And super acids

Experiments showed that high methyl ester yields can be achieved with solid bases and super acids under moderate reaction conditions. The solid bases were more effective catalysts than the solid super acids. High stability can be achieved by an ordinary inexpensive preparation process, and the catalyst can be separated easily from the reaction products in the heterogeneous catalysis process. The costly catalyst removal process can be avoided compared with the homogeneous process. Therefore, the heterogeneous process using a solid catalyst should be more economical for biodiesel production. 

Exhibit Br0nsted, Lewis, Franklin, and super acidity... 

The concept of superelectrophilic activation was first proposed 30 years ago.20 Since these early publications from the Olah group, superelectrophilic activation has been recognized in many organic, inorganic, and biochemical reactions.22 Due to the unusual reactivities observed of superelectrophiles, they have been exploited in varied synthetic reactions and in mechanistic studies. Superelectrophiles have also been the subject of numerous theoretical investigations and some have been directly observed by physical methods (spectroscopic, gas-phase methods, etc.). The results of kinetic studies also support the role of superelectrophilic activation. Because of the importance of electrophilic chemistry in general and super-acidic catalysis in particular, there continues to be substantial interest in the chemistry of these reactive species. It is thus timely to review their chemistry. 

The industrially important direct methane conversion processes comprise oxidative coupling, reductive coupling including pyrolysis reactions, partial oxidation, halogenation and oxyhalogenation,26 and ammoxidation. Other direct conversions include alkylation, electrophilic substitution, and C-H bond activation over various complex and super acid catalysts. Several of these direct conversion technologies remain to be exploited to achieve their full commercial potentials. 

Scales of gas-phase proton affinities and gas-phase acidities for numerous organic compounds, including super bases and super acids [232], can be found in references [115, 120, 232, 233] for comparisons of gas-phase and solution acidities, see references [124, 234-238]. 

A dramatic reduction of undesirable catalysis by-products requires higher catalytic selectivities, which at present are mostly attainable only with en me like catalysts or by solid catalysts with nearly uniform active sites. This latter catalyst characteristic is specially important for catalytic transformations involving strongly activated reaction intermediates, such as the carbocations formed on strong and super acids. Namely, in this activated state competing reaction paths are likely. Clearly, catalysts with uniform or at least nearly uniform active sites should be important objectives for future catalysis. 

Spectra were observed in various solvents, such as H2SO4, oleum, HSO3F, HSO3CF3 and super-acid, as well as in solids mulled in fluorolube ofl. In all of these, only ght changes were noticed by changing environments as smmnarized in Table 3. 

Clearly the epoxy structure dramatically influences the cure response of the epoxy as a function of pH. Cycloaliphatic epoxies are fast-reacting imder low pH conditions. Aromatic glycidyl ethers are faster under high pH conditions. These results generally agree with practical cures aromatic epoxies are easily ciu-ed with amines and amidoamines. Cycloaliphatics (102) are cured with acids and super acids. The behavior of the aliphatic epoxies is more complex but on balance is similar to that of cycloaliphatics. 

PROTON-, LEWIS-, HARD, SOFT AND SUPER-ACIDS... 

Acidic and basic ILs represent new classes of ILs. The acid or basic function can be attached either on the anion or cation (Figure 7) [55]. ILs containing polynuclear metallic anions, such as chloroaluminates, have been known for a long time for their potential Lewis acidity and super acidity in the presence of protons. 

Latent acidity and super acidity are two interesting phenomena in the field of acid base chemistry in ionic liquids. 

Metroke T. L., Kachurina O. and Knobbe E. T. (2002b), Spectroscopic and corrosion resistance characterization of amine and super acid-cured hybrid oiganic-inorganic thin films on 2024-T3 aluminum alloy . Prog. Org. Coat, 44,185-99. 

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