P-tolyl Isocyanate Research Articles

Preparation and post-modified of dicationic ionic liquid stationary phase and their application in mixed-mode liquid chromatography

This work prepared two dicationic ionic liquid stationary phases for mixed-mode chromatography via thioe-ene click reaction, one of which was post-modified by p-tolyl isocyanate. The successful synthesis of two stationary phases was demonstrated by several characterizations. The separation of a wide range of substances, including nucleosides and bases, alkylbenzene, polycyclic aromatic hydrocarbons, anilines, phenols, inorganic anions and organic acids, shows that homemade stationary phases can not only be applie to RPLC/HILIC/IEC mixed-mode chromatography, but also has better separation selectivity than commercial column. Therefore, the post-modification of p-tolyl isocyanate can greatly improve the separation effect in RPLC mode, which proves that this modification method is of research significance. The retention mechanisms of two stationary phases were investigated by varying the chromatographic conditions and linear solvation energy relationships (LSER). In addition, the stationary phase is able to detect preservatives in foods quickly and accurately. In actual sample testing, the limit of detection ≤ 0.074mg·L−1 and the inter-day precision was not more than 3.33 %.

Isocyanate Additives Improve the Low-Temperature Performance of LiNi0.8Mn0.1Co0.1O2||SiOx@Graphite Lithium-Ion Batteries

LiNi0.8Mn0.1Co0.1O2||SiOx@graphite (NCM811||SiOx@G)-based lithium-ion batteries (LIBs) exhibit high energy density and have found wide applications in various fields, including electric vehicles. Nonetheless, its low-temperature performance remains a challenge. One of the most efficacious strategies to enhance the low-temperature functionality of battery is the development of appropriate electrolytes with low-temperature suitability. Herein, p-tolyl isocyanate (PTI) and 4-fluorophenyl isocyanate (4-FI) are used as additive substances to integrate into the electrolytes to improve the low-temperature performance of the battery. Theoretical calculations and experimental results indicate that PTI and 4-FI can both preferentially generate a stable SEI on the electrode surface, which is beneficial to reduce the interfacial impedance. As a result, the additive, i.e. 4-FI, is superior to PTI in improving the low-temperature performance of the battery due to the optimization of F in the SEI membrane components. At room temperature, the cyclic stability of the NCM811/SiOx@G pouch cell increases from 92.5% (without additive) to 94.2% (with 1% 4-FI) after 200 cycles at 0.5 C. Under the operating temperature of -20 °C, the cyclic stability of the NCM811/SiOx@G pouch cell increases from 83.2% (without additive) to 88.6% (with 1% 4-FI) after 100 cycles at 0.33 C. Therefore, a rational interphase design involving the modification of the additive structure is a cost-effective way to improve the performance of LIBs.

Chiral Recognition of Hydantoin Derivatives Enabled by Tetraaza Macrocyclic Chiral Solvating Agents Using 1H NMR Spectroscopy.

Enantiomers of a series of hydantoin derivatives were prepared from d- and l-amino acids with p-tolyl isocyanate and 3,5-bis(trifluoromethyl)phenyl isocyanate as guests for chiral recognition by 1H NMR spectroscopy. Meanwhile, several tetraaza macrocyclic compounds were synthesized as chiral solvating agents from d-phenylalanine and (1S,2S)-(+)-1,2-diaminocyclohexane. An uncommon enantiomeric discrimination has been successfully established for hydantoin derivatives, representatives of five-membered N,N-heterocycles, in the presence of tetraaza macrocyclic chiral solvating agents (TAMCSAs) 1a-1c by means of 1H NMR spectroscopy. Several unprecedented nonequivalent chemical shifts (up to 1.309 ppm) were observed in the split 1H NMR spectra. To evaluate practical applications in the determination of enantiomeric excess (ee), the ee values of samples with different optical purities (up to 95% ee) were accurately calculated by the integration of relevant proton peaks. To better understand the chiral discriminating behavior, Job plots of (±)-G1 with TAMCSA 1a were investigated. Furthermore, in order to further explore any underlying intermolecular hydrogen bonding interactions, theoretical calculations of the enantiomers of (S)-G1 and (R)-G1 with TAMCSA 1a were performed by means of the hybrid density functional theory (B3LYP/6-31G*) of the Gaussian 16 program.

The [3+2] Annulation of CF3-Ketimines by Re Catalysis: Access to CF3-Containing Amino Heterocycles and Polyamides.

SummaryTransition metal catalyzed [3 + 2] annulation of imines with double bonds via directed C-H activation offers a direct access to amino cyclic motifs. However, owing to weak coordination and steric hindrance, trifluoromethylated ketimines have been an unaddressed challenge for TM-catalyzed annulations. Here, a rhenium-catalyzed [3 + 2] annulation of trifluoromethylated ketimines with isocyanates via C(sp2)-H activation has been disclosed. This approach provides an efficient platform for rapid access to a privileged library of CF3-containing iminoisoindolinones and polyamides by utilizing challenging CF3-ketimines as the annulation component. The capability of gram scale synthesis, the post-functionalization of the cyclization adduct, the derivation of complex natural molecules and the facile synthesis of polyamides highlight a diversity of synthetic potential of the current methodology.

P-Tolyl isocyanate derivatization for analysis of CWC-related polar degradation products by mass spectrometry

Most of the precursors and/or degradation products related to the Chemical Weapons Convention (CWC) are polar. Identification of these molecules in environmental samples provides clues regarding the alleged usage and/or synthesis of the parent toxic chemicals. Such polar compounds need to be derivatized in order to analyze them by gas chromatography-mass spectrometry (GC-MS). In this study, we developed a new derivatizing reagent, para-tolyl isocyanate (PTI), for derivatization of polar CWC-related compounds. The PTI reagent selectively derivatizes the -OH and/or-SH functional groups with high efficiency, but does not react with carboxylic acid (-COOH) or phosphonic acid (-(O)P(OH)2) groups. The PTI derivatives of dialkyl aminoethanols, dialkyl aminoethanol-N-oxides, and 3-quinuclidinol were successfully eluted through GC, and their electron ionization (EI) mass spectra were distinct and provided the structure information by which the isomeric compounds can be easily distinguished. We also calculated the GC-retention index values that can be used for further confirmation of the target compounds. All the studied PTI derivatives can be analyzed by EI-MS with direct insertion probe and/or by direct electrospray ionization mass spectrometry (ESI-MS) together with the MS-MS data; both sets of data provide full structure information. The PTI reagent was found to be better in some respects than the conventional bistrimethylsilyl trifluoroacetamide (BSTFA), a trimethyl silylating reagent. The PTI reagent is commercially available, and the PTI derivatives are highly stable for months and are not sensitive to moisture. The applicability of the PTI derivatization for trace-level determination of the target CWC-related polar compounds in environmental matrices and in human plasma samples is also evaluated.

Reactions of dimethylzirconocene complexes with a vicinal frustrated P/B Lewis pair

The intramolecular vicinal frustrated P/B Lewis pair (FLP) Mes2PCH2CH2B(C6F5)2 readily abstracts a methyl anion equivalent from dimethylzirconocene to give the salt [Cp2ZrCH3](+) [Mes2PCH2CH2B(CH3)(C6F5)2](-) that features phosphane coordination to the zirconium cation. The analogous reaction between this FLP and Cp*2Zr(CH3)2 yields the analogous salt that, however, features a methyl bridged ([Zr]···H3C-[B]) tight ion pair structure. Both these products were characterized by X-ray diffraction. They both undergo 1,2-[Zr(+)]/P addition to carbon dioxide. The [Cp2ZrCH3](+) containing compound also adds to benzaldehyde or to p-tolyl isocyanate to give the respective [Zr(+)]/P addition products which were characterized by X-ray diffraction.

Preparation of Supramolecular Extenders with Precise Chain Lengths via Iterative Synthesis and Their Applications in Polyurethane Elastomers

In this study, we synthesized a dual-functional building intermediate, 4-(3,3-diethyl-2,4-dioxoazetidin-1-yl)benzoyl chloride (DEDA-BC), from readily available starting materials, including 4-isocyanatobenzoyl chloride and p-tolyl isocyanate. In its iterative syntheses of hard segments, we first treated the highly reactive acid chloride of DEDA-BC with the monoamine (aniline) or the diamine (4,4′-methylenedianiline, 4,4′-MDA) to form first-generation azetidien-2,4-dione intermediates. We then reacted these derivatives with 4-aminobenzylamine at the more-selective azetidine-2,4-dione group of DEDA-BC to form the first-generation of benzyl amine extenders. Using this alternating method, we obtained high yields of supramolecular extenders of various chain lengths (n = 1–3) in a systematic manner, without the need for tedious purification steps, under catalyst-free conditions. The mono- and diamine extenders with numbers of repeating units ranging from one to three were synthesized precisely through this new ...

Chemical ionization mass spectral analysis of pinacolyl alcohol and development of derivatization method using p-tolyl isocyanate

A simple and routine chemical ionization method (CI) providing molecular weight information is developed for the unambiguous identification of 3,3-dimethyl-2-butanol known as pinacolyl alcohol (PA), a potential precursor for prohibited chemical weapons such as Soman, a nerve agent. This method meets the CI criteria used for the evaluation of proficiency tests conducted by OPCW avoiding use of reference chemical. In addition, a derivatization method using p-tolyl isocyanate for the analysis of PA using GC-MS has also been developed for the identification. This derivatization method facilitates the easy analysis of PA at low concentration present in environmental matrices. The efficiency of the derivatization is >99% with 10 fold increase in the sensitivity of the GC-MS signal. The electron ionization mass spectral fragmentation of the p-tolyl isocyanate (PTI) derivatives of three isomeric alcohols is also established. The positive CI of PTI derivatives of these alcohols resulted in molecular ion information and meets the OPCW criteria for CI method of analysis. Further, the retention indices for all the studied alcohols after derivatization help the unambiguous identification of these compounds present in complex environmental matrices.

Th2 Cytokine Profiles Do Not Predict Antibody Responses and Respiratory Hyperresponsiveness Following Dermal Exposure To Isocyanates

RATIONALE: Cytokine profiling of local lymph node responses following dermal exposure has been proposed as a test to identify chemicals that pose a risk of occupational asthma. The present study tested the hypothesis that relative differences in cytokine profiles for dinitrochlorobenzene (DNCB) and six isocyanates: toluene diisocyanate (TDI), diphenylmethane-4,4′-diisocyanate (MDI), dicyclohexylmethane-4,4′diisocyanate (HMDI), isophorone diisocyanate (IPDI), p-tolyl(mono)isocyanate (TMI), and meta-tetramethylene xylene diisocyanate (TMXDI) are predictive of relative differences in total serum IgE and respiratory responses to methacholine (Mch) following dermal exposure to the chemicals.

N−C Bond Formation Promoted by a Hafnocene Dinitrogen Complex: Comparison of Zirconium and Hafnium Congeners

Nitrogen-carbon bond formation from coordinated dinitrogen has been observed upon addition of 2 equiv of PhNCO to the hafnocene dinitrogen complex, [(eta5-C5Me4H)2Hf]2(mu2,eta2,eta2-N2). The resulting product most likely arises from initial N=C cycloaddition of the first equivalent of heterocumulene, followed by carbonyl insertion of a second equivalent into the newly formed hafnium-nitrogen bond. The resulting product has considerable hafnium imido character, as evidenced by the metrical parameters determined from the solid-state structure as well as reactivity studies, whereby PhNCO, p-tolyl isocyanate, and t-BuCCH each undergo cycloaddition with the hafnium-nitrogen bond. The origin of the nitrogen-carbon-forming chemistry is likely derived from the reluctance of the hafnocene dinitrogen complex to undergo ligand-induced N2 isomerization, as was observed with the zirconium congener.

Inconsistencies between Cytokine Profiles, Antibody Responses, and Respiratory Hyperresponsiveness following Dermal Exposure to Isocyanates

Cytokine profiling of local lymph node responses has been proposed as a simple test to identify chemicals, such as low molecular weight diisocyanates, that pose a significant risk of occupational asthma. Previously, we reported cytokine messenger RNA (mRNA) profiles for dinitrochlorobenzene (DNCB) and six isocyanates: toluene diisocyanate, diphenylmethane-4,4'-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate, p-tolyl(mono)isocyanate, and meta-tetramethylene xylene diisocyanate. The present study was conducted to test the hypothesis that relative differences in the cytokine profile are predictive of relative differences in total serum immunoglobulin (Ig) E and respiratory responses to methacholine (Mch) following dermal exposure to the chemicals. After a preliminary experiment to determine an exposure regimen sufficient to achieve responses to Mch following dermal diisocyanate exposure, BALB/c mice received nine dermal exposures over a period of 28 days to one of six isocyanates, DNCB, or vehicle. Mice were then challenged with increasing doses of Mch and responsiveness was assessed using whole-body plethysmography. Serum antibody responses and cytokine mRNA profiles in the draining lymph node were also assessed. In separate experiments, cytokine protein assays were performed after five dermal exposures over a 14-day period. The response pattern for interleukin (IL)-4, IL-10, and IL-13 for the different isocyanates was highly reproducible as determined by RNAse protection assay, reverse transcription-PCR, or cytokine protein levels. However, the relative differences in T-helper cytokine profiles were not predictive of relative differences in either total serum IgE or respiratory responses to Mch following dermal exposure. The data suggest that the cytokine profiling approach needs to be further developed and refined before adoption and that other approaches to hazard identification should be pursued as well. Based on the weight of evidence from all the assays performed, it appears that all six isocyanates tested have some potential to cause respiratory hypersensitivity following dermal exposure.

Influence of molecular weight and chemical structure of soft segment in reaction kinetics of polycarbonate diols with 4,4′-diphenylmethane diisocyanate

This third paper in this series regarding the mechanism and kinetics of urethane systems presents the results obtained in the study of the influence of molecular weight and chemical structure of several polycarbonate diols on the polycondensation reaction with 4,4′-diphenylmethane diisocyanate (MDI), comparing them with those obtained previously for condensation reaction with p-tolyl isocyanate ( p-TI). The substitution effect induced in the second isocyanate group by the reaction of the first isocyanate group of a symmetric diisocyanate likes MDI has been studied by size exclusion chromatography (SEC) using a model monoalcohol. The condensation reaction kinetics is adequately described by an autocatalyzed third order rate equation. The values obtained for rate constants, using a Runge–Kutta mathematical model, suggest association phenomena by hydrogen bonding implying hydroxyl groups but also urethane groups. In bulk and in stoichiometric conditions, the association phenomena observed increase proportionally on one hand, to the decrease of molecular weight of macrodiol and on the other hand, to the tendency to form intramolecular hydrogen bonds. The activation energies were obtained from the evaluation of kinetic data at different temperatures in the range 45–65 °C. As association phenomena increase, activation energies decrease. The slightly higher activation energies obtained for polycondensation compared to condensation are explained because of the rapid increase of viscosity of the medium.

Synthesis and Reactivity of Ortho-Palladated Arylcarbodiimides and Aryl Isothiocyanates. Formation of C-Palladated Quinazolines. Synthesis of 2-Aminoquinolines

The iminophosphoranes Ph3PNC6H3X-2-R-4 (X = I, R = H (1a); X = Br, R = NO2 (1b); X = Br, R = Me (1c)) react with p-tolyl isocyanate and 1a reacts with CS2 to give the carbodiimides ToNCNC6H3X-2-R-4 (To = C6H4Me-4; X = I, R = H (2a); X = Br, R = NO2 (2b); X = Br, R = Me (2c)) and the isothiocyanate SCNC6H4I-2 (3), respectively. The compounds 2 and 3 react with Pd(dba)2 ([Pd2(dba)3]·dba, dba = dibenzylideneacetone) in the presence of the appropriate ligands to give the ortho-palladated arylcarbodiimides [Pd(C6H3NCNTo-2-R-5)XL2] (L = PPh3, X = I, R = H (4a); L = PPh3, X = Br, R = NO2 (4b), Me (4c); L2 = bpy (2,2‘-bipyridine), X = I, R = H (5a)) and trans-[Pd(C6H4NCS-2)I(PPh3)2] (6), respectively. Complex 4a reacts with pyridine (py) and Tl(TfO) (TfO = triflate, CF3SO3) and 5a reacts with 4-tert-butylpyridine (tBupy) and Tl(TfO) to give the complexes trans-[Pd(C6H4NCNTo-2)(py)(PPh3)2]TfO (7a) and [Pd(C6H4NCNTo-2)(tBupy)(bpy)]TfO (8a), respectively. Complex 4a reacts with XyNC (Xy = 2,6-dimethylphenyl) to give...

One-Pot Synthesis of Dendritic Poly(amide-urea)s via Curtius Rearrangement. 1. Monomer Syntheses and Model Reactions for the Dendritic Poly(amide-urea)s Synthesis

The syntheses of two AB2 monomers, aminodicarboxylic acid (1) and aminodicarbonyl azide (2), and their model reactions for the one-pot synthesis of dendritic aromatic poly(urea-amide)s using the two AB2 monomers were carried out. The model reaction of 2 and p-tolyl isocyanate produced the target urea with two acyl azide groups in 93% yield at 25 °C for 30 min in tetrahydrofuran (THF). The Curtius rearrangement from an acyl azide to an isocyanate was completed at 140 °C for 30 min in THF. The isocyanate produced via the Curtius rearrangement readily reacted with aniline to give a urea compound in 93% yield. p-Tolyl isocyanate selectively reacted with an amine group of 1 to give a urea with end carboxylic acid groups. The end carboxylic acid groups of the urea could be activated with a condensing agent, diphenyl(2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate (DBOP), and the condensation of the active amide with 2 provided an amide with acyl azide end groups.

The influence of molecular weight and chemical structure of soft segment in reaction kinetics with tolyl isocyanate

The influence of molecular weight and chemical structure of several polycarbonate diols on the kinetics of condensation reaction with p-tolyl isocyanate has been studied. Size exclusion chromatography has been used to monitor the reaction. The condensation reaction kinetics is adequately described by an autocatalysed third order rate equation. The values obtained for rate constants, using a Runge–Kutta mathematical model, suggest an association phenomena by hydrogen bonding implying hydroxyl groups but also urethane groups. In bulk and in stoichiometric conditions, the association phenomena observed increases proportionally, on one hand to the decrease of molecular weight of macrodiol, and on the other hand to the tendency to form intramolecular hydrogen bonds.

1,3,5-Tri-p-tolylbiuret

MoOCl2(LOMe) as catalyst, where LOMe is CpCo[P(O)(OMe)2]3, reacts with p-tolyl isocyanate to afford the title compound, C23H23N3O2. The structural features are the intramolecular hydrogen bond forming a six-membered ring and a nearly planar arrangement of the biuret moiety. Each p-tolyl phenyl ring is twisted by approximately 60–80° with respect to the others. The bond lengths N1—C22 of 1.357 (3) Å and N2—C23 of 1.333 (3) Å indicate that they are partial double bonds.

A novel thermal iniferter for radical polymerization

A novel thermal iniferter, 1-hydroxy-2-( p-tolylaminocarbonyloxy)-1,1,2,2-tetraphenylethane (HTTPE), was prepared from 1,1,2,2-tetraphenyl-1,2-ethanediol (TPED) and p-tolyl isocyanate. The thermal iniferter is a complex of HTTPE with acetone, designated as HTTPE·Acetone. Characterization of HTTPE·Acetone was performed by FTIR, 1H-NMR and elemental analysis. The melting point of the complex is 98–99.5°C. The polymerization of methyl methacrylate (MMA) with HTTPE·Acetone can be carried out in bulk or in DMF solution at 70 and 80°C, and the polymerization proceeds by a “living” polymerization mechanism. The resultant polymer can reinitiate a second monomer, n-butyl methacrylate, (nBMA), to form a PMMA- b-PnBMA block copolymer.

Reaction kinetics of tolyl isocyanate with polyhexamethylene-pentamethylene carbonate diol

In the present work, the kinetics of the reaction of p-tolyl isocyanate with a polycarbonate diol has been studied, as a model for similar urethane systems. Liquid chromatography has been used to monitor the reaction, which allows direct measurement of the reaction of isocyanate group. The results obtained have enabled us to propose a reaction path and an autocatalyzed third-order kinetic model. Activation energy values have been determined from measurements taken at different isothermal temperatures.

Hydrogen-transfer polymerization of vinyl monomers derived from p-tolyl isocyanate and acrylamide derivatives

The anionic polymerization of N-acryloyl- N′- p-tolylurea ( 1) was carried out at 80°C in N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetonitrile or toluene containing N-phenyl-β-naphthylamine (1 mol.%) as a radical inhibitor for 24 h using t-BuOK or 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) (3 mol.%) as an initiator. It was found that 1 undertook selectively the hydrogen-transfer polymerization in the case of t-BuOK as an initiator but both hydrogen-transfer and vinyl polymerization proceeded in the case of DBU.

Cycloaddition reactions of titanium and zirconium imido, oxo and hydrazido complexes supported by tetraaza macrocyclic ligands ‡

The tetraaza macrocycle-supported titanium and zirconium imido complexes [Ti(NR)(Mentaa)] [R = But, Ph, Tol or 4-C6H4NO2; n = 4 or 8 where H2Mentaa = tetra- or octa-methyldibenzotetraaza[14]annulene, respectively] and [Zr(NC6H3Pri2-2,6)(py)(Me4taa)] react with isocyanates or carbon dioxide to form cycloaddition products generally of the type [M{N(R)C(O)E}(Mentaa)] (M = Ti or Zr, R = aryl or tert-butyl, E = O, NBut or N–aryl). The complex [Zr{N(C6H3Pri2-2,6)C(O)N(But)}(Me4taa)] is also formed by reaction of the bis(arylimide) [Zr(NHC6H3Pri-2,6)2(Me4taa)] with ButNCO. The crystal structures of [Ti{N(Tol)C(O)O}(Me4taa)] (Tol = p-tolyl) and [Zr{N(C6H3Pri2-2,6)C(O)N(But)}(Me4taa)] are described. The tert-butyl imido complexes [Ti(NBut)(Mentaa)] (n = 4 or 8) react with Ph2NNH2 to give the corresponding terminal N,N-diphenylhydrazido derivatives [Ti(NNPh2)(Mentaa)] and these yield the cycloaddition products [Ti{N(NPh2)C(O)O}(Mentaa)] or [Ti{N(NPh2)C(O)N(Tol)}(Me4taa)] with CO2 or TolNCO, respectively. The related titanium oxo complexes [Ti(O)(Mentaa)] (n = 4 or 8) react with p-tolyl isocyanate to form the N,O-carbamate products [Ti{N(Tol)C(O)O}(Mentaa)], and with ditolylcarbodiimide to form the N,N-ureate derivative [Ti{N(Ph)C(O)N(Ph)}(Mentaa)] in which complete rupture of the TiO linkage has occurred. Reaction of the N-phenyl-N-tolyl (asymmetric) ureate [Ti{N(Ph)C(O)N(Tol)}(Me4taa)] with an excess of PhNCO gave quantitative conversion to the N,N-symmetric product [Ti{N(Ph)C(O)N(Ph)}(Me4taa)] and TolNCO. Crossover NMR tube experiments suggest that this reaction occurs via an associative mechanism.