Dicyclopentadienoxidation. I,Unkatalysierte Flüssigphasenoxidation von Dicyclopentadien

Dicyclopentadiene Oxidation I. Uncatalyzed Liquid-Phase Oxidation of Dicyclopentadiene Dicyclopentadiene is oxidized by molecular oxygen to a mixture of the monoepoxides 2 and 3 . The identification of the epoxides 2 , 3 and 4 was executed with authentic samples prepared by epoxidation with peracetic acid or with tert-butylhydroperoxide in the presence of MoO₂(acac)₂

1 acac — Acetylacetonat

The main product is the substituted norbornene oxide 2 . Allylic oxidation is also observed. Remarkable amounts of hydroperoxides can be determined iodometrically. The formation of allylic oxidation products 7 , 8 , 9 and 10 was proved by GC-MS-analysis. It is shown that in the uncatalyzed liquid phase oxidation of dicyclopentadiene no more than 50% of epoxides are formed. The bisepoxide 4 was found in small amounts only at higher conversions of the dicyclopentadiene.     

Über die katalysierte Flüssigphasenoxidation von cis- und trans-Oct-4-en

The Catalyzed Liquid-Phase Oxidation of cis- and trans-Oct-4-ene The influences of MoO₂(acac)₂

1 acac-Acetylacetonat.

, MoO ₃ and Co(acac) ₃ on the liquid-phase oxidation of cis- and trans-oct-4-ene at 110°C were studied. In the presence of molybdenum catalysts the yield of epoxides and the stereoselectivity of epoxide formation are increased. The results are in good agreement with the hypothesis that molybdenum compounds effect only the stereospecific reaction of the hydroperoxides formed with the starting olefin yielding the corresponding epoxide. The cobaltic complex increases the rate of autoxidation, but has no remarkable influence on the yield of epoxides. In the presence of Co(acac)₃ more trans-epoxide is formed from cis-oct-4-ene than in the uncatalyzed reaction. This can be explained by an increase of the lifetime of the intermediate peroxyalkyl radical, effected by complex formation of the radical with a cobalt species.     

A polymeric amine–copper(II) complex as catalyst for the hydrolysis of 1,2,2-trimethylpropyl methylphosphonofluoridate (soman) and bis (1-methylethyl) phosphorofluoridate (DFP)

The Cu (II) complex of poly-4-vinylpyridine, quaternized with 19 mol % ethyl bromide and 36 mol % 4-chloromethyl-4′-methyl-2,2′-bipyridine, was examined as a catalyst for the hydrolysis of the toxic organophosphorous compounds bis (1-methylethyl) phosphorofluoridate ( 1 ,

1 Registry no.: 1 , 55-91-4; 2 , 96-64-0.

DFP) and 1,2,2-trimethylpropyl methylphosphonofluoridate ( 2 , soman). Studies were carried out at 25.0 and 37.0°C for both substrates in MOPS buffer at pH 7.0. In the presence of 7.31 × 10^?3 M catalyst at 25.0°C, soman is hydrolyzed with a first-order rate constant of 0.019 min^?1 (t_1/2 = 37.5 min), whereas DFP hydrolyzes with a rate constant of 0.011 min^?1 (t_1/2 = 63.8 min). For soman, this represents a 14-fold increase over the uncatalyzed rate in the same buffer. Other studies examined the effect of a strongly sorptive polymeric resin on catalysis by this copper-containing polymer and found a dramatic decrease in the hydrolysis rate of soman in the presence of the polymeric sorbent.     

The STOBBE Condensation with Dimethyl Homophthalate. Part I

The condensation of methyl 2-thienyl, methyl 2-furyl, and phenyl 2-thienyl ketone with dimethyl homophthalate in the presence of either potassium t-butoxide or sodium hydride as condensing agent, gave predominantly the (z)-half esters

1 The nomenclature of cis/trans isomers follows the IUPAC Tentative rules, Section E, Fundamental Stereochemistry, J. org. Chemistry 35 , 2849 (1970). See also N. R. El-Rayyes, J. prakt. Chem. 315 (2), 300 (1973). (E) = trans-(Heterocyclic ring/CO₂CH₃) (Z) = cis-(Heterocyclic ring/CO₂CH₃)

. The structure and configuration of the products were inferred by chemical and spectroscopic means.     

Graft polymerization of methyl acrylate onto granular starch: Comparison of the Fe+2/H2O2 and ceric initiating systems

Graft polymerizations of methyl acrylate (MA) onto granular cornstarch were carried out in water with both ferrous ammonium sulfate/hydrogen peroxide (FAS/H₂O₂) and ceric ammonium nitrate (CAN) initiation. Starch concentrations were 10, 20, and 30% in water, and the amount of MA used was either 0.5, 1, or 2 mol per AGU of starch. Two concentrations of FAS/H₂O₂ were used: 1 mol each of FAS and H₂O₂ per 100 AGU of starch, and 1 mol per 1000 AGU. Significant amounts of acetone-extractable PMA homopolymer were produced, and homopolymer formation was especially high at the 1:100 ratio. Sharp exotherms were observed, and reaction mixtures reached maximum temperature within 2 min or less. Total conversions of MA to PMA were higher at the 1:100 ratio, and conversions in some polymerizations were nearly quantitative. CAN-initiated polymerizations were run under the same conditions used for FAS/H₂O₂; however, the amount of CAN used was limited to 1 mol per 100 AGU because of low conversions at the 1:1000 ratio. Compared with FAS/H₂O₂, CAN gave more moderate exotherms; and longer time periods were required for reaction mixtures to reach maximum temperature. CAN gave quantitative conversions of MA to PMA, but only low percentages of PMA homopolymer were observed. Differences between FAS/H₂O₂ and CAN initiation are consistent with differences in the two initiation mechanisms. High levels of homopolymer produced on starch granule surface with FAS/H₂O₂ could be seen in scanning electron micrographs and were also apparent in infrared spectra obtained with an attenuated total reflectance (ATR) cell. ATR spectra of acetone-extracted products indicated that the amount of PMA actually grafted to starch granule surfaces was similar with both initiating systems. Tensile properties of extruded ribbons prepared from these polymers did not vary greatly with the initiator used. © 1996 John Wiley & Sons, Inc.

1 This article is a U.S. Government work and, as such, is in the public domain in the United States of America.

     

Neue photoreaktive Polymere mit seitenständigen Dimethylmaleinimid-Gruppen. I. Radikalische homo-und copolymerisation von N-(5-methyl-3-oxa-4-oxo-hexen-5-yl)-dimethylmaleinimid

The homopolymerisation of N-(5-methyl-3-oxo-4-oxo-hexen-5-yl)-dimethylmaleimide (DMI-MA) leads to linear poly(methylmethyacrylates) with pendant lightsensitive dimethylmaleimide groups. Due to steric hindrance of the methyl substitutents, the carbon-double bond is not involved in the reaction, even at conversions of over 90%. The reaction velocity constant for the homopolymerisation is k_p/k = 2,0 – 2,2.10^?2 (65°C, toluene, AIBN) and the activation energy E_a = 62,36 ± 2 KJ/mol^?1. Measurement of the copolymerisation reactivity ratios for the monomer pairs DMI-MA/methacrylic acid (MAS), DMI-MA/methylmethacrylate (MMA) and DMI-MA/ethylacrylate (EA) gave the following values: DMI-MA (r₁): MAS (r₂) = 1,36 ±0,06 : 0,77: ± 0,06; DMI-MA (r₁) : MMA (r₂) = 1,16 ± 0,17:0,475 ± 0,17 and DMI-MA (r₁): EA(r₂) = 1,60 ± 0,15: 0,44 ± 0,15.     

Stevensanaloge,Durch Nickelkomplexe Katalysierte Umlagerung Von Triarylphosphoryliden Und Darstellung Sowie Strukturbestimmung Von Phosphorylid-Nickeltricarbonylkomplexen

The Stevens rearrangement of the triarylphosphorusylids R₃ P=CHR′ (III) (R′ = H, CH₃, C₂ H₅) to diarylbenzylphosphines (V) is catalyzed by nickel complexes (e.g., (COD)₂ Ni (I)). Attempts to prepare trimesitylphosphine-methylene result in direct formation of dimesityl (mesitylmethyl) phosphine (XII) — the first recorded direct Stevens rearrangement of a phosphorusylid. Phosphorusylids react with nickeltetracarbonyl without rearrangement to give complexes of the type R₃P=CH_a · Ni(CO)₃ (XIV). The structure of XIV has been established by the IR and NMR spectra and confirmed by an X-ray structural determination.

1 B. L. Barnett and C. Krüger, J. Cryst. Mol. Struct., im Druck.

The ylid is bonded to the nickel through the C-atom with resulting hybridization from sp² towards sp³.     

Synthesis of polyesters as binders for deinkable inks. II. Kinetics and mechanism of polyesterification between o-phthalic anhydride and neopentyl glycol in bulk at 200°C

The kinetics of the polyesterification in bulk at 200°C between o-phthalic anhydride and neopentyl glycol (2,2-dimethyl-1,3-propanediol) in a nonequimolecular ratio and in the absence of an external catalyst was investigated. The formation of the monoester and two dimeric compounds by uncatalyzed heating of o-phthalic anhydride with neopentyl glycol was virtually complete after dissolution of the anhydride. The data were analyzed statistically by a mathematical method due to Fradet and Maréchal for the estimation of the orders of reaction. This statistical adjustment of the data analysis supports the assumption that the kinetics of polyesterification in the absence of both the solvent and catalyst may be fitted to several orders of reaction over all the conversion. At first, our experimental data may be fitted to 3, or , or 2, etc., overall orders. The results establish that the overall kinetic order of the polyesterification depend upon the goodness of the experimental results and cannot be only selected by means of a correlation coefficient. If this last criterium is adopted, the polyesterification at low, medium, as well as at high conversions may be 3 as the most probable one, order one with respect to acid group concentration, and order two with respect to alcoholic group concentration, in agreement with Flory's predictions. A mechanism consistent with the most plausible kinetic results (I_m,n = 0.9990 and m, n = 1, 2) is proposed. It consists of a dimerization of the alcoholic groups followed by an attack of the acid to the dimer. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2409–2431, 1997     

Zur übergangsmetallkatalysierten nucleophilen Epoxidringöffnungsreaktion

The Transition Metal Catalyzed Nucleophilic Epoxide Ring Opening Reaction The catalytic influence of MoO₂(acac)₂

1 Acac-Acetylacetonat

, Mo(CO) ₆ , MoCl ₅ , WCl ₆ and TaCl ₅ on the reaction of 1,2-epoxy-octane with ethanol at 100°C in dioxan or chlorobenzene as solvents is proved. Water and hydroperoxides react with a higher rate than alcohols. When changing from primary to secondary and tertiary alcohols a decrease of the reaction rate is observed. 2,3- and 3,4-Epoxyheptane and cis- and trans-4,5-epoxy-octane react more slowly than the corresponding 1,2-epoxides. Epichlorhydrin and methylglycidether react with a lower, cyclohexene oxide, styrene oxide and norbornene oxide react with a higher rate than 1,2-epoxyoctane. The reactivities of the two dicyclopentadiene monoepoxides correspond with the reactivities of the norbornene and cyclopentene oxides. In the molybdenum catalyzed epoxide ring opening reaction an isomer distribution appears in favour of the 1-hydroxy-2-ethoxy-alkane 2 . A mechanism in the coordination sphere of the transition metal complex is proposed.     

Fracture behavior of coated/uncoated graphite-epoxy composites

The static delamination behavior of graphite/epoxy composite specimens subjected to mode I tensile opening (using UDCB

1 Uniform double cantilever beam.

specimens), and pure mode II shear loading (using ENF

2 End-notched flexural.

specimens) were studied. The graphite epoxy composites for the study were made from commercially treated fibers, with and without an electropolymerized interlayer. The mode I fracture energy (G_IC) was found to be significantly higher (more than 50 percent) for the coated fibers. However, this improvement was accompanied by a high reduction (more than 3 times) in the mode II fracture energy (G_IIC). This effect is apparently related to poor adhesion between the interlayer and the epoxy resin, which may be corrected by use of a “top layer” of appropriate composition to form chemical bonds between the phases. The fracture toughness (K_IC) of composites made with commercially treated fibers was also evaluated, using double side-notched specimens.     

Solid-state polymerization in poly(butylene terephthalate): The Equilibrium constant

Poly(butylene terephthalate)

1 PBT or Poly-1, 4-butanediyl 1, 4-diearboxylate.

polycondenses readily in the presence of small amounts of organo-titanium compounds to form progressively higher molecular weight polymers, The reaction is reversible in the presence of the condensation byproduct, 1,4-butanediol. Usually this reaction is carried out in the melt phase, but the viscosity is soon limiting. In the current work the polymerization is carried out in the solid phase just below the melting point of 227°C. The equilibrium constant for this reaction is measured by subjecting the polymer to a nitrogen stream saturated with a controlled quantity of butanediol. The reaction is followed by measuring the change in the number of alcoholic end-groups by infrared spectroscopy. At about 220°C the equilibrium constant is 0.31 (σ = 0.08).     

Single-Site Calcium Initiators for the Controlled Ring-Opening Polymerization of Lactides and Lactones

Summary Single-site calcium initiators containing chelating tmhd (H-tmhd = 2,2,6,6-tetramethylheptane-33-dione) ligands [(THF)Ca(tmhd)_]2[-N(SiMe₃)₂](-tmhd) (2) and [(THF)Ca(tmhd)]₂[-OCH(Me)Ph](-tmhd) (3) have been synthesized and applied for the ring-opening polymerization of L-lactide and -caprolactone. Both 2 and 3 were highly reactive and promoted a fast polymerization of L-lactide and -caprolactone to high monomer conversions under mild conditions (THF as a solvent, room temperature). More importantly, results showed that the ring-opening polymerizations of lactides and lactones initiated by either 3 or 2 in the presence of equivalent 2-propanol are living, to provide polymers and block copolymers of controlled molecular weights and tailored end-groups. The polymerizations were first-order in monomer up to high conversions, in which the in situ initiating system 2/2-propanol revealed no induction period and much faster polymerization kinetics as compared to 3.     

The STOBBE Condensation with Pyrrolyl Aldehydes – a synthesis of indole derivatives

The condensation of pyrrolyl-2-aldehyde or 1-methyl-pyrrolyl-2-aldehyde with dimethyl succinate, using sodium hydride as condensing agent, gave predominantly the halfesters 1a and 1c respectively. Their structure and (E)-configuration

1 i. e., pyrrol ring and COOCH₃ group are in trans position. This nomenclature follows the IUPAC 1968 Tentative Rules, Section E, Fundamental Stereochemistry, J. org. Chemistry 35 , 2849 (1970).

were confirmed by their cyclisation to the corresponding indole derivatives 2a–h .     

Investigation of primers reducing the pink-ring formation in multilayer printed circuit boards

A rapid and easy screening test was applied to assess the capability of various formulated primers to reduce the defect of pink rings in multilayer printed circuit boards. The mixtures of silanes with multifunctional silanol groups (crosslinkers) and 3-glycidoxypropyl-trimethoxysilane

1 Systematic name: 3-(2,3-Epoxypropoxy)propyl-trimethoxysilane.

(referred to as silane C) or N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane

2 Systematic name: 3-[N-2-aminoethyl]aminopropyl-trimethoxysilane.

(silane B) were proved to be effective in reducing the pink rings. The performance of the mixed silanes using silane A and crosslinkers with aromatic groups were better than other formulated primers which was partly attributed to less amounts of hydrophilic groups and better integrity in the primer films. A developed primer consisting of siloxane compounds had the best performance. The online test confirmed the results from the screening test and demonstrated the feasibility of the designed screening test in assessing the performance of primers. The results of FTIR spectroscopy and thermogravimetric analyses confirmed that the effective primers coated on the copper oxides could improve the curing reaction and the thermal oxidative stability of the epoxy/CuO system.     

Functionalization of Oleyl Carbonate by Epoxidation

Carbonates (esters of carbonic acid H₂CO₃) are a class of compounds that are of increasing interest in commercial applications due to their physical properties and relatively straightforward synthesis. Herein, oleyl carbonate, an oleochemical-based compound derived from oleyl alcohol, was epoxidized utilizing performic acid generated in situ from formic acid and 50% H₂O₂. The reaction proceeded smoothly and furnished the corresponding oleyl carbonate bisepoxide, (bis[8-(3-octyloxiran-2-yl)octyl] carbonate), in good yields (83–85% isolated yields after purification by silica gel chromatography). The carbonate moiety was found stable to the reaction conditions utilized for epoxidation and the isolated oleyl carbonate bisepoxide was subsequently characterized using Fourier transform infrared spectroscopy, ¹H and ¹³C nuclear magnetic resonance spectroscopy (NMR), and liquid chromatography electrospray ionization mass spectrometry. Oleyl carbonate bisepoxide compound may be of potential interest as a plasticizer, monomer, or a substance for further chemical elaboration. Disclaimer: “Product names are necessary to report factually on available data; however, mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture.”     

Mowrah (Madhuca latifolia) seed saponin. Toxicological studies

Mowrah seed (Madhuca latifolia) meal

1 Meal refers to solvent extracted material.

contains high levels of saponin (7%) making it unsuitable for incorporation in animal feedstuff formulations. The saponin from mowrah seed meal was isolated and purified by paper chromatography. This was used for in vitro tests as well as pharmacological and acute toxicity studies for a better understanding of its properties and toxicity. The oral, intraperitoneal and intravenous LD₅₀ of mowrah saponins in mice are 1 g, 15–20 mg and 15 mg/kg body weight respectively. Processing of the meal to remove or inactivate the saponin will be essential prior to its incorporation in animal feeds.     

Rhodium-catalyzed partial oxidation of methane to CO and H2. Transient studies on its mechanism

The reaction of methane with surface oxygen as well as the interaction of methane/oxygen mixtures with a Rh(1 wt%)/-Al₂O₃ catalyst was studied by applying the temporal-analysisof-product (TAP) reactor. The product distribution was strongly affected by the degree of surface reduction. CO₂ is formed as a primary product via a redox mechanism with the participation of surface oxygen. The dehydrogenation of methane yielding carbon deposits on the surface occurs on reduced surface sites. The formation of CO proceeds with high selectivity (up to 96%)at 1013 K via fast reaction of surface carbon species with CO₂.     

Simultaneous fluorine elimination and alkylation of poly(tetrafluoroethylene)

PTFE (powder or foils) was defluorinated and derivatized in a one-step process by alkyl- and aryllithium in the presence of tetramethylethylenediamine

1 Systematic name: 1,2-Bis-[dimethylamino]ethane.

(TMEDA) as a catalyst. As evidenced by infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and elemental analysis the C₄H₉-, C₈H₁₇-, C₁₂H₂₅- or phenyl groups were attached to a partly defluorinated macromolecular chain. Analogous reactions with dilithioaryl or dilithioalkyl agents presumably lead to crosslinking of the polymeric chains through alkyl or aryl groups. When the PTFE powder is treated with more concentrated RLi (>3 mol L^?1) at temperatures >150°C, the defluorination is almost quantitative even in the absence of the catalyst. The TMEDA-catalyzed reaction proceeds via elimination and nucleophilic addition. On the other hand, more concentrated RLi in the absence of the catalyst seems to react via a radical mechanism.     

Synthesis of phosphorus-containing wofatit cation exchangers and their affinity toward selected cations

A number of solid Cationits have been prepared derived from Wofatit

1 Trademark, VEB Chemiekombinat Bitterfield.

gel and canal structures: styrene/DVB, chloromethylated ST/DVB, and acrylic acid/DVB copolymers. To functionalize the copolymers, PCl₃/AlCl₃ and dialkyl phosphites or trialkyl phosphites were used. The influence of the polymer matrix structure and the chemical structure of the functional groups of obtained Ionits on their affinity toward 23 metallic cations in acidic media has been investigated using the conductivity method. To obtain comparison data, commercial “Wofatit”–sulfonic and–carboxylic Cationits, have been tested under identical conditions.     

Catalytic behaviour and characterisation of CuO1−z(La2O3)z/2 based catalysts deposited on γ-Al2O3 and prepared in situ with 0.0 ⩽z⩽1.00, without and with addition of Pd

(CuO)_1–z(La₂O₃)_z/2 based catalysts with 0.0z1.0 supported on -Al₂O₃ have been prepared in situ and the phases formed have been identified by XRD, SEM and TEM/EDS studies. The catalyst with z=0.5 exhibited the best catalytic activity for oxidation of CO (T ₅₀=295 and 390C with degrees of conversions of 93 and 92% at 450C under rich and lean conditions, respectively) and C₃H₆ (291 and 414C; 93 and 83%) and reduction of NO (405C; 60 and 0%). This catalyst contained appreciable amounts of the perovskite phase LaAl_1–xCu_xO₃ and the enhanced catalytic properties are ascribed to the presence of this phase. Addition of Pd to this catalyst implied that the degree of conversion of NO increased and that the light-off temperatures for all involved gas species decreased. Ageing experiments revealed that LaAl_1–xCu_xO₃ decomposed and that Cu containing Pd particles were formed during this procedure which in turn deteriorated the catalytic properties of the catalyst.