Orsay system

The Gif and Gif-Orsay systems exhibit some unusual characteristics. Most importantly, they oxidize secondary carbon preferentially and ketones not alcohols are the main products 160... 

Gif-Orsay system OH, OAc, pyridine Selective oxidation of saturated hydrocarbons 3.2.2. 

The Orsay system. A good example of serendipity is the discovery by Kagan and co-workers46 at Orsay that 1 mol of water was necessary to produce the active catalyst able to oxidize prochiral sulfides to sulfoxides with high ee. Optimization of the stoichiometry of the titanium complex permitted the determination of the combination Ti(0-i-Pr)4/(/ ,/ )-DET/H20 (1/ 2/ 1) at -20 °C in CH2C12 as the optimal conditions to achieve high enantioselectivity. Table 6 shows some representative results obtained for the oxidation of several thioethers with tert-butyl hydroperoxide (TBHP) under these conditions.50,51... 

The chemical (Gif system) and the electrochemical conversion (Gif-Orsay system) have been compared in the oxidation of six saturated hydrocarbons (cyclohexane, 3-ethylpentane, methylcyclopentane, cis- and traus-decalin and adamantane). The results obtained for pyridine, acetone and pyridine-acetone were similar for both systems. Total or partial replacement of pyridine for acetone affects the selectivity for the secondary position and lowers the ratio ketone secondary alcohol. The formation of the same ratio of cis- and traws-decal-9-ol from either cis- or trans-deca in indicates that tertiary alcohols result from a mechanism essentially radical in nature. The C /C ratio between 6.5 and 32.7 rules out a radical mechanism for the formation of ketones and secondary alcohols. Ratios of 0.14 and 0.4 were reported for radical-type oxidations of adamantane and cis-decalin. Partial replacement of pyridine by methanol, ethanol or f-propanol results in diminished yields and a lower selectivity. Acetone gives comparable yields however, the C /C ratio drops to 0.2-10.7. 

The first Gif-Orsay system (Pt-anode, Hg-cathode, cpe, TEABF4 in pyridine-acetic acid, divided cell) converted adamantane to 3.5% 1-adamantanol, 0.7% 2-adamantanol and 3.0% adamantone. Replacement of acetic acid by trifluoroacetic acid and its continuous addition to maintain a constant acidity improved the coulombic yield and selectivity. The oxidation of adamantane yielded 18% product with a C /C ratio of 8.5, this one of cyclodecane 21.1% product, and this one of trans-decalin 22.2% product, with a C /C ratio of 36. The results come close to those obtained in the chemical system. The third system... 

The related Gif-Orsay system consists of components similar to those of the Gif systems with the exception that the electrons are provided by electric current, i.e. cathodic reduction is employed [127,128]. 

Balavoine, G., Barton, D.H.R., Boivin, J., Gref, A., Le Coupanec, P., Ozbalik, N., Pestana, J.A.X., and Riviere, H. (1988) Functionalisation of Saturated Hydrocarbons. Part X.l. A Comparative Study of Chemical and Electrochemical Processes (Gif and Gif-Orsay Systems) in Pyridine, in Acetone and in Pyridine-Co-Solvent Mixtures, Tetrahedron 44,1091-1106. 

The Orsay group found serendipitously that methyl p-tolyl sulfide was oxidized to methyl p-toly 1 sulfoxide with high enantiomeric purity (80-90% ee) when the Sharpless reagent was modified by addition of 1 mole equiv. of water [16,17]. The story of this discovery was described in a review [19], Sharpless conditions gave racemic sulfoxide and sulfone. Careful optimization of the stoichiometry of the titanium complex in the oxidation of p-tolyl sulfide led to the selection of Ti(0iPr)4/(7 ,7 )-DET/H20 (1 2 1) combination as the standard system [ 17]. In the beginning of their investigations, the standard conditions implied a stoichiometric amount of the chiral titanium complex with respect to the prochiral sulfide [16,17,20-23]. Later, proper conditions were found, which decreased the amount of the titanium complex without too much alteration of the enantioselectivity [24,25],... 

The Orsay group discovered that addition of 4 mol equiv. of isopropanol to the Padua complex (Ti(0-i-Pr)4/(i ,7 )-DET = 1 4) gave a complex that can be used in catalytic quantities (10 mol % with respect to sulfide) in the sulfoxidations with cumene hydroperoxide [39,40], With this catalyst system, which needs the presence of 4A molecular sieves, enantioselectivities in the range of 90% ee have been achieved for the preparation of various aryl methyl sulfoxides. Even benzyl methyl sulfoxide was obtained with 90% ee. 

The Orsay group continued working intensively on the optimization of their system to make it catalytic without losing the enantioselectivity of the stoichiomet-... 

A recent systematic study of the role played by titanium alkoxide, 2-propanol, and molecular sieves (MS) has permitted the development of an efficient catalytic system furnishing chiral sulfoxides with high ee.54 This catalyst has a new composition Ti(0-i-Pr)4/(/ ,/ )-DET/i-PrOH (1 / 4 / 4), in the presence of 4A MS, which is a combination of the Modena47 and Sharpless systems. Using this new system, the Orsay group achieved the highest enantioselectivity in catalytic asymmetric oxidation of sulfides by a nonenzymatic method (Table 8). 

Complexes based on titanium excess tartrate combination (the Padova system). In 1984, the same year the Orsay group developed their system, a group in Padova, Italy, headed by Modena,47 developed a different system, able to oxidize sulfides to sulfoxides with high selectivity, also based on a modification of the Sharpless catalyst. The Padova group used TBHP in the presence of 1 mol equiv of Ti(0-/-Pr)4/(/ ,/ )-DET, 1/4 combination. The reactions were performed at -20... 

A system based on one amplifier per wire and priority encoder is in use at the synchrotron radiation faciUty LURE in Orsay, France. The 448 x 448 mm MWPC, with a spherical drift space to avoid paralaxes in crystallographic experiments, has been developed at CERN, Geneva . The spatial resolution is (2x2)mm, ... 

The first pulse radiolysis system capable of picosecond time resolution (20 ps) was in use by 1968 at the University of Toronto [145] and others were subsequently installed at Notre Dame University, Argonne National Laboratory, Tokyo, Osaka, and Hokkaido Universities, the Hahn-Meitner Institute in Berlin, and the Institute of Chemical Kinetics and Combustion in Novosibirsk. Current developments at Brookhaven [104] and Argonne [146] National Laboratories and Tokyo University [147] are aimed at subpicosecond timescales a new picosecond facility is also being installed at Orsay [148]. 

Equipe Physico-Chimie des Systemes Polyphase, 92296 Chatenay-Malabry, France Arilait Recherches, 75382 Paris, France and laboratoire pour I Utilisation du Rayonnement Electromagnetique, 91898 Orsay, France... 

That of Carl Moser, rather oriented towards elaborated methods for the computation of smaller systems. In the late 1960 s Moser was to found the Centre Europeen de Calcul Atomique et Moleculaire (or CECAM), while his co-worker Helene Lefebvre-Brion joined the newly founded Laboratoire de Photophysique Moleculaire (PPM) at Orsay. 

We gratefully acknowledge the joint effort of our Topical Editors Miriam Blaauboer, Maciej Krzystyniak, Tomas Opatrny, David Petrosyan and Jane Salo, the financial support of our sponsors NATO and EC (through the Research Training Network on Quantum Complex Systems, "QUACS") and the technical support of Laboratoire Aime Cotton, Orsay, France. 

Photocathode-based picosecond electron accelerators are conceptually simpler than pre-bunched thermionic systems, although they require reasonably powerful, multicomponent femtosecond or picosecond laser systems to drive the photocathode. In addition, the availability of synchronized laser pulses allows the development of advanced detection capabilities with unprecedented time resolution. The combination of ease of use and powerful detection methods has stimulated strong interest in photocathode gun systems. Since the installation ofthe first photocathode electron gun pulse radiolysis system at BNL [5,13], four additional photocathode-based facilities have become operational and two more are in progress. The operational centers include the ELYSE facility at the Universite de Paris-Sud XI in Orsay, France [7,8], NERL in Tokai-Mura, Japan [9,10], Osaka University [11,12], and Waseda University in Tokyo [13]. Facilities under development are located at the Technical University of Delft, the Netherlands, and the BARC in Mumbai, India. 

Section 2 of this paper describes the apparatus we use at Orsay to study ion-molecule collision processes. The following four sections discuss the results we have obtained for reactions (1)—(4). These are a representative sample of the type of systems we can study at present. Section 7 discusses future prospects for using synchrotron radiation to study other ion-molecule reactions. 

Gerstenkorn, S. and Luc, P. (1986), Identification des Transitions du System (B—X) de la Molecule d lode et Facteurs de Franck-Condon 14,000-15,600 cm-1 , Laboratoire Aime Cotton, CNRS II, 91405, Orsay. 

S. Menage, Contribution d la modelisation structurale et fonctionnelle du systeme de degagement d oxygene des plantes synthese, etude des propri etes electroniques et de la reactivite de complexes contenant le coeur [Mn lir)20 JR.C0 ,), Ph.D. Thesis, University of Paris-Sud (Orsay) (1988). 

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