Chemical dioxane

List of Some Health Hazard Causing Solvents, Monomers and Chemicals... DIOXANE (C4H8O2)... 

Although no chemical reaction occurs, measurements of the freezing point and infra-red spectra show that nitric acid forms i i molecular complexes with acetic acid , ether and dioxan. In contrast, the infrared spectrum of nitric acid in chloroform and carbon tetrachloride - is very similar to that of nitric acid vapour, showing that in these cases a close association with the solvent does not occur. 

Temperature reaction rate profiles for representatives compounds are available (21,26). Particularly important are the operating temperatures required before destmction is initiated. Chemical reactivity by compound class from high to low is (27) alcohols > cellsolves/dioxane... 

The solubility parameter is about 19.2MPa and being amorphous they dissolve in such solvents as tetrahydrofuran, mesityl oxide, diacetone alcohol and dioxane. Since the main chain is composed of stable C—C and C—O—C linkages the polymer is relatively stable to chemical attack, particularly from acids and alkalis. As already mentioned, the pendant hydroxyl groups are reactive and provide a site for cross-linking. 

Chemical Designations - Synonyms Di (Ethylene Oxide) Dioxan p-Dioxane Chemical Formula CH2CH2OCH2CH2O... 

Dioxane, palladium (II) acetate, and triphenylphosphine were purchased from Aldrich Chemical Company, Inc. and were used without further purification. 

N HC1 in dioxane was purchased from Aldrich Chemical Company, Inc. 

Dioxane forms by the chemical cleavage of two molecules of ethylene oxide from the parent ethoxylated alcohol. Dioxane is the undesirable byproduct. The amount of dioxane ranges from traces to hundreds, even thousands, of ppm (mg/kg) depending on raw material quality and sulfonation/neutralization process conditions. 

During the sulfation of alcohol ethoxylates the undesired byproduct 1,4-di-oxane may be formed. Although the formation of 1,4-dioxane is predominantly governed by the sulfation and neutralization conditions and by the chemical composition of the organic feedstock, other factors, such as the quality of the raw material, also contribute. This prompted a reappraisal of the required quality standards for this feedstock. In Table 11 guideline specifications are presented. 

The figures reported in Table 13 represent an optimum quality target for industrial production of FAES. Nevertheless, the Dryex system affords the possibility of further reducing the content of 1,4-dioxane to below the limit of 10 ppm (referred to 100% AM content). In this case, the Dryex system operates as a stripper of the H20/dioxane mixture, being the physical and chemical characteristics of dioxane allow its removal from water solution at reduced pressure with relative ease. 

The evaporation pathway performed by the Dryex system allows for the reduction of 1,4-dioxane without any deterioration of the other chemical characteristics of the FAES product, resulting in a consistent improvement of the product quality. 

Spectral-grade p-dioxane from MC and B Manufacturing Chemists or Mallinckrodt Chemical Works was dried over Linde type 4A molecular sieves. The checkers degassed the solvent prior to use as described in Note 3. 

Five-membered unsubstituted lactone, y-butyrolactone (y-BL), is not polymerized by conventional chemical catalysts. However, oligomer formation from y-BL was observed by using PPL or Pseudomonas sp. lipase as catalyst. Enzymatic polymerization of six-membered lactones, 8-VL and l,4-dioxan-2-one, was reported. 8-VL was polymerized by various lipases of different origins. The molecular weight of the enzymatically obtained polymer was relatively low (less than 2000). 

Like the carbodiimide method, the mixed anhydride method results in an amide complex (Table 5, Figure 17). The acid-containing hapten is dissolved in a dry, inert, dipolar, aprotic solvent such as p-dioxane, and isobutyl chloroformate is added with an amine catalyst. The activated mixed anhydride is chemically stable and can be isolated and characterized. The aqueous protein solution is added to the activated acid and the pH is maintained at around 8.5. A low temperature (around 10 °C) is necessary during the reaction to minimize side reactions. 

Chemical shifts were obtained by using internal 1,4-dioxane (67.86 p.p.m.). Assignments may have to be interchanged. 

Chemical shift (p.p.m.) of model compounds in H20 relative to internal 1,4-dioxane (67.86 p.p.m.). Chemical shifts for these compounds are given at pH 5.5-7.5. Estimated precision for the chemical shifts is 0.05 p.p.m.h See Refs. 82 and 83. See Ref. 20.d These assignments may have to be interchanged. See Ref. 21 numbers in the brackets below the given chemical shift values refer to those published in Ref. 86. f See Ref. 19. The chemical shift for the -anomeric carbon atom was found to be 100.6 p.p.m. and was determined from an anomeric mixture of this compound. The existence of the a-Man — Ser unit was confirmed by the l]CH value (169 Hz) obtained for this compound. See Ref. 84. 

Estimated precision in the chemical shifts is 0.05 p.p.m. The chemical shifts are given relative to external 1,4-dioxane, which was introduced into some samples only to obtain chemical shifts. Spectra obtained at 258 for — 10% solutions. Spectra of compounds were obtained at 22.5 MHz see Ref. 20. Spectra of compounds were obtained at 22.5 MHz see Ref. 24.J Spectrum obtained at 100.6 MHz see Ref. 24. Data taken from Ref. 61. Chemical shifts for GalNAc only are given. The data given in the parentheses for compounds 51 and 32 refer to the carbon count. 

Aprotic solvents are not protogenic, but can be protophilic, e.g. acetone, 1,4-dioxan, tetrahy drof uran, dimethy If ormamide, hexamethylphos-phortriamide, propylene carbonate and sulpholane. Solvents that do not participate in protolytic reactions, i.e. do not donate or accept a proton, are usually chemically inert, such as benzene, chlorobenzene, chloroform, tetrachloromethane, etc. 

To verify the mechanism presented, the quantum-chemical calculations of proton affinity, Aa, were carried out for modifiers, since the corresponding experimental data are quite rare. The calculations were performed for isolated molecules, since the properties of species in the interlayer space are probably closer to the gas phase rather than the liquid. The values of Ah were calculated as a difference in the total energy between the initial and protonated forms of the modifier. Energies were calculated using the TZV(2df, 2p) basis and MP2 electron correlation correction. Preliminarily, geometries were fully optimized in the framework of the MP2/6-31G(d, p) calculation. The GAMESS suite of ah initio programs was employed [10]. Comparison between the calculated at 0 K proton affinities for water (7.46 eV) and dioxane (8.50 eV) and the experimental data 7.50 eV and 8.42 eV at 298 K, respectively (see [11]), demonstrates a sufficient accuracy of the calculation. 

A wide variety of alkaloids have been synthesized by this procedure although in many cases the chemical yields are low. Hexahydroapoerysopine (353), for example, has been prepared by irradiation in dioxane of either the 6 -iodo or the 7-bromo derivative of l,2,3,3a,4,5-hexahydro-/V-(3,4-di-... 

However, in 1939 this difficulty was obviated by Brauns extraction of about 3% lignin from spruce wood by means of the solvent, ethyl alcohol, at room temperature (9). He termed this preparation native lignin. It was found to be soluble in methanol, ethanol, dioxane, dilute sodium hydroxide and pyridine, and insoluble in water, ether, petroleum ether and benzene. Chemically it behaved the same as lignin as it exists in woody tissues. It also reduced Fehling s solution and gave a strong... 

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