Spectroscopic characterization of 1:1 complexes of some carbon acids activated by two sulfonyl groups with 1,5,7-triazabicyclo[4.4.0]dec-5-ene in acetonitrile

• The mass spectroscopy investigation of the ionization of a series of disulfonyl carbon acids by a strong base 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) in acetonitrile was presented.
• The data obtained from ESI-MS experiments allow to describe the proton transfer reaction and to establish the fragmentation pathways for the conjugate carbanions.
• The calculated heats of formation for ethylsulfonyl carbanions correlate well with para-substituent on phenyl ring.

The series of six carbon acids activated by two sulfonyl groups have been synthesized and the products of their deprotonation in acetonitrile solution by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) were defined by electrospray ionization mass spectrometry method. The deprotonation of carbon acids and derivative fragmentary carbanions at various cone voltage are compared. Substituent effect on the fragmentation of molecular anions and heats of formation are reported. The fragmentation pathways of the carbanions of studied carbon acids are proposed and the differences in fragmentation of these ions are discussed. The calculated heats of formation of molecular and fragmentary carbanions reveal good Hammett plots against σ values.

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