Introduction to Crystallization of Fine Chemicals and Pharmaceuticals - Molecules: Nucleation, Aggregation and Crystallization - page 145

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Introduction to Crystallization of Fine
Chemicals and Pharmaceuticals
Åke C. Rasmuson*
This chapter presents an introduction to crystallization of organic fine chemicals
and pharmaceutical compounds, written for newcomers to the field. The cover-
age includes the fundamental concepts of solubility, supersaturation, nucleation,
growth, and polymorphism. We will also discuss the control of crystal size dis-
tribution, crystal shape and purity, and specifically address cooling crystalliza-
tion and reaction crystallization processes.
Keywords: Crystallization; solubility; supersaturation; nucleation; growth;
polymorphism; size; shape; purity; control.
Introduction
In a crystallization process, the substance is separated in solid crystalline
form from a solution or a melt. Crystallization is a unit operation of great
industrial importance. Production of pure sugar and table salt are old and
well-known crystallization processes, and large volumes of inorganic salts
such as chlorides, sulphates and chlorates are produced via crystallization.
In addition, crystallization is a frequently used unit operation in the phar-
maceutical industry and in the production of organic fine and specialty
chemicals.
Crystallizations are complicated processes, since they involve discrete
solid particles, and the physical course of events is particularly sensitive
*Department of Chemical Engineering and Technology, Royal Institute of Technology,
SE-10044 Stockholm, Sweden. E-mail: [e-mail].