Various Types of Cleavage Planes

Many solid-state reactions of all types rely on cleavage planes [1]. For example a-cinnamic acid 1 (Fig. 2.1.3) or anthracene 14 (Fig.2.1.13) with slightly inclined planar molecules in double or single layers are reactive in both solid-state photolysis and bromination [16]. The molecular packing of 35 is even more favorable for solid-state reactivity at its varied functionality (Fig. 2.1.21) as the molecules lie flat and as there is additional free space between the aromatic rings. The molecules 35 adopt the zwitterionic form with hydrogen bonds exclusively within the double layers. 

Some further interesting systems may be predicted as solid-state reactive at all of the functionalities that are present, as there appear to be no restrictions with 

A similar type of cleavage plane is found in the crystal packing of 37. The crystal water is not in the cleavage plane but it occupies the bottleneck interconnected polar channels. Solid-state reactivity is predicted due to the nonpolar (001) cleavage plane (Fig. 2.1.23). 

Waste-free solid-state syntheses might be particularly valuable in synthesis or derivatization of pharmaceuticals. For example, the potassium-channel activator 38 exhibits a cleavage plane that is reminiscent of the (010) cleavage plane of a-cinnamic acid 1 (Fig. 2.1.3) even though the hydrogen bond dimers in the double layers consist of 3D-molecules (Fig. 2.1.24). Clearly, solid-state reactivity is predicted and important chemical selectivities are expected. 

The calcium channel modulators 39 and 40 might be suitable candidates for solid-state reactions. The skew cleavage plane between monolayers approximately under (110) in 39 (Fig. 2.1.25) appears very suitable for release of pressure by 

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