Methanol solutions

Solution A was prepared by dissolving potassium acetate in methanol Solution B was pre pared by adding potassium methoxide to acetic acid Reaction of methyl iodide either with solu tion A or with solution B gave the same major product Why" What was this product" ... 

Procedure. A vitamin B complex tablet Is crushed and placed In a beaker with 20.00 mL of a 50% v/v methanol solution that Is 20 mM In sodium tetraborate and contains 100.0 ppm of o-ethoxybenzamIde. After mixing for 2 min to ensure that the B vitamins are dissolved, a 5.00-mL portion Is passed through a 0.45- xm filter to remove Insoluble binders. An approximately 4-nL sample Is loaded Into a 50- xm Internal diameter capillary column. For CZE the capillary column contains a 20 mM pH 9 sodium tetraborate/sodlum dIhydrogen phosphate buffer. For MEKC the buffer Is also 150 mM In sodium dodecylsulfate. A 40-kV/m electric field Is used to effect both the CZE and MEKC separations. 

The oxidative reaction of furan with bromine in methanol solution or an electrochemical process using sodium bromide produces 2,5-dimethoxy-2,5-dihydrofuran (19), which is a cycHc acetal of maleic dialdehyde. The double bond in (19) can be easily hydrogenated to produce the corresponding succindialdehyde derivative. Both products find appHcation in photography and as embalming materials, as well as other uses. 

Analytical Procedures. Standard methods for analysis of food-grade adipic acid are described ia the Food Chemicals Codex (see Refs, ia Table 8). Classical methods are used for assay (titration), trace metals (As, heavy metals as Pb), and total ash. Water is determined by Kad-Fisher titration of a methanol solution of the acid. Determination of color ia methanol solution (APHA, Hazen equivalent, max. 10), as well as iron and other metals, are also described elsewhere (175). Other analyses frequendy are required for resia-grade acid. For example, hydrolyzable nitrogen (NH, amides, nitriles, etc) is determined by distillation of ammonia from an alkaline solution. Reducible nitrogen (nitrates and nitroorganics) may then be determined by adding DeVarda s alloy and continuing the distillation. Hydrocarbon oil contaminants may be determined by ir analysis of halocarbon extracts of alkaline solutions of the acid. 

Alcoholysis (ester interchange) is performed at atmospheric pressure near the boiling point of methanol in carbon steel equipment. Sodium methoxide [124-41 -4] CH ONa, the catalyst, can be prepared in the same reactor by reaction of methanol and metallic sodium, or it can be purchased in methanol solution. Usage is approximately 0.3—1.0 wt % of the triglyceride. 

The alcoholysis reaction may be carried out either batchwise or continuously by treating the triglyceride with an excess of methanol for 30—60 min in a well-agitated reactor. The reactants are then allowed to settle and the glycerol [56-81-5] is recovered in methanol solution in the lower layer. The sodium methoxide and excess methanol are removed from the methyl ester, which then maybe fed directiy to the hydrogenolysis process. Alternatively, the ester may be distilled to remove unreacted material and other impurities, or fractionated into different cuts. Practionation of either the methyl ester or of the product following hydrogenolysis provides alcohols that have narrow carbon-chain distributions. 

Raw Material. PVA is synthesized from acetjiene [74-86-2] or ethylene [74-85-1] by reaction with acetic acid (and oxygen in the case of ethylene), in the presence of a catalyst such as zinc acetate, to form vinyl acetate [108-05-4] which is then polymerized in methanol. The polymer obtained is subjected to methanolysis with sodium hydroxide, whereby PVA precipitates from the methanol solution. 

Manufacture. The manufacture of 1,4-cyclohexanedimethanol can be accompHshed by the catalytic reduction under pressure of dimethyl terephthalate ia a methanol solution (47,65). This glycol also may be prepared by the depolymerization and catalytic reduction of linear polyesters that have alkylene terephthalates as primary constituents. Poly(ethylene terephthalate) may be hydrogenated ia the presence of methanol under pressure and heat to give good yields of the glycol (see Polyesters) (66,67). 

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. 

Hydrogen peroxide has also been analy2ed by its chemiluminescent reaction with bis(2,4,6-trichlorophenyl) oxalate and perylene in a buffered (pH 4—10) aqueous ethyl acetate—methanol solution (284). Using a flow system, intensity was linear from the detection limit of 7 x 10 M to at least 10 M. 

Alkoxyall l Hydroperoxides. These compounds (1, X = OR , R = H) have been prepared by the ozonization of certain unsaturated compounds in alcohol solvents (10,125,126). 2-Methoxy-2-hydroperoxypropane [10027-74 ] (1, X = OR , R" = methyl), has been generated in methanol solution and spectral data obtained (127). A rapid exothermic decomposition upon concentration of this peroxide in a methylene chloride—methanol solution at 0°C has been reported (128). 2-Bromo-l-methoxy-l-methylethylhydroperoxide [98821-14-8]has been distilled (bp 60°C (bath temp.), 0.013 kPa) (129). Two cycHc alkoxyaLkyl hydroperoxides from cyclodecanone have been reported (1, where X = OR R, R = 5-oxo-l, 9-nonanediyl) with mp 94—95°C (R" = methyl) and mp 66—68°C (R" = ethyl) (130). Like other hydroperoxides, alkoxyaLkyl hydroperoxides can be acylated or alkylated (130,131). 

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) ... 

Poly(ethylene oxide) associates in solution with certain electrolytes (48—52). For example, high molecular weight species of poly(ethylene oxide) readily dissolve in methanol that contains 0.5 wt % KI, although the resin does not remain in methanol solution at room temperature. This salting-in effect has been attributed to ion binding, which prevents coagulation in the nonsolvent. Complexes with electrolytes, in particular lithium salts, have received widespread attention on account of the potential for using these materials in a polymeric battery. The performance of soHd electrolytes based on poly(ethylene oxide) in terms of ion transport and conductivity has been discussed (53—58). The use of complexes of poly(ethylene oxide) in analytical chemistry has also been reviewed (59). 

Unsaturation value can be determined by the reaction of the akyl or propenyl end group with mercuric acetate ia a methanolic solution to give acetoxymercuric methoxy compounds and acetic acid (ASTM D4671-87). The amount of acetic acid released ia this equimolar reaction is determined by titration with standard alcohoHc potassium hydroxide. Sodium bromide is normally added to convert the iasoluble mercuric oxide (a titration iaterference) to mercuric bromide. The value is usually expressed as meg KOH/g polyol which can be converted to OH No. units usiag multiplication by 56.1 or to percentage of vinyl usiag multiplication by 2.7. 

Nitroso compounds are formed selectively via the oxidation of a primary aromatic amine with Caro s acid [7722-86-3] (H2SO ) or Oxone (Du Pont trademark) monopersulfate compound (2KHSO KHSO K SO aniline black [13007-86-8] is obtained if the oxidation is carried out with salts of persulfiiric acid (31). Oxidation of aromatic amines to nitro compounds can be carried out with peroxytrifluoroacetic acid (32). Hydrogen peroxide with acetonitrile converts aniline in a methanol solution to azoxybenzene [495-48-7] (33), perborate in glacial acetic acid yields azobenzene [103-33-3] (34). 

N,]S7-bis(methoxymethyl)uron was first isolated and described in 1936 (41), but was commercialized only in 1960. It is manufactured (42) by the reaction of 4 mol of formaldehyde with 1 mol of urea at 60°C under highly alkaline conditions to form tetramethylolurea [2787-01-1]. After concentration under reduced pressure to remove water, excess methanol is charged and the reaction continued under acidic conditions at ambient temperatures to close the ring and methylate the hydroxymethyl groups. After filtration to remove the precipitated salts, the methanolic solution is concentrated to recover excess methanol. The product (75—85% pure) is then mixed with a methylated melamine—formaldehyde resin to reduce fabric strength losses in the presence of chlorine, and diluted with water to 50—75% soHds. Uron resins do not find significant use today due to the greater amounts of formaldehyde released from fabric treated with these resins. 

Heating methyUiydiazine with an i -methylpynmidiae derivative (72) in an HCl methanolic solution produces in a yield of over 50% the 4-acetylpyrazole (73) (eq. 19) (47). 

Continuous Polymerization. A typical continuous flow diagram for the vinyl acetate polymerisation is shown in Figure 12. The vinyl acetate is fed to the first reactor vessel, in which the mixture is purged with an inert gas such as nitrogen. Alternatively, the feed may be purged before being introduced to the reactor (209). A methanol solution containing the free-radical initiator is combined with the above stream and passed directiy and continuously into the first reactor from which a stream of the polymerisation mixture is continuously withdrawn and passed to subsequent reactors. More initiator can be added to these reactors to further increase the conversion. 

Nucleophilic aromatic substitutions involving loss of hydrogen are known. The reaction usually occurs with oxidation of the intermediate either intramoleculady or by an added oxidizing agent such as air or iodine. A noteworthy example is the formation of 6-methoxy-2-nitrobenzonitrile from reaction of 1,3-dinitrobenzene with a methanol solution of potassium cyanide. In this reaction it appears that the nitro compound itself functions as the oxidizing agent (10). 

Dehydrochlorination 1,1,2-Trichloroethane is easily dehydrochloriaated by a number of catalytic reagents to give 1,1-dichloroethylene and some 1,2-dichloroethylene. Refluxing with aqueous and methanolic solutions of NaOH, Ca(OH)2, and Mg(OH)2 and water gives 1,1-dichloroethylene... 

Excited-state properties of the cyanine and related dyes are complex. Most cyanine dyes exhibit small Stokes shifts for duorescence maxima. Typical carbocyanines (1) with n = 1 show 14- to 16-nm shifts in methanol solution with low quantum efficiencies for duorescence (Op ) of less than 0.05. The diearbocyanine analogues also show small Stokes shifts but higher quantum yields (Lpj = 0.3-0.5). 

In contrast to the behavior observed for (99), irradiation of a methanol solution of l-(2,4,6-trinitrophenyl)-2,3-diphenylaziridine (101) affords 1-hydroxy-4,6-dinitrobenz-imidazole (102) and benzaldehyde (68TL4801). 

Iodine General Iodine crystals in a closed chamber or spray 1% methanol solution of Iodine Brown spots which may disappear upon standing. Limited sensitivity. 

Phospholipids. For the removal of ionic contaminants from raw zwitterionic phospholipids, most lipids were purified twice by mixed-bed ionic exchange (Amberlite AB-2) of methanolic solutions. (About Ig of lipid in lOmL of MeOH). With both runs the first ImL of the eluate was discarded. The main fraction of the solution was evaporated at 40°C under dry N2 and recryst three times from n-pentane. The resulting white powder was dried for about 4h at 50° under reduced pressure and stored at 3°. Some samples were purified by mixed-bed ion exchange of aqueous suspensions of the crystal/liquid crystal phase. [Kaatze et al. J Phys Chem 89 2565 7955.]... 

The cyclic trimer (trioxane) and tetramer are obtained by a trace of sulphuric acid acting on hot formaldehyde vapour (i) Figure 19.1). Linear polymers with degrees of polymerisation of about 50 and a terminal hydroxyl group are obtained by evaporation of aqueous solutions of formaldehyde (ii). In the presence of strong acid the average chain length may be doubled. Evaporation of methanol solution leads to products of type (iii). 

Chaput, Jeminet and Juillard measured the association constants of several simple polyethylene glycols with Na", K", Cs", and Tl". Phase transfer catalytic processes and most biological processes are more likely to involve the first two cations rather than the latter two, so we will confine the discussion to these. Stability constants for the dimethyl ethers of tetra-, penta-, hexa-, and heptaethylene glycols were determined poten-tiometrically in anhydrous methanol solution and are shown in Table 7.1. In the third column of the table, the ratio of binding constants (Ks/K s) is calculated. Note that Simon and his coworkers have referred to this ratio as the selectivity constant. ... 

Fig. 23 Reflectance spectra (o—o—) of 3 pg testosterone (A) and 3 pg zT -androstendione-(3,17) (B) taken up on a silica gel layer compared with the absorption spectra determined m methanolic solution ( — —)...

Residual aromatic ether concentrations are determined from the absorbance at 278 mfi of the crude reduction products in methanol solution. Steroidal ether concentrations of 1 mg/ml are employed. The content of 1,4-dihydro compound is determined, when possible, by hydrolysis to the a, -unsaturated ketone followed by ultraviolet analysis. A solution of the crude reaction product (usually 0.01 mg/ml cone) in methanol containing about 1/15 its volume of water and concentrated hydrochloric acid respectively is kept at room temperature for 2 to 4 hr. The absorbance at ca. 240 mfi is measured and, from this, the content of 1,4-dihydro compound can be calculated. Longer hydrolysis times do not increase the absorbance at 240 mp.. 

A variety of conditions has been used to prepare oxiranes from trans-hxomo-hydrins. In general, bromohydrins are heated in a solution of 5-10% methanolic potassium hydroxide for 30 min to 8 hr. Longer reflux times are required for bromohydrins which are not anti-coplanar, e.g., diequatorial bromohydrins. A 5 % solution of potassium acetate in boiling ethanol can be used to cyclize steroidal bromohydrins containing base sensitive groups. The use of 1.1 equivalents of sodium methoxide per equivalent of steroid in methanol solution is especially recommended for 9a-bromo-l lj5-hydroxy steroids. 

Di-iodination at C-21 A solution of 3 g of 16/5-methyl-16a,17a-oxidop-regn-4-ene-3, 20-dione, 75 ml of methanol and 0.75 ml of a 10% methanolic solution of anhydrous calcium chloride is treated with 3 g of freshly calcined calcium oxide. A solution consisting of 4.2 g of iodine in 6.75 ml of a 10%... 

A-Homo-5a-cholestan-4-one (3b). A solution of sodium nitrite (2 g) in water (100 ml) is added over 1 hr to a stirred solution of 3-(5 -spiro-2, 2 -dimethyloxazolidinyl)-5a-cholestane (7 4.58 g) in aqueous 10% acetic acid (800 ml), maintained at 0-5° for 3 hr and the mixture is then allowed to stand overnight. The reaction mixture is neutralized with 10% sodium hydroxide solution and the resulting white suspension is extracted with ether. The ether extracts are washed with water, dried and concentrated to give a semisolid residue which is converted to the semicarbazone by warming in methanol solution (ca. 65 ml/g) with an excess of methanolic semicarbazide-acetate solution. The precipitate of semicarbazone is recrystallized from ethanol to give a white powder mp 239-241°. A solution of hydrochloric acid (50 ml) in ethanol (450 ml) is added to the semicarbazone and the mixture is heated at reflux for 1 hr. The clear solution is diluted with water (250 ml) and the... 

The ionic clusters observed are not limited to aqueous electrolyte solutions only. In fact very similar results were obtained for methanolic solutions as well [25]. This shows that sufficiently large and stable ionic clusters are a fairly common occurrence whenever ions are dissolved in polar solvents. The clusters are an essential factor in the facilitation of reverse osmosis purification. Since many industrially important solutions include ions in polar solvents, it is important to account for them in separation involving such solvents. 

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