Yoel Sasson

Handbook of phase transfer catalysis

Nucleophilic aliphatic and aromatic substitutions in phase transfer catalysis mechanism and synthetic applications kinetics and mechanism in phase transfer catalysis synthesis and properties of quaternary ammonium phase transfer catalysts phase transfer reactions under basic conditions applications of phase transfer catalysis in industrial organic chemistry PTC in polymer chemistry PTC in carbohydrate chemistry PTC in heterocyclic chemistry phase transfer catalysis in oxidation processes organometallic reactions under phase-transfer conditions sonochemical and microwave activation in phase transfer catalysis analytical applications of phase transfer catalysis triphase catalysis chiral phase transfer chemical modification of polymers via phase transfer catalysis phase transfer catalysis of uncharged species.

Palladium-catalyzed aryl-aryl coupling in water using molecular hydrogen: kinetics and process optimization of a solid-liquid-gas system

Abstract Coupling of substituted chlorobenzenes to the respective biphenyls is effected in water, using hydrogen gas and NaOH in the presence of catalytic PEG-400 and Pd/C. The catalyst can be efficiently recycled. The competing reduction process ( e.g. of chlorobenzene to benzene) can be minimized by altering reaction conditions. The roles of the hydrogen, the hydroxide, the Pd catalyst, and the PEG are discussed.

Palladium-catalyzed decomposition of aqueous alkali metal formate solutions

Abstract Aqueous sodium and potassium formate solutions undergo catalytic decomposition, under mild conditions, into molecular hydrogen and hydrogen carbonate in the presence of palladium on carbon. Both the formate and water hydrogen atoms are involved in the process and undergo fast exchange. Some kinetic and mechanistic features of the decomposition reaction are reported.

Reversible ion-pair extraction in a biphasic system. application in transition metal-catalyzed isomerization of allylic compounds

Abstract A two-liquid-phase catalysis is described in which aqueous metal halides of Group VIII are used for the isomerization of water-insoluble allylic compounds. With the aid of quaternary ammonium or phosphonium salts, the metal catalyst is extracted into the reagent-containing phase and returned to the aqueous layer by lipophilic anions upon completion of the catalytic process.

Catalytic hydrogenation of olefins, acetylenes and arenes by rhodium trichloride and aliquat-336 under phase transfer conditions

Abstract The ion pair formed from aqueous rhodium trichloride and aliquat-336 in dichloroethane catalyzes hydrogenation of a variety of unsaturated compounds. Aromatics are reduced to cyclohexane derivatives under exceedingly mild conditions.

Heterogeneous palladium-catalysed Heck reaction of aryl chlorides and styrene in water under mild conditions

The Heck reaction of chlorobenzene and substituted chlorobenzenes with styrene is performed in water using catalytic palladium on carbon. The presence of a reducing agent, a mild base, and a phase-transfer catalyst enhances the reactivity of chloroarenes. Transfer hydrogenation of the stilbene double bond to yield 1,2-diphenylethane is also observed in situ. The competing reactions in this system are haloaryl homocoupling and hydrodehalogenation. The effects of various process parameters on substrate conversion and product selectivity are examined for PhCl and PhBr and the unique role of the reducing agent is discussed. A series of filtration experiments indicate that, in this system, the catalysis is heterogeneous and not due to palladium leaching.

Chemical development of latent fingerprints: 1,2-indanedione has come of age.

The performance of 1,2-indanedione as a latent fingerprint reagent on some types of paper was found to exceed that of DFO, the leading fluorogenic fingerprint reagent. It even exceeds the performance of the sequence, DFO, followed by ninhydrin. No new prints could be observed when ninhydrin was applied after indanedione. On a large number of actual exhibits (used checks) indanedione developed 46% more identifiable prints than the sequence DFO-ninhydrin. A standard procedure for fingerprint development by indanedione is proposed. Best results are obtained with a 0.2% indanedione solution in HFE7100 solvent containing 7% ethyl acetate, but no acetic acid. It can be recommended to start using 1,2-indanedione, which is already commercially available, in actual fingerprint casework.

Formate salts as chemical carriers in hydrogen storage and transportation

Abstract Hydrogen is an important raw material and an attractive fuel for the near future. The availability and use of large amounts of hydrogen requires the development of suitable means of handling, storage and transportation. Recent research carried out in our laboratory in the field of hydrogenation of organic compounds by formate salts [Bar and Sasson, Tet. Lett. 22 , 1709 (1981); Zoran et al., J. Mol. Catal. 26 , 321 (1984); Bar et al., J. Mol. Catal. 26 , 327 (1984); Bar et al., J. Mol. Catal. 33 , 161 (1985)] led to the idea of using formate salts as chemical hydrogen carriers. A brief review on the use of hydrogen as a storable energy source and problems associated with its storage is followed by the presentation of the cyclic process of storing hydrogen by means of formate salts.

HYDROXIDE ION INITIATED REACTIONS UNDER PHASE TRANSFER CATALYSIS CONDITIONS---IV

Abstract The nature of the quat-anion interactions in a PTC/OH − system was probed by examining the reactivity and selectivity of a CA/O-ambident anion towards an alkylating agent in the presence of various quats. It is suggested that the accessibility of the positive N center of the qual for association with the anion is the major factor in determining the behavior of PTC/OH − reactions proceeding through the Makosza mechanism.

Comparative autoxidation of 3-Carene and α-Pinene: Factors governing regioselective hydrogen abstraction reactions

Abstract Autoxidation reactions of 3-Carene 1 and α-Pinene 2 were performed using various homogeneous catalysts. Different product and regio-selectivities were observed. The factors that promote hydrogen abstraction (HA) reactions in both molecules are discussed, and it is proposed that the difference in the product selectivities is due to the lack of “cyclic activation” in 2 . Oxidation of 1 produced mainly 3-carene-5-one 3 , while 2 yielded 2,3-epoxypinane 6 as the major product.