Diels-Alder-Reaktionen. VII. Über die Isomerisierung von 2-Vinylbicyclo[2,2,1]hepten-(5)

Diels-Alder Reactions. VII. The Isomerization of 2-Vinylbicyclo[2,2,1]hept-5-ene The isomerization of exo/endo-2-vinylbicyclo[2,2,1]-hept-5-ene in the presence of Na/Al₂O₃ rapidly gives the thermodynamic equilibrium between exo- and endo-2-vinylbicyclo-[2,2,1]hept-5-ene and cis- and trans-2-ethylidenbicyclo[2,2,1]-hept-5-ene. Far more slowly vinylnortricyclene is formed, which enriches to an equilibrium concentration of about 75% at 60°C. The dependence of equilibrium constants of isomerization on temperature allows the calculation of enthalpies and entropies of isomerization.     

Organische Phosphorverbindungen. IX. Untersuchungen zum Mechanismus der Trichlorphon-DDVP-Umlagerung

Organic Phosphorus Compounds. IX. Studies on the Mechanism of the Trichlorphone-DDVP Rearrangement The base-initiated rearrangement of 2,2,2-trichloro-1-hydroxy-ethanephosphonic acid dimethyl ester (Trichlorphone) 1 in deuterated media leads to deuterium-free O, O-dimethyl O-2,2-dichlorovinyl phosphate (DDVP) 3 . This result favours the course of reaction suggested by KHARASCH and BENGELSDORF (path A: rearrangement after deprotonation of the hydroxyl group) and rules out a mechanism via the enolphosphonate 5 as an intermediate DDVP-precursor (path B) as postulated later. In accordance with path A, C¹-substituted Trichlorphone derivatives 12 can also be transformed to corresponding vinyl phosphates 13 . Crossing experiments prove the intramolecular character of the Trichlorphone-DDVP rearrangement.     

Photochemie substituierter Cycloheptatriene. IX Zum photoreaktiven Zustand der sigmatropen Wasserstoffverschiebung

Photochemistry of Substituted Cycloheptatrienes. IX. About the Photoreactive State in the Sigmatropic Hydrogen Shift We have studied the sigmatropic hydrogen shift in mono- and diarylcycloheptatrienes. From quenching and senzitation experiments is assumed that the sigmatropic H-shift occurs in the singlet state. The population of the photoreactive state is in concurrence with the population of the fluorescent singlet state. We postulate a common pericyclic minimum for hydrogen shift of 7,3 and 1,4-diarylcycloheptatrienes, respectively. In this minimum the excited Cycloheptatrienes have a more covalent than an ionic character. This was concluded from measurements of reaction quantum yields in dependence on substituents and solvents.     

Diels-Alder-Reaktionen. IX. Über Bildung und Thermolyse der isomeren Tricyclopentadiene

Diels-Alder-Reactions. IX. On the Formation and the Thermolysis of Isomeric Tricyclopentadienes The formation of isomeric tricyclopentadienes by codimerisation of cyclopentadiene with endo- and exo-dicyclopentadiene between 100 and 140°C in the liquid phase, and the retrodiene reaction of the main isomeres of the tricyclopentadiene fraction by gas phase thermolysis were studied kinetically between 230 and 310°C. The rate constants and the parameters of activation were determined.     

Modeling of poly(ethylene terephthalate) reactors. IX. Solid state polycondensation process

A mathematical model for simulation of industrial process of solid state polycondensation of poly(ethylene terephthalate) (PET) has been developed. The model eliminates errors evident in the earlier models by proper formulation. The model results have been validated by experimental data in the literature. It enables prediction of the influence of particle shape, size, temperature, etc. on the polycondensation process correctly in all different regimes of operation, apart from bringing out the importance of gas-side resistance, influence of carrier gas, etc. for the first time.     

Monomeric Au(II) complex with hematoporphyrin IX

A stable monomeric Au(II) complex has been synthesized in the course of the Au(III)–hematoporphyrin IX (Hp, I) interaction in aqueous alkaline solution. Distorted octahedral structure with (d_xy)¹ ground state and general formula Au(II)Hp_-2H·2H₂O are suggested for the complex. Gold is located in the hole of the porphyrin macrocycle and the water molecules are in axial position. The +2 oxidation state of gold was proven by the corresponding EPR signal and the μ_eff value of 2.20 BM obtained. The α² value of 0.56 indicated a high degree of covalency of the gold–nitrogen bonds.     

单组分室温硫化硅橡胶的配制(九)

介绍了低拉丝性脱醇型室温硫化(RTV-1)硅橡胶密封剂的配制方法以及用α，w-二甲氧基聚二甲基硅氧烷、MDT硅油作增塑剂，酸性磷酸酯作催化剂，二烷氧基硅烷作扩链剂配制低模量脱醇型RTV-1硅橡胶密封剂的方法。     

Reaktive Mikrogele,IX. Interpenetrierende Netzwerke auf der basis von reaktiven Ethylendimethacrylat-Mikrogelen

Reactive microgels have been prepared by copolymerization of ethylendimethacrylate with styrene. In the interpenetrating networks obtained interparticular chains could be distinguished from intraparticular ones. The influence of the concentration of the microgels, initiator, styrene, and solvent has been studied.     

Aza-Enamine. IX. UV/VIS- und NMR-spektroskopische Interpretation der Elektronenstruktur in Aldehydhydrazonen und daraus hergestellten Aza-Trimethinen

Aza-Enamines. IX. UV/VIS and N.M.R. Spectroscopic Interpretation of the Electron Structure in Aldehyde-N,N-dialkylhydrazones and in Aza-trimethines Prepared from These The n.m.r. and u.v./vis spectroscopic data of the compounds 2 , 3 and 4 – synthesized by electrophilic substitution at the azomethine carbon atom of the aldehyde hydrazones 1 according to the aza-enamine-concept – are reported. Compared to the respective C-atom of the starting hydrazones 1 the azomethine-C-atom of the compounds 2 – 4 exhibits a ¹³C-n.m.r. shift not corresponding to usual substituent effects. Our interpretation for this and for the u.v./vis spectroscopic data, too, is a simultaneous existence of both an aza-trimethine structural unit and an aromatic structure in the compounds 2 – 4 .