Methylammonium salt

Following a similar protocol, novel hexacoordinated phosphate anions 19 to 22 bearing two different dioxo ligands could be simply prepared as their di-methylammonium salts from the reaction of tetrachlorocatechol derived phos-phoramidite 23 with a variety of symmetrical diones other than o-chloranil (a-diketones or orf/zo-quinones) and subsequent addition of tetrachlorocatechol to the corresponding phosphorane 24 (Scheme 3) [42]. 

At this point the hygroscopic potassium salt may be isolated and dried, or, more conveniently, the potassium salt may be dissolved in water and the carborane anion precipitated with one of a variety of large cations, such as the rubidium, cesium, tetramethylammonium, or trimethylammonium ions. The tri-methylammonium salt of the carborane anion is useful because it is readily purified by recrystallization from water and may be easily converted in solution to salts containing other counterions. ... 

Finally, the remaining steps were accomplished by methylation of 26a with methyl fluorosulphonate in ether to give the methylammonium salt 25, reductive cleavage of the N-0 bond with LAH and oxidation of the resulting alcohol with Jones reagent. The yields of the last three steps are almost quantitative and the overall yield of the seven steps synthetic sequence leading to optically pure (+)-luciduline (1) is 33%. 

Salts of azotetrazole (156) are energetic compounds, the guanidinium and methylammonium salts finding use as gas generators when mixed with inorganic oxidizers. Thiele ... 

A unique feature of phosphaadamantane is the reactivity of the nitrogen with alkylating agents such that ammonium salts are formed preferentially to phosphonium salts. The synthesis of the methylammonium salt of PTA as well as the phosphine oxide, 0=PTA, are described below. The latter is achieved by the reaction of PTA with 30% H202. This harsh reagent is necessary because of the resistance of PTA, as well as its nitrogen analog, hexamethylenetetraamine, to mild oxidants. 

In a 100-mL, round-bottomed flask fitted with a reflux condenser, PTA (0.5 g, 3.2x 10-3 mol) and methyl iodide (0.46 g, 3.2 x 10 3 mol) are dissolved in 60 mL of acetone. The mixture is then refluxed for 1 h, during which a white precipitate forms. The solution is filtered in air through a Buchner funnel and subsequently washed with acetone, resulting in a crude yield of 0.91 g of the methylammonium salt. The product is recrystallized by heating a 50-mL solution of methanol/ethylacetate (50 50) containing the [PTAMe+] I" until all solid material dissolves. Upon cooling in an ice bath, white, flaky crystals form. The product was then filtered in air through a Buchner funnel and washed with ethyl acetate. 

In this manner are formed pentacarbonylhalogenotungsten hydrides which, to the best of our knowledge, are new, in contrast to the corresponding anions. The neutral hydride complexes are very unstable and in aqueous solution they dissociate completely into hydronium and penta-carbonylhalogenotungstate ions. The latter can be precipitated as tetra-methylammonium salts (71) ... 

CUiHu)0, 635-51-8) see Phensuximide phenylsuccinic acid bis(methylammonium) salt (C jH2 N204 157399-22-9) see Phensuximide phenylsuccinic anhydride (C1hHs05 1131-15-3) see Phensuximide phenylsulfinyl chloride... 

Christe and co-workers (3) obtained the XeFj ion as the tetra-methylammonium salt at — 86°C, and determined its structure by x-ray diffraction as well as vibrational spectroscopy. This anion takes a highly unusual D5h structure, shown in Fig. 4-1, which can be derived from that of a pentagonal bipyramidal IF7 in which the two axial fluorine ligands are replaced by two sterically active free valence electron pairs. The XeFj anion has 12 (3x6 — 6) normal vibrations that are classified into 1/1, (R) + 2 ,, (IR) + 2E 2(R) + E2 (inactive) under Dsh symmetry. 

Hofmann degradation of the quarternary base of the methylammonium salt of Schopf s base IV (66) has been shown to lead to the olefin 67 and the macrocyclic amine 68 (73HCA553). 

Cycloaddition of thiazolium azomethine ylides with dialkyl acetylenedicarboxylates 61 provides another approach to pyrrolo[2,1 -bjthiazoles 64 <070L4099>. Quatemization of 2-methylthiothiazole with trimethylsilylmethyl trifluoromethanesulfonate (TMSChkOTf) and subsequent fluoride-induced desilylation of the resulting (trimethylsilyl)methylammonium salt generate the acyclic azomethine ylide 62. This ylide readily participates in 1,3-dipolar cycloadditions with acetylene derivatives 61 to give adducts 63, which undergo spontaneous elimination of methylmercaptan to give the A-fuse cl thiazoles 64. ... 

Acid hydrolysis of 67 back to 8 seems to require rather drastic conditions125 in keeping with the soft character127 of 67 as a base. Eventually 8 is hydrolyzed to the methylammonium salt of o-sulfobenzoic acid (52b).125 3-Alkylthiosaccharins (4) are hydrolyzed with acid to 52b and the thiol somewhat more readily.125... 

Inclusion complexes have also been shown to aid excimer formation provided that the cavity dimensions and polarity are appropriate. Thus Ueno et al. (1980) have shown that the lipophilic cavity of y-cyclodextrin can accommodate two molecules of sodium (l-naphthyl)methyl acetate and that this leads to enhanced excimer emission. Excimer formation by diaryl-methylammonium salts is promoted by y-cyclodextrin but not by a- and P-cyclodextrins (Emert et al., 1981a). The best results were obtained with compounds having fairly large aryl groups e.g. 4-biphenylyl and 1-naphthyl. The hydrophobic character of these groups helped to solubilise the compounds in the interior of the cyclodextrin. 

As usnally prepared, MDH has an absolute requirement for ammonium or methylammonium salts in the dye-linked assay system. The relatively higher concentrations required at lower pH values suggest that the... 

LAH in THF reduces ammonium salts to amines. However, the best reagent for this reaction is LiEt3BH in THF at 25°C. Methylammonium salts are selectively de-methylated [BK5, CPI, NMl, PSl] (Figure 2.27). This method has found numerous applications in synthesizing natural products [NMl]. 

Keywords gas-solid reaction, thiohydantoins, methylamine, methylammonium salts, iodomethane, alkylation... 

The pyrolysis of tetraalkylammonium salts of aliphatic and aromatic acids has been investigated by Downing (DIO) and Bailey (Bl). It was found (Bl) that in order to obtain complete conversion of the tetra-methylammonium salts of organic acids to their methyl esters, it was necessary to pack loosely the injection port of the GLC apparatus with glass wool. It was also found (Bl) that the injection port must be maintained between 360 and 400°C and that when the sample is being injected, minimum penetration of the septum by the needle is necessary. The salts were prepared from the organic acids by titration with a methanolic solution of the appropriate tetraalkylammonium hydroxide. 

Mixtures benzylated with phenyldiazomethane, however, display a number of GC peaks belonging to substances other than benzyl esters. It has been claimed [216] that a more satisfactory route to benzyl esters involves benzylation of the benzyltri-methylammonium salts of the acids with benzyl chloride. 

The aqueous solution possesses the odor of the gas, and is Tiighly caustic and alkaline. It neutralizes the acids with formation of methylammonium salts e.g., CH3H3NKO3 = methylam-luonium nitrate), which are for the most part erystallizable and very soluble in HaO. Its chloraurate crystallizes in beautiful golden-yellow needles, soluble in water, alcohol, and ether. Its chloroplatinate crystallizes in golden-yellow scales, soluble in water, insoluble in alcohol. 

In the NMR spectrum of the methylammonium salt of the monomethyl ester of H-phosphonic add, the phosphorus signal appears at 4.55 ppm as a doublet of quartets with V(P,H) = 600 Hz indicating phosphonate structure. Kers et al. [23] confirm that in the reaction mixture of diethyl H-phosphonate and pyridine or pyridine with 2 equiv. of tertiary base (TEA), there were no signals that could be assigned to Iriethyl phosphite. The results obtained show that the basic activation in these reactions involves at the first step formation of the monoalkyl H-phosphonate anion [(R0)P(0)(H)0] , which further plays the key role in interactions where the phosphorus atom acts as a nucleophile. 

This transformation takes place readily at room temperature and can be carried out quantitatively by stirring the reaction mixture at 50-70 °C under vacuum for several hours. Ethylene is formed as a result of recombination of the carbon that probably forms at the first step of the decomposition. On the other hand, it was found [292, 295, 296] that quaternary methylammonium salts obtained by alkylation of tertiary amines (MiV-dimethyl aniline or triethyl amine) with dimethyl H-phosphonate are quite stable with respect to the above conversion when heated up to 130 °C and 70 °C, respectively. 

The NMR chemical shifts are very sensitive with respect to changes in the electron density at a given carbon atom and provide useful information about differences in the structures of the salts I and II. Thus, the signal of the ot-carbon atom in the sodium salt of monoethyl H-phosphonate (type I) is shifted 2.3 ppm downfield (Table 3.5) with respect to the same signal in diethyl H-phosphonate, which indicates a deaease in its electron density. In contrast, the signal of the ot-carbon atom in the triethyl methylammonium salt of monomethyl H-phosphonate (type n) is shifted 2.1 ppm upfield with respect to dimethyl H-phosphonate as a result of an increased electron density, due to the negative charge delocalization. 

XXXIII) resembles tetraphenylboranate anion B(C6H5) in its properties, although precipitation reactions with large, monovalent cations are not as sensitive, probably because of the rigid structure of (XXXIII). The two biphenylyl groups lie in mutually perpendicular planes. Precipitation of the tetra-methylammonium salt of (XXXIII) (m.p. 370° C) from aqueous solution is one way to get the complex ion in pure form. 

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