Benzyl Isocyanate Research Articles

Experimental and Theoretical Studies on the Reactions of Aliphatic Imines with Isocyanates.

In the context of a project aiming at the replacement of the 3-substituted β-lactam ring in classical β-lactam antibiotics by an N(3)-acyl-1,3-diazetidinone moiety, we have investigated the reaction of isocyanates with imines derived from allyl glycinate and differently substituted propionaldehydes. Imines of aromatic aldehydes with anilines have been reported to react with acyl isocyanates to give 1,3-diazetidinones or 2,3-dihydro-4H-1,3,5-oxadiazin-4-ones, via [2+2] or [4+2] cycloaddition, respectively. However, neither of these products was formed with imines derived from allyl glycinate and 2-(mono)methyl propionaldehydes. α,α-Dimethylation of the imine enabled the [4+2] cycloaddition pathway, but the desired 1,3-diazetidinone products were not observed. Surprisingly, the imines obtained from thioesters of 2,2-dimethyl 3-oxo propionic acid reacted with aryl isocyanates or with benzyl isocyanate to give 5,5-dimethyl-2,4-dioxo-6-(aryl-/alkylthio)tetrahydropyrimidines, via thiol displacement and re-addition to a putative six-membered iminium intermediate. These experimental results obtained for the reactions could be rationalized by DFT calculations. In addition, we have shown that N(3)-acyl-1,3-diazetidinone and 2,3-dihydro-4H-1,3,5-oxadiazin-4-one products can be distinguished based on experimental IR data in combination with theoretical reference spectra employing the IR spectra alignment (IRSA) algorithm. This discrimination was not possible by means of 1 H, 13 C, or 15 N NMR spectroscopy.

Benzyl isocyanate: an effective high-voltage film-forming additive for lithium-ion batteries

Benzyl isocyanate: an effective high-voltage film-forming additive for lithium-ion batteries

Stereoselective and Divergent Aza-Adenosine and Aza-Guanosine Syntheses from Xylofuranose, the Key Fragments of a STING Cyclic Dinucleotide Agonist.

The stereoselective and divergent synthesis of two aza-nucleosides is reported. Starting from xylofuranose 9, aza-adenosine 2 was prepared in 13 steps and 7% overall yield, and aza-guanosine 3 was prepared in 13 steps and 7.8% overall yield. Compared to the original syntheses, some advantages of these new routes are significant yield improvement, overall step-count reduction, an optimized protecting group strategy, the development of a versatile platform for nitrogenous base incorporation, and the elimination of hazardous reagents (e.g., benzyl isocyanate, Et3N·HF).

Effects of selenate applied at two growth stages on the nutrient quality of Cardamine violifolia

Cardamine violifolia is an edible selenium (Se) hyperaccumulator that is mainly distributed in Enshi, China. Here, C. violifolia treated with different selenate concentrations (i.e., 0, 1.5, 20, and 80 μmol L − 1) at the rosette and podding stages in a hydroponic experiment was carried out to investigate the effects of Se accumulation on the nutrient quality of this crop. The shoots accumulated high levels of Se at the rosette and podding stages, and the main Se forms at these stages were selenocystine and selenate. The effects of selenate on the chlorophyll, carotenoid, soluble sugar and protein, total free amino acid, and vitamin C contents of C. violifolia differed between the rosette and podding stages. Selenate treatment reduced total flavonoid and increased the total phenolic acid content at the podding stage. Total glucosinolate content decreased after selenate treatment at the rosette stage. Ten volatile compounds were found in C. violifolia shoots and the dominant volatile observed at the two stages was benzyl isothiocyanate. Selenate treatment demonstrated mixed influences on the volatile compounds. For example, at the rosette stage, selenate treatment inhibited the emission of benzyl isothiocyanate and benzyl isocyanate but promoted the generation of 12,15-octadecadiynoic acid methyl ester. Moreover, selenate treatment reduced the emission of isobutyl isothiocyanate at the podding stage of C. violifolia. These results provide us novel insights into the comprehensive effects of Se on the nutrient quality of Se hyperaccumulators.

Benzyl isocyanate isolated from the leaves of Psidium guajava inhibits Staphylococcus aureus biofilm formation

Benzyl isocyanate (BIC), from methanol extract of Psidium guajava leaves, exhibited substantial anti-biofilm activities against Staphylococcus aureus, the common bacterial pathogen in nosocomial infections. Major components of the extract included eugenol, BIC, phenyl-2-methoxy-4-(1-propenyl)-acetate and 2,5-pyrrolidinedione,1-penta-3-4-dienyl, analyzed by GC-MS and HPLC studies. BIC exhibited substantial anti-biofilm activitiy against S. aureus, established by assaying biofilm formation, biofilm metabolic activity, bacterial adherence to hydrocarbons, exopolysaccharide formation, and optical and scanning electron microscopic studies. BIC significantly downregulated the important biofilm markers of S. aureus, viz., icaAD, sarA and agr, observed by quantitative real time polymerase chain reaction analysis. Molecular docking studies revealed thermodynamically favorable interaction of BIC with IcaA, SarA and Agr, having Gibbs energy values of −8.45, −9.09 and −10.29 kcal mol−1, respectively. BIC after binding to IcaR, the repressor of IcaA, influences its binding to target DNA site (Eshape, −157.27 kcal mol−1). The results are considered to demonstrate anti-biofilm potential of BIC against bacterial infections.

Vibrational relaxation dynamics of a potential local infrared probe: Isocyanate

Isocyanates are widely used in the production of foams, fibers, coatings, and elastomers. Herein, we use linear and nonlinear infrared spectroscopic methods to study the spectral and dynamical properties of a model compound, benzyl isocyanate. We found that the asymmetric stretching vibrational band of the isocyanate functional group has a significant extinction coefficient and locates in an uncongested region of the IR spectrum. While the frequency of this vibrational band only shows a modest dependence on solvent polarity, its dynamics is rather sensitive to the solvent. These results show that the isocyanate group could be used as a site-specific IR probe of local environments.

Synthesis of butyl acrylate–styrene–TMI latexes and their application as water-based coatings

Self-crosslinking styrene-acrylic latexes functionalized with 3-isopropenyl-α,α-dimethyl benzyl isocyanate (TMI) by semibatch emulsion polymerization were prepared. Polymerizations were performed in emulsions with aerosol EF-800 surfactant; remarkable colloidal stability of the copolymer latexes was measured in fresh and aged samples. The effects on film formation, tensile properties, permeability to water vapor, and oxygen were evaluated by varying the TMI concentrations (from 0 to 6 wt%). The obtained latexes were used as binder to prepare water-based coatings, which were applied on steel specimens; hydrolysis of TMI acts as a self-crosslinked promoter once the film was applied. Adhesion tests, scratch hardness, and gloss properties were evaluated. Water vapor permeability of latex films

Preparation of a new benzylureido-β-cyclodextrin-based column and its application for the determination of phenylmercapturic acid and benzylmercapturic acid enantiomers in human urine by LC/MS/MS.

A benzylureido-β-cyclodextrin was synthesized by the reaction of 6-amino-β-cyclodextrin with an active benzyl isocyanate. Then, it was bonded to silica gel by a thiol-ene addition reaction, obtaining a new benzylureido-β-cyclodextrin-based chiral stationary phase (BzCDP). Its chemical structure was characterized by infrared spectroscopy, elemental analysis, and solid-state nuclear magnetic resonance spectroscopy. The BzCDP was successfully used to separate phenylmercapturic acid (PMA) and benzylmercapturic acid (BMA) enantiomers, which were confirmed as biomarkers of exposure to benzene and toluene in human urine. The enantiomeric separations were also optimized through the investigation of related factors. The resolutions of PMA and BMA enantiomers could be up to 2.25 and 2.14, respectively, within 30min under reversed-phase chromatography. Based on the optimal chromatographic and mass spectrometry conditions, a new LC-MS/MS quantitative method for the PMA and BMA enantiomers was established by negative ion multiple reaction monitoring (MRM) and an isotope-labeled PMA (d2-PMA) as an internal standard. The limits of detection (LODs) of enantiomers were less than 0.17μg/L for PMA and 0.14μg/L for BMA, and the averaged recoveries of enantiomers were in the range of 86~100% for PMA and 86~113% for BMA. The method had good reproducibility levels with the RSDs (3.5~11.3% for intra-day and 3.9~13.1% for inter-day). The method was successfully applied to urine testing of 60 painting and printing workers. The results showed that only L-PMA was detected in the urine of the Printers, while a high content of L-PMA (27.5~106μg/L) and D-PMA (19.9~82.8μg/L) can be detected simultaneously in the urine of the Painters, indicating that benzene pollution was more serious in this group. The positive rate of BMA was rather higher, indicating that toluene pollution was more common than benzene. BMA also existed in the form of two enantiomers (L-BMA and D-BMA), but the difference between the two types of occupational groups was small. It is a meaningful work to deeply study the existence and content of chiral markers in human urine, which will help to better understand and evaluate the harmful effects of benzene series on human beings. Graphical abstract.

Thioether-Bearing Hyperbranched Polyether Polyols with Methionine-Like Side-Chains: A Versatile Platform for Orthogonal Functionalization.

The synthesis of thioether-bearing hyperbranched polyether polyols based on an AB/AB2 type copolymerization (cyclic latent monomers) is introduced. The polymers are prepared by anionic ring-opening multibranching copolymerization of glycidol and 2-(methylthio)ethyl glycidyl ether (MTEGE), which is conveniently accessible in a single etherification step. Slow monomer addition provides control over molecular weights. Moderate dispersities (Đ = 1.48-1.85) are obtained, given the hyperbranched structure. In situ 1 H NMR copolymerization kinetics reveal reactivity ratios of rG = 3.7 and rMTEGE = 0.27. Using slow monomer addition, copolymer composition can be systematically varied, allowing for the adjustment of the hydroxyl/thioether ratio, the degree of branching (DB = 0.36-0.48), thermal properties, and cloud point temperatures in aqueous solution in the range of 29-75 °C. Thioether oxidation to sulfoxides enables to tailor the copolymers' solubility profile. Use of these copolymers as a versatile, multifunctional platform for orthogonal modification is highlighted. The methyl sulfide groups can be selectively alkoxylated, using propylene oxide, allyl glycidyl ether, or furfuryl glycidyl ether, resulting in functional hyperbranched polyelectrolytes. Reaction of the alcohol groups with benzyl isocyanate demonstrates successful orthogonal functionalization.

Synthesis and characterization of chiral poly(alkyl isocyanates) by coordination polymerization using a chiral half‐titanocene complex

ABSTRACTA new chiral half‐titanocene complex, [CpTiCl2(O‐(S)−2‐Bu)], is synthesized and characterized by 1H and 13C NMR spectroscopy. This complex is employed for the coordination polymerization of n‐butyl and n‐hexyl‐ isocyanate leading to chiral polymers, as revealed by their CD spectra. Only the left‐handed helix is produced, due to the chiral (S)−2‐butoxy group, which is bound to the polymer chain end. The polymerization of 3‐(triethoxysilyl)propyl isocyanate produces less soluble polymers. On the other hand, phenyl isocyanate reacts slowly with the complex leading quantitatively and selectively to triphenyl isocyanurate. 2‐Ethylhexyl isocyanate is slowly and selectively cyclotrimerized in the presence of the half‐titanocene complex. However, a statistical copolymer of 2‐ethylhexyl isocyanate and hexyl isocyanate is produced. The reaction of benzyl isocyanate with the complex leads to a mixture of low molecular weight polymer and cyclotrimer. The polymers are characterized using SEC, NMR, and CD spectroscopy and their thermal properties are investigated by TGA/DSC analysis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2141–2151

Cyclic tetramers of a five-membered palladacycle based on a head-to-tail-linked isocyanate dimer and their reactivity in cyclotrimerization of isocyanates.

Reactions of [Pd(styrene)(PR3)2], generated from trans-[PdEt2(PR3)2] and styrene, with 2 equiv. of benzyl isocyanate in THF at room-temperature afforded unusual cyclic Pd-tetramers of five-membered rings consisting of organic isocyanate dimers and palladium, [Pd(PR3){-C(O)N(R)C(O)N(R)-}]4 (PR3 = PMe3, ; PR3 = PMe2Ph, ). Additionally, a cyclic trimer, (RNCO)3, (R = benzyl) was produced as a catalytic product. Treatment of the cyclic tetramer () with 4 equiv. of chelated phosphine, such as (1,2-bis(diethylphosphino)ethane) (DEPE) or (1,2-bis(dimethylphosphino)ethane) (DMPE), readily caused conversion to a metallacyclic cis-form, [Pd{N(R)C(O)N(R)C(O)}(P ∼ P)] (P ∼ P = DEPE, ; P ∼ P = DMPE, ) in quantitative yields. In contrast, reactions of Pd(0)-PR3 with 2 equiv. of Ar-NCO (Ar = Ph, p-tolyl, p-ClC6H4) afforded metallacyclic complexes having a dimeric isocyanato moiety, cis-[Pd{C(O)N(Ar)-C(O)N(Ar)}(PR3)2] (PR3 = PMe3 Ar = C6H5, ; p-MeC6H4, ; p-Cl-C6H4, ; PR3 = PMe2Ph, Ar = p-Cl-C6H4, ). Treatment of the palladacyclic complex () with an equimolar amount of chelated phosphine such as DEPE readily caused conversion to a palladacyclic cis-form, [Pd{N(Ar)C(O)N(Ar)C(O)}(DEPE)], in quantitative yield. The catalytic cyclotrimerization of benzyl isocyanate to [Pd(styrene)(PMe3)2] was achieved by varying the molar ratio of R-NCO (R = benzyl). In addition, catalytic cyclotrimerization was performed from the five-membered palladacyclic complexes or the Pd(0)-PR3 complex with excess Ar-NCO.

Synthesis of 4,6-Unsubstituted 2-Aminodihydropyrimidine-5-­carboxylates through Sequential Staudinger/Aza-Wittig/Cyclization Reactions

A novel method for constructing the dihydropyrimidine skeleton is developed. The method involves three sequential reactions: (1) the Staudinger reaction of (E)-ethyl 3-azido-2-{[(tert-butoxycarbonyl)amino]methyl}acrylate with triphenylphosphine; (2) aza-Wittig reaction of the resulting iminophosphorane with isocyanate; (3) intramolecular cyclization of the carbodiimide intermediate to give 4,6-unsubstituted 2-aminodihydropyrimidine-5-carboxylates in high overall yield. The method can be applied to various aromatic isocyanates, with substrates having electron-withdrawing groups showing high reactivities. In the case of aliphatic benzyl isocyanate, the reaction provides bicyclic dihydropyrimidine as the major product. The N-protecting group (Boc) can easily be removed to obtain N-unsubstituted dihydropyrimidines. All dihydropyrimidines in this study were previously unavailable and are difficult to synthesize by conventional methods.

“Clickable” polymers via a combination of RAFT polymerization and isocyanate chemistry

AbstractWe describe a facile, one‐pot, two‐step polymerization towards synthesizing block co‐polymers bearing reactive isocyanate functional groups. Reversible addition fragmentation chain transfer (RAFT) polymerization is used to mediate the co‐polymerization of isocyanate‐bearing monomers dimethyl meta‐isopropenyl benzyl isocyanate (TMI) and 2‐isocyanatoethyl methacrylate (ICEMA) with styrene and methyl methacrylate (MMA), respectively. ICEMA was incorporated into the polymer at a faster rate than TMI and its unhindered isocyanate group was found to be more reactive than the hindered isocyanate group of TMI. Both the TMI/styrene and the MMA/ICEMA systems maintain the reactivity of the isocyanate functionality, which was exploited by attaching representative hydroxyl‐bearing small and large molecules as well as solid substrates to the block co‐polymers. Thus, we demonstrate the versatility of the block co‐polymer system as a basis for forming branched polymers or as grafts for a solid substrate. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

'Pseudo-star' Copolymers Formed by a Combination of RAFT Polymerization and Isocyanate-Coupling

We describe the formation of pseudo-star copolymers via incorporation of an isocyanate-bearing monomer, dimethyl meta-isopropenyl benzyl isocyanate (TMI) into a homopolymer of butyl acrylate (BA) using a one-pot, two-step synthesis. The resultant product maintains the functionality of the isocyanate moiety, which is used to attach poly(ethylene glycol) methyl ether onto the copolymeric chain under benign reaction conditions. The resultant pseudo-star copolymers were isolated and their self-assembly in the presence of water studied.

Shelf Stability of Isocyanate‐Functionalized Vinyl Acrylic Latexes

AbstractCopolymerization of vinyl acetate (VA) with butyl acrylate (BA) and dimethyl meta‐isopropenyl benzyl isocyanate (TMI) was carried out at 40 °C in emulsions stabilized with sodium dodecyl sulfate (SDS) or sodium dodecyl benzene sulfonate (SDBS). Regardless of the type of surfactant employed, latexes were very unstable during storage. Moreover, the hydrolysis of TMI and undesirable premature crosslinking of the polymeric chains did occur at room temperature during latexes storage.

Facile Synthetic Route Toward High Conversion Primary Aliphatic Poly(vinyl benzyl isocyanate) via Iodination

Aliphatic isocyanato polymers, poly(vinyl benzyl isocyanate)s were synthesized via iodination and isocyanation from starting materials poly(vinyl benzyl chloride)s. This new process does not require phosgene which is highly toxic. This synthetic route takes advantage of the unique property of iodide ion which functions not only as a good nucleophile for iodination but also as a leaving group for isocyanation. The isocyanation conditions are mild with reaction temperatures ranging from 30 to 70 °C. In addition, the process is very efficient with conversions over 90%, yielding no dimer, trimer or other byproducts.

Effect of interaction between poly(ethylene terephthalate) and carbon nanotubes on the morphology and properties of their nanocomposites

AbstractPoly(ethylene terephthalate) (PET) nanocomposites were prepared by melt‐extruding mixtures of PET and functionalized multiwalled carbon nanotubes (MWNTs) with some interaction with PET molecules. For the functionalization of MWNTs, benzyl isocyanate and phenyl isocyanate with different molecular flexibility were employed on the surface of the MWNTs via chemical modification, respectively. The reaction for functionalization of MWNTs was confirmed by FTIR and transmission electron microscopy (TEM) measurements. TEM observations indicated that both benzyl and phenyl isocyanate groups covered the surface of the MWNTs after functionalization. The PET nanocomposites containing isocyanate groups showed improved mechanical properties, including the tensile strength and tensile modulus, compared with those with pristine and acid‐treated nanotubes. These improvements were ascribed to π–π interactions between the aromatic rings of PET molecules and the isocyanate group in MWNTs. The functionalized MWNTs showed a better dispersion of carbon nanotubes in the matrix polymer and a different fractured cross‐section morphology in scanning electron microscope measurements relative to the pristine MWNTs. The crystallinity of the functionalized MWNT‐PET nanocomposites was significantly higher than that of the pristine and acid‐treated MWNTs. FTIR results indicated that the presence of carbon nanotubes induced trans‐conformation of PET chains, and trans conformation was particularly dominant in PET composites incorporating MWNT‐phenyl. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 900–910, 2008

4-Bromobenzyl isocyanate versus benzyl isocyanate—New film-forming electrolyte additives and overcharge protection additives for lithium ion batteries

Electrochemical properties and working mechanisms of benzyl isocyanate compounds as polymerizable electrolyte additives for overcharge protection of lithium ion batteries have been studied by cyclic voltammetry, charge–discharge cycling, overcharge tests, accelerating rate calorimetry (ARC) and in situ Fourier transform infrared spectroscopy (FTIRS). The overcharge and FTIRS data clearly reveal that 4-bromobenzyl isocyanate (Br-BIC) can electrochemically polymerize at 5.5 V (versus Li/Li +) to form an overcharge-inhibiting (probably insulating) film on the cathode surface. In addition, is found the Br-BIC does slightly improve the charge/discharge performance of a lithium ion battery. Furthermore, Br-BIC and benzyl isocyanate show beneficial solid electrolyte interphase (SEI) formation behaviour on graphite in propylene carbonate based electrolyte solutions.

Acylation of Alkylidenepyrrolidines with Heterocumulenes — A Reinvestigation.

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Acylation of alkylidenepyrrolidines with heterocumulenes—a reinvestigation

The reactions of alkylidenepyrrolidine esters with isocyanates generally favour C-acylation, except in the case of benzyl isocyanate. Reactions with alkyl isocyanates are slow, and require forcing conditions. Reactions with isothiocyanates give exclusively the C-acylated products.