111-83-1Relevant articles and documents
Influence of Spacer Chains and Percentage Ring Substitution on Phase-transfer Catalytic Activity of Phosphonium Salts Bonded to Polystyrene Matrix
Anelli, Pier Lucio,Montanari, Fernando,Quici, Silvio
, p. 1827 - 1830 (1983)
In nucleophilic aliphatic substitutions carried out under liquid-liquid phase-transfer conditions, the catalytic activity of tributylphosphonium groups directly bonded to a polystyrene matrix through a methylene bridge decreases by about one order of magnitude on passing from 10 to 69percent ring substitution; log kobs. is linearly related to the loading of the catalytic sites.When tributylphosphonium groups are bonded to the polymer matrix by a linear spacer chain of 13 atoms for 10-30percent ring substitution, kobs. increases 1.7-3.1 times with respect to directly bonded catalysts.However, for spaced catalysts with 60percent ring substitution, the observed rate increase is 4.1-10-fold.This behaviour is explained by the combination of two opposing effects: (i) a polarity increase at the catalytic site by increasing percentage ring substitution leading to a decrease of nucleophilic activity of the anions; (ii)a polarity decrease at the catalytic site by insertion of spacer chains, due to the intrinsic lipophilicity of the alkyl chains as well as the more even distribution of catalytic sites within the polymer matrix.The reactivities of the catalysts, all prepared from chloromethylated polystyrene (200-400 mesh), are independent of the size of particles separated by sieves.
Syntheses of long-chain quaternary ammonium salts from fatty alcohols by microwave irradiation
Jiang,Hu,Pang,Yuan
, p. 847 - 850 (1996)
The phase-transfer catalysts, long-chain quaternary ammonium salts, were rapidly synthesized from fatty alcohols by the reactions with hydrogen halides in the presence of trialkyl amines under microwave irradiation. The catalysts could be widely applied in a variety of quick and new organic reactions, whether by conventional heating or under microwave irradiation. The reaction efficiencies under microwave irradiation were higher than those obtained with conventional heating.
Silicon polypodands: A new class of efficient solid-liquid phase-transfer catalysts
Maia, Angelamaria,Landini, Dario,Leska, Boguslawa,Schroeder, Grzegorz
, p. 10111 - 10115 (2004)
Silicon polypodands 1-7 were found to be powerful complexing agents of alkali metal salts, even in low polarity media (chlorobenzene) and hence very efficient phase-transfer catalysts. Their catalytic activity was measured in typical anion-promoted reactions under solid-liquid phase-transfer catalysis (SL-PTC) conditions. It is mainly determined by the complexing ability of the ligand, increasing with the number of silicon atoms and binding sites. Comparison with traditional phase-transfer catalysts showed that these polypodands are better catalysts not only than open-chain PEG400Me2 and TRIDENT, but even than more sophisticated macrocyclic polyethers such as DCH18C6.
Novel Synthesis of Long-Chain Primary Alkyl Compounds
Gibson, Thomas,Tulich, Linda
, p. 1821 - 1823 (1981)
A method has been developed for the efficient laboratory-scale synthesis of long-chain compounds involving the metathesis of α-olefins to long-chain internal olefins, followed by hydrozirconation.The latter process gives the terminally substituted zirconium alkyl exclusively, which can be converted to a wide variety of functional groups.This paper deals exclusively with the formation of long-chain primary iodides.
On the behaviour of sulfonates towards As(III) nucleophiles
Tsivgoulis, Gerasimos M.,Sotiropoulos, Demetrios N.,Ioannou, Panayiotis V.
, p. 97 - 110 (1998)
Mesylates and hydrophilic amsylates and [3]betylates were tried as substrates in an effort to create a C-As bond. In no case did we detect the formation of arsonic acids. With Na3AsO3 as nucleophile the product was the parent alcohol due to exclusive attack of the HO- present in the aqueous Na3AsO3. With (PhS)3As as the nucleophile in the absence of Lewis acid catalyst the products were diphenyl disulfide and AS2O3 while in the presence of catalyst alkyl phenyl sulfide was obtained, implying that the electron pair on As was chemically inactive. As2O3 did not react with these electrophiles, and potassium di-O-phenylenedioxyarsenate(III) was unreactive towards alkyl bromides but it gave the monoalkyl ether of catechol with amsylates and [3]betylates, again implying that the stereochemically active electron pair of As was not chemically active.
Phase-Transfer Reactions Catalyzed by Lipophilic Cryptands and Dicyclohexano-18-crown-6: Dehydrating Effect of Concentrated Aqueous Alkaline Solutions
Landini, Dario,Maia, Angelamaria,Montanari, Fernando
, p. 2917 - 2923 (1984)
A study of how the concentration of aqueous KOH affects the hydration and hence the reactivity of anions (Cl-, Br-, I-, SCN-, N3-) in aliphatic nucleophilic substitutions catalyzed by lipophilic cryptand (1a) and dicyclohexano-18-crown-6 (DCH18C6) (2) under phase-transfer conditions is reported.A comparison with the same reactions performed in classical liquid-liquid PTC and homogeneous anhydrous conditions is also included.Unlike quaternary onium salts, even at the highest KOH concentrations (53percent; ie., conditions in which aH2O ca. 0), water in the presence of 1a is not completely removed.Residual hydration depends on the nature of the anion and is the highest for anions with localized and/or less polarizable charge, such as Cl-, Br-, and N3-.As a consequence, rate constants noticeably increase in comparison with those found under conventional PTC conditions but do not reach those of anhydrous solutions.The different behavior of cryptates and quaternary salts is discussed on the basis of the different topology of the two systems.Behavior of crown ethers is in between that of quaternary salts and cryptates, since residual hydration in the presence of 53percent aqueous KOH is lower than that of cryptates, whereas anionic reactivity becomes practically identical with that found under anhydrous conditions.
Bromide-Chloride Exchange between Alkyl Halides and Metal Halide Salts under Phase Transfer Conditions
Sasson, Y.,Weiss, M.,Loupy, A.,Bram, G.,Pardo, C.
, p. 1250 - 1252 (1986)
The equilibrium position of the phase transfer catalysed exchange reaction RCl + MBr -->/-- RBr + MCl where R = primary alkyl group and M = Li, Na, K, Ca is strongly dependent on the nature of the metal cation M and the amount of water present in the reaction mixture; this has been applied in the synthetic use of the reaction in both directions.
Synthesis of isoprenoid chain-contained chemical probes for an investigation of molecular interactions by using quartz crystal microbalance
Liu, Wujun,Zhang, Yixin,Hou, Shuhua,Zhao, Zongbao Kent
, p. 6208 - 6210 (2013)
Five probes including four that contained isoprenoid chain were synthesized. These probes were assembled onto the gold-coated quartz crystal chips for analysis of their interactions with four yeast proteins by using the quartz crystal microbalance technology. Results showed that 3-phosphoglycerate phosphokinase and triosephosphate isomerase had clear interactions with certain probes, while glutathione reductase and phosphoglucose isomerase gave much lower interaction signals. It also suggested that 3-phosphoglycerate phosphokinase had two sites interacting with the probe attached with a geranyl moiety. Further molecule simulation experiments provided supportive information on these intermolecular interactions. Together, our data suggested that there are hydrophobic interactions, with relatively good selectivity, between isoprenoid chain and proteins.
The catalytic activity of ionophoric calix[4]arene analog
Okada,Sugitani,Kasai,Nishimura
, p. 586 - 588 (1994)
Calix[4]arene analog (2) having 2-[2-(2-methoxyethoxy)ethoxy]ethyl groups was prepared in 92% yield. Compound 2 showed the extraction of alkali metal ions as an ionophore and the catalytic activity for some S(N)2 reactions.
Crown ethers as phase-transfer catalysts. A comparison of an ionic activation in aqueous-organic two-phase systems and in low polarity anhydrous solutions by perhydrodibenzo-18-crown-6, lipophilic quaternary salts, cryptands
Landini, Dario,Maia, Angelamaria,Montanari, Fernando,Pirisi, Filippo M.
, p. 46 - 51 (1980)
Anion-promoted nucleophilic substitutions carried out in aqueous-organic two-phase systems in the presence of catalytic amounts of perhydrodibenzo-18- crown-6 follow the classic mechanism of phase-transfer catalysis. The observed pseudo-first-order rate constants are linearly related to the concentration of complexed crown ether in the organic phase. The narrow reactivity range and the sequence found in the reaction between n-octyl methane-sulphonate and a homogeneous series of anions in the PhCl-H2O two-phase system (N 3- > I- ～ Br- > CN - > Cl- > SCN-) remain largely unaltered in anhydrous PhCl. From this point of view complexed crown ethers differ substantially from lipophilic quaternary salts and cryptates. Indeed, removal of the hydration sphere of the anions in going from two-phase to anhydrous conditions is balanced by a larger cation-anion interaction, resulting in a very small variation of anion reactivity. This indicates that, unlike cryptates, complexed crown ethers can hardly be considered as a source of 'naked anions.' A comparison is also reported among lipophilic crown ethers, quaternary salts, and cryptands as phase-transfer catalysts.
