Methanol Table

Streitweiser et al.597 have also measured second-order rate coefficients for hydrogen exchange of fluorobenzenes with sodium methoxide in methanol, Table 182. Nucleophilic displacement of fluoride ion by methoxide ion accompanies... 

Initial protonation of iron in protodesilylation of trimethylsilylferrocene was not, however, favoured as a mechanism by Marr and Webster689, who measured rates by the spectroscopic method using hydrochloric acid in 20 vol. % aqueous methanol (Table 235) and found that the rate of desilylation of the ferrocene compound was little more than that for the 4-methoxyphenyl and 2,4-dimethyl compounds. The similarity of the spread of rates in the different media and the similar activation energies and entropies were considered as evidence that the transition states for reaction of all three compounds were similar. The lower activation energy obtained for the 4-methoxyphenyl relative to the ferrocene compound may arise from the different media involved the difference in entropy seems, however, to be rather larger than one might have expected even allowing for the solvent differences. 

The ratio of 8Z to HE is slightly better in the presence of DABCO in THF (Table 6.2 entry 9) than in pure methanol (Table 6.2 entry 7). Since the DABCO must be removed prior to the thermal rearrangement and the minimal impact on overall yield, we decided to run the Michael addition in methanol to afford a mixture of Z- and -adducts 8 in quantitative yield. The resulting solution of adducts 8 was solvent-switched to xylenes and heated at 125 °C for 2h, and at 135 °C for 4h to give a 62% assay yield of desired product 3. The reaction mixture was concentrated and hydroxypyrimidinone 3 was directly crystallized in 54% isolated yield as a white crystalline solid. 

The Hammett p values found by changing the para-substituent on the nucleophile in DMF and methanol (Table 16) support this conclusion. The larger p value in DMF indicates that the change in charge on the nucleophilic sulfur atom is greater on going from the reactant to the transition state in DMF. Therefore, the S—Ca transition state bond is shorter in DMF than in methanol. 

As for water we can expect the MVIEs for other hydrogen bonded systems in low temperature liquids to have an appreciable inverse librational contribution, and this is the case for those alcohols which have been investigated. The data on the isotopic methanols (Table 12.5) confirm this. As expected from the discussion above, the MVIE for OH/OD substitution is negative. Also the isotope effects seem to be approximately additive, MVIE(CH3/CD3) + MVIE(OH/OD) MVIE(CH3OH/CH3OD) 5.3 x 10-3 - 1.6 x 10-3 - 3.7 x 10-3 (observed = 2.9 x 10 3). 

Klan et al. determined that sulfonate esters and phosphonate esters are released in high quantum yields when 43 is irradiated in methanol (Table In... 

Lopez-Avila et al. [88] compared MAE, Soxhlet, sonication, and SFE in their ability to extract 95 compounds listed in the EPA method 8250. Freshly spiked soil samples and two SRMs were extracted by MAE and Soxhlet with hexane-acetone (1 1), by sonication with methylene chloride-acetone (1 1), and by SFE with supercritical carbon dioxide modified with 10% methanol. Table 3.16 shows the number of compounds in different recovery ranges obtained by the various techniques. Sonication yielded the highest recoveries, followed by MAE and Soxhlet, whose performances were similar. SFE gave the lowest recoveries. MAE demonstrated the best precision RSDs were less than 10% for 90 of 94 compounds. Soxhlet extraction showed the worst precision only 52 of 94 samples gave RSDs less than 10%. No technique produced acceptable recoveries for 15 polar basic compounds. The recoveries of these compounds by MAE with hexane-acetone at 115°C for 10 minutes (1000 W power) were poor. Consequently, their extraction with MAE was investigated using acetonitrile at 50 and 115°C. Ten of the 15 compounds were recovered quantitatively (>70%) at 115°C. 

No appreciable difference in absorbance values was observed between solutions in hexane or methanol (Table 5). We therefore attribute the change in fluorescence to solute-solvent interactions between the solvent and the pesticide in its excited state. 

As a first attempt to compensate for the presence of interfering substances in the mixtures, the two wavelengths 1452 and 2274 nm were used to quantitate methanol. Table 5.2 contains the methanol RMSEC and RMSEV results. A substantial... 

An alternative mode of reactivity is observed for [Os]-naphthalene when the nucleophile for the tandem addition is built into the electrophile. The normal mode of reactivity results in the formation of cis-l,4-dihydronaphthalenes (vide supra), but when a solution of the methyl vinyl ketone Michael addition product 24 in methanol (Table 6, entry 1) and a catalytic amount of triflic acid are allowed to react, the complexed hydrophenanthrenone 25 is isolated in 89 % yield [18]. This reactivity results from the pendant ketone undergoing a tauto-merization to form an enol, which can then attack the allyl cation at C2. The stereochemistry of the nucleophilic addition is still anti to the face involved in the metal coordination, but the... 

Bases are added frequently as promoters in catalytic dehalogenations to neutralize the liberated halogen acid that may inhibit the action of catalyst.196 Denton et al. studied the effects of added potassium acetate to the rates of hydrogenolysis of various halogen compounds with a Pd-C as catalyst in methanol (Table 13.8).196... 

Ottosson and Cremer [44] investigated processes I and II with the help of quantum chemical calculations to assess the stability of the various forms of 45 (compare with Figure 10). The pentacoordinated form 45b was found to be more stable than 45c by 10.4 kcal/mol in the gas phase and 6.9 kcal/mol in solution using the dielectric constant e = 32.4 of methanol (Table 6, B3LYP/6-31G(d) calculations) while theory does not support the existence of 45a. Hence, process I of Scheme 8 does not seem to be likely for cation 45. 

Table 1.25 gives the average commercial spedficadons of diemical grade methanol. Table 1.26 lists the applications of methanol in Western Europe, the United States, Japan and the world in 1984. as well as the production, capacities and consumption for these geographic areas. Capacities are also given for 1986. ... 

In a bridge-splitting reaction, (R, R )-15 reacts with (S)-(-l-)-77 in methanol to give a solution of the chloride salts [S,(i As> As)] and [ S. (Sas>S as)]-82 which, when treated with 1 equiv. NH4PFg, yields 95% of [S,(Sas,Sas)]-( + )-83 having [a]p -1- 297° (acetone) after recrystallization from acetone-benzene (Scheme Cyanide cleanly liberated R,R)- + )-75 from [S,(Sas,SaJ]-( + )-83 in a dichloromethane-water mixture the arsine was recovered from the organic phase and recrystallized from aqueous methanol (Table 5). It was found later that 1,2-diaminoethane displaced the optically active bis(tertiary... 

Potassium diphenylarsenide-2-dioxane reacts with (—)-menthyl chloride in boiling tetrahydrofuran to give (lS,2S,5i )-( + )-neomenthyldiphenylarsine, (S)-( + )-175 (neo-menars). The arsine was obtained as colourless needles in ca 40% yield after recrystallization from warm methanol (Table 9). The neomenthylarsine, upon reaction with benzyl bromide in benzene, affords the epimeric (li ,2S,5i )-benzylmenthylarsonium bromide, (i H-f-)-176, which, upon reduction with lithium aluminium hydride, affords (l/t,2S,5K)-diphenylmenthylarsine, (J )-( — )-177 (menars) (equation 25). 

Dinuclear complexes of formula [ Rh(C5Me5) 2(ir-pz )(0Me)2](C104) were obtained by treating [ Rh(C5Mes) 2(0H)3](C104) with the appropriate Hpz in methanol (Table VIII). 

L where the L is of a greatly rednced charge-transfer natnre than the corresponding L state of 1-naphthol. It follows that in the case of 2-naphthol, one expects a much smaller solvent effect on the Forster-cycle acidity than the corresponding effect on 1-naphthol acidity. This indeed seems to be the case when the photoacidity of 1-naphthol and 2-naphthol was estimated from Forster-cycle calculations in water and methanol (Tables 1 and 2). 

Interestingly, Forster-cycle calculations of the pAla in methanol (Table 2) seem to confirm the substituent effect on the polarity of the emitting state of 1-naphthol as discussed above the less polar the emitting state of the acid compared to the emitting state of its conjugate base, the larger the Forster-cycle acidity of the photoacid. The calculated Forster-cycle difference between the ground-state and excited-state acidities in methanol was 12.3, 11.3, 10.9, 9.3 and 8.8 for the 2-substituted, 3-substituted, unsubstituted 4- and... 

Catalytic oxidation of electron rich alkenes such as styrene with ruthenium complexes gave mainly benzaldehyde rather than the expected epoxide. When styrene was oxidised with CHP as the oxidising agent benzaldehyde was the major detectable product. Polymerisation of styrene occurs in solvents like methanol. Table-4 shows the oxidation of styrene with CHP. Substitution of methyl groups in the pyridine ring increases the yield of benzaldehyde. When RuCl2(4-Mepy)4 was the catalyst, negligible amounts of styrene oxide was also detected. However with other catalysts benzaldehyde was the only detectable product. Other oxidation products like phenyl acetaldehyde and acetophenone were not detected [10,11]. 

The alkylation of different amines has been performed with methanol. Table 1 shows the results obtained with n-octylamine. 

Methanol in Hydrocarbon-Rich Vapor and Liquid. The volumetric properties of methanol gas (12) and the second virial cross coefficients of methanol and light gases (13) were used to determine the pure-component parameters AP(TC) and a for methanol. Table II shows the enthalpy departure of gaseous methanol from ideal gas at three temperatures and several pressures. For comparison, the experimental values (14) and the values calculated by the Soave equation (1) are also shown. Table II indicates that the Won modified equation of state predicts the enthalpy departure of methanol very well at low temperatures and fairly well at high temperatures, but that the original Soave equation considerably underestimates the enthalpy departure at all temperatures and pressures. Since the original Soave equation was meant to be applied only to hydrocarbons, we are not surprised at this result. Comparison of calculated and experimental second virial cross coefficients between methanol and methane (and also C02) is presented elsewhere (15).)... 

Propanol is both a weaker acid and a weaker ba.se than methanol (Tables 8-2 and 8-3). 

Transesterifications of methyl esters with high boiling alcohols, as shown in (Eq. 56), occurred readily under MW irradiation because of the displacement by evaporation of the polar volatile methanol (Table 6.23) [llj. 

A 4.465-gm sample of the polymer is dissolved in 70 ml of THF in a 200-ml beaker. To the solution is added 70 ml of methanol and 2 drops of concentrated sulfiiric acid. After allowing the mixture to settle for 24 hr at room temperature, the first fraction is isolated by decanting the solvent into another beaker. The polymer in the first beaker is dried to constant weight. The solvent in the second beaker is treated with 30 ml of methanol and again allowed to settle for 24 hr to produce a second fraction of the polymer. This polymer fraction is isolated as the previous fraction and dried. To the filtrate is added 70 ml of methanol to yield a third fraction. The last fraction is obtained by adding 100 ml of methanol to the filtrate. Thus, 4.465 gm of polymer is dissolved in 70 ml of THF and precipitated with a total of 270 ml of methanol. Table VIII gives details of the properties of these fractions. 

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