required for any reaction system depend on the requirements of the particular reaction involved. The above diagram (see Figure 1) identifies the fundamental constituent parts of a reaction unit. A reaction unit usually consists of the reactor vessel, a means of heating/cooling and string the reactor vessel and an overhead arrangement including some means of feeding the reaction. This brochure outlines typical equipment available and assists in the specification of a reaction unit.