Solubility DMSO-based

PANI is more commonly prepared by polymerization of aniline usiag (NH 2S2 8 HCl (112,127). As prepared, it has stmcture (16) known as emeraldine hydrochloride. In this form, PANI is highly conductive but completely insoluble. When emeraldine hydrochloride is deprotonated with NH OH, the highly soluble emeraldine base (17) is produced. It is processible from oiganic solvents such as aqueous acetic acid or DMSO. It must then be treated with HCl to regenerate the again insoluble conducting form of the polymer. 

Acetylation of the 0 /0H group results in DMP being much more soluble in organic solvents than IBX. Both are excellent and selective reagents for oxidation of primary alcohols to aldehydes and secondary alcohols to ketones. Both have a number of advantages over DMSO-based (see Section 6.9) and transition-metal-based protocols. 

A wide variety of solution condensation systems were devised and tested including one and two liquid combinations and salt-containing systems. Only the system using the stannane dissolved in DMSO and dextran with sodium hydroxide in water yielded the desired modified cellulosic product (Table 1). Other results indicate that the presence of a strong base is conducive to effecting the modification of the cellulose. The DMSO systems had the NaOH present only as a largely undissolved solid. Further studies should consider the use of DMSO, DMF, etc. soluble strong bases such as triethylenediamine. 

The phenyl ether linkage of butoxy substituted 44 was cleaved with boron tribromide to give a hexaphenol derivative (45) in 60% yield (Scheme 14). The hexaphenol derivative was found to be remarkably soluble in most polar organic solvents, such as ethanol, DMF, DMSO, and dioxane, as well as in aqueous base solution. Condensation with octanoic acid in the presence of DCC and catalytic H+ afforded the inverse ester (46) in high yield. 

The generalization as to binned solubility ranges is based on experimental aqueous solubility assays that are primarily intended for early discovery use. Most often these assays employ a drug in DMSO stock solution rather than a powder... 

In general the rate of false negatives are by definition difficult to ascertain. There are two general approaches to get a handle on false negatives. The first approach is based on what is known about the aqueous solubility of screening compounds since truly active compounds out of solution are the most common cause of false negatives. One can infer that perhaps 15% of true positives will be missed in an HTS. This inference comes from an analysis of the concordance or lack of concordance between nominal concentrations in DMSO stocks and nominal... 

Solubility generally decreases with increase in chain size and extent of branching. The solubility of dextran can be divided into four groups — those that are readily soluble at room temperature in water, IMF, DMSO and dilute base those that have difficulty dissolving in water those that are soluble in aqueous solution only in the presence of base and, those that are soluble only under pressure, at high temperatures (> 100°C) and in the presence of base. Dextran B-512 readily dissolves in water and 6M, 2M glycine and 50% glucose aqueous solutions. 

Lipinski et al. [12] and Pan et al. [463] compared several commonly used methods of solubility measurement in early discovery, where samples are often introduced as 10 mM DMSO solutions. Turbidity-based and UV plate scanner-based detections systems were found to be useful. The methods most often used in discovery and in preformulation will be briefly summarized below. 

As we have already mentioned, CDCI3 should be avoided as a solvent for salts for two reasons. Firstly, salts are unlikely to be particularly soluble in this relatively nonpolar solvent but more importantly, spectral line shape is likely to be poor on account of relatively slow proton exchange at the protonatable centre. The remedy is simple enough - avoid using CDCI3 and opt for one of the more polar options instead, e.g., deuterated DMSO or MeOH and you should obtain spectra every bit as sharp as those of free bases. 

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