Methanol effect

Methanol is frequently used to inhibit hydrate formation in natural gas so we have included information on the effects of methanol on liquid phase equilibria. Shariat, Moshfeghian, and Erbar have used a relatively new equation of state and extensive caleulations to produce interesting results on the effeet of methanol. Their starting assumptions are the gas composition in Table 2, the pipeline pressure/temperature profile in Table 3 and methanol concentrations sufficient to produce a 24°F hydrate-formation-temperature depression. Resulting phase concentrations are shown in Tables 4, 5, and 6. Methanol effects on CO2 and hydrocarbon solubility in liquid water are shown in Figures 3 and 4. 

Azeotrope formers, generally polar compounds, have the ability to form, with hydrocarbons, nonideal mixtures having vapor pressures higher than either component in the mixture and therefore lower boiling points. Fortunately, different types of hydrocarbons show different degrees of nonideality with a given azeotrope former. For example, benzene and cyclohexane boil at about 176° F., while the methanol-cyclohexane azeotrope boils at 130° F., and the methanol-benzene azeotrope boils at 137° F., a difference of 7° F. Hence, fractionation of a mixture of benzene and cyclohexane in the presence of methanol effectively separates the two hydrocarbons. 

If it is assumed that the pooled run variance is a reasonable estimate for the residual variance. Table 7 can be reworked and the variance ratios (F values) calculated for each of the effects. The results of this rework are shown in Table 10. This approach confirms that the methanol effect is the largest by a very long way. The F value (1,8 df) is 5.32. Whilst this confirms that A is not significant. 

Oxidative ring fission of furans using the commercially available reagent pyridinium chlorochromate (PCC) has been studied as well (80T661). Experimental evidence supports the preliminary formation of intermediate (87) formed by 1,4-electrophilic attack of chlorochromate anion upon the furan ring. This intermediate then breaks down by heterolytic cleavage of the Cr—O bonds to afford initially the cis enedione which isomerizes to the trans product. Treatment of (88) with sodium hydroxide in methanol effects ring closure with formation of the 4-methoxycyclopentenone (89 Scheme 22). 

Magnesium in methanol effects the reductive ring opening of the cyclic peroxide 911, recyclization of which affords 4,6,6-trimethyl-5,6-dihydropyran-2-one in good yield (Equation 362) <2004JOC2851>. 

An interesting steric effect caused by a neighboring group ( Fernwir-kung ) was encoimtered in 1935 by Lieser and Leckzyck, who found that treatment of methyl 6-0-benzoyl-2-0-[(methylthio)thiocarbonyl]-/3-D-glu-copyranoside (III) with silver carbonate in methanol effected conversion... 

Another approach is to go directly to an eluent that is miscible with water, such as methanol. This approach is most effective when the method of detection is liquid chromatography. The methanol also effectively wets the smallest pores and removes bound water, replacing it with methanol. The methanol effectively infiltrates the C-18 bonded phase and elutes the atrazine efficiently. A third choice is a solvent, such as ethyl acetate, that effectively replaces water bound at the surface of the sorbent and infiltrates the C-18 bonded phase. However, the ethyl acetate has a low solubility for water, so that the water is displaced from the sorbent as a second phase and is pushed out ahead by the ethyl acetate during the elution process. Thus, in the example of atrazine analysis by GC/MS, either the ethyl acetate or the chloroform-methanol are two examples of eluting solvents. 

Coupling of allylic compounds [1, 722-723, before references] revision and extension. Bauld s observation of the coupling of allylic acetates by Ni(CO)4 cited in ref. 12 was preceded by the discovery of Webb and Borcherdt14 (du Pont) in 1951 that nickel carbonyl in methanol effects coupling of allylic chlorides in excellent yield, for example ... 

Pikal, M. J., J. E. Lang, and S. Shah. 1983. Desolvation kinetics of cefamandole sodium methanolate Effect of water vapour. Int. J. Pharm. 17 237-262. 

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