p-Toluenesulfonyl Isocyanate: Environmental Fate，Reagent and Impact on LIB Electrolyte

p-Toluenesulfonyl isocyanate is a liquid with moderate vapor pressure that reacts rapidly with water to form the corresponding carbamic acid, which in turn undergoes immediate decomposition to carbon dioxide and p-toluenesulfonamide. Mobility in soil, volatilization, and biodegradation are not important environmental fate properties due to the rapid rate of hydrolysis: the supporting chemical p-toluenesulfonamide is not readily biodegradable. The rate of atmospheric photooxidation is slow; however, this substance will likely react with moisture in the atmosphere. p-Toluenesulfonyl isocyanate is expected to have low persistence and low bioaccumulation potential. Acute oral toxicity of p-toluenesulfonyl isocyanate is low. In a combined oral gavage repeated dose/reproductive/developmental toxicity study in rats with the supporting chemical p-toluenesulfonamide, dose-related hypersalivation was noted in all treatment groups.

p-Toluenesulfonyl isocyanate as a novel derivatization reagent

Tibolone [7α, 17α-7-methyl-17-hydroxyl-19-norpregn-5(10)-en-20-yn-3-one], also called 7-methyl-norethynodrel or Org OD14, is a synthetic steroid used in the hormonal replacement therapy (HRT) for postmenopausal women since 1985. It is well known that oxygen atom possessed by hydroxyl has a weak nuclephilicity owing to its low electron density. Therefore, the derivatization procedures for hydroxyl compounds need either high temperature or long reaction period, which makes the derivatization not so convenient to be utilized. Sulfonyl isocyanates are a series of compounds which have the general formula RSO2NCO. Here we reported p-toluenesulfonyl isocyanate as a novel derivatization reagent for hydroxyl compounds. Using this facile liquid phase derivatization procedure, an LC–ESI/MS bioanalytical method for the two 3-hydroxyl metabolites of tibolone was developed and validated to achieve an LOQ of 100 pg/ml in human plasma. In our study, we found that the derivatization reaction of p-toluenesulfonyl isocyanate with 3α-hydroxyl-7-methyl-norethynodrel and 3β-hydroxyl-7-methyl-norethynodrel can be accomplished in 2 min under room temperature, and generated p-toluenesulfonylcarbamic ester.[1]

The derivatization reaction can be accomplished in 2 min under room temperature without the existence of catalyse. A highly sensitive analytical method for the two pharmacologically active 3-hydroxyl metabolites of tibolone in human plasma was developed using LC–ESI/MS after derivatization by p-toluenesulfonyl isocyanate. The use of chemical derivatization greatly improved analyte's sensitivity in electrospray ionization, which in turn enabled us to achieve the desired lower limit of quantitation at 100 pg/ml. p-Toluenesulfonyl isocyanate has been demonstrated to be an attractive derivative reagent for hydroxyl compounds.

P-toluenesulfonyl isocyanate on the solvation structure and solid electrolyte

Among the series of sulfur-containing additives, P-toluenesulfonyl isocyanate (PTSI) possesses good physical properties and a wide electrochemical window. The LUMO and highest occupied molecular orbital (HOMO) of PTSI are lower than those of common solvents and additives utilized in LIBs, which indicates that PTSI readily accepts electrons as well as possesses a high oxidation potential. A comprehensive theoretical analysis is of great significance in thoroughly investigating the fundamental chemistry and the underlying mechanism involved in Li+-ion electrolyte environment with PTSI additives. In this study, we systematically explored the influences of the p-Toluenesulfonyl Isocyanate additive in the LiPF6/EC/DMC electrolyte on the graphite anode under high temperatures by combining MD and AIMD simulations. The solvation structure of the LiPF6/EC/DMC electrolyte with and without the PTSI additive and their detailed reduction behaviors on graphite anode was obtained. Our simulations demonstrated that the addition of p-Toluenesulfonyl Isocyanate additive changed the first solvation shell of Li+, suppressing electrolyte components decomposition and thus a much more stable SEI film on graphite anode at evaluated temperatures.[2]

The influence of the p-Toluenesulfonyl Isocyanate additive in the LiPF6/EC/DMC electrolyte on the solvation structure and SEI formation mechanism under high temperatures was systematically elucidated using MD and AIMD simulations. An in-depth understanding of the underlying mechanism of how PTSI participates in the interfacial chemistries as an electrolyte additive was also provided. Overall, our research provides a comprehensive understanding of SEI formation mechanisms utilizing the p-Toluenesulfonyl Isocyanate additive under high temperatures and will further serve to investigate more novel solvent/additive combinations to meet the specific requirements for improving the electrochemical performance of LIBs.

References

[1]Zuo, Ming et al. “p-Toluenesulfonyl isocyanate as a novel derivatization reagent to enhance the electrospray ionization and its application in the determination of two stereo isomers of 3-hydroxyl-7-methyl-norethynodrel in plasma.” Journal of chromatography. B, Analytical technologies in the biomedical and life sciences vol. 814,2 (2005): 331-7. doi:10.1016/j.jchromb.2004.10.054

[2]Wang, Qianqian et al. “The influence of P-toluenesulfonyl isocyanate on the solvation structure and solid electrolyte interphase formation on graphite anode under high temperatures.” Journal of colloid and interface science vol. 679,Pt B (2025): 1010-1020. doi:10.1016/j.jcis.2024.10.153

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