Abstract
A spectrophotometric method, based on the use of a diode array spectrophotometer, is proposed in order to determine the pKa of pyrrolidinedithiocarbamic (HPyr-I) and piperidinodithiocarbamic (HPip-II) acids. The high speed of data acquisition of the equipment made it possible to minimize the problem of acid decomposition. The values obtained were 3.10(I) and 3.51(II) in I = 0.50 mol L-1 (NaClO4) at 25.0 °C, and are consistent with the acid decomposition mechanism. A discussion is presented based on the shape of the compound spectra in acidic and basic media and their relation to the order of the pKa values for I and II.
Highlights
Dithiocarbamates (DTC) have been widely applied in several industries, agriculture, medicine, organic synthesis, and in analytical chemistry[1,2,3,4,5,6,7,8,9,10]
The low stability of the DTC in acidic media has been indicated as the major limitation to the use of these versatile compounds
Zahradnick and Zuman[11] first studied the decomposition reaction, and Chakrabarti et al.[12,13,14,15,16] proposed a degradation mechanism which may be related to the acidic form, represented by an unstable intermediate and generating an amine and carbon disulfide, according to the reaction: (1). These authors proposed that the instability of the intermediate, whose structure is presented in the Fig. 1, is due to the positive charge density in the carbon and nitrogen atoms of the carbamate bond (N-C), which induces the molecule decomposition in acidic media
Summary
Dithiocarbamates (DTC) have been widely applied in several industries (e.g. rubber), agriculture, medicine, organic synthesis, and in analytical chemistry (especially inorganic species analysis)[1,2,3,4,5,6,7,8,9,10]. Zahradnick and Zuman[11] first studied the decomposition reaction, and Chakrabarti et al.[12,13,14,15,16] proposed a degradation mechanism which may be related to the acidic form, represented by an unstable intermediate and generating an amine and carbon disulfide, according to the reaction:. These authors proposed that the instability of the intermediate, whose structure is presented, is due to the positive charge density in the carbon and nitrogen atoms of the carbamate bond (N-C), which induces the molecule decomposition in acidic media.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
