Tetrapropylammonium hydroxide

Taramasso et al. (5) had originally reported two methods for the hydrothermal synthesis of TS-1. The first method (mixed alkoxide method) involves the preparation of a solution of mixed alkoxides of titanium and silica (preferably ethoxides) followed by hydrolysis with alkali-free solution of tetrapropylammonium hydroxide (TPAOH), distillation of the alcohol and crystallization of the resulting gel at 448 K. In the second method (dissolved or hydrolyzed titanium method) a soluble tetrapropylammonium peroxo-titanate species was prepared initially and then colloidal SiC>2 (Ludox AS-40) was added. This entire operation had to be carried out at 278 K. The TS-1 samples obtained by these two synthesis routes differed, particularly because of the presence of impurities such as Al3+ usually present in colloidal silica (33). 

Howden, M. G. "Preparation and evaluation of an amorphous silica-aluminia catalyst synthesized in the presence of tetrapropylammonium hydroxides", CSIR Report CENG 441, Pretoria, 1982. 

A radiochemical procedure is proposed for the determination of technetium activities from mixed fission products of uranium and thorium. The chief decontamination step is the extraction of TcO into a tetrapropylammonium hydroxide-bromoform mixture from 4.0 M NaOH solutions. Decontamination factors of 10 with chemical yields of 50-70% have been obtained. 

Foster et al. have developed a method for determining technetium in dissolved nuclear fuel solutions. Tetrapropylammonium pertechnetate is doubly extracted from a basic medium into chloroform and the colored technetium (V) thiocyanate complex is formed in the chloroform phase by the addition of sulfuric acid, potassium thiocyanate and tetrapropylammonium hydroxide. The colored complex absorbs at 513 nm, has a molar extinction coefficient of 46,000 and is stable for several hours. Of more than 50 metals studied, none impairs measurements at ratios less than 100 to 1 mol with respect to technetium. Most anions do not disturb the determination of technetiiun. The standard deviation for a single determination is 0.09 fig over the range of 1 to 20 fig of technetium. 

Tetramethyammonium hydroxide Tetraethylammonium hydroxide Tetrapropylammonium hydroxide... 

Ion exchange can be used to convert one salt into another. For example, we can prepare tetrapropylammonium hydroxide from a tetrapropylammonium salt of some other anion ... 

Scholle et al. (220) used 27A1 MAS NMR at 130.3 MHz to study the intermediates of zeolite ZSM-5 containing tetrapropylammonium hydroxide (TPAOH) as template as a function of crystallization time. For the samples... 

Ion-pair chromatography has also been used for the separation of aspartame from other sweeteners. The ion-pair reagents commonly used are triethylammonium phosphate (32), tetra-ethylammonium hydroxyde (47), tetrapropylammonium hydroxide (40), pentanesulfonate (52), tetrabutylammonium phosphate (34), tetrabutylammonium hydrogen sulfate (66), and tetrabutyl-ammonium p-toluenesulfonate (24). 

Abbreviations p, ratio between ionic radii of cation and anion TBHP, rm-butyl hydroperoxide EBHP, ethylbenzene hydroperoxide PO, propylene oxide TBOT, tetrabutyl orthotitanate TEOT, tetraethyl orthotitanate TIOT, tetraisopropyl orthotitanate TEOS, tetraethyl orthosilicate THF, tetrahydrofuran TPA-OH, tetrapropylammonium hydroxide TMOS, tetramethyl orthosilicate TBA-OH, tetrabutylammonium hydroxide TBP-OH, tetrabutylphophonium hydroxide TEA-OH, tetraethylammonium hydroxide TMA-OH, tetramethylammonium hydroxide. 

The SAPO-37 samples were synthesized following a procedure similar to that described by Saldarriaga et al.(21). H3PO4 (85 ), AlpOj (pseudobohemite), tetrapropylammonium hydroxide (40% TPAOH, Alfa products with K+Na= 340 ppm), tetramethyl ammonium hydroxide pentahydrate (TMAOH.5H2O, from Aldrich) and Aerosil-200 were used as starting materials. 

The isomorphous substitution of T atoms by other elements produces novel hybrid atom molecular sieves with interesting properties. In the early 1980s, the synthesis of a zeolite material where titanium was included in the MFI framework of silicalite, that is, in the aluminum-free form of ZSM-5, was reported. The name given to the obtained material was titanium silicalite (TS-1) [27], This material was synthesized in a tetrapropylammonium hydroxide (TPAOH) system substantially free of metal cations. A material containing low levels (up to about 2.5 atom %) of titanium substituted into the tetrahedral positions of the MFI framework of silicalite was obtained [28], TS-1 has been shown to be a very good oxidation catalyst, mainly in combination with a peroxide, and is currently in commercial use. It is used in epoxidations and related reactions. TS-1, additionally an active and selective catalyst, is the first genuine Ti-containing microporous crystalline material. 

Basic silicate solutions were prepared by using silicic acid (ex Baker, dried at 350 °C) and a solution of the organic bases [25 wt % tetramethylammonium hydroxide (TMAOH), 40 wt % tetra-ethylammonium hydroxide (TEAOH), 20 wt % tetrapropylammonium hydroxide (TPAOH) ex Fluka] and, optionally, dimethyl sulfoxide (DMSO). A solution of hexamethonium hydroxide [ (MejNCgH NM ) (OH) 2] was prepared from the bromide salt (ex Sigma) and A O. 

Silicalite was synthesized according to Grose and Flanigen (15), using tetrapropylammonium hydroxide and Ludox AS-40 as a source of silicon. The product was washed, dried and calcined in air at 600°C giving crystalline silicalite with Si/Al=563 as determined by x-ray fluorescence (XRF) and atomic absorption (AA). 

Crystal Structure of Tetrapropylammonium Hydroxide-Aluminum Phosphate Number 5... 

The precursor to the AIPO4 5 molecular sieve crystallizes at 150°C from a hydrothermal system containing an aluminophosphate gel and tetrapropylammonium hydroxide. Its ideal chemical composition is TPAOH I2AIPO4. Removal of the TPAOH by calcination at 400-600°C produces a molecular sieve for which absorption studies are consistent with unconnected pores bounded by 12-rings. The AlPOtt 5 sieve is thermally stable to 1000°C above which it transforms to the AlPO. analog of tridymite. 

Mixed alkoxide method. Hydrothermal synthesis using tetraethylorthosilicate (TEOS) as the source of Si, tetraethyltitanate (TEOT) as the source of Ti, tetrapropylammonium hydroxide (TPAOH) as structure directing agent (template), base and distilled water... 

The tetraalkylammonium hydroxides (TAA) including tetramethylammonium hydroxide (TMA), tetraethylammonium hydroxide (TEA), tetrapropylammonium hydroxide (TPA), and tetrabutylammonium hydroxide (TEA) and diamines (DA) like ethylenediamine (en), 1,6-diaminohexane (1,6-DHA), and 1,10-diaminooctane (1,10-DO A) were used to intercalate into the layers of H-OL-1. The TAA or DA was added to the gel of H-OL-1. The whole mixture was stirred for certain times and the resultant nanometer-sized and larger sized colloids or sols were characterized. 

Taramasso and others first prepared TS-1 at the end of the 1970s, using two different methods for the preparation of the crystallization gel [10]. In the most commonly used mixed alkoxide method, this was obtained by the controlled hydrolysis of tetraethyltitanate and tetraethylsiUcate in the presence of tetrapropylammonium hydroxide. Crystallization under hydrothermal conditions produced crystalline TS-1. In the preparation of the gel, it is crucial to prevent segregation of Ti phases by the correct choice of procedure and control of the conditions. The maximum Ti content, expressed as the atomic ratio Ti/(Ti-i-Si), was reported to be ca 0.025 [11]. Other information is available in Refs. [6-9] and references therein. 

As indicated in the original patent, the absence of alkali metal ions in the synthesis mixture is critical for the incorporation of Ti in the lattice. Their presence as impurities in commercial samples of tetrapropylammonium hydroxide was not recognized in several studies, particularly in early ones, with the result that TS-1 was impure, containing Ti02 particles and amorphous Ti-silicates. Sometimes, however, the presence of alkali and other impurities is the consequence of a deliberate decision, in an attempt to decrease the cost of production of the catalyst by the use of cheaper sources of Si, Ti and tetrapropylammonium hydroxide [12]. 

The H-ZSM-5 (Si/Al=25, PQ Corp.) and Silicalite (S-1) zeolites were used to prepare the microporous copper-containing catalysts, Cu-ZSM-5 and Cu-S-1. ( We recall that S-1 has the same framework topology of ZSM-5, but without AP+ ions in the framework, and therefore S-1 is an all silica materials as MCM-41.) S-1 was prepared using TEOS and a 20% aqueous solution of tetrapropylammonium hydroxide (TPA-OH) (Fluka-purum). TEOS was poured in the TPA-OH solution. The resulting mixture was kept at 333 K for 3 h and then heated under autogenous pressure in a 350 mL stainless autoclave in an oven at 448 K for 24 h, without stirring. The solid was washed with water, dried 2 h at 383 K and finally treated in air at 823 K for 5 h. Further details were reported in Ref 4. 

R- triethylamine Ri-tetrmethylammomium hydroxide R2- tetrapropylammonium hydroxide and R3-tetraethylammonium hydroxide)... 

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