Molecular confirmation and crystal structure of the β form of poly(ethylene oxybenzoate)

The crystal structure of the β form of poly(ethylene oxybenzoate) was analyzed by x-ray diffraction. Four nearly extended molecular chains pass through a unit cell with parameters a = 8.19 Å, b = 11.07 Å, c (fiber axis) = 19.05 Å, β = 114.8°, and the space group P2₁/n-C. The structural difference between the α and β forms is mainly due to the internal rotation angles for the virtual bond and the ? CH₂? CH₂? bond. They are essentially in trans confirmation in the β form, while the α form contains cis and gauche (? CH₂? CH₂? ) conformations.     

Darstellung und Eigenschaften von Ti-substituierten N-Heterocyclen

Preparation and Properties of Ti-substituted N-Heterocycles The compounds (x = 2 to 6) have been prepared by transamination of Ti(NMe₂)₄ with the heterocyclic amines and have been characterised by elemental analyses and ¹H NMR and IR spectroscopy. The dependence on both x and n of the thermal decomposition has been studied for the series and . The results can be interpreted in terms of the steric strain of the R₂N and substituents. Apart from the piperidido groups none of the ligands exhibit protective group properties comparable to the R₂N groups.     

HNO,an Intermediate in (Light-induced) Rearrangement Reactions of Nitrosooxy Compounds and Nitrosamines

IR-spectroscopic investigations of light-induced rearrangement reactions of nitrosooxymethane (CH³ONO³), nitrosooxyethane (CH₃CH₂ONO) and N,N-dimethylnitrosamine ((CH₃)₂NNO) in low-temperature rare-gas matrices have established that these molecules are transformed in two photolysis steps to the previously unknown C-nitroso compounds nitrosomethanol (CH₂(OH)(NO)), 1-nitrosoethanol (CH₃CH(OH)(NO)), and methyl(nitrosomethyl)amine CH₂(NO)(NH)(CH₃). Evidence for a similar rearrangement reaction has been advanced for N-Nitrosopyrrolidine which is converted to C-nitrosopyrrolidine . The matrix-isolation technique in combination with wavelength-selective irradiation allowed to trap and characterize an intermediate of rearrangement which revealed to be nitroxyl (HNO) complex (CH₂…HNO, CH₃CHO…HNO, CH₃N = CH₂…HNO, and ). Since these findings have a close resemblance with rearrangement reactions of more complex nitrosooxy compounds, nitrosamines, or nitrosohydrazines used in organic synthesis, it is suggested that also in these reactions nitroxyl is present as an intermediate species.     

Étude des Paramètres de Résonance Magnétique Nucléaire et de la Stéréochimie de Thiono-2 R-2 Dithiaphosphorinanes-1,3,2

The ¹H, ¹³C and ³¹P n.m.r. spectra of eleven 2-R-2-thiono-1,3,2-dithiaphosphorinanes with various R groups attached to the phosphorus atom have been recorded and analysed. In the compounds where R=Cl, OMe or N, the molecule adopts a chair conformation with the R group axially oriented. When the molecule adopts a chair conformation with equatorially oriented R. In the case of the derivatives with R=phenyl, Me, N(Me)₂ or NHt-Bu, a chair–chair conformational equilibrium was observed. The hindered rotation about the P? N bond was also examined in the derivative with      

Effect of gegen ion in cationic polymerization and copolymerization of trioxane

p-Chlorophenyldiazonium hexafluorophosphate has been reported to be a superior catalyst for cationic polymerization and copolymerization of trioxane as compared to boron trifluoride dibutyl etherate (BF₃·Bu₂O)¹. In the present investigation the effect of anions derived from elements in Group VA, AsF and SbF, has been ascertained. It has been concluded that p-chlorophenyldiazonium hexafluoroarsenate is also a superior catalyst to boron trifluoride dibutyletherate (BF₃·Bu₂O), while p-chlorophenyl-diazonium hexafluoroantimonate is inferior. Copolymers with the highest polymer yield (>95%) and molecular weight (intrinsic viscosity = 4 to 5) were obtained with Simple dependences on catalyst concentration have been observed to hold for a wide catalyst concentration range ([M]/[C]) = (1 to 20) × 10⁵: For the same relationships hold. However, the polymer yield (75%) and molecular weights (intrinsic viscosity ?1) are considerably lower while the extent of chain transfer is higher. Furthermore, the polymerization proceeds with explosive violence. The quantitative aspects resulting from polymerization, for the most part, can be interpreted in terms of the extent of dissociation of the propagating ions.     

Determination of the composition and the stability constants of complexes of silver(I) with some sulphur containing pyridines a potentiometric investigation

A series of sulphide-containing pyridines of general formula ? (CH₂)_x? S? R where R = CH₃, C₂H₅, CH₂CH₂OH and x = 1, 2 has been prepared and studied potentiometrically in the presence of Ag⁺ in 0.5 M (K)NO₃ medium at 25°C. The complex formation is discussed in terms of the Taft σ*-parameters for the substituents. In acid region, where the complexes AgLH²⁺ and AgL₂H₂³⁺ were formed, coordination occurs through the thioether group. In neutral and alkaline medium their was evidence for the species AgL₂H²⁺, AgL⁺, AgL₂⁺, Ag₂L₂²⁺ and Ag₂L²⁺ in which Ag⁺? S and Ag⁺? bonds are involved. The five membered chelate rings for the AgL⁺ and AgL²⁺ species are found to be more stable than the six-membered ones.     

The oxidation of diethylhydroxylamine by nitrogen dioxide

Diethylhydroxylamine, (C₂H₅)₂NOH, was oxidized by NO₂ at 25°C in a long-path-length infrared gas cell. The measured products of the reaction were HONO and CH₃CHO. The reaction scheme which explains the reaction is was oxidized by NO₂, and the reaction was found to be very rapid with k₁ > 10^?16 cm³/s. The products of the reaction were verified by both infrared absorption (CH₃CHO, C₂H₅NO) and gas chromatography (CH₃CHO, NO).     

Fragmentations of protonated acetophenones via intermediate ion–molecule complexes

Protonated acetophenones, substituted with a methoxymethyl group in the para and meta positions, have been generated by electron impact induced fragmentation of the correspondingly substituted 2-phenylpropan-2-ols. The metastable ions, formed in the second field-free region of a VG ZAb 2F mass spectrometer, react unimolecularly by elimination of CH₃OH, formation of CH₃CO⁺ and ions, loss of CH₃COOCH₃, and loss of CH₂O. The mechanisms of these fragmentations have been elucidated with the aid of deuterated analogues of the protonated acetophenones. It is shown that these reactions are initiated by an endothermic transfer of the proton at the carbonyl group of the protonated acetophenones to the benzene ring. A further migration of the proton to the ether O atom of the methoxymethyl side-chain leads eventually to the elimination of CH₃OH. Protolytic bond cleavages of either side-chain gives rise to the CH₃CO⁺ and ions. At low internal energies both these ions may be trapped by the aromatic neutral fragment in ion-molecule complexes. Reactions within these complexes result in the energetically favourable losses of CH₃COOCH₃ and CH₂O, respectively. With respect to these reactions, the protonated acetophenones behave analogously to the correspondingly substituted and protonated benzaldehydes.     

ESR study on radical conversions in irradiated low-density polyethylene

ESR studies were carried out on radical conversions by thermal and photochemical mechanisms in low-density polyethylene irradiated mainly with electron beams at ?196°C both in vacuum and in the presence of CO. According to the spectral change, the following radical conversions were elucidated for the samples irradiated in vacuo [eqs. (1) and (1′)] and in the presence of CO [eqs. (2) and (2′)]. From the resemblance of the ESR spectrum observed after direct photolysis of polyethylene to that observed after photo-induced radical conversions of the allylic radicals, it is concluded that an eight-line ESR spectrum observed immediately after photolysis of polyethylene at ?196°C could be attributed more reasonably to the alkyl radicals ? CH₂CHCH₃ than to ? CH₂CH₂ and ? CH₂CHCH₂? .     

The loss of CH3⋅ from some unsaturated dithioesters

The mechanism for the loss of CH₃? (and C₂H₅?) from the molecular ions of some unsaturated dithioesters of the type with n=0, 1, 2, has been studied. Based on first field free region metastable ion characteristics it is proposed that 1,3-dithiolium type product ions are generated. Deuterium labelling experiments indicated that the molecular ions of the 2-alkenyl alkanedithioates undergo a rearrangement prior to fragmentation which resembles the [3,3]sigmatropic rearrangement in solution chemistry.     

Zur Darstellung von Cyclophosphaten,Cyclophosphatophosphonaten, Diphosphonaten und Diphosphiten in Harnstoffschmelzen

Preparation of Cyclophosphates, Cyclophosphatophosphonates, Diphosphonates, and Di-phosphites in Urea Melts Ammonium cyclotriphosphate (NH₄)P₃O₉, ammonium cyclotetraphosphate [P^IV? P^IV ? O? ]₂, ammonium cyclotriphosphatophosphonates Ammonium organyldiphosphonates And ammonium diphosphites are prepared in high yields on heating acidic phosphates, phosphonates, and phosphites in urea or urea/ammonium nitrate melts. The mechanism of the dehydration of phosphorus compounds containing POH groups in molten urea is discussed.     

Novel C‐acylated triazole derivatives of ravuconazole,an azole antifungal agent

Novel C‐acylated triazoles were synthesized from ravuconazole via bicyclic triazole lactone. The synthesis and antifungal activity of these C‐acylated derivatives are described.     

Dipolmomente 1, 6-überbrückter [10]- Annulene

The dipole moments of 1, 6-bridged [10]-annulenes of type I (X = CH₂, O, NH) and of bromo derivatives with X = CH₂, O are in agreement with the previously established structure of these compounds if a partial moment of approximately 0,8 D is assigned to the non-planar π-electron system.     

Anionic copolymerizations of acrylonitrile with β-propiolactone

Anionic copolymerizations of acrylonitrile (monomer 1) with β-propiolactone (monomer 2) and the structures of the resulting copolymers were studied. The copolymerization with sodium cyanide in N,N-dimethylformamide gave copolymers of the structure I containing acid anhydride linkage in the molecular chains, with the monomer reactivity ratios, r₁ = 1.20, r₂ = 0.00. The copolymerization with potassium hydroxide gave either copolymers of the structure II (r₁ = 0.00, r₂ = 3.64 at 30°C; r₁ = 0.00, r₂ = 5.00 at 40°C) in N,N-dimethylformamide or only β-propiolactone homopolymer in toluene.      

Darstellung neuer Spiro-Alkoxy-cyclophosphazatriene

Preparation of New Spiro-Alkoxy-Cyclophosphazatrienes New spiro-Alkoxy-cyclophosphazatrienes of the general formula are described. The preparation of the substances and their mass spectroscopic data are reported.     

Double Layer of Au(100)/Ionic Liquid Interface and Its Stability in Imidazolium‐Based Ionic Liquids

Ring any bells? The differential capacitance curve of Au(100) in neat [BMI]BF₄ (BMI=1‐butyl‐3‐methylimidazolium) ionic liquid has a bell‐shaped feature (see picture). The adsorption of BMI⁺ shows a disorder–order transition and depends on the structure of the surface. Ordered adsorption in a micelle‐like structure stabilizes the underlying Au surface.

     

Kinetic study of the gas-phase reaction c-C5H8 + I2 ⇄ c-C5H6 + 2HI the heat of formation and the stabilization energy of the cyclopentenyl radical

The gas-phase dehydrogenation of cyclopentene to cyclopentadiene catalyzed by iodine in the range 178–283°C has been found to obey a rate law consistent with the slow rate-determining step, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm I} + {\rm c} - {\rm C}_5 {\rm H}_8 \stackrel{4}{\rightarrow}{\rm HI} + {\rm c} - {\rm C}_5 {\rm H}_7 $\end{document}, log [k₄/(1 mole^?1 sec^?1)] = 10.25 ± 0.08 - (12.26 ± 0.18)/θ, where θ = 2.303 R T in kcal/mole. Surface effects are not important. This value of E₄ leads to a value of DH = 82.3 ± 1 kcal/mole and ΔH_f298 = 38.4 ± 1 kcal/mole. From difference in bond strengths in the alkane and the alkene, the allylic resonance stabilization in the cyclopentenyl radical is 12.6 ± 1.0 kcal/mole, in excellent agreement with the value for the butenyl radical. Arrhenius parameters for the other steps in the mechanism are evaluated. The low value of A₄ (compared with A₄ for cyclopentane) suggests a “tighter” transition state for H-atom abstraction from alkenes than from alkanes.     

The potential energy surface for the [C2H2O]+˙ system: The ketene radical cation [CH2CO]+˙ and its isomers

Ab initio molecular orbital calculations with large, polarization basis sets and incorporating valence electron correlation have been employed to examine the [C₂H₂O]^+˙ potential energy surface. Four [C₂H₂O]^+˙ isomers have been identified as potentially stable, observable ions. These are the experimentally well-known ketene radical cation, [CH₂?C?O]^+˙ (a), and the presently unknown ethynol radical cation, [CH₂?C? OH]^+˙ (b), the oxirene radical cation (c) and an ion resembling a complex of CO with [CH₂]^+˙, (d). The calculated energies of b, c and d relative to a are 189, 257 and 259 kJ mol^?1, respectively. Dissociation of ions a and d is found to occur without reverse activation energy.     

Metastable decompositions of cyclopentanol ions and [C5H10O]+˙ ions with the oxygen on the first carbon

Ionized cyclopentanol and [C₅H₁₀O]+˙ ions with the oxygen on the first carbon lose methyl, ethylene, ethyl, ethane and water in their metastable decompositions. We show by collisionally activated decompositions of the products that the losses of ethyl form CH₃CH₂C?O⁺, the losses of ethylene form , and the losses of methyl probably yield . Deuterium labeling indicates that ethyl loss from ionized cyclopentanol occurs following α-cleavage of the ring, isomerization to the enol isomer of ionized n-pentanal and subsequent isomerization to the 3-pentanone ion.     

Synthese und Eigenschaften der 1,3-Benzazaphosphole

Synthesis and Properties of the 1,3-Benzazaphospholes 1H-1,3-Benzazaphospholes (R = H, CH₃, C₆H₅, N(CH₃)₂) are synthesized not only rom o-aminophenylphosphines and different cyclisation compounds such as R? C(OR)?NH · HCl, R? C(O)Cl, R? COOR′, R? C(OCH₃)₂NR′₂, or Cl₂C?N(CH₃)₂Cl but also from secondary o-aminophenylphosphines PRH? C₆H₄? NH₂ (R = C₆H₅, C₂H₅) and CH₃? C(OR)?NH · HCl under elimination of ether or from 1,3-benzazaphospholines after oxidation or thermal treatment. Whereas the 1,3-benzazaphospholes don't react with acetyl chloride or methyl iodide the N-acetyl- and P-methyl-1,3-benzazaphospholes are formed starting with the ambident anion. Further reactions of the 1,3-benzazaphospholes and the nmr data of the compounds prepared are discussed.