Linear polybiurets: Facile synthesis and characteristic properties

Linear polybiurets have been synthesized by polyaddition of benzyloxyamine and diisocyanates, and properties of the novel polymeric materials have been elucidated. Prior to polymerization, model reactions between benzyloxyamine and phenyl isocyanate were examined in detail and proved to be controlled by the molar ratio of reagents and by catalysts to give the urea (1:1 adduct) and/or biuret (1:2 adduct). Under appropriate conditions, the biuret was synthesized in a quantitative yield. Polymerization of equimolar amounts of benzyloxyamine and diphenylmethane or hexamethylene diisocyanate proceeded smoothly to give polybiurets with inherent viscosities up to 0.52 dL/g. The benzyl group of the model biuret and polybiuret could be removed by catalytic hydrogenation. Both the N-benzyloxy-type and N-hydroxy-type polybiurets showed excellent solubility in common organic solvents. The two kinds of polybiurets as well as model biurets adsorbed metal cations efficiently. The N-hydroxybiuret structure exhibited particularly high affinity for iron(III) and was useful for selective removal of iron from metal cation mixtures. © 1996 John Wiley & Sons, Inc.     

Preparation of brassylic acid from 5,6,7,8,9,10,11,12,13,14-decahydrocyclododeca[1,2-d]pyrimidine(1H, 3H)-2,4-dione obtained by the condensation of cyclododecanone and urea or biuret

A simple method is proposed for the preparation of brassylic acid by the alkaline hydrolysis of 5,6,7,8,9,10,11,12,13,14-decahydrocyclododeca[1,2-d]pyrimidine(1H, 3H)dione-2,4, which is the product of the condensation of cyclododecanone with urea or biuret. The condensation of the cyclododecanone with thiourea proceeds differently, leading to 5,6,7,8,9,10,11,12,13,14-decahydrocyclododeca[1,2-d]pyrimidine(1H, 3H)spirocyclododecane-2-thione-4.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 226–229, January, 1992.     

Study of Dehydrocoupling Reactions of Diorganotin Dihydrides R^1R^2SnH2 with Biuret

The reaction of unsymmetrical phenylmethyltin dihydride （PhMeSnH2）, phenylethyltin dihydride （PhEtSnH2）, phenylbutyltin dihydride （PhBuSnH2） and butylmethyltin dihydride （BuMeSnH2） with biuret （HAL） proceeds via SnH/NH dehydrocoupling to afford the corresponding tetra-coordinate cyclic products. The reactions in the molar ratios of 1 ： 1, 2 ： 1 and 1 ： 2 have been studied. The yellow derivatives so isolated were soluble in polar solvents and insoluble in nonpolar solvents. It was found that 1 ： 1 reaction went to completion while 2 ： 1 and 1 ： 2 did not go to completion. The derivatives had been characterized by elemental analysis and spectroscopic techniques viz. IR, ^1H NMR, ^13C NMR, ^119Sn NMR. DSC and TGA of the reaction products have also been studied. All the derivatives were thermally stable upto （1904- 10）℃ and degradation occurred after that.     

Spectrophotometric Method of Assaying Urease Activity

Abstract

A kinetic method for the assay of urease and urea is reported. The method measures the change of absorbance with time of the indicator phenol red. The change in absorbance is due to a pH shift from neutral to alkaline caused by the enzyme hydrolysis of urea. The method is also suitable for kinetic studies of deaminase enzyme systems.     

微波辐射固相法合成缩二脲铜配合物

The copper(Ⅱ) complexes of biuret have been synthesized by solid phase reaction with microwave irradiation. The compositions and structures of the complexes are characterized by elemental analysis, molar conductance, in-frared spectra, electronic spectra, magnetic susceptibility, thermogravimetric and differential thermal analysis, X-ray powder diffraction. The two complexes have the compositions of [Cu(bi)₂]Cl₂(A) and [Cu(bi)₂](NO₃)₂(B)(bi=NH₂CONHCONH₂) and the molecular formulae of CuC₄H₁₀O₄N₆Cl₂ and CuC₄H₁₀O₁₀N₈, respectively. The molar conductance data show that the complexes are 1∶2 electrolyte. Infrared spectra of the complexes show oxygen atoms have been coordinated with divalent copper ion. The thermal decomposition processes of the complexes show that the final residues are all cupper oxide. The results of indexes to the X-ray powder diffraction data indicate that the crystal structure of the complexes belong to monoclinic system, the lattice parameters are: a=0.6976nm,b=1.1546 nm,c=2.1689nm,β=96.80°,V=1.7346nm³ for A; and a=0.7096nm,b=1.1359 nm,c=2.1002 nm,β=97.05°,V=1.6800nm³ for B, respectively.     

13C-NMR Study of Anomalous Linkages in Polyurethane

Several kinds of model compounds for anomalous linkages in polyurethanes (branching or crosslinking; allophanate and biuret) were prepared. The phenylisocyanate (PHI) based models were identified by IR and NMR. The ¹³C-NMR chemical shifts effects due to the anomalous linkages were determined. The 4,4′-diphenylmethane diisocyanate (MDI) based models were purified incompletely but the characteristic signals of the aromatic carbons were nevertheless found in their spectra. Two types of segmented polyurethane (SPU) were prepared and the anomalous linkages were investigated by ¹³C-NMR. The signals due to the allophanate (Al) and the triphenylbiuret (TB) linkages were observed in the spectra of the SPU prepared at high temperature (>80°C) or prepolymer gels yielded by abnormal reaction. A small signal due to a phenyl carbon of biuret (Bi) linkage was observed even in a normally prepared SPU (polyetherurethane-urea). Employing the phenyl carbon signals was advantageous for the determination of anomalous linkages because of their larger intensities.     

Zur Reaktion von Diphenoxyphosphorylchlorid mit N,N-disubstituierten Harnstoffen – Bildung von phosphorylierten Biuret-Verbindungen

Reaction of Diphenoxyphosphorylchloride with N,N-disubstituted Ureas – Formation of Phosphorylated Biuret Compounds N′,N′-disubstituted N-diphenoxyphosphorylureas, (PhO)₂P(O)? NH? CO? NR¹R² (R¹ = R² = Et, 1 ; n-Pr, 2 ; n-Bu, 3 ; i-Bu, 4 ; R¹ = Me and R² = Ph, 5 ) as well as phosphorylated biuret compounds, (PhO)₂P(O)? NH? CO? NH? CO? NR¹R² are obtained in the reaction of diphenoxyphosphorylchloride with N,N-disubstituted ureas and triethylamine. The biuret derivatives are formed via (PhO)₂P(O)NCO. Their yield rises if the reaction is carried out without amine. The X-ray crystal structure analysis of (PhO)₂P(O)? NH? CO? NH? CO? NPr₂, 8 , shows that dimers exist in the crystal with intermolecular as well as intramolecular hydrogen bonds. The framework formed by atoms P? N1? C1(O4)? N2? C2(O5)? N3(C3)C6 is planar. The existence of a rotation barrier along the bond C2–N3 was detected by NMR spectroscopy.     

交联型非线性光学聚合物的合成

利用六亚甲基二异氰酸酯的缩二脲与对硝基偶氮苯甘油单醚的电场极化交联反应合成交联型聚合物非线性光学材料．采用变温红外光谱、ＤＳＣ、紫外可见吸收光谱研究交联反应时间对非线性生色基团的取向及松弛的影响．     

Lewis Acid Assisted Brønsted Acid Catalysed Decarbonylation of Isocyanates: A Combined DFT and Experimental Study

An efficient and mild reaction protocol for the decarbonylation of isocyanates has been developed using catalytic amounts of Lewis acidic boranes. The electronic nature (electron withdrawing, electron neutral, and electron donating) and the position of the substituents (ortho/meta/para) bound to isocyanate controls the chain length and composition of the products formed in the reaction. Detailed DFT studies were undertaken to account for the formation of the mono/di-carboxamidation products and benzoxazolone compounds.