Collect. Czech. Chem. Commun. 1994, 59, 1368-1383

Dehalogenation of Chlorobenzenes with Sodium Dihydridobis(2-methoxyethoxo)aluminate

Jaroslav Včelák, Anna Friesová, Roman Řeřicha and Jiří Hetflejš

Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 165 02 Prague 6-Suchdol, Czech Republic


The dehalogenation of a series of 9 mono- to pentachlorinated benzenes with the title hydride in toluene has been found to be first order in the substrate and half order in the hydride. The reactivities of the chlorobenzenes, expressed by rate constants for the first-step dehalogenation, increased with increasing number of chlorine atoms over three orders of magnitude. The rate data revealed the unexpected acceleration of benzene formation during exhaustive dehalogenation of the higher chlorinated benzenes. For comparison, dehalogenation of several isomeric dibromobenzenes and bromochlorobenzenes with the same hydride and the product distribution for the dehalogenation of some chlorobenzenes with LiAlH4 are also reported.