Pyridine solubility

Z values are obtained from Eq. (8-76) for solvents having Z in the approximate range 63-86. In more polar solvents the CT band is obscured by the pyridinium ion ring absorption, and in nonpolar solvents l-ethyl-4-carbomethoxy-pyridinium iodide is insoluble. By using the more soluble pyridine-1-oxide as a secondary standard and obtaining an empirical equation between Z and the transition energy for pyridine-1-oxide, it is possible to measure the Z values of nonpolar solvents. The value for water must be estimated indirectly from correlations with other quantities. Table 8-15 gives Z values for numerous solvents. 

Recognition that substrates are oxidized by dehydrogenation is usually attributed to H. Wieland. During the years 1912-1922 he showed that synthetic dyes, such as methylene blue, could be substituted for oxygen and would allow respiration of cells in the absence of Oz- Subsequent experiments (see Chapter 15) led to isolation of the soluble pyridine nucleotides and flavoproteins and to development of the concept of an electron transport chain. 

Catalysis of the synthesis of benzoic anhydride and the hydrolysis of benzoyl chloride, diphenyl phosphorochloridate (DPPC), and benzoic isobutyric anhydride in dichloromethane-water suspensions by water-insoluble silanes and siloxanes, 3- and 4-trimethylsilylpyridine 1-oxide (3b and 3c, respectively), 1,3-bis(l-oxypyridin-3-yl)-l,1,3,3-tetramethyldisiloxane (4), and poly[methyl(l-oxypyridin-3-yl)-siloxane] (5) was compared with catalysis in the same systems by water-soluble pyridine 1-oxide (3a) and poly(4-vinylpyridine 1-oxide) (6). All catalysts were effective for anhydride synthesis and promoted the disproportionation of benzoic isobutyric anhydride. Hydrolysis of benzoyl chloride gave benzoic anhydride in high yield ( 80%) for all catalysts except 3a, which gave mixtures of anhydride (52%) and benzoic acid (39%). The order of catalytic activity for DPPC hydrolysis was 5 > 4 > 3b > 3a > 3c > 6. The results suggest that hydrophobic binding between catalyst and lipophilic substrate plays an important role in these processes. 

The kinetics of inverse PT-catalytic extraction of species into the water phase was carried out with partially water-soluble pyridines or derivatives [36,38,40,59,73], as shown in mechanism (9). These reactions can be described by a pseudo-first-order hypothesis... 

Solvent solubility has been used to separate coal tar pitch [65] into heptane solubles, heptane insolubles but toluene soluble (asphaltenes), and toluene insolubles (preasphaltenes). The same pitch was separated into acetone-soluble, pyridine-soluble, and pyridine-insoluble fractions [66]. The same pitch, a coal digest, and a low-temperature coal tar were similarly fractionated [67,68]. 

Boonstra, B., Rathbone, D.A., French, C.F., Walker, F.H., and Bruce, N.C. (2000) Cofactor regeneration by a soluble pyridine nucleotide transhydrogenase for biological production of hydromorphone. Appl. Environ. Microbiol., 66, 5161—5166. 

There appear to be at least two zinc chloride complexes of pyridine, one of m.p. 207 and composition 2CsH,N,ZnCh, sind the other of m.p. 152° and probable composition 2C,H,N,ZnClt,HCl. The former is slightly soluble in water and in hot ethyl alcohol the latter passes into the former in aqueous solution, is readily soluble in hot absolute ethanol and can therefore be readily recrystaUised from this solvent. 

The conversion of a carbonyl compound by ammonium polysulphide solution into an amide with the same number of carbon atoms is known as the Willgerodt reaction. The procedure has been improved by the addition of about 40 per cent, of dioxan or of pyridine to increase the mutual solubility of the ketone and aqueous ammonium polysulphide the requisite temperature is lowered to about and the yield is generally better. 

These compounds are soluble in ether, are comparatively stable, and exhibit many of the reactions of Grignard reagents but are more reactive. Because of their greater reactivity, organohthium compounds can often be used where Grignard reagents fail thus they add to the azomethine linkage in pyridines or... 

It has been mentioned ( 4.4.2) that nitronium tetraffuoroborate reaets with pyridine to give i-nitropyridinium tetraffuoroborate. This compound and several of its derivatives have been used to effect what is called the transfer nitration ofbenzeneandtoluene. i-Nitropyridinium tetraffuoroborate is only sparingly soluble in acetonitrile, but its homologues are quite soluble and ean be used without isolation from the solution in which they are prepared. i-Nitropyridinium tetra-fluoroborate did nitrate toluene in boiling aeetonitrile slowly, but not at 25 In eontrast, i-nitro-2-pieolinium tetraffuoroborate readily... 

Alkylselenazoles are oily alkaline liquids possessing a smell similar to that of the corresponding thiazole or pyridine derivatives. The crystalline picrates or 3-methylselenazolium iodides have been used for the purpose of characterization. Alkyl derivatives are partially soluble in water aryl derivatives are insoluble. 

Chain-Growth Associative Thickeners. Preparation of hydrophobically modified, water-soluble polymer in aqueous media by a chain-growth mechanism presents a unique challenge in that the hydrophobically modified monomers are surface active and form micelles (50). Although the initiation and propagation occurs primarily in the aqueous phase, when the propagating radical enters the micelle the hydrophobically modified monomers then polymerize in blocks. In addition, the hydrophobically modified monomer possesses a different reactivity ratio (42) than the unmodified monomer, and the composition of the polymer chain therefore varies considerably with conversion (57). The most extensively studied monomer of this class has been acrylamide, but there have been others such as the modification of PVAlc. Pyridine (58) was one of the first chain-growth polymers to be hydrophobically modified. This modification is a post-polymerization alkylation reaction and produces a random distribution of hydrophobic units. 

TiF is a colorless, very hygroscopic soHd and is classified as a soft fluorinating reagent (4), fluorinating chlorosilanes to fluorosilanes at 100°C. It also forms adducts, some of them quite stable, with ammonia, pyridine, and ethanol. TiF sublimes at 285.5°C, and melts at temperatures >400° C. It is soluble in water, alcohol, and pyridine, hydroly2ing in the former, and has a density of 2.79 g/mL. 

Bisa.codyl, 4,4 -(2-PyridyLmethylene)bisphenol diacetate [603-50-9] (Dulcolax) (9) is a white to off-white crystalline powder ia which particles of 50 p.m dia predominate. It is very soluble ia water, freely soluble ia chloroform and alcohol, soluble ia methanol and ben2ene, and slightly soluble ia diethyl ether. Bisacodyl may be prepared from 2-pyridine-carboxaldehyde by condensation with phenol and the aid of a dehydrant such as sulfuric acid. The resulting 4,4 -(pyridyLmethylene)diphenol is esterified by treatment with acetic anhydride and anhydrous sodium acetate. Crystallisation is from ethanol. 

Meclizine Hydrochloride. Pipera2ine Antivert, and Bonine are trade names for mech2ine dihydrochloride monohydrate [31884-77-2] (20). It is a white or slightly yellowish crystalline powder with a slight odor, no taste, and a melting point of 217—224°C. The hydrochloride is practically insoluble in water and ether. It is freely soluble in chloroform, pyridine, methylacetamide, and mild acid alcohol—water mixtures, and is slightly soluble in dilute acids or alcohol. See Reference 16 for synthesis. 

It has also been found that polymers possessing functional groups such as amines and pyridines are soluble in pregeUed sol solutions, especially, poly(2-vin5ipyridine) and poly(N-vinylpyrroHdinone) (PVP) (49). There, materials were made as part of a study of the synthesis of nonshrinking sol—gel-derived networks (49). 

Norethindrone may be recrystakhed from ethyl acetate (111). It is soluble in acetone, chloroform, dioxane, ethanol, and pyridine slightly soluble in ether, and insoluble in water (112,113). Its crystal stmcture has been reported (114), and extensive analytical and spectral data have been compiled (115). Norethindrone acetate can be recrystakhed from methylene chloride/hexane (111). It is soluble in acetone, chloroform, dioxane, ethanol, and ether, and insoluble in water (112). Data for identification have been reported (113). The preparation of norethindrone (28) has been described (see Fig. 5). Norethindrone acetate (80) is prepared by the acylation of norethindrone. Norethindrone esters have been described ie, norethindrone, an appropriate acid, and trifiuoroacetic anhydride have been shown to provide a wide variety of norethindrone esters including the acetate (80) and enanthate (81) (116). 

A.cetohexamide. Acetohexamide or l-[(p-acetylphenyl)sulfon5l]-3-cyclohex-ylurea, mol wt 324.42, is a white, practically odorless crystalline powder that has the trade name Dymelor. It is practically insoluble in water and in ether, soluble in pyridine and in dilute solutions of alkaU hydroxides, and slightly soluble in alcohol and in chloroform. 

Iron(III) iodide [15600-49-4], Fefy, is prepared by the oxidative photodecarbonylation of diiodotetracarbonylkon(II) ki the presence of dkodine (7). The black soHd obtained is extremely hygroscopic, spariagly soluble only ki dichloromethane, and decomposes to kon(II) iodide and dkodine when exposed to donor solvents such as tetrahydrofuran, acetonitrile, water, or pyridine. It also decomposes when exposed to light. 

Solubility and Solvent Resistance. The majority of polycarbonates are prepared in methylene chloride solution. Chloroform, i7j -l,2-dichloroethylene, yy -tetrachloroethane, and methylene chloride are the preferred solvents for polycarbonates. The polymer is soluble in chlorobenzene or o-dichlorobenzene when warm, but crystallization may occur at lower temperatures. Methylene chloride is most commonly used because of the high solubiUty of the polymer (350 g/L at 25°C), and because this solvent has low flammabiUty and toxicity. Nonhalogenated solvents include tetrahydrofuran, dioxane, pyridine, and cresols. Hydrocarbons (qv) and aUphatic alcohols, esters (see Esters, organic), or ketones (qv) do not dissolve polycarbonates. Acetone (qv) promotes rapid crystallization of the normally amorphous polymer, and causes catastrophic failure of stressed polycarbonate parts. 

SolubiHty of the three commercial polysulfones foUows the order PSF > PES > PPSF. At room temperature, all three of these polysulfones as weU as the vast majority of other aromatic sulfone-based polymers can be readily dissolved in a few highly polar solvents to form stable solutions. These solvents include NMP, DMAc, pyridine, and aniline. 1,1,2-Trichloroethane and 1,1,2,2-tetrachloroethane are also suitable solvents but are less desirable because of their potentially harmful health effects. PSF is also readily soluble in a host of less polar solvents by virtue of its lower solubiHty parameter. 

Historical. Pyridines were first isolated by destructive distillation of animal bones in the mid-nineteenth century (2). A more plentifiil source was found in coal tar, the condensate from coking ovens, which served the steel industry. Coal tar contains roughly 0.01% pyridine bases by weight. Although present in minute quantities, any basic organics can be easily extracted as an acid-soluble fraction in water and separated from the acid-insoluble tar. The acidic, aqueous phase can then be neutrali2ed with base to Hberate the pyridines, and distilled into separate compounds. Only a small percentage of worldwide production of pyridine bases can be accounted for by isolation from coal tar. Almost all pyridine bases are made by synthesis. 

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