Synthesis and High-resolution Mass Spectrometric Elucidation of a Novel Symmetrical N,N′-Hexamethylene Bis-Thiourea Derivative

Abstract

Aims: This study aimed to synthesise and elucidate a novel symmetrical bis-thiourea derivative, N,N′-hexamethylene bis[borneoylcarbamate] N,N′-bis(phenylthiourea), obtained from N,N′-hexamethylene bis[borneoylcarbamate] and phenyl isothiocyanate. Study Design: An experimental synthetic organic chemistry study was conducted to optimise solvent, catalyst, reaction time and temperature for improving the isolated product yield and confirming the structure of the target compound. Place and Duration of Study: The work was carried out in the Department of Chemical Technology, Navoi State University of Mining and Technologies, Uzbekistan, between January and July 2025. Methodology: The biscarbamate precursor (0.0025 mol, 1.11 g) was reacted with phenyl isothiocyanate (0.0050 mol, 0.676 g) in the presence of triethylamine in N,N-dimethylformamide. Reaction conditions were varied using different solvents, base catalysts, reaction times and temperatures from 0°C to 60°C. The isolated crystalline product was purified by recrystallisation and examined using thin-layer chromatography, ATR-FTIR spectroscopy and high-resolution electrospray ionisation mass spectrometry in positive-ion mode. Results: The highest isolated yield, 62.2%, was obtained at 30°C after 6 h in DMF with triethylamine. Lower temperatures gave reduced yields, whereas temperatures above 30°C decreased the yield from 58% at 40°C to 48% at 60°C. FTIR analysis showed disappearance of the precursor carbamate ester C=O band near 1730 cm⁻¹ and the appearance of a diagnostic ν(C=S) band at 632 cm⁻¹. HR-ESI-MS gave a dominant fragment at m/z 476.27848, assigned to [C28H35N4O3]+, with a mass error of 0.26 mDa (0.55 ppm). Conclusion: The results support the formation of the proposed symmetrical bornyl-functionalised bis-thiourea under mild reaction conditions.