The bromination of para-cresol in the presence of strong acids

Citation

Datin, Richard C. (1927) The bromination of para-cresol in the presence of strong acids. Bachelor's thesis, California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-12062004-130128

Abstract

The purpose of this work has been to determine whether or not the formation of an oxonium compound of a cresol would change the directing influence of the hydroxyl group.

On the theory of electron displacement in derivatives of benzene, Hart has studied the bromination of para cresol in the presence of strong acids; under the conditions employed by Hart, Kendall and Carpenter have shown that two addition products between para cresol and 100% H2SO4 could be isolated. These two compounds have formulae (C7]H7OH)2H2SO34 m.p. 11.0 C. and C7H7OH(H2SO4)2 m.p. 93.5 C. The sharpness of the maximum of the freezing point curve in addition to its high melting point indicates that the latter compound is quite stable. On the basis of the electron displacement theory it would be predicted that the formation of an addition product between para cresol and 100% H2SO4 would change the ortho and para directing hydroxyl (OH) group to a meta directing oxonium (OH(H2SO4)2) group. Due to unexpected sulphonation Hart was unable to draw any conclusion from his results as to whether or not the presence of the strong acid had any influence on the directing power of the hydroxyl group.

Hart carried out the bromination in the absence of a carrier. Prof. Lucas suggested on the basis of considerations taken up in the next section that the presence of a carrier would speed up the bromination and perhaps avoid sulphonation. This work has to do in particular with the carrying out of this suggestion.

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