Tetrabutyl ammonium bromide

Benzofurans have been prepared by microwave-accelerated cyclocondensation of differently substituted salicylaldehydes 182 with esters of chloroacetic acid 183 in the presence of K2CO3 (used as the solid support) and tetrabutyl-ammonium bromide (TBAB) as phase transfer catalyst [120]. This method seemed general regarding the variations at the benzene ring and the nature of the ester moiety (Scheme 66). 

The first example deals with poly[bis(trifluoroethoxy)phosphazene],PTFEP, film, whose surface is intrinsically hydrophobic but can be converted to hydrophilic by the action of NaOH in dioxane at 80 °C in the presence of tetrabutyl-ammonium bromide [514,515], or by metathetical exchange of trifluoroethoxy moieties with variable types of alkoxides groups [482,483,515] (vide supra). 

Benzo[h]furans have been formed by condensation of salicylaldehydes with a variety of esters of chloroacetic acids, in the presence of tetrabutyl ammonium bromide (TBAB), under the action of irradiation without solvent [86] (Scheme 8.61). 

Equation 11.8 Arylation of methyl acrylate under phase-transfer conditions. (TBAB = tetrabutyl ammonium bromide)... 

ZSM-5 and ZSM-11 samples were prepared as previously described (11) using tetrapropy 1 ammonium hydroxide and tetrabutyl ammonium bromide, respectively. The nature and crystallinity of the materials were verified by X ray diffraction, ir spectroscopy of lattice vibrational bands ( 1 2 ), n-hexane adsorption capacity at room temperature and constraint index (13) measurements. All samples correspond to highly crystalline ZSM-5 or ZSM-11 materials. The chemical compositions of the samples as determined from chemical analysis of A1 and Na contents, are given in table 1. 

Preparation of the Active Polvformals under Phase-transfer Catalysis. The polycondensation of DHTN or DHCH with dibromo- or dichloro-methane was carried out under phase transfer catalysis as shown in equations 2 and 3. Best results were obtained with dibromomethane, 60% aqueous KOH and tetrabutyl ammonium bromide. 

Polvcondensation of DHTN with dibromomethane under phase transfer conditions. The polycondensation of DHTN [13.13g, 0.080 mole] with 32mL dibromomethane was carried out in the presence of tetrabutyl ammonium bromide [2.48g or 0.008 mole] and 160mL 60 wt% aqueous KOH solution with vigorous stirring at room temperature for 24h. The polymer was precipitated in methanol and purified by reprecipitation from THF solution into distilled water to afford 13.51 g (94.8%) of the desired polyether which exhibits a reduced viscosity of 0.27 dL/g [measured at 30°C in DMF at a concentration of 0.5g/dL]. The polymer had an IR spectrum with a prominent C-O-C peak at 1210 cm". The NMR spectrum of the polyether [CDC13] showed peaks atff 1.7-2.5 (C-CH2-CH2-C), 4.6-5.3 (0-CH2-0), and 7.3-8.0 (aromatic). 

Calo s group have reacted both a-substituted and 3-substituted acrylates with haloaromatics in presence of a Pd-benzothiazole carbene complex using tetrabutyl ammonium bromide as the solvent. The reactions were found to be fast and efficient in the ILs when compared to conventional solvents. 

If the a2-P2W17061(Mnni-0H2)7- is metathesized with tetrabutyl ammonium bromide at a pH < 4, the compound partially degrades (10-20%, as seen by 31PNMR, showing the importance of 31P NMR to follow these... 

Co Pell ODS 16.2 mM-tetrabutyl-ammonium bromide in 50 mM-acetate buffer (pH 4.5), containing 4% of methanol. 254 nm Analysis in boiled water without interference with metal ions. [59]... 

Cathodic reduction of nonconjugated steroidal ketones has been found to give the equatorial alcohols with a high degree of stereoselectivity and in very good yields 134 These reactions were run at -2.6 V in aqueous ethanol-tetrabutyl-ammonium bromide. a-Methyldesoxybenzoin gave only the erythro form of 1,2-diphenylpropanol-1 on reduction at mercury in 40 % ethanol at pH 8 (veronal buffer) at -1.85 V (SCE) 13S>. 

Zorbax ODSS (10 pm), Nucleosil ODSS (5 pm) Octadecylsulfonated silica(ODSS) Separation of nucleotides, dinucleotides, transfer-ribonucleic acids MeCN-aqueous phosphate 35 65 v/v, 9.75 mM phosphate, 3.25 mM tetrabutyl ammonium bromide, pH 6.50 MeCN-MeOH-12mM ammonium phosphate30 40 30, v/v/v, pH 6.0 [93]... 

Alkylation of (4) with ethyl bromo acetate was effected under phase-transfer conditions with powdered potassium hydroxide and tetrabutyl ammonium bromide in tetrahydrofuran to yield compound (5), and the azide function in (5) was then reduced by catalytic hydrogenation (over Pd/C) to give (6). The aminoester (6) was resolved into its enantiomers via... 

Figure 27 Typical electrochromatogram of mono-, di- and triphosphate nucleotides. Capillary column, packed with 10-pm ODSS stationary phase, 20.5/27 cmx 100 pm i d. mobile phase, hydroorganic eluent containing 9.75 mM phosphate, 3.25 mM tetrabutyl-ammonium bromide and composed of 35% (v/v) acetonitrile and 65% (v/v) aqueous sodium phosphate, pH 6.50 running voltate, 20 kV, elec-trokinetic injection, 1.0 kV for 2 s. Solutes 1, CMP 2, UMP 3, AMP 4, GMP 5, CDP 6, UDP 7, ADP 8, CTP 9, GMP 10, UTP 11, ATP 12, GTP. (Reprinted from Ref. 119, with permission.)...

The reaction of diazine substituted t-butylthioureas 32 with methyl iodide under phase transfer conditions (l,2-dichloroethane/30 % NaOH) in the presence of tetrabutyl-ammonium bromide affords diazinyl substituted t-butylcarbodiimides 33 in 62-76 % yields. The reaction involves the intermediacy of the S-methylisothiourea derivative. 

Key to Figures 16 and 17 1, Pyrazine 2, 2-Methylpyrazine 3, 2,6-Dimethyl-pyrazine 4, Quinoxaline 5, 2-Methylquinoxaline 6,, 4-Diazabicyclo, 2,2 -octane 7, Pyridine 8, Dioxan 9, Tetramethylammonium bromide 10, Tetror ethylammonium bromide 11, Tetrcq>ropylaminonium bromide 12, Tetrabutyl-ammonium bromide 13, n-propanol. 

Mobile-phase modifiers. The modifiers that have been used with the AGP CSP encompass uncharged and charged compounds and include 2-propanol, N,N-dimethyIoctyIamine, tetrapropyl- and tetrabutyl-ammonium bromide, and octanoic acid (see Fig. 12). The addition of these modifiers to the mobile phase usually results in a decrease in the retention of solutes, with an accompanying decrease in enantioselectivity (a). However, in some instances, the addition of a modifier results in an increase in a. 

In refluxing tetrachloroethylene (121 °C), with collidine as the acid scavenger, the guanidinium salts are superior to tetrabutyl ammonium bromide (TBAB). Moreover, the comparisons of experiments without collidine in o.dichlo-robenzene under vacuum demonstrated a decisive advantage of HBGCl.HCI over TBAB as shown in scheme 98,... 

A modification of Elguero s procedure was developed by Armanasco,250 which involved stirring a mixture of 3,5-dimethylpyrazole, chloroform, potassium carbonate, and tetrabutyl ammonium bromide at room temperature for a week. During this time the initially colorless reaction mixture became increasingly brown. The separation of the ligands from the respective reaction mixtures was extremely tedious and difficult (chromatography or fractional sublimation when the compounds are volatile). 

Ethylene carbonate is produced industrially by the reaction of carbon dioxide with ethylene oxide (reaction 8.36), in the presence of a catalyst, such as tetrabutyl-ammonium bromide. 

Schullerer et al. developed a method for the enrichment of lOS compounds for aromatic sulfonates from water samples. The sum parameter is based on the principle of ion-pair solid-phase extraction. Analogous to the ion-pair chromatography, a reversed-phase Cjg material is used as adsorbent while tetrabutyl ammonium bromide is used as ion-pairing reagent, as already mentioned in previous chapters. 

A -Benzylepimine 160 reacted with a mixture of ammonium and tetrabutyl-ammonium bromide or iodide to give the respective diequatorial bromo (193) or iodo (194) derivatives as the sole products. This formation is the result of an equilibrium between the starting epimine and the diaxial halo derivative, which is formed initially by aziridine-ring cleavage. This equilibrium could be set up readily because of the instability of the diaxial halo derivatives and their tendency to undergo back-cyclization of the aziridine ring. To prove the existence of the equilibrium, the diaxial bromo derivative 191 was prepared by the action... 

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