Tetra methyl ammonium salts

Tetra-methyl Ammonium Salts.— Not only do these tri-amines unite directly with the hydrogen halides forming ammonium salts as above, but, being much more strongly basic than the mono- or di-amines, they unite also with the alkyl halides themselves forming salts of similar character. Thus ... 

These salts are known as tetra-methyl ammonium salts or quaternary compounds. 

The tertiary amine group in this last compound being more strongly basic than the primary amine group in amino acetic acid would more readily form an inner ammonium salt. There is also a tetra-methyl ammonium iodide compound formed analogous to the tetra-methyl ammonium salts of the alkyl amines. 

With acids this salt loses potassium iodide, KI, and yields an acid. This acid has the constitution of an inner salt and would be related to what we may term the normal tetra-methyl ammonium iodide acid, by the loss of hydrogen iodide, and to a tetra-methyl ammonium... 

Potassium tetra-methyl ammonium acetic acid iodide salt)... 

Betaine is the tetra-methyl ammonium inner salt compound already referred to (p. 386). It is really a tri-methyl derivative of glycine. 

The salt is sometimes called methylamine hydrochloride, and its formula is written CH3NH2.HCI. The replacement of hydrogen in ammonium hydroxide by positive alkyl groups yields compounds which react with water and form bases much stronger than ammonium hydroxide. The accumulation of positive radicals in the quarternary ammonium bases results in the production of marked basic properties in these compounds. Tetra-methyl-ammonium hydroxide shows about as strong basic properties as potassium hydroxide. 

Sol-gel technology is another approach for preparation of electocatalysts. Recently, Pt-Ru catalysts were prepared by hydrolysis of acetylacetonate salts of Pt(ll) and Ru(ll) in the presence of tetra methyl ammonium hydroxide and subsequent solution evaporation to xerogel formation and thermal treatment under controlled atmosphere [15]. 

Sulfoxides without amino or carboxyl groups have also been resolved. Compound 3 was separated into enantiomers via salt formation between the phosphonic acid group and quinine . Separation of these diastereomeric salts was achieved by fractional crystallization from acetone. Upon passage through an acidic ion exchange column, each salt was converted to the free acid 3. Finally, the tetra-ammonium salt of each enantiomer of 3 was methylated with methyl iodide to give sulfoxide 4. The levorotatory enantiomer was shown to be completely optically pure by the use of chiral shift reagents and by comparison with a sample prepared by stereospecific synthesis (see Section II.B.l). The dextrorotatory enantiomer was found to be 70% optically pure. 

Methyl esters undergo trans-esterification with the quaternary ammonium salts at high temperature and the reaction has been used with some effect for the preparation of, for example, n-butyl esters by heating the methyl ester with tetra-n-butylammo-nium chloride at 140°C [31]. Optimum yields (>75%) are obtained in HMPA or in the absence of a solvent. A two-step (one-pot) trans-esterification under phase-transfer catalysed conditions in which the carboxylate anion generated by initially hydrolysis of the ester is alkylated has been reported for Schiff s bases of a-amino acids [32] and for A-alkoxycarbonylmethyl [1-lactams [33]. Direct trans-esterification of methyl and ethyl esters with alcohols under basic catalytic conditions occurs in good yield in the presence of Aliquat [34, 35]. 

On the other hand, the addition of a quaternary ammonium salt to the reaction medium accelerates the isomerization of the radical intermediate [36]. Thus, the epoxidation of c/j-stilbene in the presence of A -benzylquinine salt gives rranr-stilbene oxide with 90% ee as major product (Table 6B.1, entry 24). This protocol provides an effective method for the synthesis of trans-epoxides. In contrast to the epoxidation of c/s-di- and tri-substituted olefins for which complexes 11-13 are the catalysts of choice, the best catalyst for the epoxidation of tetra-substituted conjugated olefins varies with substrates (Table 6B.1, entries 27 and 28) [37]. The asymmetric epoxidation of 6-bromo-2,2,3,4-tetramethylchromene is well-promoted by complex 14 and that of 2-methyl-3-phenylindene, by complex 12a. 

Manufacture. First Michler s ketone(tetra methyl diamido benzophenone) is prepared by the condensation of dimethyl aniline and phosgene in the presence of a catalyst such as zinc chloride. Then the Michler s ketone is melted at 150 C with ammonium chloride and zinc chloride. This material is sold on the market as the HCl salt. 

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