Aqueous methanol solution

Water-methanol mixtures are important solvent media in both chemistry and biochemistry. It was found that water-methanol mixtures utilize the phenomenon of preferential solvation of ions and hydrophobic solutes. It is worth mentioning here that the dipole moment of methanol is slightly lower than that of water. Moreover the presence of the methyl group not only prevents the strong electrostatic interaction with the other species but also makes methanol molecules considerably more bulky as compared with water molecules. Apart from the structural particulars, the dynamics of this cosolvent along with water is rather complex in water-methanol mixtures. 

The diffusion coefficients of ionic solutes show nonideal behavior with variation of composition of the solvent mixture in water-methanol binary mixtures. The degree of non-ideality of the solute diffusion is found to be similar to the nonideality that is observed for the diffusion of water and methanol molecules in these mixtures and is attributed to the enhanced stability of the HBs and formation of interspecies complexes in the mixtures. The diffusion coefficient of water is found to be minimum at 0-5 and that of methanol shows the minimum at = 0.7. However, the observed deviation from linear behavior with composition is found to be a bit weaker than that found in simulations of water-DMSO mixtures [11,12], 

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Arabinan. This highly soluble polymer is found in the extracts of many fmits and seeds, in the boiling water extracts of pine wood (127), in the extracts of marshmallow roots (A/t/jaea officina/is) (128), and aspen (63) and willow (Sa/ix a/ba F) (129) bark. Because arabinan can be isolated from mildly degraded pectin fractions, it is often difficult to determine whether it is a hemiceUulose or a labile fragment of a larger polysaccharide and/or lignin complex. Arabinans have a complex stmcture composed almost entirely of 5-linked a-L-arabinofuranosyl units with similar residues linked to them at C-2 and/or C-3 and is soluble in 70% aqueous methanol solution. 

An example of an alkyl monoperoxycarbonic acid, 0-ben2yl monoperoxycarbonic acid [52123-51 -0] was prepared ia aqueous methanol solution by basic perhydrolysis of diben2yl peroxydicarbonate [2144-45-8] and subsequendy isolated ia 97% purity. It has been used as an epoxidi2iag agent (185) ... 

Data on the behaviour of a-ethylenic (82) and a, a-diethylenic (83) sulphoxides in aqueous-methanolic solutions are also available76. The sulphoxide function, when activated both by benzylic and propargylic moieties (as in 84), gives76 a reduction wave (E = — 1.44 V vs. SCE) in basic aqueous methanolic media. However, no results are available for cathodical reduction of activated sulphoxides. 

The thermodynamic standard potential of the methanol electrode has a value of + 0.02 V (RHE) that is, it is quite close to the hydrogen electrode potential. The steady-state potential of a platinum electrode in aqueous methanol solutions is about + 0.3 V (RHE). 

Water insoluble tetrabutylammonium metaperiodate, which can be prepared from sodium metaperiodate and tetrabutylammonium hydrogen sulphate in aqueous solution, was found to be a useful reagent for the selective oxidation of sulphides in organic solvents . The reaction was generally carried out in boiling chloroform and gave dialkyl, alkyl aryl and diaryl sulphoxides in yields which are comparable with those reported for sodium metaperiodate in aqueous methanol solution (Table 4). In the case of diaryl sulphoxides, the yields decrease with prolonged reaction time. 

Recovery of acetamiprid, IM-1-2 and IM-1-4. Combine 20 g of the air-dried soil with 100 mL of a mixed solvent of methanol and 0.1 M ammonium chloride (4 1, v/v) in a 250-mL stainless-steel centrifuge tube, shake the mixture with a mechanical shaker for 30 min and centrifuge at 8000 r.p.m. for 2 min. Filter the supernatant through a Celite layer (1-cm thick) under reduced pressure into a 500-mL flask. Add a second 100 mL of mixed solvent to the residue and then extract and filter in the same manner. Combine the filtrates and add 150mL of distilled water with 1 g of sodium chloride. Transfer the aqueous methanol solution into a 1-L separatory funnel and shake the solution with 200 mL of dichloromethane for 5 min. Collect the dichloromethane in a flask and adjust the pH of aqueous methanol to 13 with sodium hydroxide. Extract the solution with two portions of 200 mL of dichloromethane for 5 min. Combine the dichloromethane extracts and pass through a filter paper with anhydrous sodium sulfate. Add 0.5 mL of diethylene glycol and then concentrate the dichloromethane extract to about 0.5 mL on a water-bath at ca 40 °C by rotary evaporation. 

Jing, D., Zhang, Y., and Guo, L. (2005) Study on the synthesis of Ni doped mesoporous Ti02 and its photocatalytic activity for hydrogen evolution in aqueous methanol solution. Chemical Physics Letters, 415 (1-3), 74—78. 

Recently, tert- butyl (phenylsulfonyl)alkyl-A-hydroxycarbamates (343), which are readily obtained from the reaction of aldehydes and tert -butyl-A -hydroxy-carbamate in an aqueous methanol solution, were used as an equivalent of N -(/iocprotected nitrones in the nucleophilic addition of Grignard reagents (Scheme 2.144) (571). 

Moses has patented a process for the separation of gramicidin from tyrothricin198. The 80% aqueous methanol solution is passed through a cation ion exchange resin in the hydrogen cycle followed by an anion resin in the hydroxyl cycle. 

An aqueous methanolic solution of (3-nitrophenyl)aminomethylenema-lonate (1547) was boiled in the presence of potassium hydroxide for 8 hr to give 3-amino-3-(3-nitrophenyl)acrylate (1548) in 53% yield (87EUP228845). 

RP-HPLC has been employed for the determination of flavonoids and other phenolic compounds in cranberry juice. The neutral and acidic analytes were preconcentrated octadecyl silica SPE cartridges conditioned with distilled water (neutral analytes) or with 0.01 M HC1 (acidic compounds). Hydrolysis of samples was carried out in aqueous methanol solution acidified with 6 M HC1 at 35°C for 16h. Chromatographic separation was performed in an ODS column (150 X 4.6mm i.d. particle size 5/.an). Solvents A and B were water-acetic acid (97 3, v/v) and methanol, respectively. The gradient started with 0 per cent B (flow rate, 0.9 ml/min), reached 10 per cent B in lQmin (flowrate, 1.0 ml/min) and increased to 70 per cent B in 40min (flowrate, 1.0 ml/min). Analytes were detected at 280 and 360 nm. Some typical chromatograms are presented in Fig. 2.71. The concentrations of flavonoids and phenolic acids are compiled in Table 2.69. It was stated that the SPE-HPLC procedure makes possible the simultaneous determination of phenolic compounds and flavonoids, therefore, it can be employed for the measurement of these classes of analytes in other fruit juices [188],... 

Also, a brief note has appeared concerning electrospray ionization mass spectrometry of mixtures of -carotene with ft- and with y-cyclodexlrin in aqueous methanol solutions. Whereas negative ion ESI produced 1 1 adduct ions of -carotene with both of the cyclodextrin isomers, positive ESI gave these adducts only in the case of ft-cyclodextrin302. 

The triplet state of 4-nitrobiphenyl has been observed in laser flashed benzene solution (. max 540 nm, t 10 ns at room temperature) 32). 4-Nitrobiphenyl and 4,4 -dinitrobiphenyl have been photoreduced by sodium formate in buffered aqueous methanolic solution 43i>) 15% 4-aminobiphenyl and 11% 4,4 -azobi-phenyl as well as 49% 4-amino-4 -nitrobiphenyl and 20% 4,4 -(p-nitrophenyl)-azoxybenzene, respectively, could be isolated and identified by comparison with authentic samples. 

CASRN 148-79-8 molecular formula C10H7N3S FW 201.25 Photolytic. When thin films of thiabendazole on glass plates were exposed to sunlight for 128 d, benzimidazole-2-carboxamide and benzimidazole formed as photolysis products. Both compounds also formed when aqueous methanolic solutions of thiabendazole were subjected to UV light for 1 h (Zbozinek, 1984). 

Extract the aqueous methanol solution three times with equal volumes of chloroform. This is done by shaking in a separatory funnel. 

Reactions were carried out in presence of sacrificial agents. O2 evolution aqueous silver nitrate solution. Hi evolution aqueous methanol solution,... 

Wu NL, Lee MS (2004) Enhanced Ti02 photocatalysis by Cu in hydrogen production from aqueous methanol solution. Int J Hydrogen Energy 29 1601-1605... 

When labeled potassium cyanide reacted with the complex in an aqueous methanol solution, the bromide was rapidly replaced and the labeled cyanide ion entered slowly into the coordination complex. When the reaction was conducted at higher temperatures in ethylene glycol dimethyl ether as the solvent, the label was distributed among the benzyl isonitrile, benzyl formamide, and the polymer resulting from benzyl isonitrile and the iron isonitrile complexes. 

Commercial formalin was used. This aqueous-methanolic solution contains 37% formaldehyde by weight. It is sometimes called 40% formalin because 100 ml. of the solution contains 40 g. of formaldehyde. 

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