Organic quaternary ammonium

I. Hasegawa and S. Sakka, Silicate Species with Cagelike Structure in Solutions and Rapid Solidification with Organic Quaternary Ammonium Ions, Zeolite Synthesis (ACS Symposium Series 398) Am, Chem. Soc., Washington, DC 1989, p.140/51... 

Synthesis from (3-Pinene. Pyrolysis of /3-pinene yields myrcene, which is converted into a mixture of predominantly geranyl, neryl, and linalyl chloride by addition of hydrogen chloride in the presence of small amounts of catalyst, e.g., copper(I) chloride and an organic quaternary ammonium salt [29]. After removal of the catalyst, the mixture is reacted with sodium acetate in the presence of a nitrogen base (e.g., triethylamine) and converted to geranyl acetate, neryl acetate, and a small amount of linalyl acetate [30]. 

Silicate Species with Cagelike Structure in Solutions and Rapid Solidification with Organic Quaternary Ammonium Ions... 

Organic quaternary ammonium ions are effective in forming silicate anions with cage-like structures. 

Synthesis of silica-based materials with controlled skeleton structures, such as zeolites, requires controlling the structure of oligomeric silicate species at the first reaction step. Organic quaternary ammonium ions, which are known as organic templates in zeolite synthesis (1 ), have a role in making up the specific structures of silicate anions, whereas silicate anions randomly polymerize in aqueous solutions containing alkali metal ions, resulting in the presence of silicate anions with different structures. 

It is possible to obtain such silicates as solids by evaporation to dryness of the organic quaternary ammonium silicate aqueous solutions. In this case, however, the process is very slow and accordingly a problem of impurity incorporation arises. It was reported that silicate solids consisting of the double four-membered ring structure were abruptly separated out after an exothermal reaction on stirring the mixture of (2-hydroxyethyl)trimethylammonium hydroxide aqueous solution and tetraethoxysilane (26). 

In the first section of this paper, formation of silicate species with cage-like structures in organic quaternary ammonium silicate solutions are reviewed. In the last section, the process of the rapid selective formation of the silicate solids having the... 

Effect of the Structure of Organic Quaternary Ammonium Ions. The tetramethylammonium ion (N C J ), first introduced in zeolite synthesis by Barrer and Denny (30), and Kerr and Kokotailo (21) is effective in forming the cubic octameric silicate anion (Sig02Q°, cubic octamer) (2-16). In the tetramethylammonium silicate aqueous solutions at higher S3.O2 concentrations or cation-to-silica molar ratios (abbreviated to the N/Si ratios), the cubic octamer is singularly formed. 

Sakka, S., unpublished data.)- In the solutions, a number of methylsilsesquioxane species, formed by the hydrolysis of methyltriethoxysilane, with different structures are present even under the conditions where the cubic octamer is dominant in the aqueous silicate solutions. This indicates that the use of a silica source with tetra-functionality is required for the selective structure formation with the aid of organic quaternary ammonium ions. 

Effect of Temperature. The temperature of a silicate solution also affects the polymerization of silicate anions in the solution. The distribution of silicate anions in an organic quaternary ammonium silicate solution at a fixed N/Si ratio and SiC concentration varies with the temperature of the solution (7,8,13,14,16). Ray and Plaisted (8) reported the temperature dependence of the distribution of silicate anions in the tetramethylammonium silicate aqueous solution at a N/Si ratio of 2/3 and a SiC>2 concentration of 1.0 mol dm. The amount of the cubic octamer in the solution decreases with increasing temperature, and the cubic octamer practically disappears above 50 °C, indicating that the cubic octamer is unstable at higher temperatures. However, Groenen et al. (14) found that the cubic octamer remained in a significant concentration even at 85 °C, which was close to the temperature of actual zeolite formation, in the tetramethylammonium silicate aqueous solution at a N/Si ratio of 1.0 and a Si02 concentration of 1.3 mol dm-. ... 

Effect of Addition of Sodium Ions to Tetramethylammonium Silicate Aqueous Solution. In zeolite synthesis, alkali metal cations are combined with organic quaternary ammonium ions to produce zeolites with different structures from the one produced with only the organic quaternary ammonium ion (2) It is then expected that other types of silicate species are formed in the silicate solutions when organic quaternary ammonium ions and alkali metal cations coexist. In such silicate aqueous solutions, however, alkali metal cations only act to suppress the ability of the organic quaternary ammonium ions to form selectively silicate species with cage-like structures (13,14,28,29). 

Rapid Solidification of Organic Quaternary Ammonium Silicates... 

In this section, the results of our study on the rapid solidification of organic quaternary ammonium silicates are presented. 

Tetramethylammonium or (2-hydroxyethyl itrimethylammonium silicate solid, consisting solely of the SigC Q0- silicate structure, was abruptly separated out by cooling the single phase solution which was obtained after an exothermal reaction by mixing the organic quaternary ammonium hydroxide aqueous solution and tetraethoxysilane. The change between the solid and the solution was reversible and very rapid. 

When metal ions are used as counter ions, instead of organic quaternary ammonium ions, in the packing material, the hydroxy (-OH-) fimctional groups of the carbohydrates and other sugars interact with these metals ion. Pb, Ca, and Na, are typical metal ions in the packing material. Depending upon the type of counter ions used, the intensity of the interaction changes and therefore, the retention between different carbohydrates vary. Some of the carbohydrates are also retained because of the size of the molecule under these conditions. 

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