Basic side arm

ESI has been used to study the effect of the basicities of the side arms on the abilities of these lariat ethers to extract metal ions from solution. A series of compounds of structure 9 were studied and the authors conclude that the lariat ether with the least basic side arm binds best to the smaller cations (Table 6). Specifically for Li+, it was found that it is best bound to the lariat ether with the ester side arm. It is proposed that electrostatic repulsion of the lariat ether side arm and the electron-rich jt cloud of the adjacent aromatic ring play a dominant role in determining cation selectivities. The least basic side arm has lower electron density and thus these compounds have smaller cavity sizes and are more selective for smaller ions. ... 

A basic group of the enzyme catalyzes the proton transfer characteristics of transaminations. Bruice found that imidazole buffer can catalyze transamination reactions in model systems [6], We conjectured that transamination rates should be improved by attaching a basic side arm to pyridoxamine. Thus we synthesized a series of simple pyridoxamine derivatives carrying basic groups at the end of flexible chains of various lengths [7-9]. We measured the transamination rates of these pyridoxamine derivatives in the presence of Zn(OAc)2 at pH 4.00 in methanol. 

Table 2.1 Relative transamination rates at pH 4.0 in methanol with Zn(OAc)2 of small pyridoxamine analogs incorporating basic side arms.

The basic design of a Warburg manometer is illustrated in Figure 8.15 and consists of a U-tube manometer connected by a side arm to the reaction... 

Irradiation of the NiFi/AF/aHF mixture necessarily results in a decrea.se in the fluoro-basicity of the solution as F(HF), is converted toNiFs" +2aHF. In these two experiments, a. solid hydrofluoride in equilibrium with its saturated aHF solution, placed in the non-irradialed side arm, look up aHF from the irradiated mixiiire as the quantity of F(HF), in that mixture decreased. 

Basically, the technique is as follows. A small (but constant) volume of sediment, soil or cuttings is placed into the mixer cell along with two ceramic or stainless steel ball-bearings, and water is added to bring the remaining headspace to 10 cc. The mill is sealed and placed in a SPEX/Mixer-Mill and agitated for about five minutes. The cell is then immersed into a hot-water bath at 90°C for three minutes. A 1 ml aliquot of gas-free water is injected into the cell through a septum-sealed side arm on the cell, and then a 1... 

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