Occurrence of Chromosomal Aberrations in Pre-spermatocytic Cells of Irradiated Male Mice.

one proton on nitrogen, the other must be on oxygen. Acetylglycine shows the same behavior. It can also be concluded that the bisulfate ion is a poor base for exchanging the N-H proton of secondary amides in sulfuric acid. Primary Amides.-The N-H proton magnetic resonance absorption of acetamide has been observed in saturated aqueous solutions at pH 7 and in 100 per cent sulfuric acid. Here, also, exchange of the N-H proton in sulfuric acid appears to be slow in comparison with its relaxation time. By measuring the areas under the absorption peaks it has been possible tentatively to assign O-protonation of acetamide in 100 per cent sulfuric acid. This interpretation is in accord with that of Hantzch, based upon ultraviolet spectroscopy,7 and that of Huisgen and Brade,8 based upon potentiometric pK determinations. Experimental.-All spectra were determined with the Varian 4300 B, 40-mc., 9,400-gauss n-m-r spectrometer, equipped with spinner and superstabilizer. Samples were sealed in 5-mm. o.d. Pyrex tubes. Chemical shifts were calibrated by a combination of the method of side bands9 and the use of toluene markers in capillary tubes as secondary standards. The cryoscopic measurements in 100 per cent sulfuric acid were conducted as described by O'Brien and Niemann.I The N,Ndimethylcyclopropylcarboxamide was kindly supplied by Mr. David Schuster. All other materials were obtained by the purification of samples of commercial origin.