Synthesis and characterization of N-phenylated aromatic polyureas from N,N′ -dichloroformyl-p-dianilinobenzene and N,N′ -bistrimethylsilyl-diamines

NovelN-phenylated aromatic polyureas having inherent viscosities of 0.13–0.35 dL/g were synthesized by the solution polycondensation of N,N′-dichloroformyl-p-dianilinobenzene with N,N′-bistrimethylsilyl derivatives of bis(4-aminophenyl)ether, piperazine, and p-dianilinobenzene in sulfolane. Except the polyurea containing piperazine unit, the other polyureas were amorphous and readily soluble in a variety of organic solvents such as tetrahydrofuran. The polyurea derived from p-dianilinobenzene, which has no vulnerable hydrogen on the urea linkage, did not melt below 350°C and was stable up to 450°C in air.     

N,N,N′,N′‐Tetraalkylaminoazoxybenzene Derivatives; Convenient Synthesis and Mechanistic Study

N,N,N′,N′‐tetraalkyaminoazoxybenzene derivatives were conveniently prepared by the coupling of N,N‐dialkylnitrosoaniline in the presence of acetone and KOH. The reaction mechanism was proposed and investigated, and the structure of compound 3b was also confirmed by single crystal X‐ray diffractometry.     

Synthesis of substituted polymethylenes by radical polymerization of N,N,N′,N′-tetraalkylfumaramides and their characterization

Radical polymerization of N,N,N′,N′-tetraalkylfumaramides (TRFAm) bearing methyl, ethyl, n-propyl, isopropyl, and isobutyl groups as N-substituents (TMFAm, TEFAm, TnPFAm, TIPFAm, and TIBFAm, respectively) was investigated. In the polymerization of TEFAm initiated with 1,1′-azobiscyclohexane-1-carbonitrile (ACN) in benzene, the polymerization rate (R_p) was expressed as follows: R_p = k [ACN]^0.28 [TEFAm]^1.26, and the overall activation energy was 102.1 kJ/mol. The introduction of a bulky alkyl group into N-substituent of TRFAm decreased the R_p in the following order: TMFAm > TEFAm > TnPFAm > TIBFAm > TIPFAm ～ 0. The relative reactivities of these monomers were also investigated in radical copolymerization with styrene (St) and methyl methacrylate (MMA). In copolymerization of TRFAm (M₂) with St (M₁), monomer reactivity ratios were determined to be r₁ = 1.07 and r₂ = 0.20 for St–TMFAm, and r₁ = 1.88 and r₂ = 0.11 for St–TEFAm, from which Q₂ and e₂ values were estimated to be 0.35 and 0.44 for TMFAm, and 0.19 and 0.47 for TEFAm, respectively. The other TRFAm were also copolymerized with St, but copolymerization with MMA gave polymers containing a small amount of TRFAm units. The polymer from TRFAm consists of a less-flexible poly(N,N-dialkylaminocarbonylmethylene) structure. The solubility and thermal property of the polymers were also investigated.     

Polymerization of butadiene initiated by the 1:1 chelate of n-butyllithium and N,N,N′,N′-tetramethylethylenediamine

Evidence is given for the species involved in the initiation and propagation steps in the polymerization of butadiene with n-butyl lithium: tetramethylethylene diamine (TMEDA) as being the monomeric butyl lithium and the solvated ion pair, (A), respectively. Species A is also produced on the metalation of polybutadiene with butyl lithium: TMEDA.     

Über Chalkogenolate. 168. Reaktion von N,N′-Diphenylformamidin mit Kohlenstoffdisulfid 1. Darstellung und Eigenschaften von N,N′-Diphenyl-N-form-imidoyldithiocarbamaten

On Chalcogenolates. 168. Reaction of N,N′-Diphenyl Formamidine with Carbon Disulfide. 1. Synthesis and Properties of N,N′-Diphenyl N-Formimidoyl Dithiocarbamates N,N′-Diphenyl formamidine H? N(C₆H₅)? CH?NC₆H₅ reacts in different solvents with CS₂ in the presence of an alkali metal hydroxide to produce N,N′-diphenyl N-formimidoyl dithiocarbamate solvates. The properties of the prepared compounds (L = H₂O, acetonitrile, dioxane, dimethoxyethane, acetone, and mixed solvates) and of the Tl, Ba, and Pb salts are described.     

N,N,N′,N′‐Tetrasubstituted Piperazinium Salts of Perfluorinated Acids

Well crystallized diquaternary piperazinium salts of perfluorocarboxylic acids can be prepared by thermal rearrangement of a primary product obtained from the appropriate fluorinated acid chloride and N,N‐dialkylamino‐ethanol. The mechanism of the ring closure step is discussed. The synthetic strategy easily gives access to structurally different piperazinium perfluorocarboxylates. The title compounds show surface activity and can be regarded as ionic amphiphiles.     

Unusual mass spectrometric fragmentation of N,N′-diethyl-N,N′-diphenylurea

The electron impact mass spectrum of N,N′-diethyl-N,N′-diphenylurea contains the ion m/z 164 which is of low abundance at normal energy of ionizing electrons but prominent at 15-20eV. The mechanism of its formation has been revealed by means of labelled compounds. It is rationalized in terms of an unusual formation of styrene lost as a neutral molecule.     

Synthesis,Characterization, and Crystal Structure of Complexes of Lanthanide Picrates with N,N,N′,N′-tetraphenyl-3,6-dioxaoctanediamide

Lanthanide picrate complexes with the ligand N,N,N′,N′-tetraphenyl-3,6-dioxaactanediamide (tdd): [Ln(Pic)₃(tdd)] (Ln = La, Nd, Eu, Tb, Er) have been prepared in a nonaqueous medium and characterized by elemental analysis, conductivity measurements, IR, and ¹H-NMR spectra. The crystal structures of the complexes for Ln = Nd and Er were determined. The early lanthanide, Nd^III, crystallizes as the nona-coordinate complex [Nd(Pic)₃(tdd)]. 2 CH₃CN in the monoclinic space group P2₁n with a = 11.384(2), b = 18.805(4), c = 27.526(5) Å, β = 99.41(1)°, V = 5832(2) ų, and D_c = 1.58 gcm^?3 for Z = 4. The structure was refined to R = 0.0505, based on 4772 observed Deflections. The late lanthanide, Er^III, forms an octa-coordinate complex [Er(Pic)₃(tdd)]; crystals are triclinic, P1, with a = 12.449(2), b = 17.065(2), c = 26.243(4) Å, α = 72.12(1), β = 87.86(1), γ = 84.60(1)°, V = 5282(1) ų, and D_c = 1.68 g cm^?3 for Z, = 4. The structure was refined to R = 0.0469, based on 10666 observed reflections, The results reveal that tdd forms a ring-like structure with its four O-atoms, coordinating to the metal ions as multidentate ligand, together with one O-atom of the bidentate picrate. The structure of the complexes is greatly affected by the ionic radius due to participation of the picrates in coordination.     

Stable conformations of N,N,N′,N′- tetraisopropylthiuram disulphide and monosulphide found in low temperature 1H N.m.r. spectra

¹H N.m.r. spectra of N,N,N′,N′-tetraisopropylthiuram disulphide and monosulphide in CS₂ suggested that internal rotations both around the carbamate C? N and isopropyl–nitrogen bonds are restricted at low temperatures. As a result, both compounds exist as two dl pairs of isomers with respect to rotation around the isopropyl–nitrogen bond. The spectra further suggest that one pair of the isomers is subdivided into two sets of dl pairs, possibly owing to the restriction of torsion of the two carbamate planes with respect to each other. Possible conformations of these three dl pairs of isomers are proposed, and the assignments of each proton signal are described.     

N,N′,N′′,N′′′‐Tetraethylterephthalamidinium bis(tetrazolate)

The crystal structure of the title 2:1 salt of tetrazole and a substituted terephthal­amidine, C₁₆H₂₈N₄²⁺·2CHN₄^?, contains an infinite network of hydrogen bonds, with short N?N distances of 2.820 (2) and 2.8585 (19) Å between the tetrazolate anion and the amidinium cation. Involvement of the lateral N atoms of the tetrazole in the hydrogen bonding appears to be a typical binding pattern for the tetrazolate anion.