Methanol conditions

Hanefeld and coworkers developed a straightforward process for the encapsulation of 7/iHNL under low methanol conditions. By adding a sol, prepared by hydrolysis of tetra-methoxysilane-methyltrimethoxysilane at pH 2.8 with continuous removal of methanol, to a stirred solution of the enzyme in a buffer at pH 6.5, at least 65% of the activity of the free enzyme could be recovered after the encapsulation. The aquagels were successfully used in the synthesis of (5)-cyanohydrins [54]. 

In addition to these examples, several polynuclear mercury alkynyl derivatives have been prepared. Examples of such derivatives include compounds 50-56 which have been obtained by reaction of the MeHgGl with the primary alkyne in basic methanolic conditions.67,68 The phenyl analogs have also been isolated. Most of these compounds have been characterized by FTIR, NMR, and FABMS, and in the case of 51-53 by single crystal X-ray diffraction. 

Individual stock solutions of the test compounds were prepared in methanol at a concentration of 50 mg/mL. A standard test mixture was prepared by adding 100-/iL aliquots of each of the individual stock solutions to 500 mL of ultrapure water to give a concentration of 10 ppm per component. Samples requiring the addition of 500 ppm of methanol (conditioning solvent) were prepared by adding 6.3 /uL of methanol to 10-mL aliquots of the aqueous standard mix just prior to extraction. The pH of the samples was adjusted with either 6 M HC1 (for pH 2 samples) or 6 M NaOH (for pH 8 samples). To separate ionic strength effects from pH effects, the ionic strength of the samples was held constant. 

Biodiesel fuel was prepared by a two-step reaction hydrolysis and methyl esterification. Hydrolysis was carried out at a subcritical state of water to obtain fatty acids from triglycerides of rapeseed oil, while the methyl esterification of the hydrolyzed products of triglycerides was treated near the supercritical methanol condition to achieve fatty acid methyl esters. Consequently, the two-step preparation was found to convert rapeseed oil to fatty acid methyl esters in considerably shorter reaction time and milder reaction condition than the direct supercritical methanol treatment. The optimum reaction condition in this two-step preparation was 270°C and 20 min for hydrolysis and methyl esterification, respectively. Variables affecting the yields in hydrolysis and methyl esterification are discussed. 

The separations are carried out under aqueous or aqueous-methanolic conditions at pH between 1 and 3.5 preferentially adjusted with perchloric acid. 

The formation of 3,5-bis(methoxymethyl)-5,6-dihydro-27/-l,3,5-oxadiazin-4(3//)-one (114 R = MeOCH2) by reaction of urea with methanal under carefully controlled acidic methanolic conditions has been shown to proceed via cyclization of the tris(hydroxyethyl) urea (113) as outlined in Scheme 11 <89BCJ1930>, rather than via a tetrakis(hydroxymethyl)urea or a perhydro-1,3,5-oxadiazin-4-one as suggested originally <36BCJ248>. 7V-Methylurea under the same conditions gives the 3-methoxymethyl-5-methyl derivative (114 R = Me) but in only 27% yield. 

HiU AJ, Pas SJ, Bastow TJ, Burgar MI, Nagai K, Toy LG, Freeman BD. Influence of methanol conditioning and physical aging on carbon spin-lattice relaxation times of poly(l-trimethylsilyl-l-propyne). J Membr Sci 2004 243(l-2) 37-44. 

Stork and Williard have noted that when certain olefinic a,/8-epoxy-ketones are treated with hydrazine in methanol, conditions normally resulting in the Wharton reaction, anomalous behaviour resulting in cyclization is observed.Thus the epoxy-ketone (185) was converted into the bicyclic alcohol (186) in 85% yield. 

Ha S, Rice CA, Masel Rl, Wieckowski A (2002) Methanol conditioning for improved performance of formic acid fuel cells. J Power Sources 112 655-659... 

The reaction of Ru3(GO)i2 with l,4-dichloro-but-2-yne in GH3OH/KOH solution leads to the loss of chlorine and formation of the allylic (/x-H)Ru3(GO)9(MeGGHGH) and of (/x-H)2Ru3(G0)9 H2G=G(H)G=GG(=0)0GH3 24, containing an acetate substituent. The formation of this ligand requires the activation of GO and methanol, a process frequently observed under basic methanolic conditions (Figure 6). 

SPE extraction Activate a C18-cartridge with methanol, condition with 0.1 N sodium carbonate solution Apply sample and washing the cartridge with 0.1 N sodium carbonate solution Elute with 1 mL acetone/chloroform (50 50) Evaporate eluate to dryness... 

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