Acetic methanol complex

A solution of 3 g of the nitrile, water (5 moles per mole of nitrile), and 20 g of boron trifluoride-acetic acid complex is heated (mantle or oil bath) at 115-120° for 10 minutes. The solution is cooled in an ice bath with stirring and is carefully made alkaline by the slow addition of 6 A sodium hydroxide (about 100 ml). The mixture is then extracted three times with 100-ml portions of 1 1 ether-ethyl acetate, the extracts are dried over anhydrous sodium sulfate, and the solvent is evaporated on a rotary evaporator to yield the desired amide. The product may be recrystallized from water or aqueous methanol. Examples are given in Table 7.1. 

Two competing chain-transfer mechanisms in copolymerization of CO and ethene catalyzed by Pd11 acetate/dppp complexes were found. One involves termination via an isomerization into the enolate followed by protonation with methanol the rate of this reaction should be independent of the concentration of the protic species. The second chain-transfer mechanism comprises termination via methanolysis of the acylpalladium species, and subsequent initiation by insertion of ethene into the palladium hydride bond.501... 

This product was characterized by its NMR spectrum and also by reaction with HC1 followed by BF3/methanol to yield methylcyanoacetate ester. The reaction occurs readily, and in the absence of detectable amounts of the oxidative addition product of acetonitrile with the iridium complex, [Hlr-(depe)2CH2CN]+. In contrast, neither Rh(depe)2Cl nor Rh(dmpe)2Cl (dmpe = Me2PCH2CH2PMe2) react with C02 in acetonitrile, though Rh(dmpe)2Cl does react with C02 in nitromethane to form the analogous nitro-acetate hydride complex, (57). 

Methanol, platinum complex, 26 135 tungsten complex, 26 45 Methyl, iridium complex, 26 118 manganese complex, 26 156 osmium complex, 27 206 rhenium complexes, 26 107 Methyl acetate, iron complex, 27 184 osmium complex, 27 204 Methyl benzoate, chromium complex, 26 32 Methylene, osmium complex, 27 206 Molybdate(l -), (acetato)pentacarbonyl-, M.-nitrido-bis(triphenylphosphorus) (I-h), 27 297... 

Figure 29.15 The two steps of complex formation and double proton exchange in the methanol—acetic acid complex [62].

Figure 29.16 Comparison of experimental [61] and theoretical [62] bimolecular rate constants of proton exchange in the methanol—acetic acid complex in tetrahydrofuran-c/g, represented by symbols and solid lines, respectively, for HH, HD and DD exchange.

The anticancer agent, taxol, is now obtained from a number of Taxus species but invariably occurs with with sizeable amounts of the congener, cephalomannlne. These complex diterpenes differ only in the nature of the amide carboxylic acid attached to the amine of the phenylisoserine side chain. In the case of taxol this is a benzoic acid moiety, whereas in cephalomannlne it is a tiglic acid group. These two impart very little selective polarity to the two natural products, and separation of them is notoriously difficult. Almost baseline separation of a small sample (6.1 mg) was achieved, however, by Chu and his coworkers (6), using a system of hexane-ethyl acetate-methanol-etha-nol-water (10 14 10 2 13) with the aqueous phase mobile. In this system, taxol had a partition coefficient of 1.8 and cephalomannlne of 1.42. 

Catalyst - Tetrabutyl Phosphonium Acetate acetic acid complex (as 7% solution in methanol)... 

The data for cadmium thiourea complexes in water-methanol mixed solvent are presented in Table 9.14. Dependence of stability constant on the solvent composition is very complex in the mixed solvents formed by two solvate-active components as defined by the relative activity, L, of A and B. Dependencies of stability constant for some complexes in water-B solution (where B is methyl acetate, methanol, etc. ) are presented in Figures 9.21 and 9.22 for complex NiEn (En=ethylenediamine) in water-non-aqueous solution (the constants are presented relative to stability constant in water). 

Jacob (1992) has reviewed studies on the TLC of porphyrins and noted that this technique is a versatile one for separating these compounds. The sorbent most often used is silica gel. TLC allows for the separation of most of the common classes of porphyrins—i.e., the porphyrin carboxylic acids and their esters, alkyl porphyrins, and porphyrin-metal complexes. TLC is also useful for the separation of the diagnostically important porphyrins from clinical specimens such as urine, feces, and blood. Routine methods for the separation by TLC of porphyrins from human specimens are now available. With various combinations of the mobile-phase benzene-ethyl acetate-methanol and silica gel sorbent, porphyrin methyl esters can be separated according to the number of carboxyl groups, with the values being inversely proportional to that number (Jacob, 1992). 

C02EtHL2 (180 mg, 0.34 mmol) was dissolved in methanol and cadmium(II) acetate dihydrate (183 mg, 0.68 mmol) and sodium acetate (56 mg, 0.68 mmol) added. The yellow solution was subsequently refluxed for 30 min and then allowed to cool to room temperature and sodium hexafluorophosphate (115 mg, 0.68 mmol) added. After filtration the yellow solution was left to evaporate at room temperature to leave a yellow oil. Attempts to crystallize the complex from a range of solvents were unsuccessftil. The complex was, however, readily formed as confirmed by mass spectroscopic measurements. After repeated (5x) evaporation of the methanolic complex solution a white powder was obtained. 

A couple of examples have been included in Table 3.8, using as solvent system a mixture of -hexane/ethyl acetate/methanol/water to isolate flavanones, and chloroform/methanol/water to isolate flavones ° with successful separation of flavonoids from complex matrices. 

Fig. 13 Elution profiles corresponding to the classical mode and MDM separation of (a) ( )-WSA (solvent system, hexane-ethyl acetate-methanol-water (9 1 9 1, v/v) CS, 100 mM (5)-naproxen diethylamide in the upper phase). An increase in Rs is observed in MDM over classical mode which is dependent on the RP period, (b) DNB-( )-Leu (solvent system MTBE-sodium phosphate buffer 50 mM pH 6.0 CS, 90 mM (5)-naproxen diethylamide in the lower phase). The separation does not improve even after three complete cycles of MDM. The modification in MDM, which consists of stopping the centrifugal rotation during NP periods, results in an improved separation. Differences observed are the result of the partition of the CS/enantiomer complexes between the two liquid phases in the case of ( )-WSA. Adapted from [77]...

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