The very strong 1560hyphen;cmminus;1band of the Nhyphen;substituted amide group has been assigned previously either to ngr;(Csngbnd;N) or to dgr;(Nsngbnd;H). This investigation consisted of a study of the frequency shifts of this and other bands in the infrared spectra of several Nhyphen;butylhyphen; and N,Nhyphen;dibutylhyphen;ethanamides upon substitution of chlorine and fluorine in the 2 position. On the basis of these shifts and other properties of the band in question, observed in the spectra both of the pure compounds and of their CCl4solutions, it is concluded that the ngr;(Csngbnd;N) assignment is correct. The apparent absence of the corresponding band from the spectrum of the N,Nhyphen;disubstituted amide group is explained by the accidental degeneracy of ngr;(Cdblbnd;O) and ngr;(Csngbnd;N). Other bands were cataloged and assigned where possible.
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