Tetraalkylammonium compounds

In zeolite synthesis (ref. 2) an aqueous mixture containing a silicon source, an aluminum source, an alkali source (usually NaOH) is autoclaved and subjected to hydrothermal treatment. Hydrated Na-ions are then filling the pore system in the as-synthesized zeolite. In the case of relatively high Si/Al zeolites an organic template is required which is usually a tetraalkylammonium compound, applied as the bromide or the hydroxide. 

To draw conclusions concerning the templating effect of different molecules, comparable conditions for the crystallization process must be used. In this paper we present a systematic investigation on the effect of mono-, di- and tri-n-alkylamine and tetraalkylammonium compounds (alkyl = C. - C,) upon the rate of crystallization, yield and the properties of the products. Also the field of a template-free synthesis is studied. The products were characterized by magic-angle-spinning nuclear magnetic resonance spectroscopy (MAS NMR) and X-ray diffraction. 

Methyl sulfate is not only of analytical interest as a counter ion of pharmaceutically relevant compounds. Rychtman [71] describes the trace analysis of this substance in pharmaceutical products that have been produced via alkylation with dimethyl sulfate. Tetraalkylammonium compounds, for example, may be synthesized by quatemation of tertiary amines with dimethyl sulfate ... 

MacKinnon and coworkers [391-393] have studied a number of organic compounds as additives and have shown that tetrabutylammonium chloride improves surface morphology and current efficiency during zinc electrowinning from acidic chloride solutions. A similar influence was observed using other tetraalkylammonium compounds as additives [371, 374, 375, 394]. 

Attempts have been made to mimic the above reactions under nonenzymatic conditions. Methylcobalamin methylates homocysteine, but the reaction is a free radical process . Also, MeH4THF does not methylate cobaloxime(I) or Bj2s. AI-Methylamines are also unreactive toward Co(I) species. Tetraalkylammonium compounds alkylate Co(I) nucleophiles to form alkylcobalt compounds" it is possible that MeH4THF is protonated by the enzyme and Ais methylates the cobalamin. Methylation in low yield of cobalamin(I) by MeH4THF at low pH has been disputed. ... 

The lanthanides form many compounds with organic ligands. Some of these compounds ate water-soluble, others oil-soluble. Water-soluble compounds have been used extensively for rare-earth separation by ion exchange (qv), for example, complexes form with citric acid, ethylenediaminetetraacetic acid (EDTA), and hydroxyethylethylenediaminetriacetic acid (HEEDTA) (see Chelating agents). The complex formation is pH-dependent. Oil-soluble compounds ate used extensively in the industrial separation of rate earths by tiquid—tiquid extraction. The preferred extractants ate catboxyhc acids, otganophosphoms acids and esters, and tetraaLkylammonium salts. 

This reaction is illustrative of a general procedure for the alkylation of active methylene functions in the presence of concentrated aqueous alkali catalyzed by tetraalkylammonium salts. This catalytic method has been used to alkylate arylacetonitriles with monohaloalkanes,2 dihaloalkanes,3 a-chloroethers,4 chloronitriles,.5 haloacetic acid esters,6 and halonitro aromatic compounds.7 It has also been used to alkylate ketones,8 lf/ indene,9 9i/-fluorene,ll) and the Reissert compound.11 The reaction is inhibited by alcohols and by iodide ion.2... 

In the Koenigs-Knorr method and in the Helferich or Zemplen modifications thereof, a glycosyl halide (bromide or chloride iodides can be produced in situ by the addition of tetraalkylammonium iodide) is allowed to react with a hydrox-ylic compound in the presence of a heavy-metal promoter such as silver oxide, carbonate, perchlorate, or mercuric bromide and/or oxide,19-21 or by silver triflu-oromethanesulfonate22 (AgOTf). Related to this is the use of glycosyl fluoride donors,23 which normally are prepared from thioglycosides.24... 

When reacted with tetraalkylammonium halides, hydrated [Me2Sn(IV)], [Bu2Sn(IV)]2-",2 [Ph2Sn(IV)]2-", 5 and [EtPhSn(lV)]2-",2 ester derivatives of 2,6-pyridinedicarboxylic acid yield tetraalkylammonium diorganohalogeno(2,6-pyr-idinedicarboxylato)stannates. Both classes of compounds exhibit high in vitro antitumor activity. 

Group-IIIB element-transition-metal compounds have been synthesized by means of anionic metal bases and halide-free group-IIIB compounds. The carbonylate anions of Mn and Re interact with BHj to give [HjBMfCOlj]", which are best isolated as the tetraalkylammonium or phosphonium salts ... 

A method for the development of a generic LC-electrospray-MS method for the analysis of acidic compounds using experimental design has been reported [5], From an HPLC perspective, this type of analysis often requires the use of an ion-pairing reagent to obtain separation however, many of these, such as tetraalkylammonium ions, are involatile and have undesirable effects on the performance of the mass spectrometer and more volatile alternatives have to be found - in this case, triethylamine was used. 

A wide variety of aromatic compounds can be brominated. Highly reactive ones, such as anilines and phenols, may undergo bromination at all activated positions. More selective reagents such as pyridinium bromide perbromide or tetraalkylammonium tribromides can be used in such cases.18 Moderately reactive compounds such as anilides, haloaromatics, and hydrocarbons can be readily brominated and the usual directing effects control the regiochemistry. Use of Lewis acid catalysts permits bromination of rings with deactivating substituents, such as nitro and cyano. 

The reactions of white phosphorus with tetraalkylammonium cyanides in the presence of a crown ether in acetonitrile give rise to the dicyanophosphide ion, which is found to react with a variety of anionic phosphorus nucleophiles with displacement of cyanide ion to generate new P-P bonded compounds.7... 

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