Dimethyl sulfoxide average

Several cleaning formulations for specific uses contain unreacted polyamines. Examples include mixtures of ammonium alkylbenzenesulfonate, solvents, and PIP which give good cleaning and shine performance on mirrors and other hard surfaces without rinsing (305), and a hard-surface cleaner composed of a water-soluble vinyl acetate—vinyl alcohol copolymer, EDA, cyclohexanone [108-94-1] dimethyl sulfoxide [67-68-5] a surfactant, and water (306). TEPA, to which an average of 17 moles of ethylene oxide are added, improves the clay sod removal and sod antiredeposition properties of certain hquid laundry detergents (307). 

H). As shown, a disordered structural model was obtained for the guest. The model comprises two mirror-related guest molecules. The oxygen atom and the proximal methyl C-atom are practically overlapping the same atomic positions in both orientations. However, the sulphur atomic positions do not average in the X-ray data and show a nearly 50/50 occupancy. As indicated by the comparison of the respective bond distances and intra-associate contact distances of the DMSO molecule (Table 17), the effect of disorder is serious (e.g. the S=0 distances appear abnormally short in the 20 DMSO instance). This precludes the possibility of assessing interaction between the O atom of the carboxyl and a methyl of dimethyl sulfoxide. 

This rule works best for apolar, quasi-spherical molecules. Large deviations occur when chemical association is involved (e.g., carboxylic acids), from molecular dipolarity (e.g., dimethyl sulfoxide), and from molecular asphericity (e.g., neopentane/ -pentane). Strongly associating solvents (e.g., HF, H2, NH3, alcohols, carboxylic acids) have Trouton constants which are higher than the average value of 88 J mol K" found for nonassociating solvents such as diethyl ether and benzene. 

The first soluble Schiff base coordination polymer was reported by Archer et al. in 1985,31 which was prepared by condensation of 1,2,4,5-tetra-amino benzene (TAB) with tetrakis(salicyladehydato)zirconium(IV) (Zr(sal)4) in dry dimethyl sulfoxide (Fig. 15). The polymer has a number-average molecular weight of up to 4.9 X 104 based on inherent viscosity, gel permeation chromatography, and elemental analyses and shows no decomposition at temperature <500°C. 

Fig. 2-11. NMR chemical shift of Na as a function of the mole fraction of dimethyl sulfoxide (DMSO) in a binary mixture of DMSO and acetone (according to [295]). Straight line ideal case without preferential solvation, primary solvation shell of the same composition as the bulk solvent mixture. Curved line real case with preferential solvation of Na by DMSO and isosolvation point at xoMso/(cmol mol ) 0.21, that is, the mole fraction of the bulk solvent for which the solvated ion chemical shift is the average of the shifts obtained in the pure solvents (A<5 = <5dmsO - Acetone)-...

In contrast, dipolar aprotic solvents possess large relative permittivities (sr > 15), sizeable dipole moments p > 8.3 10 ° Cm = 2.5 D), and average C.f values of 0.3 to 0.5. These solvents do not act as hydrogen-bond donors since their C—H bonds are not sufficiently polarized. However, they are usually good EPD solvents and hence cation sol-vators due to the presence of lone electron pairs. Among the most important dipolar aprotic solvents are acetone, acetonitrile [75], benzonitrile, A,A-dimethylacetamide [76, 77], A,A-dimethylformamide [76-78], dimethylsulfone [79], dimethyl sulfoxide [80-84], hex-amethylphosphoric triamide [85], 1-methylpyrrolidin-2-one [86], nitrobenzene, nitro-methane [87], cyclic carbonates such as propylene carbonate (4-methyl-l,3-dioxol-2-one) [88], sulfolane (tetrahydrothiophene-1,1-dioxide) [89, 90, 90a], 1,1,3,3-tetramethylurea [91, 91a] and tetrasubstituted cyclic ureas such as 3,4,5,6-tetrahydro-l,3-dimethyl-pyr-imidin-2-(l//)-one (dimethyl propylene urea, DMPU) [133]. The latter is a suitable substitute for the carcinogenic hexamethylphosphoric triamide cf. Table A-14) [134]. 

Second-order rate constants have been determined for the alkaline hydrolysis of 2-methoxycarbonylpyrazine in methanol-water (80%w/w) at 10° as 5.2x10 l/mol sec (1263) and for 2-ethoxycarbonylpyrazine at 30° in 50 and 60% dimethyl sulfoxide-water and 60, 70, and 80% ethanol-water as 95.9, 199, 12.4, 10.2, and 8.86x10 1/mol sec (1359). The failure of 2,5-dimethoxycarbonyl-pyrazine to undergo the Schmidt reaction has been accounted for in terms of its normal ionization, and I values in 100% sulfuric acid gave an average of 2.55 (1176). 

The distances between the carbonyl carbon atoms of the substrates and the ring comprised of the 6 0-2 atoms of a-cyclodextrin are determined from the time-averaged conformations (Fig. 3) in the 1 1 (v/v) mixture of 1 N deuterium chloride and dimethyl sulfoxide-dj. 

The solvatochromic parameters are derived from spectroscopic and other measurements specifically designed to measure only a single interaction. In addition, the values are averages of the results from several solutes for each parameter and somewhat independent of solute identity. The most comprehensive solvatochromic treatment of solvent selectivity are the Tti, ai and Pi parameters of Kamlet and Taft, Table 4.15 [568-570, 578]. The rti value is an index of solvent dipolarity/polarizability, normalized to dimethyl sulfoxide = 1. The i scale of hydrogen-bond acidity measures the... 

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