Reinvestigation of benzothiazoline-2-thione and 2-mercaptobenzothiazole tautomers: Conformational stability, barriers to internal rotation and DFT calculations

Mohamed, Tarek A.; Mustafa, Ahmed M.; Zoghaib, Wajdi M.; Afifi, M. S.; Farag, Rabei S.; Badr, Y.

doi:10.1016/j.theochem.2008.07.037

Cited by 33 publications

(26 citation statements)

References 32 publications

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“…The medium Raman band at 395 cm −1 is assigned to ␦N-C S mode. This is in line with Mohamed et al [24] in the case of benzothiozoline-2-thione.…”

Section: N-c S Vibrationssupporting

confidence: 92%

“…11-15) 1573 and 1245-1143 cm −1 (DFT-mode nos. [22][23][24][25][26][27]. The DFT method is in agreement with experimental data and earlier works [35].…”

Section: C-n and C N Vibrationssupporting

confidence: 87%

“…Krishnakumar and Ramasamy [23] studied the structure and vibrational spectra of 2-(methylthio) benzimidazole using standard basis sets: B3LYP/6-31G* and B3LYP/6-311+G**. Mohamed et al [24] reinvestigated the vibrational spectra of benzoythiazoline-2-thione and 2-mercaptobenzothiazole tautomers. The molecular geometry, vibrational frequencies and NBO analysis of phenylisothiocyanate in the ground state have been calculated by using DFT calculations with 6-311++G(d, p) basis set [25].…”

Section: Introductionmentioning

confidence: 99%

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Vibrational spectroscopic study and NBO analysis on bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) methane using DFT method

Subashchandrabose

Krishnan

Saleem

et al. 2010

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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“…The medium Raman band at 395 cm −1 is assigned to ␦N-C S mode. This is in line with Mohamed et al [24] in the case of benzothiozoline-2-thione.…”

Section: N-c S Vibrationssupporting

confidence: 92%

“…11-15) 1573 and 1245-1143 cm −1 (DFT-mode nos. [22][23][24][25][26][27]. The DFT method is in agreement with experimental data and earlier works [35].…”

Section: C-n and C N Vibrationssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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Vibrational spectroscopic study and NBO analysis on bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) methane using DFT method

Subashchandrabose

Krishnan

Saleem

et al. 2010

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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“…Contini et al [12] stated that MBT exists in the vapor phase only in its tautomeric thione (benzothiazoline-2-thione) form, which contains a C=S bond and a hydrogen bonded to the nitrogen, rather than the thiol form, which contains an endocyclic C=N bond and a hydrogen bonded to sulfur. According to Wu et al [13] and Mohamed et al [14] , thione is the dominant form in the solid state. For a better understanding of the structural differences, the thione form of the MBT molecule is shown in Figure 1.…”

Section: Methodsmentioning

confidence: 99%

TG/FT-IR characterization of additives typically employed in EPDM formulations

2015

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SbstractThermogravimetric analysis coupled to Fourier transform infrared spectroscopy (TG/FT-IR) is a very popular technique for rubbers characterization. It involves analyses of the base polymer and additives. Ethylene-propylene-diene (EPDM) rubbers are frequently investigated by TG/FT-IR; however, the focus has been the degradation temperature range of the polymer. In this study, unvulcanized and vulcanized EPDM rubber and its additives were investigated by TG/FT-IR, without solvent extraction, and in a wide temperature range. Initially, the additives were individually characterized. TG/FT-IR identified the characteristic groups of all the additives analyzed and distinguished them from each other. Afterwards, unvulcanized and vulcanized EPDM rubbers were investigated without prior extraction. TG/FT-IR detected absorptions due to the additives tetramethylthiuram monosulfide and 2-mercaptobenzothiazole. Both of these sulfur-containing additives were present in the EPDM formulation at concentrations of 0.7 phr (0.63 wt %). The TG/FT-IR technique had some limitations, because not all the additives in EPDM rubber were detected. Paraffin oil, stearic acid and 2,2,4-trimethyl-1,2-dihydroquinoline functional groups were not observed in either the unvulcanized or vulcanized EPDM. Nevertheless, in addition to the ability of this method to detect sulfur-containing groups, the lack of a pre-extraction reduces the time and effort required for additive analysis in rubbers.

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“…The thione form has a C=S bond and a hydrogen atom bonded to the nitrogen instead of the sulfur and endocyclic C=N bond (thiol form). According to Wu et al [33] and Mohamed et al [34] , thione is also the dominant form in the solid state.…”

Section: Infrared Analysis Of Additivesmentioning

confidence: 99%

Characterization of Additives Typically Employed in EPDM Formulations by using FT-IR of Gaseous Pyrolyzates

Sanches¹,

Cassu²,

Diniz³

et al. 2014

Polímeros

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Abstract:In this study, Fourier transform infrared spectroscopy (FT-IR) was employed to investigate the gaseous pyrolysis products of ethylene-propylene-diene rubber (EPDM). The objective was to evaluate the potential of FT-IR analysis of gaseous pyrolyzates (PY-G/FT-IR) for characterization of EPDM additives. Two EPDM formulations, containing additives typically employed in EPDM rubbers, were analyzed. Initially, gaseous pyrolysis products from paraffin oil, stearic acid, 2,2,4-trimethyl-1,2-dihydroquinoline, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), and 2-mercaptobenzothiazole (MBT) were characterized separately, and their main absorptions were identified. Subsequently, the gaseous pyrolysis products of raw, unvulcanized, and vulcanized EPDM formulations were analyzed. The similarities observed in the FT-IR spectra of unvulcanized and vulcanized EPDM show that the vulcanization process does not interfere with the pyrolysis products. The identification of the functional groups of the studied additives was possible in both unvulcanized and vulcanized EPDM samples, without solvent extraction. Results also demonstrate that the PY-G/FT-IR technique can identify additives containing sulfur in concentrations as low as 1.4 phr (1.26%) in both unvulcanized and vulcanized EPDM. However, the method showed some limitation due to overlapping and to similarities of TMTM and TMTD PY-G/FT-IR spectra, which could not be distinguished from each other. The PY-G/FT-IR technique is a faster and cheaper alternative to the sophisticated techniques usually applied to detection of additives in rubbers.

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Reinvestigation of benzothiazoline-2-thione and 2-mercaptobenzothiazole tautomers: Conformational stability, barriers to internal rotation and DFT calculations

Cited by 33 publications

References 32 publications

Vibrational spectroscopic study and NBO analysis on bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) methane using DFT method

Vibrational spectroscopic study and NBO analysis on bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) methane using DFT method

TG/FT-IR characterization of additives typically employed in EPDM formulations

Characterization of Additives Typically Employed in EPDM Formulations by using FT-IR of Gaseous Pyrolyzates

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