Decomposition of a Diazonium Salt

Solvolytic Decomposition of Benzenediazonium Tetrafluoroborate1

Adapted from reference 1 by J. M. McCormick

Last Update: January 17, 2012

 

Introduction

The decomposition of benzenediazonium tetrafluoroborate in aqueous solution will be studied by following the change in p[H+] as a function of time.  Please refer to the literature procedure for the necessary background and procedure.1

 

Experimental

You will be provided with benzenediazonium tetrafluoroborate synthesized according to a literature procedure.2  CAUTION! Aryldiazonium salts are explosive, and while the compound used here is one of the most stable of these salts, care should be taken in handling it.

 

You will use a Vernier pH electrode interfaced to a computer using the LabPro interface and LoggerPro software.  Click here to review the use LoggerPro.  You will do a two-point calibration of the electrode (pH 4 and 7), and the calibration will need to be repeated at each new temperature as the pH is temperature-dependent. 

 

The reaction will be run in a water-jacketed reaction vessel attached to a water bath.  The initial temperature at which the reaction is to be studied is 25 °C.  Several other temperatures are to be studied so that the reaction’s activation energy can be determined from an Arrhenius plot.

 

Results

Present a typical kinetics run and any graphs that you used to determine the order with respect to the reactant.  Present your Arrhenius plot and the activation energy with associated uncertainty.

 

Conclusions

Discuss the accuracy and precision of your results.  Put your results in the context of this reaction of other aryldiazonium compounds.3

 

References

1. Wiseman, F. L. J. Chem. Educ. 2005, 82, 1841.  Click here to obtain this file in PDF format (Truman addresses only).
 
2. Dunker, M. F. W.; Starkey, E. B. and Jenkins, G. L. J. Am. Chem. Soc. 1936, 58, 2308-2309. Click here to download this paper as a PDF file (Truman addresses only).
 
3. Crossley, M. L.; Kienle, R. H. and Benbrook, C. H. J. Am. Chem. Soc. 1940, 62, 1400-1404. Click here to obtain this paper as a PDF file (Truman addresses only).