Methanol hydroxyls

The possibility of an interaction between the methanol hydroxyl group and the Ca ion has been discussed in an extensive study of the structure of PQQ and its possible mechanism by Zheng and Bruice (1997) using ab initio and molecular orbital calculations. However, the hydroxyl group of methanol appears to be too distant from the Ca for coordination of the Ca ion to substrate to have any importance in the mechanism. 

Linear alkanes yield a mixture of secondary alcohols and ketones (Table 18.2). In methanol, hydroxylation is reduced at more internal positions, while in water and in acetone it occurs randomly. The yield increases with the chain length up... 

The LT study of the [1 species (F2) shows many similarities to the a species, as at short bond length the methanolic hydroxyl proton is transferred to 0-4 and at long bond lengths the nucleophile exhibits the orienting effect of H-bonding to 0-4. However, two notable differences between a and fj are apparent. One, the species closest to a glycoside is not in a chair conformation and at C-1-Om equal to approximately 2.32 A the [I species exhibits an abrupt conformational change. This corresponds to the discontinuity in Fig. 7B and is most dramatically seen in the 3D-conformational space plot (Fig. 8B). However, the final species is still close in conformational space to the B04//3 conformation. 

Hiroya, K., M. Ishigooka, T. Shimizu, and M. Hatano (1992). Role of Glu318 and Thr319 in the catalytic function of cytochrome P450d (P4501A2) Effects of mutations on the methanol hydroxylation. FASEB J. 6, 749-751. 

The reported data indicates that the reaction of (J) begins with and interaction between the methanol hydroxylic proton and the complex. Studies with several alkylating agents have shown that the site of interaction is not either of the two CO2 oxygen atoms, but it was not possible to ascertain whether this interaction takes place at the oxygen or the nitrogen atom of the ArNO fragment. 

In solvents in which association effects occur the intensity is greatly increased [124], so that in ether the intensity of the methanol hydroxyl group is approximately eight times as large as in carbon tetrachloride, and in triethylamine this ratio increases to twelve times. 

Figure 1. MAS NMR spectra [26] of (a) CH3OH adsorbed on zeolite H-ZSM-5 (b) neat liquid CH3OH (c) CH3OH dissolved in CDCI3. Asterisks denote spinning sidebands, arrows point to the position of the resonance from the methanol hydroxyl.

Hydrolysis of a compound A in dilute aqueous hydrochlonc acid gave (along with methanol) a compound B mp 164—165°C Compound B had the molecular formula CigHig04 it exhibited hydroxyl absorption in its IR spectrum at 3550 cm but had no peaks in the carbonyl region What IS a reasonable structure for compound B" ... 

With aldehydes, primary alcohols readily form acetals, RCH(OR )2. Acetone also forms acetals (often called ketals), (CH2)2C(OR)2, in an exothermic reaction, but the equiUbrium concentration is small at ambient temperature. However, the methyl acetal of acetone, 2,2-dimethoxypropane [77-76-9] was once made commercially by reaction with methanol at low temperature for use as a gasoline additive (5). Isopropenyl methyl ether [116-11-OJ, useful as a hydroxyl blocking agent in urethane and epoxy polymer chemistry (6), is obtained in good yield by thermal pyrolysis of 2,2-dimethoxypropane. With other primary, secondary, and tertiary alcohols, the equiUbrium is progressively less favorable to the formation of ketals, in that order. However, acetals of acetone with other primary and secondary alcohols, and of other ketones, can be made from 2,2-dimethoxypropane by transacetalation procedures (7,8). Because they hydroly2e extensively, ketals of primary and especially secondary alcohols are effective water scavengers. 

The aromatic ring of alkylphenols imparts an acidic character to the hydroxyl group the piC of unhindered alkylphenols is 10—11 (2). Alkylphenols unsubstituted in the ortho position dissolve in aqueous caustic. As the carbon number of the alkyl chain increases, the solubihty of the alkah phenolate salt in water decreases, but aqueous caustic extractions of alkylphenols from an organic solution can be accomphshed at elevated temperatures. Bulky ortho substituents reduce the solubihty of the alkah phenolate in water. The term cryptophenol has been used to describe this phenomenon. A 35% solution of potassium hydroxide in methanol (Qaisen s alkah) dissolves such hindered phenols (3). 

Addition of chlorine or bromine in the presence of water can yield compounds containing haUde and hydroxyl on adjacent carbon atoms (haloalcohols or halohydrins). The same products can be obtained in the presence of methanol (13) or acetic acid (14). As expected from the halonium ion intermediate, the addition is anti. As expected from Markovnikov s rule, the positive halogen goes to the same carbon that the hydrogen of a protic reagent would. 

The UV spectra of quinoxalines have been examined in several solvents. In cyclohexane, three principal absorptions are observed (Table 2). In hydroxylic solvents the vibrational fine structure disappears and in methanol or water the weak n- ir transitions are obscured by the intense ir->ir transition (79HC(35)l). 

The oxaziridine ring itself is stable towards alkali there is, for instance, no substitutive ring opening by hydroxyl ions as in oxiranes. 2-r-Butyl-3-phenyloxaziridine (56) is not attacked by methoxide ion in methanol during 12 h at room temperature 3-isopropyl-2-r-octyloxaziridine does not react at room temperature with either solid potassium hydroxide or potassium methoxide solution (57JA5739). 

HgCl2, CH3CN, H2O, 25°, 1-2 h, 88-95% yield. If 2-methoxyethanol is substituted for water, the MTM ether is converted to a MEM ether. Similarly, substitution with methanol affords a MOM ether. If the MTM ether has an adjacent hydroxyl, it is possible to form the formylidene acetal as a byproduct of cleavage. 

Me3SiNEt2- Trimethylsilyldiethylamine selectively silylates equatorial hydroxyl groups in quantitative yield (4-10 h, 25°). The report indicated no reaction at axial hydroxyl groups. In the prostaglandin series the order of reactivity of trimethylsilyldiethylamine is Cii > Ci5 C9 (no reaction). These trimethylsilyl ethers are readily hydrolyzed in aqueous methanol containing a trace of acetic acid. The reagent is also useful for the silylation of amino-acids. ... 

Solid esters are easily crystallisable materials. It is important to note that esters of alcohols must be recrystallised either from non-hydroxylic solvents (e.g. toluene) or from the alcohol from which the ester is derived. Thus methyl esters should be crystallised from methanol or methanol/toluene, but not from ethanol, n-butanol or other alcohols, in order to avoid alcohol exchange and contamination of the ester with a second ester. Useful solvents for crystallisation are the corresponding alcohols or aqueous alcohols, toluene, toluene/petroleum ether, and chloroform (ethanol-free)/toluene. Esters of carboxylic acid derived from phenols... 

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