P-N COMPOUNDS 28. PHOSPHAMINIMIDES 3. 4-NITROBENZYLATION OF PHOSPHINYL-1, 1-DIMETHYL HYDRAZIDES AND FORMATION OF A UNIQUE HYDRAZINIUM INNER SALT1

Abstract

The treatment of diethoxyphosphinyl-1,1-dimethylhydrazide with 4-nitrobenzylbromide at 82–90°C resulted in the loss of EtBr and the formation of EtO(^?O)P(O) NHN⁺(CH₃)₂CH₂-4-NO₂Ph, a novel type of phosphaminimide. At lower temperatures the diethoxyhydrazide gave the hydrazinium bromide which slowly underwent loss of EtBr to yield the same product. The diphenoxy compound similarly lost HBr at high, but not lower, temperature with production of the normal phosphaminimide. The diphenyl derivative yielded the expected hydrazinium bromide which was dehydrobrominated to the usual phosphaminide with NaOH. The reaction between all three hydrazides and iodomethane, followed by dehydroiodination, gave the usual phosphaminimides.     

Anodic Protection. Theory and Practice in the Prevention of Corrosion.: O.L. Riggs,Jr. and C.E. Locke,Plenum Press,New York, 1981, 284 pp., US$39.50.

The specific adsorption of chloride, bromide, iodide, azide, and thiocyanate has been studied at an electropolished polycrystalline silver-aqueous interface using differential capacitance measurements. For chloride, bromide, and azide, quantitative estimates of the surface concentration of specifically adsorbed anions were obtained from capacitance-potential data in mixed fluoride electrolytes having a constant ionic strength of 0.5. The dependence of the measured capacitance upon the ionic strength of sodium fluoride was also investigated in order to check the behavior of the polycrystalline surface in comparison with the predictions of conventional double-layer models. Estimates of the specifically adsorbed charge densities of chloride, bromide, and thiocyanate anions were also obtained from a “kinetic probe” technique which entailed monitoring the response of the outer-sphere reduction rate of CO(NH₃)₅F²⁺ and Co(NH₃)₆³⁺ to the addition of the appropriate adsorbing anion. At the average potential of zero charge for the polycrystalline silver surface, the standard free energies of adsorption ? Δ₃^o for chloride, bromide, and azide were found to be within ca. 5 kJ mol^?1 of the corresponding quantities obtained at mercury electrodes. However. significantly greater increases in ? Δ₃^o in the sequence Cl^? < N₃^? < Br^? are seen at silver compared to mercury. Electrochemical roughening in chloride media, giving silver surfaces displaying intense surface Raman scattering, yields only minor changes in the surface concentration of specifically adsorbed chloride anions.     

The chloride,bromide and iodide salts of 1‐(diaminomethylene)thiouron‐1‐ium

Crystals of 1‐(diaminomethylene)thiouron‐1‐ium chloride, C₂H₇N₄S⁺·Cl⁻, 1‐(diaminomethylene)thiouron‐1‐ium bromide, C₂H₇N₄S⁺·Br⁻, and 1‐(diaminomethylene)thiouron‐1‐ium iodide, C₂H₇N₄S⁺·I⁻, are built up from the nonplanar 1‐(diaminomethylene)thiouron‐1‐ium cation and the respective halogenide anion. The conformation of the 1‐(diaminomethylene)thiouron‐1‐ium cation in each case is twisted. Both arms of the cation are planar and rotated in opposite directions around the C—N bonds involving the central N atom. The dihedral angles describing the twisted conformation are 22.9 (1), 15.2 (1) and 4.2 (1)° in the chloride, bromide and iodide salts, respectively. Ionic and extensive hydrogen‐bonding interactions join oppositely charged units into a supramolecular network. The aim of the investigation is to study the influence of the size of the ionic radii of the Cl⁻, Br⁻ and I⁻ ions on the dimensionality of the hydrogen‐bonding network of the 1‐(diaminomethylene)thiouron‐1‐ium cation. The 1‐(diaminomethylene)thiouron‐1‐ium system should be of use in crystal engineering to form multidimensional networks.     

Pyrolysis of 5-chloropentan-2-one and 4-chloro-1-phenylbutan-1-one. Participation of the carbonyl group

The rates of elimination of 5-chloropentan-2-one and 4-chloro-1-phenylbutan-1-one in the gas phase have been determined in a static system, seasoned with allyl bromide, and in the presence of the chain inhibitor propene. The reactions are unimolecular and follow a first-order rate law. The working temperature and pressure ranges were 339.4–401.1°C and 46–117 torr, respectively. The rate coefficients for the homogeneous reactions are given by the following Arrhenius equations: for 5-chloropentan-2-one, log k₁(s^?1) = (13.12 ± 0.88) - (207.8 ± 11.0)kJ/mol/2.303RT; and for 4-chloro-1-phenylbutan-1-one, log k₁(s^?1) = (12.28 ± 1.09) - (185.2 ± 12.0)kJ/mol/2.303RT. The carbonyl group at the γ position of the C? Cl bond of haloketones apparently participates in the rate of pyrolysis. The five-membered conformation appears to be a favorable structure for anchimeric assistance of the C?O group in the gas-phase elimination of chloroketones.     

1-Methylallyl(cyclooctatetraene)titanium

The complex 1-methylally(cyclooctatetraene)titanium has been prepared by the reaction of cyclooctatetraenetitanium chloride and 1-methylallylmagnesium bromide. The IR spectrum shows the vibrations of the h⁸-C₈H₈ ligand and of a π-bonded methylallyl group. The mass spectrum is also discussed.     

Copper(II) Halide Complexes with 1‐tert‐Butyl‐1H‐1,2,4‐triazole and 1‐tert‐Butyl‐1H‐tetrazole

1‐tert‐Butyl‐1H‐1,2,4‐triazole (tbtr) was found to react with copper(II) chloride or bromide to give the complexes [Cu(tbtr)₂X₂]_n and [Cu(tbtr)₄X₂] (X = Cl, Br). 1‐tert‐Butyl‐1H‐tetrazole (tbtt) reacts with copper(II) bromide resulting in the formation of the complex [Cu₃(tbtt)₆Br₆]. The obtained crystalline complexes as well as free ligand tbtr were characterized by elemental analysis, IR spectroscopy, thermal and X‐ray analyses. For free ligand tbtr, ¹H NMR and ¹³C NMR spectra were also recorded. In all the complexes, tbtr and tbtt act as monodentate ligands coordinated by Cu^II cations via the heteroring N⁴ atoms. The triazole complexes [Cu(tbtr)₂Cl₂]_n and [Cu(tbtr)₂Br₂]_n are isotypic, being 1D coordination polymers, formed at the expense of single halide bridges between neighboring copper(II) cations. The isotypic complexes [Cu(tbtr)₄Cl₂] and [Cu(tbtr)₄Br₂] reveal mononuclear centrosymmetric structure, with octahedral coordination of Cu^II cations. The tetrazole compound [Cu₃(tbtt)₆Br₆] is a linear trinuclear complex, in which neighboring copper(II) cations are linked by single bromide bridges.     

(Cyclopentadienyl)(1-methylallyl)(butadiene)titanium

(Cyclopentadienyl)(1-methylallyl)(butadiene)titanium, C₁₃H₁₈Ti, has been obtained from the reaction between (C₅H₅)TiCl₃ or (C₅H₅)TiCl₂ and 1-methylallylmagnesium bromide in ether. The brown compound is diamagnetic and thermally stable, but very sensitive to oxygen. The nature of the new compound has been elucidated from its reaction with bromine and by IR, ¹H and ¹³C NMR, and mass spectral analysis.     

Spectrophotometric determination of traces of bromide based on its catalysis of the pyrocatechol violet/hydrogen peroxide reaction

A kinetic-spectrophotometric method for the determination of bromide (0.004–0.3 mg l^?1) based on its catalysis of the oxidation of pyrocatechol violet by hydrogen peroxide in HCl/H₂SO₄ is described. The effect of bromide is greatly increased in the presence of large amounts of chloride. The relative standard deviations are 6.4 and 13% for 0.034 and 0.010 mg l^?1 bromide, respectively (n = 10). Most ions commonly occurring in natural waters do not interfere except for iodide.     

Kinetics of the I2-catalyzed isomerization of allyl chloride to cis- and trans-1-chloro-1-propene. The stabilization energy of the chloroallyl radical

The I₂-catalyzed isomerization of allyl chloride to cis- and trans- l-chloro-l-propene was measured in a static system in the temperature range 225–329°C. Propylene was found as a side product, mainly at the lower temperatures. The rate constant for an abstraction of a hydrogen atom from allyl chloride by an iodine atom was found to obey the equation log [k,/M^?1 sec^?1] = (10.5 ± 0.2) ?; (18.3 ± 10.4)/θ, where θ is 2.303RT in kcal/mole. Using this activation energy together with 1 ± 1 kcal/mole for the activation energy for the reaction of HI with alkyl radicals gives DH⁰ (CH₂CHCHCl? H) = 88.6 ± 1.1 kcal/mole, and 7.4 ± 1.5 kcal/mole as the stabilization energy (SE) of the chloroallyl radical. Using the results of Abell and Adolf on allyl fluoride and allyl bromide, we conclude DH⁰ (CH₂CHCHF? H) = 88.6 ± 1.1 and DH⁰ (CH₂CHCHBr? H) = 89.4 ± 1.1 kcal/ mole; the SE of the corresponding radicals are 7.4 ± 2.2 and 7.8 ± 1.5 kcal/mole. The bond dissociation energies of the C? H bonds in the allyl halides are similar to that of propene, while the SE values are about 2 kcal/mole less than in the allyl radical, resulting perhaps more from the stabilization of alkyl radicals by α-halogen atoms than from differences in the unsaturated systems.     

25,26-Dialkoxycalix[4]arenes. Part 1: 25-Alkoxy-26,27-diacetoxy route

Acetylation of calix[4]arene 1,3-dialkyl ethers yielded the corresponding monoacetates. The ¹H NMR spectral analysis indicated that the products’ alkoxy moieties were ‘rotation restricted’. Acylation of calix[4]arene monoalkyl ethers with acetyl chloride yielded monoacetates and/or 2,3-diacetates in different reaction conditions. A simple recrystallization process was able to isolate 2,3-diacetates in good yield. The ¹H NMR spectra of the diacetylated products indicated that those compounds also possessed the ‘rotation restricted’ alkoxy moieties. In the presence of K₂CO₃ as reaction base, alkylation of 2,3-diacetates produced the acetyl-migrated 1,3-dialkyloxy derivatives. Basic hydrolysis of the acetyl-migrated compounds yielded the known 1,3-dialkoxycalix[4]arenes. In the presence of NaH as reaction base, 2,3-diacetates were alkylated with and without the acetyl-migration. For the highly reactive benzyl bromide and allyl bromide, the majority of alkylation proceeded without acetyl-migration. In the other alkyl halides, the products were the acetyl-migrated 1,3-dialkoxy derivatives along with less than one-fourth the amount of non-migrated 1,2-dialkoxy derivatives.     

Gold bromide complexes in acidic aqueous solutions from 25° to 300°C. A laser raman spectroscopic study

Raman spectra of gold bromide complexes in acidic solutions (pH=–0.3–3) have been recorded at 25° to 300°C and at pressures on the liquid vapor curve for the system. At 25°C, only the square planar Au(III) bromide complex, AuBr ₄ ^– , is present in solution with bands at approximately 105, 197 and 215 cm^–1. However, in these acidic solutions, when the temperature is 50°C or higher, the square planar Au(III) bromide complex is partially transformed into the linear Au(I) bromide complex, AuBr ₂ ^– , with a single band near 208 cm^–1. The transformation of the Au(III) square planar tetrabromo complex into the Au(I) linear dibromo complex is also favored by a reduction of the oxygen fugacity and an increase in pH.     

Intramolecular cyclization of 4,7‐bis(2‐bromo­acetyl)‐1‐thia‐4,7‐di­azacyclo­nonane

The reaction of 1‐thia‐4,7‐di­azacyclo­nonane with bromo­acetyl bromide in CHCl₃ affords the unexpected salt 4‐(2‐bromo­acetyl)‐8‐oxo‐1‐thionia‐4,7‐di­aza­bi­cyclo­[5.2.2]­un­decane bromide, C₁₀H₁₆BrN₂O₂S⁺·Br⁻. Two units of the salt are linked by S⋯Br contacts about a crystallographic inversion centre, thus forming dimers that are linked by Br⋯Br contacts into extended ribbons. S⋯O contacts between these ribbons generate a two‐dimensional sheet.     

Structural Diversity in Thallium Chemistry. Part V

From thallium(III) bromide solution, the unsubstituted pyridinium cation yields a complex ( 1 ) with the [Tl₂Br₉]^3? anionic stoichiometry. The Raman spectrum and single‐crystal X‐ray crystallographic analysis showed that the salt contains independent [TlBr₄]^? and bromide anions. A variety of mono‐ and disubstituted pyridinium cations were also employed in similar syntheses. The 2‐bromopyridinium cation gave a salt 2 with [TlBr₅]^2? stoichiometry, but the crystal structure revealed very weakly interacting [TlBr₄]^? and bromide anions with a Tl ???Br^? distance of 4.1545(6) Å. The 2‐(ammoniomethyl)pyridinium and 2‐amino‐4‐methylpyridinium cations yielded complexes containing [TlBr₅]^2? ( 3 ) and [TlBr₄]^? ( 4 ) species, respectively, which were confirmed by Raman spectroscopy and X‐ray crystallographic analyses. For 3 , the [TlBr₅]^2? anion has a highly distorted trigonal bipyramidal conformation with one long axial Tl ???Br bond of 3.400(2) Å. Microanalytical results in conjunction with Raman spectra from a further five salts confirmed that they all contain the simple [TlBr₄]^? anion. N? H ???Br Hydrogen bonds clearly influence the nature of the anionic species obtained in these systems.     

Synthesis and Structure of Mixed Ba12F19ClδBr5–δ Crystals

In the structure Ba₁₂F₁₉Cl₅ [hexagonal space group P6 2m] the two chlorides on the sites Cl(1) and Cl(2) can partially be replaced by bromide ions. Single crystals of the type Ba₁₂F₁₉Cl_δBr_5–δ with a chloride to bromide ratio up to 2 : 3 could be obtained by cooling a flux of 75 mol% BaF₂ and 25 mol% BaX₂ with X = Cl, Br. The crystal quality decreases with increasing bromide concentration. Structural parameters of five selected single crystals with different chloride/bromide ratio were studied by single crystal X-ray diffraction methods. The refined total Cl^?/Br^? population ratio in the crystals is close to the one of the flux. The lattice parameters and interatomic distances change in various ways, when the smaller chloride ion is replaced by the bigger bromide ion. The refinements show a statistical disorder on the halide sites with preferential bromide substitution on site Cl(1).     

Synthesis of 2-aryl-6-(4-bromophenyl)-4-(2,2-dichlorovinyl)pyridines with the use of 1-aryl-5,5-dichloropenta-2,4-dien-1-ones

Heating 1-aryl-5,5-dichloropenta-2,4-dien-1-ones with 4-bromophenacylpyridinium bromide in AcOH in the presence of AcONH₄ gave 2-aryl-6-(4-bromophenyl)-4-(2,2-dichlorovinyl)pyridines. The reaction products were structurally characterized by¹H and¹³C NMR spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 955–957, May, 2000.     

Polarographic behaviour of DL aspartic acid at the D.M.E.

dl Aspartic acid is reduced at the d.m.e. in 0.1M tetramethylammonium bromide, tetraethylammonium bromide, sodium chloride, potassium chloride, potassium nitrate, sodium perchlorate and lithium sulphate; in aqueous media. The waves are irreversible, diffusion controlled involving one electron transfer process determined by millicoulometry. The values of the kinetic parameters, transfer coefficient () and formal rate constant (k° _{f, h}) have been calculated byKoutecky's method and are 0.479 and 15.9×10^–16 respectively.With 1 Figure     

Substitution électrophile aromatique dans l'anhydride sulfureux liquide. Influence de la concentration en bromure et rôle du solvant sur la réactivité des anisoles au cours de la réaction de bromation

Electrophilic Aromatic Substitution in Liquid Sulfur Dioxide. Kinetic Dependance of Rate on the Bromide Concentration and Influence of the Solvent during the Course of the Reaction On the reported data for bromination of anisole and eleven of its derivatives in liquid SO₂, it was shown that, with a large excess of bromide, the rate of reaction, obeys a first-order law. Rate constants thus obtained do not discriminate between the two different forms of bromide, e.g. Br₂ and Br^?₃ present as the A⁺Br^?₃ form, and corrections were made by use of the apparent equilibrium constant K′ for tribromide formation. The variations of rate constants with initial concentration of bromide has been studied and the effect results in a retardation of the bromination rate. Moreover, the ratio [Br₂] [A⁺Br^?]_T, which is constant during an experiment, varies with initial bromide concentrations, this variation affecting the total rate. To account for the bromide effect on the reactivity, variations of k^o,p_g {1 + K′[A⁺Br^?]_T}VS[A⁺Br^?]_T were studied over a 0.01 to 1M range of bromide concentration. The mechanism proposed shows that liquid SO₂ helps the reactive intermediate to be deprotonated and because of solvation of reactive species this step would probably be rate determining. Bromination by molecular bromine is more sensitive to substituent effects in liquid SO₂ than in water. This result is ascribed to the +M effect of the methoxy group which increase the conjugation of ortho-substituted derivatives (p⁺_p = ?7.83; p⁺_o= ?10.47).     

Slow motions undergone by surfactant molecules in micelles. A 1H and 14N nuclear magnetic relaxation study

Surfactant motion in spherical micelles of the system cetyltrimethylammonium bromide/D₂O has been investigated by ₁H and ¹⁴N longitudinal relaxation at different frequencies. Such measurements allow extraction of the correlation time characterizing the overall reorientation of the surfactant molecule, which includes micelle tumbling and lateral diffusion around the micelle. The proton data, which reflect the alkyl chain mobility, require the definition of a local director, distinct from the normal to the aggregate surface, thus making possible the occurrence of an additional slow motion. Conversely ¹⁴N data can be analyzed accord- ing to the classical two-step model; this yields a correlation time associated with the slow motion of as ≈5 ns leading to a value of 4× 10⁻⁷ cm² s⁻¹ for the lateral diffusion coefficient.     

Facile one-pot synthesis of 2-arylbenzothiazoles catalyzed by H3PO4/TiO2-ZrO2 (1/1) under solvent-free conditions

A highly efficient and simple protocol for the preparation of 2-arylbenzothiazoles through condensation of 2-aminothiophenol and different aldehydes in the presence of H₃PO₄/TiO₂-ZrO₂(1/1)-cetyl pyridinium bromide (CPB) is described. The reaction proceeded under mild and solvent-free conditions to afford 2-arylbenzothiazole derivatives. In this method, the title compounds were obtained in good to excellent yields and short reaction times. The structures of synthesized products were identified by infrared, ¹H NMR, ¹³C NMR, and mass spectroscopy.     

Anodic reactions of the halides in dimethyl sulfoxide at the pyrolytic graphite electrode

The anodic reactions of the halide ions in dimethyl sulfoxide at the pyrolytic graphite electrode have been studied. The iodide ion demonstrates a 3-step oxidation; the bromide, a 2-step oxidation and chloride, a 1-step oxidation. The electrode reaction (X^-→$\text{1}\text{2}$ X₂ + e^-) is complicated by a catalytic reaction occurring after the electrode reaction. The catalytic reaction is important for only bromide and chloride causing a considerable diffusion current enhancement. The αn_a value for all 3 primary reactions is of the order of 0.5.