Bound glycerol

The quality of biodiesel is regulated by standards. The most important regards the content of free and bound glycerol. This cannot be modified by effective separation techniques. Therefore, the major element in design should be to obtain a composition of the mixture leaving the reaction system capable of matching the biodiesel specifications. This is difficult to achieve in view of the variety of raw materials. 

The position of the preferentially substituted hydroxylic groups is not known. This is probably a matter of little importance, as is, perhaps, the presence of some non-l,6-glucosidic linkages. An unknown number of one-sided bound glycerol residues is also attached to the network. 

Figure 18.37. Glycerol 3-Phosphate Shuttle. Electrons from NADH can enter the mitochondrial electron transport chain by being used to reduce dihydroxyacetone phosphate to glycerol 3-phosphate. Glycerol 3-phosphate is reoxidized by electron transfer to an FAD prosthetic group in a membrane-bound glycerol 3-phosphate dehydrogenase. Subsequent electron transfer to Q to form QH2 allows these electrons to enter the electron-transport chain.

A protocol involving the intermolecular cyclization between acetals and ureas has been developed to synthesize imidazolones on solid support. Reaction of polymer-bound glycerol 1148 with bromoacetaldehyde diethyl acetal gives the cyclic acetal bromide 1149. Amination followed by urea formation affords the resin-bound urea acetals 1150. The aldehydes released from the resin upon treatment with TFA immediately cyclize to give 2-imidazolones 1151 in good yields and purity (Scheme 279) <2002TL4571>. 

Official methods of chemical analysis of conventional diesel are often not adequate to characterize biodiesel. Tests for the levels of sulfur and aromatic components in biodiesel are useful but usually reveal that the concentrations of compounds containing these atoms or functional groups are very low. Analysis of biodiesel chemistry can reveal characteristics conferred by the source of the oU, the method of manufacture, and duration of storage (20, 21). For example, free and bound glycerol is measured to ascertain if biodiesel has been completely formed during synthesis. Fatty acid content, residual soaps, iodine value, peroxide value, and fatty acid composition all may reflect the quality of biodiesel (Table 1) but are unimportant and inapplicable in conventional diesel fuel quality determination. 

Glycerol (free, total) Biodiesel Ultrasound-assisted extraction into a NaIC>4 plus acetylacetone aqueous-ethanol solution UV—Vis 0.0028, 0.0310% (m/m) Flow injection system LLE without [431] phase separation ethyl acetate for free/ bound glycerol discrimination... 

At least superficially, the mitochondrial and Golgi acyltransferase activities resemble those of the better-studied ER system. All three compartments have membrane-bound glycerol-... 

Zheng, Z., Xia, Q., Dauk, M., Shen, W., Selvaraj, G., and Zou, J. Arabidopsis AtGPATl, a member of the membrane-bound glycerol-3-phosphate acyltransferase gene family, is essential for tapetum differentiation and male fertility. Plant Cell 15, 1872-1887, 2003. 

Ameyama M, Shinagawa E, Matsushita K, Adachi O (1985) Solubilization, purification and properties of membrane-bound glycerol dehydrogenase from Gluconohacter industrius. Agric Biol Chem 49(4) 1001-1010... 

Resuspend the resin in 50 /A of elution buffer E (20 mM Tris-HCl [pH 7.5], 100 mM KC1, 5 mM MgCl2, 0.5 mM /J-mercaptoethanol, 1 mM phenylmethylsulfonyl fluoride, 250 mM imidazole, 10% (v/v) glycerol, 1X Complete Protease Inhibitor Mix tablets [Roche]), briefly vortex, and elute the bound proteins by mixing on a rotator at 4° for 20 min. Please note that a concentration of imidazole and the kind of Roche tablets differs from BB buffer. 

---