Different parameters were explored in the synthesis of oleic acid coated iron oxide nanoparticles by microwave heating such as the nature of the solvents with different dielectric constant (octadecene, dibenzyl ether, benzyl alcohol, phenyl ether, and dimethyl sulfoxide (DMSO)), the Fe concentration, and the heating ramps (2-4[degrees]C/min).
Dibenzyl ether, with a dielectric constant of 3.86, was chosen as the best one in this case, given the magnetic properties of synthesized nanoparticles, and the price that is 10 times lower than benzyl alcohol, solvent utilized by the majorities of research groups using microwave heating [4, 7-9, 30].
Microwave samples were synthesized using dibenzyl ether (Figure 3(a)) and benzyl alcohol (Figure 3(c)) as solvents (MwE8 and MwA8), while the samples prepared by thermal decomposition were obtained using dibenzyl ether (Figure 3(b)) and octadecene (Figure 3(d)) as solvents (TdE12 and TdO15).
First, it should be noted that the largest size is always obtained for the particles prepared in the solvent with the highest boiling point (dibenzyl ether = 160[degrees]C, benzyl alcohol = 205[degrees]C, and octadecene = 315[degrees]C) [14, 24, 33].
Dibenzyl ether was chosen as the best solvent for this synthesis given its dielectric constant, the optimal ramp was set at 3.75[degrees]C/min, the iron concentration was 4 mgFe/ml, and (oleic/Fe) molar ratio was 5 giving rise to the most uniform nanoparticles.
While the rubber compound is certainly much more complex than their proposed mechanism, shown in scheme 2, the attack on the ether linkage of the dibenzyl ether by zinc chloride, as shown, is a viable option for understanding the degradation mechanism in polyether elastomers.
Bell, "Cleavage of dibenzyl ether in the presence of zinc halides," Journal of Catalysis--87, pp.
To a solution of dibenzyl ether 6 (1.13 mg, 2.58 mmol) in anhydrous C[H.sub.2][Cl.sub.2] (20 mL) [BBr.sub.3] (500 [micro]L, 5.28 mmol, 1.025 eq) was added dropwise at -78[degrees]C under argon atmosphere.
Efficient synthesis of (2R,3R)- and (2S,3S)-2,3-diaminobutane-1,4-diol and their dibenzyl ethers. Tetrahedron: Asymmetry, 1997, 8, 1243-1251.