Processes Known, but not Used for Safety Reasons

Some processes have been known and investigated for a long time, even over decades, but are not used for industrial production or even for common laboratory-scale practice. Although promising, safety reasons may restrict widespread permission to use them or render them inconvenient. The processes are investigated but at extreme dilution or in complex special apparatus. 

The aromatic substitutions give rise to defined, characteristic substitution patterns. 

According to the information given above, several reasons exist for why promising processes actually do not find application. Literature descriptions refer especially to the following reasons  

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