Formamide solubility products

Substrate to give a soluble product (plate assays) 0.1% / -Nitrophenyl phosphate in 10 mAfdiethanolamine, pH 9.5, containing 0.5 mAfMgClg. Substrate to give an insoluble product (Western blots) NBT stock— 5% nitroblue tetrazolium in 70% dimethyl formamide. BCIP stock—5% disodium bromochloroindolyl phosphate in dimethyl formamide. Alkaline phosphatase buffer—100 mAf diethanolamine, pH 9.5, containing 100 mAfNaCl and 5 m AfMgClj. Just before use, add 66 lL of NBT stock solution to 10 mL of alkaline phosphatase buffer, mix well, and add 33 pL of BCIP stock soludon. 

Formamide has probably been examined most thoroughly. Several solubility studies have been reported since the publication of Seidell and Linke. Gopal and Husain have determined the solubilities of over twenty electrolytes in formamide and at various temperatures, and Gopal and co-workers used the data to evaluate heats of solution in this solvent. Berardelli and co-workers have also reported heats of solution for several electrolytes, including some alkaline earth and transition metal halides. Alexander and co-workers have reported solubilities, in terms of the log of the solubility product, for numerous electrolytes in several solvents including some amides. Povarov and co-workers have measured the solubility of AgCl by radioactive tracer techniques in pure formamide and in solutions of NaCl and CsCl in formamide. Their results show AgCl to be considerably more soluble in formamide than indicated by the results of Alexander and coworkers. However, the latter workers point out that solubilities of silver salts in... 

Solubility products and instability constants [of silver, caesium, and potassium 239 salts] in water, methanol, formamide, dimethylformamide, dimethylaceta-mide, dimethyl sulphoxide, acetonitrile, and hexamethylphosphorotriamide... 

The characteristics of this product are as follows. It is a pale yellow, nonodorous, slightly bitter, crystalline powder, very soluble in water (>1.5 g/cc), soluble in methanol and formamide, slightly soluble in ethanol and isopropanol, insoluble in ether, benzene and chloroform MP 162° to 163°C with decomposition uncorrected). 

Characterization of product is confirmed via H NMR, IR, and mass spectra. Mass spectra of all these isocyanides exhibit a parent ion of maximum intensity and characteristic fragmentation peaks. Mass spectroscopy is also a useful tool for detecting unreacted amine or formamide. Isocyanides decompose in acid and are soluble in hexane, THF, toluene, CH2CI2, CH3CN, and alcohols. 

Solid Mo02Br2(DMF)2 melts at 139-141°C with decomposition. The IR spectrum, taken as a KBr dispersion, has characteristic bands for i moO 903 and 940 cm The NMR spectrum in acetone-t/g exhibits signals at S 3.03 (s, 3H, CHa), 3.22 (s, 3H, CH3), 8.26 (s, IH, CH). The complex is insoluble in hexane and diethyl ether and is soluble in methanol, ethanol, dichloromethane, chloroform, acetone, dimethyl formamide, and dimethyl sulfoxide. It is stable in air at room temperature and can be manipulated without special care. This product is specially useful for the synthesis of a number of adducts with pyridine and related bases, since the dimethyl formamide displaced can be readily removed by washing with most common organic solvents. 

The commercial production carried out by various companies is estimated to be ca. 2000 tyear-1 worldwide [7]. Due to the common solubility in water and various other solvents (e.g. DMSO, formamide), the biocompatibility, and the ability of degrading in certain physical environments, dextran is already successfully applied in the medical and biomedical field [8]. The physiological activity of dextran and its derivatives, indicated also by a very large number of publications in this area of research, is in contrast to inadequate structural analysis of both dextran and their semi-synthetic products. Only a few publications, in contrast to extensive studies in cellulose and starch chemistry [9,10], deal with the defined functionalisation and characterisation of dextran for adjusting desired features. 

This section deals only with solvents whose reduction products are insoluble in the presence of lithium ions. The list includes open chain ethers such as diethyl ether, dimethoxy ethane, and other polyethers of the glyme family cyclic ethers such as THF, 2Me-THF, and 1,4-dioxane cyclic ketals such as 1,3-dioxolane and 1,3-dioxane, esters such as y-butyrolactone and methyl formate and alkyl carbonates such as PC, EC, DMC, and ethylmethyl carbonate. This list excludes the esters, ethyl and methyl acetates, and diethyl carbonate, whose reduction products are soluble in them (in spite of the presence of Li ions). Solutions of solvents such as acetonitrile and dimethyl formamide are also not included in this section for the same reasons. Figure 6 presents typical steady state voltammo-grams obtained with gold, platinum, and silver electrodes in Li salt solutions in which solvent reduction products are formed and precipitate at potentials above that of lithium metal deposition. These voltammograms are typical of the above-mentioned solvent groups and are characterized by the following features ... 

Soluble starch, available from chemical supply houses, is readily dispersed in water. The iodine-starch complex has limited water solubility, and it is therefore important not to add the starch indicator until near the end point when the iodine concentration is low. Because starch is subject to attack by microorganisms, the solution usually is prepared as needed. Among the products of hydrolysis is dextrose, which can cause large errors because of its reducing action. Various substances have been recommended as preservatives, including mercury(II) iodide and thymol. With formamide a clear solution containing 5% starch is obtained that is stable indefinitely. 

A classical example is the hydrogenation of CO2 in the presence of secondary amines to yield formamides (eq. (7)). The formation of carbamates from the amine and CO2 leads to the presence of a liquid phase that cannot be dissolved in CO2 even at temperatures and pressures way beyond the critical data of pure CO2. Nevertheless, the reaction occurs with extraordinarily high turnover numbers and reaction rates [17, 34], even with catalysts that have no solubility in SCCO2 [35,72]. Most likely, the reaction occurs in the liquid phase, but the supercritical CO2 phase ensures rapid mass transfer of the reactants (CO2, H2) and the product (DMF) between the two phases. It has been shown recently that the addition of ionic liquids (vide infra) can help to control the distribution of reactants, intermediates, and products between the two reaction phases. Additional control over the chemoselectivity of the transformation is thus possible by judicious segregation of various components of the reaction mixture [36, 74]. 

Various solvents and antisolvents were screened experimentally. Among them, dimethyl formamide (DMF) and IP AC appeared to offer the best combination based upon product solubility and the ability to retain the desired crystal form. 

Solvents can also be used to promote prodr uct isolation and purification. An ideal solvent system is one that exhibits high solubility with the reagents and starting materials but only limited solubility with the reaction product. Precipitation of the reaction product from the mixture can increase the reaction rate, drive reactions in equilibrium to completion, and isolate the product in the solid state to minimize the risk of undesirable side reactions. Solvents can also aid in the regio control of the reaction pathway. It was found in the preparation of nevirapine (3) that, when diglyme was used as the reaction solvent with sodium hydride, the ring closure of (lXSchemel2.1) proceeded by the desired reaction pathway (6). However, when dimethyl formamide was used for this reaction, the exclusive product was the oxazolopyridine (2). In this particular case, the solvation effects may have helped to stabilize the transition state of the desired product. 

AMPS is a water-soluble monomer it is also soluble in polar organic solvents such as methanol, dimethyl formamide (DMF), and dimethyl sulfoxide (DMSO). MPDMA is soluble in similar polar solvents. Because of the solubility characteristics of these two species, the reactions (that is, the formation of the ion pairs) were conducted in water, methanol, or DMF. The product, MPDMA AMPS, was very hygroscopic and apparently had a tendency to polymerize spontaneously during the course of isolation (solvent stripping and precipitation by non-solvents). The preferred medium for preparation was found to be anhydrous THF which also had been used for other ionic monomer pairs (13). In addition, a slight excess of MPDMA was used to ensure complete reaction of AMPS. The excess base, MPDMA, was removed using cold THF (which did not dissolve the product). 

Coatings with Thermoplastic Fluoropolymers. Poly(vinylidene fluoride), PVDF, is the only conventional thermoplastic fluoropolymer that is used as a commercial product for weather-resistant paints. This crystalline polymer is composed of -CHjCFj- repeating units it is soluble in highly polar solvents such as dimethyl-formamide or dimethylacetamide. Poly(vinylidene fluoride) is usually blended with 20 30 wt% of an acrylic resin such as poly(methyl methacrylate) to improve melt flow behavior at the baking temperature and substrate adhesion. The blended polymer is dispersed in a latent solvent (e.g., isophorone, propylene carbonate, dimethyl phthalate). The dispersion is applied to a substrate and baked at ca. 300 °C for ca. 40-70 s. The weather resistance of the paints exceeds 20 years [2.16]-[2.18]. 

Dextran is a microbial biopolymer [58] whose molecular structure is composed exclusively of monomeric 2-D-glucopyranosil units, linked mainly by (P-1,6) glucosidic bonds (Fig. 13.11). Its applications depend on its molecular mass [59]. Two dextran products are available in most countries for clinical purposes dextran 70, with a molecular mass of about 70 000 and dextran 40 with a molecular mass 40 000. Dextran fractions are readily soluble in water and electrolyte media to form clear, stable solutions significantly insensitive to pH. They are also soluble in some solvents such as methyl sulphide, formamide and ethylene glycol [60]. 

The choice of solvent is also important, as the enthalpy measured is essentially that of the displacement of the solvent from the filler surface by the probe molecule. For acid-base characterisation a non-polar solvent such as n-heptane is ideal. However, poor solubility of the desired probe molecule may demand the use of a polar solvent, when this is the case the enthalpy of interaction of the solvent with the filler must be considered when interpreting the results. If the probes in question are only capable of weak physical adsorption, (i.e., not via hydrogen bonding), and are only soluble in highly polar solvents such as tetrahydrofuran and dimethyl formamide, situations can arise where apparently no adsorption occurs. This is due to the solvent having equal or stronger interaction with the substrate than the probe. In such cases the value of performing FMC experiments should be questioned and the use of more soluble model compounds considered. If chemical adsorption of the probe occurs the polarity of the solvent is somewhat less critical, provided the solubility of reaction products is not enhanced. 

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