Reaction of acyl isocyanates with pyridine derivatives

Conclusions Trichloroacetyl isocyanate reacts with 2- and 4-picolines to form substituted trichloroacetylamidates. Benzoyl isocyanate forms a dimer in the presence of picolines. Depending on the nature of the solvent, trichloroacetyl isocyanate adds to 4-vinylp'yridine either at the vinyl group or at the ring nitrogen atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2127–2130, September, 1984.     

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

We 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     

Novel glutathione conjugates of phenyl isocyanate identified by ultra‐performance liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance

Phenyl isocyanate is a highly reactive compound that is used as a reagent in organic synthesis and in the production of polyurethanes. The potential for extensive occupational exposure to this compound makes it important to elucidate its reactivity towards different nucleophiles and potential targets in the body. In vitro reactions between glutathione and phenyl isocyanate were studied. Three adducts of glutathione with phenyl isocyanate were identified using ultra‐performance liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance (NMR). Mass spectrometric data for these adducts have not previously been reported. Nucleophilic attack on phenyl isocyanate occurred via either the cysteinyl thiol group or the glutamic acid α‐amino group of glutathione. In addition, a double adduct was formed by the reaction of both these moieties. NMR analysis confirmed the proposed structure of the double adduct, which has not previously been described. These results suggest that phenyl isocyanate may react with free cysteines, the α‐amino group and also with lysine residues whose side chain contains a primary amine. Copyright © 2014 John Wiley & Sons, Ltd.     

An unexpected result from the reaction of hydroxymethyl-2-oxazolidinones with isocyanates

The reaction of hydroxymethyl-2-oxazolidinones with 4-chlorophenyl isocyanate and phenyl isocyanate was studied. It was established that the investigated hydroxymethyl-2-oxazolidinones can react with isocyanates either at the NH group alone or at the NH and OH groups.     

Synthesis and mesogenic properties of diaromatic cyanates and isocyanates-monomers for liquid crystalline thermosets

Five pairs of mesogens with identical cores having either a cyanate or an isocyanate reactive terminal group have been synthesized. The monofunctional mesogens have a n-butoxy or a methoxy substituent as the second terminal group. The influence of the two isomeric OCN moieties on the formation of a mesophase and on the thermal transitions has been investigated. The mesophases observed were identified as nematic. A tremendous difference in the mesogenic power (stabilizing effect on a mesophase) has been found for the two reactive terminal groups. The isocyanates have lower melting points than the isostructural cyanates and clearing points which are approximately 30°C higher per isocyanate group, as compared to a cyanate moiety.     

Ringschlussreaktionen von 1-(2-Aminophenyl)-1-phenyl-äthylenen durch Kondensation mit Phosgen

Cyclization of 1-(2-aminophenyl)-1-phenyl-ethylenes or 1-(2-aminophenyl)-1-phenyl-propenes (II) by condensation with phosgene led to 4-phenyl-carbostyrils (III) or 2-chloro-4-phenyl-quinolines (IV). Similarly, thiophosgene afforded 4-phenyl-thiocarbostyril. Treatment of 1-(2-aminophenyl)-2-methyl-1-p-tolyl-propene (VII) with phosgene led to the corresponding isocyanate IX, which cyclized in the presence of aluminum chloride with loss of a methyl group to 3-methyl-4-p-tolyl-carbostyril (III-6). However, 1-(2-aminophenyl)-2-methyl-1-phenyl-propene (VIII) treated with phosgene gave the isocyanate XI and 3-phenyl-3-isopropenyloxindole (X). Cyclization of the isocyanate XI with aluminium chloride led simultaneously to 3-methyl-4-phenyl-carbostyril (XIV), and with migration of a methyl group to 3-methylene-4-methyl-4-phenyl-3. 4-dihydro-carbostyril (XV).     

Reactions of 1,2,2,2-tetrachloroethyl isocyanate with trialkyl and trimethylsilyl phosphites

The reaction of 1,2,2,2-tetrachloroethyl isocyanate with trialkyl phosphites is unselective. It involves chlorine substitution, addition by the isocyanate group, and dehydrochlorination and gives rise to a mixture of mono- and diphosphorylated compounds. Diethyl trimethylsilyl phosphite more selectively reacts with 1,2,2,2-tetrachloroethyl isocyanate. At a 1:1 molar reagent ratio, an -phosphorylated trichloroethyl isocyanate is formed, and at a 2 : 1 ratio, chlorine substitution and addition by the isocyanate group take place to give a related 1,3-diphosphonate.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 9, 2004, pp. 1456–1459.Original Russian Text Copyright © 2004 by Onysko, Maidanovich, Sinitsa.This revised version was published online in April 2005 with a corrected cover date.     

Latent reactive polymers containing isocyanate moiety that show extreme stability under aerobic atmosphere

This article deals with the latent reactive polymers having isocyanate moiety obtained from the radical copolymerization of 2‐propenyl isocyanate ( 2PI ) with styrene, 2PI with methyl methacrylate ( MMA ), and 2‐methacryloyloxyethyl isocyanate ( MOI ) with styrene. The radical copolymerization was carried out in benzene (5.00 M by total monomer) in the presence of AIBN (3.00 mol % of total monomer) at 60 °C for 24 h. The isocyanate moiety in each copolymer was stable at room temperature for more than 6 months under aerobic atmosphere, because no change of the infrared absorption based on isocyanate group of the resulting copolymer at around 2250 cm^?1 was observed. Isocyanate moiety of obtained copolymer (poly( 2PI ‐co‐ St )) reacted with excess diamines or diols at 80 °C in THF solution to afford the crosslinked polymer quantitatively. These results could demonstrate that isocyanate moiety in the copolymers showed thermal and reactive latency. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2448–2453, 2006     

Control synthesis of isocyanate and alkoxy-silane terminated macromers

The kinetics of the reactions in bulk of 4,4′-dicyclohexyl methane diisocyanate (H₁₂ MDI) and 5-isocyanato-1,3,3-trimethylcyclohexylmethyl isocyanate or isophorone diisocyanate (IPDI) with benzylic alcohol (BZA) and α-hydroxy-ω-methyl ether-terminated polyethylene oxide PEO (M?_w = 350) were studied by size exclusion chromatography (SEC) and ¹³C nuclear magnetic resonance (¹³C-NMR). The substitution effect is exhibited in the case of H₁₂ MDI reactivity. The kinetic constants were calculated by a numerical method. The second-order kinetic mechanism was shown to be valid. In the IPDI case, the cycloaliphatic isocyanate group is shown to be more reactive than the aliphatic group in our conditions, without catalysis, in agreement with previous results from the literature, in our obtained by ¹H-and ¹³C-NMR without any catalyst. The reactivity ratio is found to be on the order of 3. This difference in reactivity of the two isocyanate groups is used for the control synthesis of isocyanate and alkoxy-silane-terminated macromers.     

NMR Analysis of Hydroxyl-Terminated Polybutadiene End Groups and Reactivity Differences with Monoisocyanates

Nuclear magnetic resonance (NMR) spectroscopy was employed to investigate both the end group microstructure of R-45HTLO hydroxyl-terminated polybutadiene (HTPB) and reactivity rate differences among the different types of end groups. There is some conflict in the literature about the exact nature of the end groups and which resonance frequencies represent the three main types of methylene-hydroxyl end groups (cis, trans, or vinyl) and other possible branch point end groups (geraniol). NMR spectral analysis of small molecule model compounds supports the cis, trans, and vinyl end groups model. A model reaction scheme is proposed that produces branch points without the requirement of any “geraniol” structures. The reaction, with and without catalyst, of the various HTPB end groups with three different monoisocyanates (2-fluorophenyl isocyanate, phenyl isocyanate, and tert-butyl isocyanate) monitored by NMR spectroscopy, revealed different reactivity rates that are correlated with the assigned structures. In both the catalyzed and uncatalyzed reactions, the vinyl end groups reacted slower than the cis or trans end groups. As expected, the bulky isocyanates were the slowest to react, while the isocyanate group with electron withdrawing groups reacted the fastest. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2665–2671     

Polymerization of 3,4-dihydro-2H-carboxyaldehyde (acrolein dimer). Part II. Copolymerization with isocyanates

Copolymers of 3,4-dihydro-2H-pyran-2-carboxyaldehyde (acrolein dimer) with phenyl isocyanate were obtained under several conditions. Infrared and NMR analyses showed that the isocyanate always reacted with acrolein dimer forming urethane linkages, not block units of isocyanate. An alternating copolymer was obtained from the copolymerization in the presence of anionic catalysts such as butyllithium at room temperature, irrespective of the monomer ratios employed. The isocyanate content in the copolymer prepared with an Al(C₂H₅)₂Cl catalyst was increased by elevating polymerization temperature. The copolymerizability of aldehydes with the isocyanate depends upon the polarity of aldehyde group.     

Synthesis of new polyaryl-substituted imidazoles bridged on enamine or urea moieties and evaluation of their optical and electrochemical properties

Research on Chemical Intermediates - The reaction of the free amine group in polyaryl-substituted imidazole structures with phenyl isocyanate or dimethyl acetylenedicarboxylate gave two new series...     

Reactions of group IV organometallic compounds : XXVII. Some reactions of [(trimethylsilyl)imino]phosphorane

The reaction of [(trimethylsilyl)imino]methyldiphenylphosphorane: Ph₂MePNSiMe₃ (I) with several acid anhydrides or alkyl isocyanates took place by the simple cleavage of silicon-nitrogen bond. In contrast the interaction of (I) with phenyl isocyanate, isothiocyanate or carbon disulphide led to addition-elimination reactions of the Wittig type. Detailed investigation in the case of phenyl isocyanate indicated the usual elimination of Ph₂MePO is suppressed by the strong affinity of the trimethylsilyl group for anionic oxygen atom.     

Conformational analysis and comparison between theoretical and experimental vibrational spectra for chloroacetyl isocyanate

The conformational stability and vibrational infrared and Raman spectra of chloroacetyl isocyanate (CH2ClCONCO) were investigated by ab initio MP2 and density functional B3LYP calculations using the 6-311 + + G** basis set. From the potential energy scans of the internal rotations of both the halomethyl and the isocyanate rotors, chloroacetyl isocyanate was predicted to exist predominantly in a mixture of the cis-cis (chlorine atom and NCO group eclipse C=O bond) and the gauche-cis (one hydrogen atom and NCO group eclipse C=O bond) conformations with a comparable relative stability. The vibrational wavenumbers of each of the two conformers of the molecule were computed at DFT-B3LYP/6-311 + + G** level. Normal coordinate calculations were carried out to obtain the potential energy distributions (PED) among the symmetry coordinates of the normal modes for each of the stable conformers of chloroacetyl isocyanate. The theoretical vibrational assignments are compared with experimental ones and a ratio of observed/calculated wavenumbers of about 0.97-1.04 was obtained.     

The Nature of the Cross-linking Reaction in Polymers of Unsaturated Isocyanates∗

Copolymers of vinyl isocyanate, β-allyloxylethyl isocyanate, and 9-decenyl isocyanate having low mole fractions of isocyanate monomer were soluble, linear structures. However, at high mole fractions of the isocyanate monomer in the copolymer, the copolymers were insoluble and cross-linked. Evidence has been obtained which supports the postulation that the cross-links are formed at high isocyanate ratios by a mechanism similar to that by which isocyanates are converted to dimers, the uretidenedione structure, or to trimers, the isocyanurate structure.     

Interfacial polymerization of an isocyanate and a diol

The interfacial reaction between a liquid polyfunctional aromatic isocyanate and a diol was studied using infrared spectroscopy to follow the reduction in concentration of the isocyanate group. It was shown that the product polyurethane formed a gel layer around dispersed isocyanate droplets which were swollen by the diol but not by the isocyanate. A model for the process is suggested based on the reaction occuring at the interface of a diminishing droplet surface. It is suggested that the reaction is controlled by the reaction kinetic parameters and the mass transfer by diffusion of the diol through the product layer. Quantitative evaluation is based on steady and nonsteady state diffusion theories.     

Versatile stereoselective cycloadditions between heterocumulenes and phosphagermaallene Tip(tBu)Ge=C=PMes*: experimental and theoretical investigations

Phosphagermaallene Tip(tBu)Ge=C=PMes* 1 (Tip=2,4,6-triisopropylphenyl, Mes*=2,4,6-tri-tert-butylphenyl) reacts with phenyl isocyanate and tert-butyl isocyanate by a [2+2] cycloaddition that involves the Ge=C and C=O double bonds to afford 1-oxa-2-germacyclobutanes 2 and 3. With N,N'-dicyclohexylcarbodiimide, a [2+2] cycloaddition is observed between the Ge=C and C=N unsaturations to lead to 1-aza-2-germacyclobutane 6 with exocyclic P=C and C=N double bonds. In sharp contrast, 1 reacts with phenyl isothiocyanate, ethyl isothiocyanate, and carbon disulfide according to a [3+2] cycloaddition that involves the whole Ge=C=P unit and the C=S double bond to give transient phosphagermacarbenes (PGeHCs) 11, 12, and 13. These new PGeHCs undergo C-H insertions into one o-tBu group of Mes* (in the case of 11 and 12) or one o-iPr group of Tip (in the case of 13) with formation of tricyclic compounds 8, 9, and 10, respectively. The reaction mechanisms that involve 1 and the phenyl isocyanate and the phenyl isothiocyanate are described and their regioselectivity is explained by theoretical calculations.     

The Effect of Alkyl Side Chain and Additives on the Anionic Polymerization of Isocyanates with Carbamate Group

The synthesis of new isocyanate monomers and their polymerization by anionic route is reported. Reaction of 1,6-diisocyanatohexane with aliphatic alcohols such as methanol, n-propanol and n-pentanol in 1:0.5 molar ratios was carried out in the presence of pyridine such that one  NCO group remained unreacted. The anionic polymerization of n-alkoxycarbonylaminohexyl isocyanates was carried out using sodium napthalenide (Na-Naph) initiator in the presence of 15-crown-5 (15C5) and sodium tetraphenylborate as the additives. While polymerization of n-propyloxycarbonylaminohexyl isocyanate (PAHI) and n-pentanoxycarbonylaminohexyl isocyanate (PEAHI) was feasible that of methoxycarbonylaminohexyl isocyanate (MAHI) led to an insoluble material. The polymers were isolated in high yields with NaBPh₄ as the additive.     

Water‐stable copolymers containing isocyanate moiety protected by hydrophobic styrene segment and their reaction with amines

Reactive isocyanate groups were protected and stabilized by the hydrophobic styrene segment and acquired high tolerance toward water. Copolymers containing isocyanate groups were synthesized by a radical copolymerization of 2‐propenyl isocyanate (2PI) and styrene (St). The stability of the obtained copolymers on water was examined to find that isocyanate groups were protected by the hydrophobic polystyrene segment and were stable on water and these isocyanates reacted with primary amines including amino acids to form urea selectively on water. Primary amines with a higher octanol‐water partition coefficient or smaller steric hindrance were more reactive to the isocyanate groups in the side chain of the copolymer. The protection of reactive isocyanate groups using the hydrophobic styrene segment did not give side products which are produced in the usual chemical protection/deprotection process. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1934–1940     

Synthesis of fungitoxic derivatives of benzimidazole with a radioactive label

Methyl-1-butylcarbamoyl-2-benzimidazolylcarbamate with a radioactive label in the imidazole ring or methoxy group was obtained by successive reaction of barium C¹⁴-cyanamide with methyl C¹⁴-chloroformate, o-phenylenediamine, and butyl isocyanate.