IV.A -Dimethylformamide

Further substitution of 2,4-disubstituted and most 2,3-disubstituted thiophenes occurs in the free a-position, except when a - -M-substituent in the 3-position strengthens the 4-directing power of a —1—M-sub-stituent in the 2-position. Thus methyl 3-methyl-2-thiophenecar-boxylate is brominated in the 4-position and 3-brorao-2-thiophene-aldehyde is nitrated in the 4-position. Recent investigations on the chloromethylation, sulfonation, mercuration, and nitration of 2,4-di-chlorothiophene, which without proof are assumed to occur in the 5-position serves as examples of the reactivity of a 2,4-disubstituted thiophene. Formylation with iV,A-dimethylformamide and... 

Fig. 3 Electrochemical and homogeneous standard free energies of activation for self-exchange in the reduction of aromatic hydrocarbons in iV.A -dimethylformamide as a function of their equivalent hard sphere radius, a. 1, Benzonitrile 2, 4-cyanopyridine 3, o-toluonitrile 4, w-toluonitrile 5, p-toluonitrile 6, phthalonitrile 7, terephthalonitrile 8, nitrobenzene 9, w-dinitrobenzene 10, p-dinitrobenzene 11, w-nitrobenzonitrile 12, dibenzofuran 13, dibenzothiophene 14, p-naphthoquinone 15, anthracene 16, perylene 17, naphthalene 18, tra 5-stilbene. Solid lines denote theoretical predictions. (Adapted from Kojima and Bard, 1975.)...

It is not always easy to remove the A -substituent after the initial nucleophilic addition, although demethylation of iV-methylpyridinium salts can be achieved by heating in iV,A -dimethylformamide, and iV-benzyl groups are cleaved by hydrogenolysis (heating over Pd/C in the presence of hydrogen). 

Solvents and scavengers methylene chloride (DCM), trifluoroacetic acid (TFA), A,A-diisopropylethylamine (DIEA), 100% ethanol, iV,A-dimethylformamide, di-methylsulphoxide (DMSO), acetonitrile, trifluoromethanesulfonic acid (TFMSA), dimethylsulfide (DMS), p-cresol, dimercaptoethane. 

The most general and convenient method for the metallation of porphyrins is the procedure employing iV,A-dimethylformamide (DMF) as the reaction medium. Previous methods employed either bases such as pyridine or organic acids such as acetic acid for the reaction medium. These methods are thermodynamically inefficient, as the base competes with the porphyrin for the metal in the former procedure and the protons of the solvent compete with the metal for the porphyrin in the latter. - The DMF method has been applied to the synthesis of a wide variety of materials with a considerable variation in both the chelating structure and the metal chelated. - - ... 

Dehydrobromination of a -bromoketones by the action of nitrogenous bases, and more recently by lithium salts in iV,A -dimethylformamide, is probably of unexceptional mechanism when it leads to the simple elimination product. However, 2a-bromo-3-oxo-5a-steroids (24) tend to give abnormal products, the A -3-ketones (26) [138]. The equatorial conformation of the 2 a-bromo substituent makes it relatively un-reactive to elimination, and it has been proposed that a 1,4 -elimination from the A -enol derivative (25) intervenes to give the observed A4-3 ketone (26) in considerable yield. It is known that i,4 -elimination is stereoelectronically favoured... 

It should be emphasized that the parameters involved in the activity coefficients are adjustable parameters which cannot be obtained easily from the properties of the mixed solvents, for instance the vapor-liquid equilibria. However, for the solubilities of structurally related caffeine and theophyllene in water/iV,iV-dimethylformamide, the values of the Wilson parameters are close to each other (1.96 and 0.12 for caffeine and 1.81 and 0.10 for theophyllene). If the Wilson parameters for theophyllene are used to predict the solubility of caffeine in water/iV,A -dimethylformamide, a deviation of 8.8% from experimental data is obtained. The deviation was, however, 6.5% when the Wilson parameters were determined by fitting the experimental solubility data (Table 1). The values of the Wilson parameters determined from the solubilities of the structurally more different sulfonamides (sulfadiazine, sulfadimidine, sulfamethizole, sulfamethoxazole, sulfapyridine, sulfamethoxypyridazine, sulfanilamide and sulfisomi-dine) in water/dioxane mixtures are listed in Table 3. Even for such cases, the average values of the Wilson parameters can be used for a first estimation of the solubilities of the above group of drugs (Table 3). 

D-lyxofuranosyladenine (62) was also accomplished, by heating (61) with sodium benzoate in iV,A -dimethylformamide, and then saponifying... 

Alditol derivatives containing non-terminal double bonds have also been reported. Treatment of 1,2 5,6-di-0-isopropylidene-3,4-di-O-p-tolylsul-fonyl-D-mannitol with sodium benzoate in iV,A -dimethylformamide afforded, in addition to saturated products of displacement, 3-deoxy-1,2 5,6-di-0-isopropylidene-4-0-p-tolylsulfonyl-D-(/ireo-hex-3-enitol and the corresponding tetrol formed by hydrolysis of the acetal rings. 1,2 5,6-Di-O-isopropylidene-D-mannitol and -D-altritol have been converted into the trans and cis isomers, respectively, of 1,2 5,6-di-O-isopropylidene-3,4-dideoxy-D-(/irco-hex-3-enitol by the thionocarbonate method. ... 

The cis isomer is soluble in benzene, carbon disulfide, ethanol, and iV,A -dimethylformamide, whereas the trans isomer is highly soluble in most organic solvents. 

There are no detailed reports on the mechanism of the Bateho-Leimgruber process, but it is proposed below. In the presence of the base, o-nitrotoluene is coupled with iV.A dimethylformamide dimethyl acetal [DMFDMA, Me2NCH(OMe)2] to offer the dimethylamino imine. Hydrogenation then reduces the nitro group to aniline. When workup with an acid, cyclization and re-aromatization then delivered the indole. 

In order to achieve a good dispersion and coating of the nanotube surface with the polymer, Mandal and Nandi have designed a new compatibilizer (P2) containing a thiophene moiety and a poly(dimethylamino ethyl methacrylate) group. This compatibilizer was prepared by atom transfer radical polymerisation (Figure 4.2). The dispersion of compatibilizer-coated MWNT in iV,A -dimethylformamide was stable for more than for 3 months. The addition of the P2-coated MWNTs to the poly(vinylidene fluoride)... 

BBN bcc bp bpy Bq "Bu 9-borabicyclo[3.3.1]nonane body-centred cubic boiling point 2,2 -bipyridine becquerel (unit of radioactivity) w-butyl DME DMF dmgH2 DMSO DNA dimethoxyethane iV,A-dimethylformamide dimethylglyoxime dimethylsulfoxide deoxyribonucleic acid... 

Liquid-liquid equilibrium data of poly(ethersulfone) in iV,A -dimethylformamide and ethanol 1... 

Figure 5 Synthesis of 1-3 using liquid-assisted grinding (LAG). Coordinated water molecules are shown in light gray, O in black, C in gray, and Zn in dark gray. H atoms and the DMF molecules included in the channels of 2 are omitted for clarity. DMF, iV,A-dimethylformamide. (Reproduced from Ref. 33. Wiley-VCH, 2010.)...

The acyl phosphate (I) hydrolyzes in Tris buffer at pH 7.7 at least 100-fold faster than does acetyl phosphate, as shown by the inability of (I) to inactivate adenylosuccinate-lyase after a 15-sec exposure to the buffer before addition of the enzyme. Compound (I) also lost its ability to inactivate AMP aminohydrolase after 15-sec hydrolysis at pH 6.5. After the solution of (I) in iV,A -dimethylformamide had been stored at —25° for 2 days, it showed UV spectral changes (upon dilution into aqueous solutions) indicative of A -acylaminopurine nucleoside formation. In the case of AMP aminohydrolase, this change is associated with a marked reduction in the degree of enzyme inactivation, and the use of freshly prepared solutions of (I) in studies of enzyme inactivation is therefore indicated. 

The environmentally benign synthesis of arylated thiophenes 147 in pure water is possible via desulfinylative cross-coupling between nucleophilic 2-thienylsulfinates 146 and differently substituted bromoarenes (Scheme 58, Table 36) [356]. The reaction proceeds efficiently within short reaction times in the presence of tetrakis (triphenylphosphine)palladium(O) (Pd(PPh3)4) without the need for additives, base, cocatalysts, or water-soluble ligands. Additionally, the apphcation of a highly aqueous solvent mixture consisting of water and iV,A -dimethylformamide at a ratio of 3 1... 

Solubility Soluble in water, iV,A -dimethylformamide, dimethyl sulfoxide, methanol Absorption 535 nm (H2O/DNA) 498 (H2O)... 

Solubility Soluble in iV,A-dimethylformamide, dimethyl sulfoxide, methanol Melting Point 200-201... 

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