A Colour Reaction for Aromatic Amidines


Ekeley and Ronzio1 have described a series of coloured compounds which are obtained when aromatic amidines are heated with glyoxal in alkaline solution. The reaction is complex, and the results are uncertain and dependent on the conditions employed. By heating with a very small amount of glyoxal at pH 9 in the presence of a borate buffer, the reaction is made much more sensitive and reliable, and is suitable for the quantitative estimation of amidines down to 1 in 100,0002. The buffer is made up from 4 gm. of boric acid neutralized in hot solution with caustic soda to pH 9, and diluted to 100 ml. The glyoxal reagent is a 0·5 per cent aqueous solution of glyoxal sodium bisulphite

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Ekeley, J. B., and Ronzio, A. R., J. Amer. Chem. Soc., 57, 1353 (1935).

  2. 2

    Evans, D. G., Fuller, A. T., and Walker, J., Lancet, ii, 523 (1944).

  3. 3

    Devine, J., Ann. Trop. Med. and Parasitol., 38, 35 (1944).

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.