Solvents isopropanol

The transformations are not sensitive to the presence of oxygen or changes in the solvent (isopropanol, ethanol, dioxane, benzene, 1,3-pentadiene). Results from studies with aliphatic and monocyclic epoxy ketones ... 

The aldehyde or ketone, when treated with aluminum triisopropoxide in isopropanol as solvent, reacts via a six-membered cyclic transition state 4. The aluminum center of the Lewis-acidic reagent coordinates to the carbonyl oxygen, enhancing the polar character of the carbonyl group, and thus facilitating the hydride transfer from the isopropyl group to the carbonyl carbon center. The intermediate mixed aluminum alkoxide 5 presumably reacts with the solvent isopropanol to yield the product alcohol 3 and regenerated aluminum triisopropoxide 2 the latter thus acts as a catalyst in the overall process ... 

PfefFer, de Vries and coworkers developed the use of ruthenacycles, based on chiral aromatic amines as enantioselective transfer hydrogenation catalysts. These authors were able to develop an automated protocol to produce these catalysts by reacting ligand and metal precursor in the presence of base, KPFS in CH3CN. After removal of the solvent, isopropanol was added followed by the substrate, acetophenone, and KOtBu. In this way, a library of eight chiral... 

While ether is the common solvent for LiAlH4, in which it is soluble, hydroxylic solvents like water, methanol and ethanol are preferred for NaBH4, It is more soluble in methanol than in ethanol, but since it reacts with the former at an appreciable rate than the latter, hence ethanol is the preferred solvent. Isopropanol, in which NaBH4 is stable, is used for kinetic studies of the reduction of aldehydes and ketones. 

Okamura and coworkers151 studied the base catalyzed Diels-Alder reactions between 3-hydroxy-2-pyrone (224) and chiral l,3-oxazolidin-2-one based acrylate derivatives. Catalysis of the reaction between 224 and 225 by triethylamine gave fair to good de values, somewhat dependent on the solvent system used (equation 63, Table 7). Addition of 5% of water to the solvent isopropanol, for example, increased the de of the endo adduct 226 substantially. When the amount of water was increased, however, the triethylamine catalyzed reaction became less endo and diastereofacially selective, a small amount of exo 227 being obtained. Replacing triethylamine by the chiral base cinchonidine also improved the de, but now independently of the solvent system used. 

Fig. 2 Product distribution as a function of acetophenone conversion. Solvent Isopropanol(1) cyclohexane(2).

Pauls (83) examined the effect of the composition of binary solvent mixtures upon the selectivity and resolution of olive oil TG components. Separation factors (a values) and resolution were calculated for the linoleyldiolein (LOO)-linoleyl-palmitylolein (LPO) and triolein (OOO)-palmityldiolein (POO) pairs in olive oil. Five strong solvents (isopropanol, dichloromethane, chloroform, tetrahydrofuran, and acetone) as well as two weak solvents (methanol and acetonitrile) were employed. 

Powdered tablets of chlorthalidone and reserpine are extracted with acetonitrile/water (9 l), centrifuged and the supernatant layer is injected to HPLC using a column of Pellamidon at 35°c and the solvent isopropanol/acetic acid/water/hexane (60 3 1 36) as the mobile phase. Detection is carried out under UV at 25b nm. 

Solvent Isopropanol-hep tane-H2 SO4 Titration-semiautomatic Titration-photometric Titration-manual colorimetric Milk Cream, whole milk powder Milk, cream Driessen et al. (1977) Evers et al. (2000) Deeth et al. (1975),... 

Solids 40.0+-1% Solvent Isopropanol Water Amine Ammonia pH >8... 

Lagokvist and Berg (1962) also use the isobutyric acid 0.5 M ammonia (5 3, v/v) paper chromatography solvent. They describe a number of other solvents isopropanol water ammonia (85 15 1.3, v/v/v) isopropanol aceticacid water(6 3 l, v/v/v) and isopropanol n-butanol 12 N HCl water (114 56 49 39) which they used in purification of oligoribonucleotides. 

Fiq. 2. Map of i values of amino acids commonly found in biological fluids or tissues as obtained with two-dimensional chromatography on cellulose TLC microplates. First dimension solvent pyridine acetone NHiOH (28%) H20 (225 15 2.6 10 by volume). Second dimension solvent isopropanol formic acid H20 (27.5 6.25 by volume), if/ values of unknowns should be considered as only approximating those illustrated here and are best determined by relating their position on the chromatogram to more easily recognized spots, e.g., proline or hydroxyproline, or to standard solutions. 

Neutral Solutes. In the reversed-phase mode, water is used as the weak solvent and acetonitrile, methanol, or THF (where applicable) is used as the strong solvent. (It is notable that the addition of acid or base to the mobile phase used for neutral molecules does not preclude separation, and, as such, the approach outlined later for ionizable components is equally viable.) In normal-phase HPLC, hexane is used as the weak solvent and isopropanol is used as the strong solvent. To change selectivity based on the strong solvent, isopropanol may be replaced (in part) with methylene chloride, methyl t-butyl ether, or ethyl acetate. However, note should be made of the relatively high UV cutoffs of these solvents when UV detection is to be used and precautions should be taken to ensure solvent miscibility across the range of the gradient. 

Contact with an organic solvent Isopropanol is known to be nondenaturing for DNA hence, its effect was considered to be negligible. 

Increasing the temperature increases the selectivity of the reaction. This can be explained by the fact that the hot solvent (isopropanol) makes the polymer expand and then "core" sites can be reached by the substrate. There, cavities have a better defined shape making the system more selective. Therefore reaction should be performed at 60°C rather than at room temperature. The swelling-selectivity relationship is not absolute, the use of a very polar solvent such as N,N-dimethylacetamide, leads to such a swelling of the polymer that no more selectivity is observed Thus, one can assume that this increase of selectivity is due to an... 

Figure 17. Time dependence of the multiplet polarization PM/AM in the product 22 upon quenching of the radical R (21 ) by an olefin Q solvent isopropanol. For further explanation, see Chart XI and the text. (Left) Constant concentration (3.3 x 10-3M) of the quencher CH2=CPh2, variable initial radical concentration (open circles, [R ] = 11.6 x 10 5 M stars, [R ] = 2.1 x 10-5 M). (Right) Variable concentration of the quencher CH2=CHCN (open circles, [Q] = 3.4 x 10 4M stars, [Q] = 7.5 x 10 4M), constant initial radical concentration ([R ] = 10.9 x 10 5 M). [Adapted from S. N. Batchelor and H. Fischer, J. Phys. Chem., 100, 9794 (1996) with permission. Copyright 1996 American Chemical Society.]...

SAMPLE CLIDINIUM BROMIDE SOLVENT ISOPROPANOL SLOPE 0 03%... 

In the polar solvent isopropanol, benzyl alcohol is predominantly formed at low temperatures, and the amount of toluene formed increases continuously with increasing temperature. In contrast, in the nonpolar solvent hexane, toluene is the predominant final product of the hydrogenation, in spite of the small excess of hydrogen and the low pressure. Between 120 and 130 °C the selectivity with respect to... 

Rinsing solvent (isopropanol water, 1 1) for ion source (NB Avoid plastic bottle with phthalate softeners). 

Fig. 159. TLC-separation of the diffusates from sections of fruit axes from Fritillaria meleagris L. and treatment of the chromatogram in chemical (left) and biological (right) characterisation of the separated substances. Layer silica gel HF251 solvent isopropanol-25% ammonium hydroxide-water (85 + 5 + 15) 60 mm run in S-chamber, saturated with isopropanol (cf p. 476) (according to [45])...

Fig. 173. TLC of an extract of the urine of a patient with carcinoid syndrome. 2.5—10 (xl extract applied, with 0.25—1.0 jxg YMA or 5-HIA as standards. The 5-HIA concentration is greatly increased in the urine, that of VMA is normal [143 a]. Layer silica gel G solvent isopropanol-ethyl acetate-ammonium hydroxide-Avater (45 + 30 -f- 17 -f 8) visualisation with diazotised p-nitroaniline...

The second method of determining MWD is turbidimetric titration. Beattie [156] developed an absolute turbidimetric titration method for determining solubility distribution (which is closely related to MWD) of PS. In this method a polymer is precipitated from its solution in methyl ethyl ketone by addition of a non-solvent (isopropanol) of the same refractive index as that of the solvent. He showed, by the use of light scattering theory, that under these conditions the concentration of polymer that is precipitated can be calculated from the maximum turbidity on an absolute basis. Beattie concluded that with PS, under the specified conditions, the reproducibility of turbidimetric precipitation curves is very good and that the method is accurate. Gooberman [157] also studied PS but dissolved the polymer in butanone and titrated with isopropanol. 

NP chromatography [1,85] has the advantage of tolerating relatively heavy loads of fatty material and separating vitamin D from its hydrox-ylated metabolites nevertheless, it cannot resolve vitamins D2 and D3. Hexane containing a small percentage (less than 5% v/v) of a more polar solvent (isopropanol, dichloromethane, or ethyl acetate) is the most used mobile phase [85]. 

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