Dimethyl sulfoxide , solubility determination

Pure dimethyltriazanium chloride decomposes at 133 to 134° (the checker reports 135 to 136°). The salt is very hygroscopic and should be stored in a desiccator. It is readily soluble in water, methanol, ethanol, and dimethyl sulfoxide. An aqueous solution is stable at room temperature. Free iodine is liberated from an acidic iodide solution, and this reaction makes it possible to determine the triazanium content.3... 

The glass-transition temperature, Ts, of fully hydrolyzed PVA has been determined to be 85°C for high molecular weight material. Poly(vinyl alcohol) is only soluble in highly polar solvents, such as water, dimethyl sulfoxide, acetamide, glycols, and dimethylformamide, The solubility in water is a function of degree of polymerization (DP) and hydrolysis. 

For a solvent that is not listed, the procedure for estimating the M number is to determine the cut-off point for miscibility using a sequence of known solvents. A correction term of 15 is then either added or subtracted, whichever is appropriate. Solvents used in these tests should of course be pure. After the miscibility number is determined, an experiment should be run to verify the solubility of the two solvents. For example, if a liquid has borderline solubility in dimethyl sulfoxide (M = 9), the M number assigned is 24. On the other hand, if an unknown liquid was borderline soluble in p-xylene (M = 24) its M number is estimated to be 9. Reference 20 has a list of approximately 400 liquids and should be consulted by those who are interested. 

Marsh and Weiss determined the solubilities in 26 solvents at 21 1 1 C. In general, sodium cephalothin is very soluble in water, formamide, dimethyl sulfoxide, and ethylene and propylene glycol, slightly soluble in lower alcohols, and insoluble in non-polar organic solvents. 

Fini A, de Maria P, Guarnieri A, Varoli L. Acidity constants of sparingly water-soluble drugs from potentiometric determinations in aqueous dimethyl sulfoxide. J Pharm Sci 1987 Jan 76(l) 48-52. 

As noted previously, the solubility of a sample in the liquid matrix has been shown to have a major influence in determining FAB sensitivity. If the analyte is not soluble, effective diffusion of sample molecules to the surface of the matrix will not occur, and the resulting spectrum will be dominated by matrix ions. In order to improve solubility in the matrix, the sample is often first dissolved in a mutually compatible co-solvent (e.g. methanol, dimethyl sulfoxide, water, etc.) and acid or base is added. A few microliters of this solution is then... 

For a good therapeutic effect the choice of the active substance and the choice of the vehicle are important. Physical and chemical factors play an important role. The solubility of the active substance in the vehicle and the concentration, the size of the molecule of the active substance, the partition between vehicle and skin, the particle size (in case of suspensions) and the nature of the vehicle (aqueous or lipid) determine the penetration speed and depth. Hydrocortisone, for example, is more lipid soluble in the ester form (hydrocortisone acetate). The latter will penetrate into the skin faster and more complete. Hydrocarbons, such as soft and liquid paraffin, release lipophilic active substances only very slowly and substances formulated in these bases will penetrate only in limited amounts into the skin. Fatty oils (vegetable oils, triglycerides) are able to pass into the upper layers of the skin. Penetration enhancers (salicylic acid, dimethyl sulfoxide, propylene glycol, urea) increase the penetration of active substances into the skin. 

The nonlinear optical (NLO) susceptibilities of bioengineered aromatic polymers synthesized by enzyme-catalyzed reactions are given in Tables 2, 3, and 4. Homopolymers and copolymers are synthesized by enzyme-catalyzed reactions from aromatic monomers such as phenols and aromatic amines and their alkyl-substituted derivatives. The third-order nonlinear optical measurements are carried out in solutions at a concentration of 1 mg/mL of the solvent. Unless otherwise indicated, most of the polymers are solubilized in a solvent mixture of dimethyl formamide and methanol (DMF-MeOH) or dimethyl sulfoxide and methanol (DMSO-MeOH), both in a 4 1 ratio. These solvent mixtures are selected on the basis of their optical properties at 532 nm (where all the NLO measurements reported here are carried out), such as low noise and optical absorption, and solubility of the bioengineered polymers in the solvent system selected. To reduce light scattering, the polymer solutions are filtered to remove undissolved materials, the polymer concentrations are corrected for the final x calculations, and x values are extrapolated to the pure sample based on the concentrations of NLO materials in the solvent used. Other details of the experimental setup and calculations used to determine third-order nonlinear susceptibilities were given earlier and described in earlier publications [5,6,9,17-19]. 

Dimethyl sulfoxide is a favored solvent for displacement reactions in synthetic chemistry. The rates of reaction in DMSO are many times faster than in an alcohol or aqueous medium [6]. Dimethyl sulfoxide is the solvent of choice in reactions where proton (hydrogen atom) removal is the rate determining step. Reactions of this type include olefin isomerizations and reactions where an elimination process produces an olefin. Another application that uses DMSO is its use as an extraction solvent to separate olefins from saturated paraffins [7]. Several binary and ternary solvent systems containing DMSO and an amine (e.g., methylamine), sulfur trioxide, carbon disulfide/ amine, or sulfur trioxide/ammonia are used to dissolve cellulose, and act as spinning baths for the production of cellulose fibers [8,9]. Organic fungicides, insecticides, and herbicides are readily soluble in DMSO. Dimethyl sulfoxide is used to remove polymer residues from polymerization reactors. 

Solubilities of modified polymers were determined by placing about one mg of product in about three ml of liquid. These mixtures were allowed to stand at room temperature, with occasional agitation for one week. The following liquids were tested acetone, acetonitrile, bromobenzene, chlorobenzene, 2-chloro-propionic acid, diethyl sulfate, dimethyl sulfoxide, hexachloro-acetone, 5% LiCl/dimethyl sulfoxide, 5% LiCl/dimethylfuran, toluene and triethylphosphate. 

To determine the ability of the polymer to dissolve in a particular solvent, it is important to know the solubility of the solvent used. For a solute to dissolve in a particular solvent, the solubility values between the solute and solvent should be less. Thus, the difference between the solubility values of the two components is the main criteria for solubility. A similar concept was used to determine the difference of solubility parameters of water and different solvents used in nanoprecipitation (A5s -w)- The A5s-w value increases in the following order ethanol < dimethyl sulfoxide < isopropyl alcohol < ethyl lactate < acetone for Methaciytic acid copolymer as the polymer. Nanopaiticles were prepared using these solvents, keeping the polymer concentration constant. The order of size obtained was as follows ethanol < dimethyl sulfoxide < isopropyl alcohol < acetone < ethyl lactate. It can be seen that the order obtained is almost the same as the previous order of A5s w. This relationship suggests that when the affinity between the solvent and water is high, it has lower A5s-w value, which means that the solvent diffuses into the aqueous phase more effectively resulting in the formation of smaller nanopaiticles [22]. 

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