Inorganic chemistry, thehigh dilution principle is a strategy for somemacrocyclization reactions, i.e. the synthesis ofmacrocycles. Unlike the synthesis of 5- and 6-membered rings, the preparation of larger rings competes unfavorably with polymerization reactions.Polymers arise from coupling of long chain precursors. Such reactions are disfavored when the acyclic compounds are dilute.[1] Although high dilution reactions can be conducted in a batch reactor with large volumes ofsolvent, an alternative practical implementation entails slow addition of reactants, under conditions that the reactants are more rapidly consumed than the rate of addition. Typically, additions use one or moresyringe pumps. Illustrative is the synthesis of thiacyclopentadecane from 1,14-dibromotetradecane and sodium sulfide in 45% yield:
A range of specialized glassware[2] and instrumentation are often used, e.g.syringe pumps.
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