Solid-liquid Phase-transfer Conditions Research Articles

Effects of ultrasound emitter type and power on a heterogeneous reaction

In the course of our current interest in designing appropriate reactors for sonochemistry, we have investigated a heterogeneous reaction which is highly improved by ultrasound, with the aim of trying to understand the mechanism of the reaction rate enhancement and the influence of the sonication parameters. The chosen model reaction is a Michaël reaction: the addition of ethyl malonate to chalcone in toluene under solid-liquid phase transfer conditions. This reaction is very sensitive to sonic irradiation: the initial reaction rate is increased by a factor of 10 under sonication. In order to separate the physical and chemical effects of ultrasound, we have studied the disruption of the solid catalyst (KOH) in toluene and compared the particle sizes with the values obtained during the reaction with and without ultrasound. It can be seen that sonication prevents particle agglomeration as the reaction proceeds. The effect of the generator power has been studied using a cuphorn. The reaction yield is dramatically increased near the cavitation power threshold and then remains nearly constant. Finally, different sonication systems have been compared, the cleaning bath giving the poorest results.

Mechanism and anion activation in solid–liquid phase-transfer reactions catalysed by cyclophosphazenic polypodands. Comparison with cyclic analogue crown ethers

A kinetic study of the nucleophilic substitution of the methanesulfonic group by anions (Cl–, Br–, I–, SCN–, C6H5O–, C6H5CH2COO–) catalysed by cyclophosphazenic polypodands has been performed under solid–liquid phase-transfer conditions. The results obtained show that the mechanism of PTC previously found for cyclic ligands (crown ethers, cryptands) also operates in the case of these open-chain ligands: the attack by the anionic nucleophile on the substrate occurs in the organic phase and is rate determining of the overall process. The nucleophilicity scales found (I– > C6H5O–≈ SCN– > C6H5CH2COO–; I– > Br– > Cl–) as well as the anion activation are comparable with those found for cyclic crown ethers. This indicates that the anionic reactive species involved are similar in the complexes of both ligands.

Cobalt Catalysed Carbonylation of Organic Halides under Solid-Liquid Phase Transfer Conditions

Abstract Organic halides are carbonylated under solid liquid phase transfer conditions using Co−(CO)4 as catalyst under CO (1 atmosphere) at 25°C to afford corresponding esters in good yields. No Carbonylation is effected in absence of phase transfer agent (PTA). The striking example is the carbonylation of ethyl haloacetate to diethyl malonate, an important organic intermediate. The parameters such as concentration of PTA, and catalyst and temperature are optimised.

Palladium-catalysed desulphonylative vinylation of arenesulphonyl chlorides under solid–liquid phase-transfer conditions

The reaction of arenesulphonyl chlorides (1a–n) with butyl acrylate (2a) in the presence of a catalytic amount of bis(benzonitrile)dichloropalladium [PdCl2(PhCN)2] under solid–liquid phase-transfer conditions gave the corresponding butyl (E)-3-arylprop-2-enoates (3a–n) in good yield. The alkenes (2b–g) could also be used in place of (2a).

Reaction of non-activated olefins with CH-acids; a novel method for the preparation of electrophilic cyclopropanes

Reaction of non-activated olefines with active methylene compounds was accomplished under solid-liquid phase-transfer conditions, in the presence of iodine, to give electrophilic cyclopropanes of a wide range of substituents. Several data to the mechanism of the reaction are also given.

A facile synthesis of α,β-unsaturated epoxides via allyldi-isobutyltelluronium bromide

In the presence of solid KOH, allyldi-isobutyltelluronium bromide 2 reacts directly with aromatic aldehydes at room temperature under solid–liquid phase-transfer conditions to afford α,β-unsaturated epoxides 3 in excellent yields.

Phase-Transfer Catalyzed Monoalkylation of Ethyl 2-(p-Tolylsulfonyl) Acetate

Abstract The facile monoalkylation of ethyl 2-(P-tolylsulfonyl)acetate under solid-liquid phase transfer conditions is reported.

ChemInform Abstract: Organic Synthesis Using PTC. Part 8. Synthesis of Macrocyclic Systems Containing Nitrogen and/or Oxygen as Heteroatom(s).

AbstractThe reaction of benzenesulfonamide and p‐toluenesulfonamide with p‐toluenesulfonate esters of diols under liquid‐liquid or solid‐liquid phase‐transfer conditions (NaOH, triethylbenzylammonium chloride, benzene) gives cyclic products of type (I) and/or (II).

Esterification of 1,4-dichlorobutane with sodium formate under solid–liquid phase transfer catalysis. A kinetic study

Kinetic data are reported regarding the esterification of 1,4-dichlorobutane with sodium formate catalyzed by quaternary ammonium salts as a model for reactions in series, under solid–liquid phase transfer conditions. The process was found to follow a consecutive first-order mechanism of the general type A → R → S. The reactivity of the quaternary ammonium salts with regard to the counteranion was Cl− > Br− > 1− > HSO4−. The reaction rate was linearly dependent on catalyst concentration up to 12 mol% of catalyst relative to the substrate. Above this concentration the rate was constant and independent of the amount of the catalyst. The activation energy of the two consecutive steps was found to be similar (21 kcal/mol). Therefore, the product distribution (R/S) is not appreciably affected by temperature. A mechanism termed "Thin aqueous boundary layer" is suggested for nucleophilic displacement reactions under solid–liquid phase transfer conditions. Keywords: phase transfer catalysis, series reactions, kinetic study.

Palladium-catalyzed desulfonylative coupling of arylsulfonyl chlorides with acrylate esters under solid-liquid phase transfer conditions

The reaction of arylsulfonyl chlorides with acrylate esters in the presence of a catalytic amount of PdCl 2(PhCN) 2 under solid-liquid phase transfer conditions gives the corresponding 3-aryl-2-propenoates in good yields.

Copper(I) and phase transfer catalysed allylic substitution by terminal alkynes

The Cu(I) catalysed allylic substitution of (un)substituted allyl halides by alk-1-ynes can proceed smoothly at or near room temperature under solid-liquid phase transfer conditions.

ChemInform Abstract: Reactions of Heteroarylhydrosilanes with Dichlorocarbene Under Phase‐Transfer Conditions.

Abstract The reactions of dimethyl(2-thienyl)-, methyl[di(2-thienyl)]-, tri(2-thienyl)- and dimethyl(2-furyl)silanes (I–IV, respectively) with dichlorocarbene generated from sodium trichloroacetate under solid-liquid phase-transfer conditions afford the corresponding dichloromethylsilanes in 38–66% yield. The reactivity of the thienylsilanes decreases with the number of electron-accepting thienyl substituents at the silicon atom. Using the competition reactions, the relative rate constants for the reaction of dichlorocarbene insertion into the SiH bond of thienyl- and furyl-silanes (I and IV) were measured. The reactivity of these silanes was found to be greater than had been expected taking as a basis the Taft σ* constants for the substituent at the silicon atom. This is apparently due to the existence of a pπ—dπ interaction between the heterocyclic π-system and the d-orbitals of silicon.

Organic Synthesis Using Ptc-41: Synthesis of Cyclic Ethers Using Phase Transfer Catalysis

Abstract The reaction of (1) and (2) uith (3a)2 2nd (3b)3 under liquid-liquid (L-L) and solid-liquid (3-L) phase transfer (PT) conditions furnish the corresponding (4) and (6) respectively and the reaction of (2) with (5) gives dioxolane derivative (7)

Reactions of heteroarylhydrosilanes with dichlorocarbene under phase-transfer conditions

The reactions of dimethyl(2-thienyl)-, methyl[di(2-thienyl)]-, tri(2-thienyl)- and dimethyl(2-furyl)silanes (I–IV, respectively) with dichlorocarbene generated from sodium trichloroacetate under solid-liquid phase-transfer conditions afford the corresponding dichloromethylsilanes in 38–66% yield. The reactivity of the thienylsilanes decreases with the number of electron-accepting thienyl substituents at the silicon atom. Using the competition reactions, the relative rate constants for the reaction of dichlorocarbene insertion into the SiH bond of thienyl- and furyl-silanes (I and IV) were measured. The reactivity of these silanes was found to be greater than had been expected taking as a basis the Taft σ * constants for the substituent at the silicon atom. This is apparently due to the existence of a p π— d π interaction between the heterocyclic π-system and the d-orbitals of silicon.

ChemInform Abstract: 2‐(Chloromethyl)‐3,5‐dioxahex‐1‐ene. An Effective Acetonylating Reagent.

AbstractThe reagent (II) mentioned in the title is prepared from the dichloro acetal (I) under solid‐liquid phase‐transfer conditions.

Copper(I)- and phase-transfer-catalysed iodination of terminal alkynes

A convenient synthesis of 1-iodoalk-1-ynes is reported, involving copper(I)-catalysed iodination of terminal alkynes with molecular iodine under solid–liquid phase-transfer conditions.

Organic synthesis using ptc-5: Nucleophilic aromatic substitution under liquid-liquid and solid-liquid phase transfer conditions

The reaction of 1-chloro-4-nitrobenzene(l) with dithiols generated in situ from thiouronium salts(2) under PT conditions, which in turn have been procured by the reaction of appropriate α,ω-dibromoalkanes with thiourea have been investigated. The reactions of (1) with various diols have also been investigated and their reaction mechanism is discussed.

Phase-Transfer Catalyzed Alkylative Elimination of Methyl 2-Phenylsulfinylacetate. A One-Pot Synthesis of Substituted Cinnamates

Abstract The facile alkylative elimination of the anion of methyl 2-phenylsulfinylacetate under solid-liquid phase-transfer conditions is described. Application of this one-pot method to the synthesis of ring-substituted cinnamates is presented.

Aldehydes and Ketones Epoxidation with Trimethylsulfonium Bromide in a Slightly Hydrated Solid-Liquid Medium

Abstract Trimethylsulfonium bromide used in low hydrated solid-liquid phase transfer conditions is a very efficient agent for aldehyde and ketone epoxidation.

Palladium catalyzed carbonylation of organic halides: the first example of carbonylation under solid-liquid phase transfer conditions

Palladium catalyzed carbonylation of aliphatic halides, iodobenzene, benzyl and substituted phenacyl halides affords effective yields under solid-liquid phase transfer conditions at mild pressures and short durations.