Nonprotonated benzene carbons

B,j3,B"-Trichloroborazine forms white crystalline needles, m.p. 83.9 to 84.5°. It is extremely sensitive to moisture and decomposes violently in water. It is soluble without decomposition in anhydrous nonprotonic organic solvents such as benzene, ethyl ether, and carbon tetrachloride. 

The nonequivalence of some signals that are equivalent in solution NMR complicates the interpretation of the 13C CP/MAS NMR spectra of azo dyes, even for simple compounds where the chemical shifts measured in solution and their interpretation are available. The dipolar dephasing experiment permits the selective measurement of nonprotonated carbon (i.e. with no directly bound hydrogen). We have used Q,Ds deuterated isotopomers88 in the analysis of the 13C CP/MAS spectra of azo dyes. I3C CP/MAS NMR spectra of 4-[/V,/V-bis(2-hydroxyethyl)amino]azobenzene (28), 2-hydroxy-5-ter -butylazo-benzene (29) 4-(Ar,A-dimethylamino)azobenzene (30), 4-methoxyazobenzene (31) and 4-hydroxybenzene (32) were recorded. 

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