Tetraethylammonium bromide catalyst

Ga-MOR was hydrothermally synthesized by using tetraethylammonium bromide as a template. Ga content was controlled by removing Ga through HCl treatment in the same way as the dealumination of zeolite [1], The numeral at the end of catalyst name stands for Si02/Ga203 ratio in Ga-MOR thus prepared. Ga203/Ga-M0R catalyst was prepared by... 

Onium salts, such as tetraethylammonium bromide (TEAB) and tetra-n-butylammonium bromide (TBAB), were also tested as PTCs immobilized on clay. In particular, Montmorillonite KIO modified with TBAB efficiently catalyzed the substitution reaction of a-tosyloxyketones with azide to a-azidoketones, in a biphasic CHCI3/water system (Figure 6.13). ° The transformation is a PTC reaction, where the reagents get transferred from the hquid to the solid phase. The authors dubbed the PTC-modified catalyst system surfactant pillared clay that formed a thin membrane-hke film at the interface of the chloroform in water emulsion, that is, a third liquid phase with a high affinity for the clay. The advantages over traditional nucleophilic substitution conditions were that the product obtained was very pure under these conditions and could be easily recovered without the need for dangerous distillation steps. 

The 2-benzazepin-3-ones 259 have been made in moderate yields by sequential intramolecular acid-catalyzed addition followed by thiol elimination from the precursor phenylsulfanylacrylamides 258 (Scheme 33). The acrylamides 258 were prepared from reaction of the benzylamines 255 with the PNB-ester 256 to give the amides 257, and then N-methylation with Mel in the presence of potassium hydroxide and tetraethylammonium bromide, as a phase-transfer catalyst. Other noncyclized products were also observed depending on the structure of the A-aryl methyl group in 258 and on the nature of the solvent <2002H(57)1063>. 

For general or typical procedures for 1,1-dichlorocyclopropanes (from chloroform and base under phase-transfer catalysis conditions), see Houben-Weyl, Vol. E19b, p 1527 1,1-di-chloro-2-methylcyclopropane (from propene, chloroform, oxirane and tetraethylammonium bromide as a catalyst), see Houben-Weyl, Vol. 4/3, p 376 7,7-dichlorobicyclo[4.1.0]heptane (from chloroform and potassium /er -butoxide), see Houben-Weyl, Vol. 4/3, p 162 and Vol. 5/3, pp 977-978 (from thermal decomposition of sodium trichloroacetate and from ethyl trichloroacetate and sodium methoxide)," see Houben-Weyl, Vol. 4/3, pi62. 

Alkenes of low reactivity such as hex-l-ene, hept-l-ene " and oct-l-ene, give 1-bromo-l-chlorocyclopropanes exclusively (selectivity 100%) with dibenzo-18-crown-6 catalyst, yet a mixture of all dihalocyclopropanes was formed in low yield in the case of 3,3-dimethylbut-l-ene. 1-Bromo-l-chlorocyclopropanes 1 were prepared via the reaction of dibromochloromethane with oxirane, a catalytic amount of tetraethylammonium bromide and an alkene. 

Potassium ert-butoxide, sodium hydride, butyllithium have all been used for this purpose. The alkyl(aryl)sulfanylcarbene (carbenoid) thus generated undergoes addition, often effectively, across the double bond of alkenes, enol ethers, ketene acetals and enamines. The use of chloromethyl phenyl sulfide, oxirane, tetraethylammonium bromide as a catalyst and an alkene gave phenylsulfanylcyclopropanes in rather low yield. For the synthesis of l,l-dimethyl-2-phenylsulfanylcyclopropane, see Houben-Weyl, Vol.4/3, p250 and of endoj exo-7-phenylsulfanylbicyclo[4.1.0]heptane, see Vol. E19b, pl691. 

Dioxolanes. Carbonyl compounds react with ethylene oxide in the presence of a neutral catalyst such as tetraethylammonium bromide to form 1,3-dioxolanes, generally in yields of 70-85%. The reaction is carried out without solvent in an autoclave at 80-150° the products are isolated by distillation.1... 

Benzyl trimethyl ammonium hydroxide Cetrimonium bromide Dimethyl diallyl ammonium chloride Laurtrimonium bromide Laurtrimonium chloride Methyl tributyl ammonium chloride Tetrabutyl ammonium bromide Tetrabutyl ammonium chloride Tetrabutyl ammonium fluoride Tetra-n-butyl ammonium hydrogen sulfate Tetra-n-butyl ammonium hydroxide Tetrabutyl ammonium iodide Tetrabutylphosphonium acetate, monoacetic acid Tetrabutylphosphonium bromide Tetrabutylphosphonium chloride Tetraethylammonium bromide Tetraethylammonium hydroxide Tetrakis (hydroxymethyl) phosphonium chloride Tetramethylammonium bromide Tetramethylammonium chloride Tetramethylammonium hydroxide Tetramethyl ammonium iodide Tetraphenyl phosphonium bromide Tetrapropyl ammonium bromide Tetrapropyl ammonium iodide Tributylamine Tributyl phosphine Tributyl (tetradecyl) phosphonium chloride Trioctyl (octadecyl) phosphonium iodide catalyst, phase-transfer Tetraethylammonium chloride Tetraoctylphosphonium bromide Tri-n-butyl methyl ammonium chloride Tri methyl phenyl ammonium hydroxide catalyst, phenolics Triethylamine... 

Cyclohexene heated 5 hrs. at 150° with chloroform and ethylene oxide in the presence of tetraethylammonium bromide, which furnishes the halogen ions necessary as catalysts, in an autoclave 7,7-dichloronorcaran. Y 79%. — In contrast to previous carhene prepns. this method is reversible. Also further reaction of the cyclopropane derivatives s. F. Nerdel and J. Buddrus, Tetrah. Let. 1965, 3585. 

Figure 1. DSC thermogram for the reaction of PGE and MDI with tetraethylammonium bromide as catalyst.

Products of Phenylglycidyl Ether and 4,4 -Diiso-cyanatodiphenylenemethane from the DSC Study using Tetraethylammonium bromide (R NBr) or Ethylmethylimidazole (EMI) as Catalyst... 

Following a procedure similar to Dileone s, we have reacted diepoxides, including BADGE, with MDI. The catalysts used were lithium butoxide and tetraethylammonium bromide. Products were isolated by additions to the DMF solution of first water and then, in some reactions, methanol. 

A novel preparative synthesis of aporphines which should prove of appreciable utility in the future involves the cathodic cyclization of a l-(o-iodo-benzyl)isoquinoline methiodide salt. Gottlieb and Neumeyer have shown that electrolysis of l-(o-iodobenzyl)isoquinoline methiodide in dry acetonitrile containing tetraethylammonium bromide, and using a mercury cathode, furnished an 867o yield of the yellow didehydroaporphine which was reduced over Adams catalyst in methanolic hydrochloric acid to produce aporphine hydrochloride. The formation of didehydroaporphine proceeds via two one-electron reduction steps as shown below. 10,11-Dimethoxyaporphine was also prepared by this route. 

Kinetics of the aralkyl hydroperoxides decomposition in the presence of tetraethylammonium bromide (Et NBr) has been investigated. Et NBr has been shown to reveal the catalytic properties in this reaction. The use of Et- NBr leads to the decrease up to 40 kJmol of the hydroperoxides decomposition activation energy. The complex formation between hydroperoxides and Et NBr has been shown by the kinetic and H NMR spectroscopy methods. Thermod5aiamic parameters of the complex formation and kinetic parameters of complex-bonded hydroperoxides have been estimated. The model of the reactive hydroperoxide - catalyst complex structure has been proposed. Complex formation is accompanied with hydroperoxide chemical activation. 

Only under combined action of anion and cation the most essential changes of the peroxide fragment (C-O-O-C) conformation in the ROOR molecule are observed. It is the dominant factor of peroxide bond activation. Considering models V and VI it is impossible to prefer finally only one structure. But comparative analysis of all considered models allows conclude about selective association of peroxide with tetraethylammonium bromide ions i.e. catalyst attack should be stereospecific. 

More impressive results were observed in two other asymmetric reactions both based on the use of well-known catalysts developed for other transformations that turned out to perform well in new reactions, thanks to the beneficial use of water as solvent. One case is based on the oxidative kinetic resolution of secondary alcohols with chiral Mn(salen) complexes using PhI(OAc)2 as the oxidant (Scheme 23.40). The reaction is poorly enantioselective in dichloromethane (2% ee Krei < 1.1), while in water, in the presence of tetraethylammonium bromide as the phase transfer agent, the reaction is fast (63.4% conversion in 2 h) and highly enantioselective (85.2% ee withKrei 23.7). 3... 

The reaction of aliphatic isothiocyanates with alkylene oxides is more complex. For example, methyl isothiocyanate reacts with ethylene oxide in the presence of a tertiary amine catalyst at 20-90 °C to give trimethylthioisocyanurate. When the reaction is conducted at 90 °C, in the presence of tetraethylammonium bromide, the spirotriazine derivative 88 is obtained . 

As expected, HTMAB made a respectable showing in these experiments. Trioctylmethylammonium chloride (TOMAC) and trioctylmetliylammonium bromide (TOMAB) outperformed all other catalysts. It was postulated that the three octyl groups were the proper length for solvation of the polymer while at the same time small enough to avoid sterically hindering the reaction. In order to determine if TOMAB could be used to catalyze PET depolymerization for more than one treatment cycle, the catalyst was recovered upon completion of one treatment and added to a second run for 60 min. Tetraethylammonium hydroxide (TEAOH) was studied as a catalyst in order to demonstrate the effect of hydroxide ion as a counterion. The percent PET conversion for the second cycle was 85.7% compared to a conversion of 90.4% for the first treatment cycle. 

In a 300-mL round-bottom flask, a 5% sodium hydroxide solution (250 mL) was heated to 80° C in a constant-temperature bath. The catalysts were added in the following amounts in separate experiments trioctylmethy-lammonium chloride (TOMAC) (0.04 g, 0.0001 mol) trioctylmethylammo-nium bromide (TOMAB) (0.045 g, 0.0001 mol) hexadecyltrimethylammo-nium bromide (HTMAB) (0.045 g, 0.0001 mol) tetraethylammonium hydroxide (TEAOH) (0.015 g, 0.0001 mol) and phenyltrimethylammonium chloride (PTMAC) (0.02 g, 0.0001 mol). PET fibers (1.98 g, 0.01 mol) were added to the mixture and allowed to react for 30, 60, 90, 150, and 240 min. Upon filtration, any remaining fibers were washed several times with water, dried in an oven at 130-150°C, and weighed. The results are shown in Table 10.1. 

In this study they condensed the a-glycosyl bromide (243) with the disaccharide (245) in the presence of silver carbonate — silver perchlorate to give the a-linked tri-saccharide (241) in 58% yield or the bromide (244) with the disaccharide (246) in the presence of the mixed silver catalysts to give the a-linked trisaccharide (242) in 63 % yield. In the earlier approach, the preparation of the P-chloride (237) required a previous treatment of the a-bromide with tetraethylammonium chloride under carefully controlled conditions. 

Catalyst retention can be further optimised if a charged derivative of the (QN)2PHAL-ligand is used. Quatemisation of one of the nitrogen atoms with benzyl bromide affords the cationic ligand (QN)(QN-Benz)PHAL, and indeed recyclability was improved in the presence of this ligand, however at the cost of lower ee, as shown in Scheme 5.14.[66] The addition of one equivalent of tetraethylammonium acetate was found to improve the selectivity. 16 11... 

Thallium(I) cyanide was introduced by Taylor and McKillop as a reagent. Aromatic and heteroaromatic acyl cyanides are produced in go yield, whereas aliphatic acid halides lead under these conditions mainly to dimerization products. 18-Crown-6 is a good catalyst for the preparation of cyanoformate in methylene chloride with potassium cyanide and chloroformates. Similarly, tetraethylammonium cyanide gives cyanoformates in high yield under very mild conditions. Aroyl cyanides are generated easily by phase transfer catalysis with tetra-n-butylammonium bromide. Tri- -butyltin cyanide proved successful only with aromatic acid halides, leading to dimerization products with aliphatic compounds. ... 

All of these results were already presented at the ACS Houston Meeting on March, 1980.11 12 Since that time, further efforts have been made to synthesize novel condensation polymers by phase transfer catalyzed polycondensation. The present article deals with our recent works on the syntheses of carbon-carbon chain polymers and new types of polysulfides.1 The following abbreviations of phase transfer catalysts have been used throughout this article tetra-methylammonium chloride (TMAC), tetraethylammonium chloride (TEAC), tetrabutylammonium chloride (TBAC), benzyltriethylammonium chloride (BTEAC), cetyltrimethylammonium chloride (CTMAC), cetyltrimethyl-ammonium bromide (CTMAB), benzyltriphenylphosphonium chloride (BTPPC), cetyltributylphosphonium bromide (CTBPB), 15-crown-5 (15-C-5), 18-crown-6 (18-C-6), dibenzo-18-crown-6 (DB-18-C-6), dicyclohexyl-18-crown-6 (DC-18-C-6), dibenzo-24-crown-8 (DB-24-C-8), and dicyclohexyl-24-crown-8 (DC-24-C-8) ... 

---